Horticultural intensification and plant-based diets of 18^th century CE Waikato Māori in Aotearoa New Zealand

Domain: neuroscience
Published: 2026-04-07
Editorial outcome: minor_revision

Abstract
In Aotearoa New Zealand, Māori oral histories, ethno-historical accounts, and archaeological evidence indicate that kūmara (sweet potato; Ipomoea batatas) and taro (Colocasia esculenta) horticulture were key drivers of population growth and cultural change. We investigated diet, childhood residency, and chromosomal sex of Māori tūpuna (ancestors) who were discovered accidentally during road works in the Waikato region, an area with widespread evidence for intensive horticulture from the sixteenth century CE. The kōiwi tangata (human remains), dated to ca. 250–170 cal BP, were interred as a commingled secondary burial in a borrow pit during the Traditional Period of Māori history, a time characterized by highly distinctive art, architecture, cosmology, and whakapapa (genealogy). Using isotope and enamel peptide analyses we find that all seven tūpuna relied primarily on plant foods. Two children (chromosomally male and chromosomally female, respectively) were likely local and weaned onto plant foods within the first two to three years of life. These findings demonstrate that horticulture was central to life in the Waikato during the Traditional Period, to the extent that some individuals ate predominantly plant-based diets.

Introduction
Archaeologically, the earliest evidence for the first settlement of Aotearoa New Zealand (henceforth Aotearoa) places people arriving from east Polynesia in the mid-13th century CE1,2. Some Māori origin stories tell of an earlier date of arrival, but regardless of the exact timing, Polynesians voyagers arriving on the shores of Aotearoa would have stepped into a starkly different environment than their tropical Polynesian homeland, traditionally known as Hawaiki. Evidence from Early Period sites (ca. 1250-1450 CE) in Aotearoa shows a broad-spectrum reliance on marine and terrestrial animals3–5, highly mobile populations that circumnavigated both main islands in less than 100 years4,6, the establishment of exotic horticultural crops brought from east Polynesia7,8, large-scale landscape modification9,10, and hunting specializations that focused on large marine mammals and terrestrial birds, the most well-known being the now extinct moa (Aves: Dinornithiformes)11,12. During the Transitional/Middle Period (ca. 1450–1650 CE) and subsequent Traditional Period (ca. 1650–1769 CE), there was a move toward more regionalized settlement patterns5,13. In Te Ika-a-Maui (the North Island) and, to a lesser extent, Te Waipounamu (the South Island), this was accompanied by the intensification of horticulture14–16, although practices consistent with what is now termed mahinga kai (working in concert with the natural environment for sustainable food resources) was likely important in shaping food production and evironmental use as it is to Māori today7 (Glossary of Māori and Moriori terms presented in Supplementary Note 1).

The Waikato Basin near the city of Kirikiriroa (Hamilton) (Fig. 1) is home to the Waikato Horticultural Complex, an area recognized in oral histories, ethno-historical accounts and the archaeological record as a region of intensive horticulture from the 16th century CE reviewed in 15. The tephra-derived allophanic soils found in the middle Waikato Basin are extremely favourable for gardening because they have a high organic carbon content, are free draining, and have good aeration and nutrient exchange attributes13. The major root crops cultivated by Māori were kūmara (Ipomoea batatas) and, to a lesser degree, taro (Colocasia esculenta) and uwhikāho (yam; Dioscorea alata), all of which were brought to Aotearoa from east Polynesia, possibly at different times8,15,17,18. Forest clearance by fire transformed the landscape across Aotearoa from ca. 1250 CE, although in different ways because of regional, environmental, and climactic variations9,19,20. In the middle Waikato and elsewhere, Māori established gardens by first felling trees and burning stumps and slash to clear the land. Garden soils conducive to growing kūmara in temperate environment were created by modifying the natural parent soils with ‘lithic material’ such as sand and gravel, sometimes in specialized garden mounds, known as puke, to improved drainage and soil temperature. Lithic material was quarried from ‘borrow pits’, deep shafts dug into the underlying subsoil13,15,21,22.

There is unequivocal archaeological evidence for widespread and intensive kūmara horticulture in the middle Waikato Basin in the form of modified garden soils (e.g., the Tamahere soil series), borrow pits, puke and pits for the storage of cultivated tubers15,22. However, there is a dearth of marine, freshwater and terrestrial faunal remains found in local archaeological sites, which raises questions about the overall diet and lifestyle of Māori communities in the region. Here, we investigate the lives of seven tūpuna (ancestors) dating to ca. 1700-1780 CE who were interred in a borrow pit in the middle Waikato Basin (Table 1, Supplementary Discussion, Supplementary Table 1 and Supplementary Fig. 1). We report on the burial ritual and osteological assessment of kōiwi tangata (human remains) alongside isotope and enamel peptide analyses used to determine chromosomal sex and investigated diet, weaning practices and childhood place of residence. This study is an investigation of the daily lives of Māori ancestors during the Traditional Period, immediately prior to colonization, a period of significant cultural development in art, architecture, cosmology, and expression of whakapapa (genealogy/ancestral connections)7,13. Our results provide direct isotopic evidence that the diets of some Waikato Māori were almost entirely plant-based, underscoring not only the centrality of horticulture in Māori society at this time, but also contributing to a broader understanding of the importance of plant foods to traditional diets globally. The significant dietary changes that occurred from the time of initial East Polynesian settlement of Aotearoa to the Traditional Period reflect cultural innovation alongside environmental adaptation over a period of ~500 years. Our findings advance understanding of Māori lives in the past, including cultural dietary practices, and are of ongoing relevance to descendant communities seeking to record, revitalize, and restore traditional foodways and cultural practices.

Results
Bone collagen stable isotope results are presented in Table 1 for the seven kōiwi. Only two individuals (Kōiwi 2 and Kōiwi 4) had permanent first molars and enamel peptide, dentine micropunch (δ¹³C and δ¹⁵N) and enamel isotope results (δ¹³C, 87Sr/86Sr) are presented in Supplementary Tables 2 and 3 for these tūpuna.

Enamel peptide analysis
Amelogenin peptides were recovered from both individuals, Kōiwi 2 and Kōiwi 4, who had teeth sampled for analysis. Kōiwi 4 displayed both AMEL-X and AMEL-Y peptides (i.e., chromosomally male) whereas Kōiwi 2 displayed only AMEL-X peptides (i.e., chromosomally female). Both the raw intensities and intensity ratios of the quantified peptides are presented in the Supplementary Fig. 2. All dimorphic peptides were monitored, but only SM IRPPY from AMEL-Y and SIRPPYPSY from AMEL-X were targeted and reported. These peptides displayed the strongest intensities and showed and AMEL-Y/AMEL-X intensity ratio of >1 for chromosomally male and <0.01 for chromosomally female individuals, indicating a clear link between the observed ratios and chromosomal sex.

Bone collagen δ13C and δ15N analyses
All the bone collagen samples (n=7) met the standard collagen quality indicators (CQI) of a %N between 11 and 16 wt%, a %C > 30 wt% and a C:N ratio between 2.9 and 3.623,24.

The average (±1 SD) δ13C and δ15N values are presented in Table 2. Although the overall sample size was too small (n=3 adults and n=4 non-adults) for inferential statistics to be applied, there was a small difference in the average δ15N (adults 0.7‰ higher than non-adults) but there was only a 0.1‰ difference between the average δ13C value of the two age groups. The non-adults were aged between 5 and 15 years old (Table 1). There was a statistically significant, very strong positive correlation between the δ13C and δ15N values (Spearman’s rs (7)=0.94, p<0.01).

After the correction for diet-tissue spacing was applied to the δ13C and δ15N values (5‰ δ13C for and 3‰ for δ15N values)25,26 the results were compared to a dietary baseline for Māori Era Aotearoa (Fig. 2).

Tooth dentine micropunch δ13C and δ15N analyses
The dentine micropunch samples also met the CQI for this sample type, which is identical to the bone collagen CQI24 except that the C:N ratio of bulk dentine should be between 3.1 and 3.627 (Supplementary Table 2). Tooth dentine micropunch δ13C values ranged from −21.1 to −20.0 for Kōiwi 2 and −20.8. to −20.3 for Kōiwi 4. Tooth dentine micropunch δ15N values ranged from 6.0 to 11.5 for Kōiwi 2 and 6.8 to 10.5 for Kōiwi 4 (Supplementary Table 2). Age alignment (assigning age mid-points) followed the method outlined in Czermak et al.27 and are presented in Fig. 3.

Tooth carbonate δ13C values and whole vs protein diet from tooth dentine and tooth carbonate
The tooth δ13C value for Kōiwi 2 was −13.5‰ and for Kōiwi 4 was −13.9‰.

For each individual, the average δ13C value of the two crown dentine micropunch samples located nearest to the cemento-enamel junction (CEJ) was compared to the δ13C value of tooth enamel chip sampled from the corresponding area of the crown (Supplementary Tables 2 and 3). This was to ensure the protein and ‘whole’ diet analysed from the δ13C and δ13C represented a similar age (ca. ~1.9–3.5 years old)28.

The δ13C and δ13C values were correlated and plotted against regression equations developed to determine the contribution of C3 and marine/C4 foods in the diet from bone collagen and apatite26 (Fig. 4). The results from the two individuals (Kōiwi 2 and Kōiwi 4) show that their childhood diet around the age of ~1.9 to 3.5 years old was a C3-based. The ‘whole’ diet (carbohydrates, lipids and protein) can be determined from the δ13C of the tooth enamel of Kōiwi 2 and Kōiwi 4 by applying a correction for diet-tissue spacing (~12‰)29,30.

The corrected values (−25.5‰ and −25.9‰) are representative of foods sourced from a C3-terrestrial based ecosystem.

Tooth enamel 87Sr/86Sr
Both Kōiwi 2 and Kōiwi 4 displayed similar tooth enamel 87Sr/86Sr ratios of 0.706533 (±0.000030) and 0.706611 (±0.000035), respectively.

An updated Aotearoa-specific strontium isoscape based on Kramer et al.31 was used to create probability maps of the likely regions where the individuals resided in early childhood, around the age of 1.9 to 3.5 years old (Supplementary Fig. 3). Tamahere and nearby surrounds are highlighted as likely areas where the two individuals spent their early childhood. The other potential area of childhood residency was the Rotorua Lakes District to the east of the Waikato. The young age of death of both Kōiwi 2 (7–9 years old) and Kōiwi 4 (9–15 years old) means that the most parsimonious explanation for their specific 87Sr/86Sr ratios is that they were likely local to the area around the Tamahere site.

Methods
Permissions and permits
This research was developed in direct collaboration with, and with support from, mana whenua (customary indigenous landowners) (Supplementary Note 2). The research was undertaken at the request of four iwi (tribes) and hapū (sub-tribes), Ngāti Maahanga, Ngāti Wairere, Ngāti Koroki Kahukura, Ngāti Hauā, who hold customary and territorial rights over the land. The four iwi and hapū had representatives on the Tangata Whenua Working Group (TWWG) who acted as kaitiaki (cultural monitors) for the Waka Kotahi New Zealand Transport Agency-led construction of the Hamilton Section of the Waikato Expressway. Archaeological investigation of the Hamilton Section of the Waikato Expressway was undertaken by S. Keith on behalf of Waka Kotahi New Zealand Transport Agency under archaeological authority 2015/958. No specific permits were needed in Aotearoa for this bioarchaeological research. All approvals, sampling and destructive analyses followed the Heritage New Zealand Pouhere Taonga (HNZPT) Archaeological Guidelines Series Kōiwi Tangata Human Remains and were undertaken in accordance with the Heritage New Zealand Pouhere Taonga Act (2014). HNZPT is the New Zealand government’s statutory authority responsible for administering heritage protection laws and regulating archaeological work in Aotearoa.

Enamel peptide analysis
Enamel peptide analyses are used for chromosomal-linked sex assessment, which is especially helpful to provide sex determinations for non-adult individuals and incomplete skeletal remains58. The method is based on identifying isoform-specific peptides of amelogenin, a protein involved in enamel formation that is encoded as different isoforms on the X and Y chromosomes (AMEL-X and AMEL-Y)59,60.

Enamel peptide preparation followed established methods59,60 at the Centre for Protein Research, Research, Infrastructure Centre, University of Otago, Ōtepoti (Dunedin). First, the enamel was washed in 3% H2O2 for 30s and quenched in MilliQ H2O for 30 seconds. The enamel chip was then conditioned in 60 μL of 5% (vol/vol) of a 35% (w/w) HCl solution for 2 minutes. The HCL conditioning solution was removed and discarded. Another 60 μL of the 5% (vol/vol) HCl was added to the enamel chip and incubated for 2 min for peptide extraction. The HCl extraction solution containing the peptides was then recovered and centrifuged for 5 min at 30,000 × g to remove any particulates. The extracted peptides were then purified by solid phase extraction on a ZipTip with 0.6 μL C18 resin (Merk Millipore, Mass. USA) essentially following the manufacturer’s instructions. In brief, after rinsing of the C18 resin in pure acetonitrile (ACN), the ZipTip was equilibrated in 0.1% formic acid (FA) in water before loading the sample of extracted peptides. The bound peptides were then washed on-tip with 0.1% formic acid (FA) in water and eluted in 60% ACN, 0.1% formic acid (FA) in water. The eluate was dried using a centrifugal vacuum concentrator and stored as dried samples at −80 °C.

For peptide analysis by untargeted liquid chromatography-coupled tandem mass spectrometry (LC-MS/MS) samples were reconstituted in 20 μL of 5% ACN, 0.1% FA in water of which 5 μL were loaded into an Ultimate 3000 nano-flow uHPLC system inline coupled to a LTQ-Orbitrap mass spectrometer (Thermo Scientific, Mass. USA). Peptides were separated on a 75µm ID silica emitter tip (CoAnn Technologies, Wash. Calif. USA) column that was in-house packed with Aeris 2.6µm PEPTIDE XB-C18 100Å bead material (Phenomenex, Calif. USA) on a length of 20 cm. The LC gradient between mobile phase A (0.1% formic acid in water) and mobile phase B (0.1% formic acid in 90% aqueous ACN) was developed from 5% B to 25% B over 13 min followed by an increase to 40% B over 3 min. and 90% B over 2 min. at a flow rate of 300 nl/min. The LTQ-Orbitrap mass spectrometer was operated in an untargeted data acquisition mode. The precursor ion scan was performed in a m/z window of 400 to 2000 at a resolution of 60,000. The precursor ion scan was followed by 9 data-dependent collision-induced dissociation (CID) fragment ion spectrum acquisitions, of which the first three scans were setup as semi-targeted acquisitions of pre-specified precursor masses if present in the precursor ion scan at a threshold intensity of at least 5000 counts. The following 6 CID acquisitions were setup as data-dependent scans of the 6 most intense ions. The peptide targets included in the precursor ion list were three peptidoforms of the AMELY encoded amelogenin isoform (SMIRPPY at m/z 432.23, SM IRPPY at m/z 440.22 and SM IRPPYS at m/z 483.74), one peptide specific for the AMELX encoded isoform (SIRPPYPSY at m/z 540.28) and one peptide common to both isoforms (MPLPPHPGHPGYINF at m/z 837.42).

Raw data were analysed by both software-assisted sequence database searches and manual spectrum interpretation. The Proteome Discoverer software (version 2.5, Thermo Scientific, Mass. USA) was used for sequence assignment using the Sequest HT program to search the human reference and UniProt amino acid sequence databases. Enzyme cleavage was set to non-specific and methionine oxidation was included as a variable modification. Precursor and fragment ion intensities (area under the curve) were extracted manually using the QualBrowser program of the Xcalibur software package (version 2.0.7, Thermo Scientific, Mass. USA). Proteomic data are presented in Supplementary Table 3 and Supplementary Fig. 2.

Stable isotope background information
Stable isotope analysis of human bone collagen and tooth dentine is a well-established method to investigate diet61,62. Carbon and nitrogen stable isotope values are measured by parts per thousand (‰) relative to a standard (VPBD for carbon and Air for nitrogen) and denoted by the δ symbol. The δ15N values of bone collagen are only representative of dietary protein as carbohydrates and lipids do not contain nitrogen63. The δ¹³C values of bone collagen are primarily representative of dietary protein because amino acids from protein are routed for collagen synthesis, but some carbon from carbohydrates or lipids may be used, especially in cases where there is low protein in the diet41. Carbon stable isotope values are primarily used to assess the consumption of plants with differing photosynthetic pathways (C3 vs. C4 plants) and to help determine the proportion of marine and terrestrial foods in the diet. C4 plants and marine systems display higher δ13C values compared to C3 and terrestrial systems64. Importantly, there very few native and no cultivated C4 terrestrial plants in Aotearoa during the Māōri-era44 and C4 cultivars only arrived after European colonization. Nitrogen stable isotope values are used to understand the trophic position of an organism because δ15N values increase approximately 2–6‰ with every trophic step, although stepwise increase for omnivores is likely in the lower threshold65,66. Marine and freshwater systems also typically display higher δ15N values compared to terrestrial systems because there are more trophic steps in aquatic ecosystems64,67. Used in conjunction, bone collagen δ¹³C and δ15N values can provide information about the consumption of plant, meat, marine and freshwater organisms41,62,67.

Trophic differences in δ15N values of infant and adult female bone collagen or microsamples of dentine from an individual’s tooth are commonly used to determine patterns of breastfeeding and weaning in the past47,68,69. Infants move up a trophic level when they consume the breast milk of their mother, resulting in the enrichment in 15N of infant collagenous tissues, including bones and teeth70. This is signalled by a 2–5‰ increase in infant δ15N values and a ~0–2‰ increase in δ13C values, relative to maternal isotopic values69,71. If a child is fed supplemental weaning foods that are from a lower trophic level than breast milk (i.e., similar food to the mother’s diet), the δ15N values (and, potentially, δ13C values) of the child’s tissues will lower to reflect this dietary change at the rate of tissue formation (for teeth or new bone) or remodelling (for bone and keratinous tissues like hair and nails)69,72.

Bone collagen δ13C and δ15N analysis
All the bone samples were prepared at the Stable Isotope Prep Lab, Archaeology Programme, University of Otago, Ōtepoti, using a modified Longin method, described in Kinaston et al.42. Specifically, bone fragments were cleaned using aluminium oxide air-abrasive equipment (Bego Easyblast) and demineralised in 0.5M HCl at 4°C for several days. Samples were then rinsed in MilliQ H₂O until a neutral pH was reached. Collagen was gelatinised at 70°C in a pH 3 solution for 48h, followed by filtration using 5–8µm Ezee® mesh filters (Elkay Laboratory Products) to remove reflux-insoluble residues. The resulting solution was subsequently ultrafiltered using Millipore Amicon Ultra-4 centrifugal filters (30kDa NMWL) to retain molecules larger than 30kDa. Prior to ultrafiltration, Millipore Amicon Ultra-4 centrifugal filters were pre-cleaned by centrifuging Milli-QH₂O through the units three times at 4000 × g.

The purified collagen was analysed at IsoAnalytical (Cheshire, UK). The reference material used for δ13C and δ15N analysis of the collagen samples was IA-R068 (soy protein, δ13C = -25.22‰, δ15N = 0.99‰). IA-R068, IA-R038 (L-alanine, δ13C = -24.99‰, δ15N = -0.65‰), IA-R069 (tuna protein, δ13C = −18.88‰, δ15N = 11.60‰) and a mixture of IAEA-C7 (oxalic acid, δ13C = −14.48‰) and IA-R046 (ammonium sulfate, δ15N = 22.04 ‰) were run as quality control check samples during analysis of the collagen samples. IA-R068, IA-R038 and IA-R069 were calibrated against and traceable to IAEA-CH-6 (sucrose, δ13C = −10.43‰) and IAEA-N−1 (ammonium sulfate, δ15N = 0.40‰). IA-R046 was calibrated against and traceable to IAEA-N−1. IAEA-C7, IAEA-CH-6 and IAEA-N-1 are inter-laboratory comparison standards distributed by the International Atomic Energy Agency, Vienna. All measured values for the quality control standards were in the range of the accepted values. Analytical error, calculated from replicate measurements of samples, was routinely ±0.1‰ for δ¹³C values and ±0.2‰ for δ¹⁵N values (1 SD, n=7). Descriptive and inferential statistics for the Tamahere and other individuals were calculated in Excel (version 16.16.27) and R (version 4.5.1) and these are presented in Table 2, Fig. 5 and in the text.

Bulk tooth dentine micropunch sampling and δ13C and δ15N analysis
Teeth were sectioned at the Bioarchaeology Laboratory, Department of Anatomy, University of Otago, Ōtepoti. Each tooth was cleaned by manual abrasion with a toothbrush to remove any contaminants. Following this, the tooth was partially embedded in gypsum (Victor® Casting Plaster) in a silicone mold and cut with a Buehler Isomet low-speed saw. The mesial or distal root of the tooth was not embedded, which helped to direct the blade when cutting the tooth. The tooth was secured into a chuck and then longitudinally cut to obtain a 2mm slice from the centre of the tooth. The slice and the rest of the tooth were removed from the gypsum using MilliQ water.

The dentine was prepared at the Stable Isotope Prep Lab, Archaeology Programme, University of Otago, Ōtepoti. The 2mm wide tooth section was demineralized in 0.5M HCl for approximately 7–10 days until the dentine was flexible, but still retained its original shape, then rinsed three times with Milli-QH2O. The tooth was sampled sequentially from the crown cusp to the apex of the root along the mesial or distal side using a KAI Medical 1mm diameter biopsy punch needle with a plunger. Depending on tooth size, between 10 and 11 micro-samples per tooth were obtained using this method.

The 1×2mm cylindrical microsamples were then transferred to 1.5ml eppindorf microtubes and weighed. The microtubes were labelled numerically in a sequence from crown to root apex, indicating their anatomical sampling location, allowing age alignment in later analyses. Each sample was frozen, before being lyophilised for 48h.

The dentine micropunch samples were analysed at IsoTrace, Dunedin, New Zealand. Analytical precision was determined through repeated analyses of laboratory standards EDTA-OAS and IAEA MA-A-1 (copepod) and comparing the results against accepted values. All measured values for the quality control standards were in the range of the accepted values. All dentine micropunch stable isotope data are presented in Supplementary Table 2.

The age (midpoint of age range) of formation for each dentine micro-punch sample was estimated using the age-alignment method from Czermak et al.27, which considers differences in the rate of dentine formation between anatomical regions of the tooth (crown, neck, upper and lower root). The age range of formation for each dentine micro-sample was dependent on the anatomical region it was obtained from. By dividing the average time of formation for an anatomical region28 by the number of dentine samples obtained from that region, the age of formation for dentine samples from each anatomical zone of the tooth were estimated and visualized using Excel (version 16.16.27). Midpoints of each section were then calculated (Fig. 3).

Enamel carbonate δ13C analysis
Carbonate is present in biological apatites that form the inorganic part of bones and teeth, especially tooth enamel73. As carbonate is formed using CO2 within the blood, the δ13C values of biological apatite are a reflection of the total the macronutrients (e.g., carbohydrates, proteins and lipids) in an individual’s diet25,73,74. The diet-tissue spacing of δ13C values between diet and bone/enamel carbonate has been found to range between ~9‰ – 14‰, and 12‰ is commonly used for humans29,75,76.

Enamel samples were cleaned by abrasion of surface contaminants, using a Dremel® rotary tool with a clean diamond cutting blade at the Stable Isotope Prep Lab, Archaeology Programme, University of Otago, Ōtepoti. An enamel chip of approximately 10–20mg was taken from each tooth directly next to the cemento-enamel junction (CEJ). Any residual contaminants, including dentine, were removed using the Dremel® with a diamond cutting blade. The samples were then weighed. To remove organic and diagenetic contaminants, the enamel chips were treated by soaking in 1% NaClO for 24h, then rinsed three times by Milli-QH2O, soaked in 0.1M acetic acid for 24h and rinsed three more time with Milli-QH2O and dried and powdered.

Carbon and oxygen stable isotope analyses from the carbonate was undertaken at Isotrace Research Laboratory, Dunedin, New Zealand using a Thermo Delta Plus Advantage linked to a Gasbench II via a GC PAL autosampler. The dried, homogenised sample were weighed in an 8×5mm tin (Sn) capsule for analysis. Carbonate values were normalized by a 3-point calibration. Normalization was made using International Standards (NBS-18 [δ13C=-5.01][δ18O=−23.01]; IRU-Marble [δ13C=2.04][δ18O=−2.58]; NBS-19 [δ13C=1.95][δ18O=−2.20]). Delta values were normalized and reported against the international standards Vienna Pee Dee Belemnite (VPDB). Analytical precision was checked by comparing results from analysed quality control standard IRU-Marble against accepted values. All measured values for the quality control standards were in the range of accepted values. Carbonate stable isotope data are presented in Supplementary Table 3 and Fig. 4.

Strontium isotope analysis
Strontium isotope analysis has been used to assess the mobility and migration patterns of humans around the world77,78 but this method has only been reported once previously to investigate mobility in Māori-era individuals3. The method is based on the premise that the biologically available strontium a human or animal ingests during the time of tooth mineralization is retained within the enamel, which is generally resistant to diagenetical alteration in the burial environment. Underlying rocks exhibit variable ⁸⁷Sr/⁸⁶Sr ratios depending on lithology, age, and original rubidium (Rb) content. Erosion of the underlying bedrock, airborne dust (loess), sea-spray, atmospheric deposition, groundwater, and stream water are all contributors to the bioavailable strontium. Strontium purified from enamel should be representative of the biogenic strontium available during the time of tooth mineralization79,80. The 87Sr/86Sr ratio of tooth enamel reflects the bioavailable strontium isotope signature of the food and drink a person consumed during the time of tooth mineralization78.

For radiogenic strontium isotope analysis, 10–20mg enamel samples from the crown region adjacent to the CEJ of the first molars of Kōiwi 2 and Kōiwi 4 were chemically prepared within the Class-10 (ISO 4) workstations of the Class 100 (ISO 5) clean laboratory suite of the Centre for Trace Element Analysis, Department of Geology, University of Otago, Dunedin, New Zealand. Prior to transferring to the clean lab, the enamel was cleaned through abrasion with a sonicated Dremel® reinforced diamond cutting wheel to remove possible surface contaminants. Any additional adhering materials, such as organic matter or dentin, were removed and the enamel sample was sonicated in MilliQH2O for five minutes. Samples were then transferred to the clean lab and an appropriate mass of each sample was weighed into an acid-cleaned perfluoroalkoxy alkane (PFA) vial (Savillex Ltd, USA) and digested in 2ml of 3M HNO3 overnight at 110°C. The digests were then evaporated to dryness then reconstituted in 2ml of 3M HNO3 and subsampled for the determination of strontium concentration by ICP-MS using a 7900 instrument (Agilent Technologies, USA) after appropriate dilution.

Strontium was separated from the sample matrix and purified using established protocols in ion exchange chromatography81,82. The column eluant containing the strontium was evaporated to dryness, reconstituted in 2% (v/v) HNO3, then analysed for its 87Sr/86Sr composition using a Nu Plasma-HR MC-ICP-MS instrument (Nu Instruments Ltd, UK). All 87Sr/86Sr data were first corrected for instrumental mass fractionation and isobaric interferences from Kr and Rb across the Sr mass range using standard procedures, then normalized to the composition of the NIST SRM 987 primary standard (87Sr/86Sr = 0.710248). An additional in-house HPS standard was used to independently monitor the accuracy and external precision of the measurements. All 87Sr/86Sr results for HPS were in excellent agreement, within error, with the long-term mean value of 0.70762 ± 0.00003 (2 SD, n=189). Procedural blanks were run with each batch of 48 samples and all yielded negligible Sr levels of <250pg. Strontium isotope data are presented in Supplementary Table 3 and prediction maps using an Aotearoa isoscape (detailed below) are presented in Supplementary Fig. 3.

Isoscape interpretations
A strontium isotope map, or isoscape, is a model that predicts the spatial distribution of 87Sr/86Sr values across the landscape by incorporating the multitude of strontium sources that contribute to the bioavailable strontium ‘pool’ of a region83. Country and region-specific isoscapes are developed using a machine learning approach (a random forest model) that considers a plethora of atmospheric and geological variables (precipitation, temperature, soil depth, silt/sand/gravel content, underlying bedrock, etc.) e.g.,.84–86. The random forest model predicts the expected strontium isotope value for every location (1×1km2) across the targeted regions using the strontium isotope values from real-world plant, animal, and soil samples and the known environmental variables. If there is no real-world sample information for a location, the random forest model will predict the strontium isotope value using the nearby known environmental variables and similar geological 87Sr/86Sr values31.

The kōiwi tooth enamel 87Sr/86Sr results are interpreted using an updated version of the Aotearoa isoscape developed by Kramer et al.31. The interpretations use assignR (version 2.4.3), which operates in a semi-parametric Bayesian framework to calculate the posterior probability of the sample belonging to each cell within the isoscape raster. Maps of the North Island were created using R (version 4.5.1) and ArcGIS Pro (version 2.1) detailing the likely area of childhood residency for each individual (Supplementary Fig. 3). To facilitate visualization, maps are presented displaying the top 33% probability by area of the predicted isoscape surface for each sample with the top 33% areas coded as 1 (blue colour) and other areas coded as 0 (no colour). The top 20% and the 10% probability by area maps of the predicted isoscape surface are also presented. It has been found that there is a trade-off between accuracy and precision moving from the 33% to the 10% probability thresholds, where 33% is the highest accuracy and 10% the highest precision (i.e., least amount of areas selected)31. This means that, although a wider area is selected for the top 33%, the accuracy of the place of origin prediction is higher on these maps compared to the 10% and 20% maps, where fewer regions of potential origin are predicted31. Comparisons are made between the maps showing the predicted cells for the top 33%, top 20% and top 10% probability surfaces to assess the possible variation in accuracy and precision for these thresholds.

Dietary baseline
Human dietary isotope data should be interpreted using a dietary baseline of potential plant and animal food resources. For this study, published stable isotope data of modern and Māori-era plants and animals3,44,87,88 were compiled to establish an Aotearoa-specific dietary baseline. Food-value ellipses were calculated in Excel (version 16.16.27) from the mean δ13C and δ15N values and their covariance matrix, incorporating correlation between the two isotopes. These ellipses represent 95% confidence intervals for the bivariate distribution of each food group.

Supplementary Data 3 details the data used to create the dietary baseline. To address the global decline in ¹³C following the Industrial Revolution (known as the Suess effect), baseline data for modern Pacific island plant and animal δ13C values were adjusted by adding +1.5 for terrestrial systems and +0.86‰ for marine systems89,90. To interpret the edible fraction of the potential food resources, bone δ13C values were corrected by −3.7‰ for fish and −1.5‰ for birds and mammals and δ15N values by −0.6‰ for all species25,30,89. Plants and animals were categorized into groups (C3 plants, terrestrial birds, freshwater organisms, waterfowl, marine shellfish, marine fish, marine birds and marine mammals) and visualized using 95% confidence ellipses.

We included only edible C3 plants that would have been available in Aotearoa during the Traditional Period. Four samples of kūmara (Ipomoea batatas) collected by B. F. Leach from an Auckland market were used as reference material44. These kūmara were likely grown locally in Auckland, a region with rainfall (~1100–1200mm annually) and mean temperature (15.5°C vs. 14.0°C) similar to Tamahere, suggesting minimal regional differences in δ¹³C values of C3 plants grown in each area. The average δ¹³C value of the kūmara (-26.7‰) aligns with global averages for C3 plants (–26‰ to –27‰), though values can range between –20‰ and –37‰ depending on aridity and canopy effects91,92. The average kūmara δ15N values (4.0‰) are comparable to non-N2-fixing plants ranging from 0 to + 6‰ but average 3‰93, although factors such as animal fertilizers and burning/swidden cultivation can increase plant δ15N values94. The kūmara δ¹³C values used are also consistent with those of modern potatoes (Solanum tuberosum), pumpkin (Curcurbita spp.) and peas (Pisum sativum) (−25.6‰) grown in Aotearoa, but slightly higher than the average δ15N values for the non N2-fixing vegetables (potatoes and pumpkin) (n=4, and 2.8), which may be related to environmental factors95. There are very few C4 plant species native to Aotearoa (exceptions being Atriplex buchananii and Zoysia spp.) and C4 plants would not have contributed to the diet of Māori until the introduction corn (Zea mays) and sugarcane (Saccharum officinarum) by European colonists in the 19th and early 20th centuries. A correction for diet-tissue spacing was applied to the human δ13C and δ15N values (5‰ δ13C for and 3‰ for δ15N values)25,26,96.

Comparative human stable isotope results
Due to unethical archaeological and collection practices during the 19th and 20th centuries, very little bioarchaeological research was conducted in Aotearoa after the 1970s, especially work involving destructive analyses of human remains97,98. Today, kōiwi are never excavated for purely research purposes. Instead, remains are recovered only when accidentally disturbed through erosion, construction, or other activities. Once identified as archaeological (pre-1900 CE) by police and (bio)archaeologists alongside Heritage New Zealand Pouhere Taonga, decisions about analysis and reburial of the kōiwi rest with the hapū who hold kaitiakitanga (guardianship) over the rohe and the tūpuna. In many cases, kōiwi are immediately reburied at the request of the hapū, or limited information is obtained and reported only in confidential reports.

As a result, comparative Māori Era isotopic studies are extremely limited. Only one large isotopic study, focused on kōiwi from Wairau Bar (site P28/21), has been published3 and is used for comparison with the Tamahere results (Table 2, Supplementary Data 1, Fig. 5). Leach et al.44 reported on the isotopic analysis of kōiwi and kōimi (human skeletal remains from Rēkohu/Chatham Island) from four sites and one Historic-era European individual, but did not report the collagen quality indicators associated with the stable isotope results and did not report δ13C and δ15N values for all the individuals analysed. Taking into consideration that there is no information for the collagen quality indicators, we cautiously use the Leach et al44 stable isotope values for comparison with the Tamahere kōiwi. We have compiled the stable isotope data for: (1) five kōimi from the Waihora site on the southwest coast of Rēkohu (Chatham Island) likely dating to the Middle/Traditional Periods; (2) one kōiwi from the Lagoon Flat Archaic site complex (site O32/31) on the Kaikoura coast north of the Conway River mouth dating to the Early Period; (3) four kōiwi from an inland Bay of Plenty site near Lake Rotoiti likely dating to the Traditional Period; (4) one 87 year old European male buried in 1876 (identification known) from the Withells Road Methodist Cemetery in Christchurch, Canterbury (included in the European comparative analyses below) (Table 2, Supplementary Data 1, Fig. 1 and Fig. 5)44. Leach et al.44 also analysed one individual (B41a) from Wairau Bar and their results (δ13C = −15.9‰ and δ15N = 16‰) were similar to those reported by Kinaston et al3 for the same individual (δ13C = −15.7‰, δ15N = 17.8‰) (Supplementary Data 1). Only the data from for Wairau Bar Burial 41 reported by Kinaston et al. (2013) is used in Figs. 2 and 5. Stable isotope data from a total of 37 Māori and Moriori individuals were used for comparison with the Tamahere kōiwi.

The only other isotopic research of archaeological human remains in Aotearoa has been focused on Pākehā (European) and Chinese burials from Colonial Era cemeteries in the South Island of Aotearoa. Bone collagen, dentine, and hair stable isotope values have been compiled from published research (Supplementary Data 1 and 2) and include: (1) European adults (n=7 bone collagen, n=3 hair) and non-adults (n=1 dentine, n=7 hair) from the St. John’s Anglican cemetery in Milton, Otago (majority graves dating to between AD 1860-1880); (2) European adults (n=3 bone collagen, n=3 hair) from the Ardrossan St. cemetery in Lawrence, Otago (ca. AD 1861-1864); (3) Chinese adults (n=6, n=4 bone collagen, n=4 hair) and one European adult (n=1 bone collagen) from the Gabriel St. cemetery in Lawrence, Otago (AD 1864-late 1890s); and (4) one European (bone collagen and hair) and one likely Chinese individual (only bone collagen) from the Litany St cemetery, Cromwell, Central Otago (likely AD 1890s)45–48 (Supplementary Data 1 and 2). A number of these individuals have been genetically analysed to confirm ancestry and, for the untested individuals, their ancestry was determined using morphometrics and associated material culture in graves99. The enamel δ13C values and post-weaning dentine δ13C and δ15N values of the Colonial Era adult individual were not used for comparative purposes because these values reflect the childhood diet of these people likely before immigration to Aotearoa45,48.

For the Colonial Era individuals, both hair and bone stable isotope data were presented (Supplementary Data 1 and 2 and Fig. 5) because of the potential issue that most of the adult individuals were immigrants to Aotearoa from Europe or China. It is thought the turnover rate for cortical bone is ~10 years for adults100 and therefore the stable isotope values of adult bone may be representative of the individual’s diet before they moved to Aotearoa. Hair isotope values represent the diet of an individual in the months or years before a person’s death, depending on the length of the hair and is therefore likely more representative of the NZ-based diet of these immigrants. Hair was sampled incrementally and the average δ13C and δ15N values of the well-preserved increments is presented for each individual (Supplementary Data 2). The stable isotope values of increments of child dentine and hair were only compiled if it represented the diet of the child post-weaning to avoid any possibly influence of trophic enrichment from breastmilk. Because hair is slightly enriched in 13C and 15N relative to bone collagen, we applied a conservative correction of -1‰ to the hair δ13C and δ15N values to make them comparable with bone and dentine δ13C and δ15N values101,102. Due to the fact the dietary baseline of the Māori-Era and Colonial Era individuals was different, we only compared δ13C and δ15N averages (±SD) between the groups to address dietary trends because the diets of the colonial-era individuals were previously interpreted as being heavily reliant on C3-terrestrial based resources45–48. The hair isotope values of one individual, Burial 12, from the Ardrossan St cemetery, were removed from the summary statistics as this person was likely eating a diet with a large proportion of C4 plant foods at the time before death. Descriptive statistics for all comparative samples were calculated using Excel (version 16.16.27) and R (version 4.5.1) and results are presented in Table 2 and Fig. 5.

Peer review rounds
[{"round": 1, "reviewer_comments": {"reviewer_1": "This study is an important contribution as it documents the first direct evidence that some Waikato Māori had a diet that was primarily plant-based, and the authors present a compelling case. The archaeological evidence, Māori oral histories, and ethno-historical accounts, are reconciled with the results of the isotope analysis to show how important horticulture was during the Traditional Period in Aotearoa in the middle Waikato Basin. The collective efforts of the archaeologist, bioarchaeologists, and the affected iwi, and hapū, along with the resulting collaboration with descendant communities represented by the Tangata Whenua Working Group, are greatly appreciated.\nThis study is a great start in establishing baseline data to infer weaning practices in Aotearoa during 18th century AD. Sweeping generalizations on weaning practices based on two cases cannot be made, because, as you note, there are unknowns including food preference, availability of resources, and differential access to existing resources. Please clarify how you determined 5 years of age was the likely age of weaning for Kōiwi 2 and Kōiwi 4, as opposed to another age such as 4 years.\nIt may be of interest to the reader to note if you were able to determine the general health of the individuals based on the skeletal remains that were recovered (besides the caries you documented in 3 individuals). Furthermore, was there enough of present to infer any familial connections between individuals (e.g., a suite of cranial/dental nonmetric or unusual traits in common that might suggest a familial relationship)? I am not asking you to add this to your study, I leave it up to you if you want to clarify further for the reader (I admit I want to satisfy my own curiosity).\nFigures:\nThe figures are helpful especially Figures 2, 3, and 4. However, Fig. S3's key is unclear – “Not likely” is not shown on the map and is the same key as “Coastal & Terrestrial Boundaries.”\nI enjoyed reading your manuscript.", "reviewer_2": "This manuscript presents a multi-element stable isotope analysis and peptide-based sex determination of indigenous Māori skeletal remains from New Zealand’s North Island, dating from the mid-17th century to the terminal 18th century, in order to elucidate their dietary practices. Previous studies have demonstrated that, in the early period (13th–15th centuries), a wide range of both marine and terrestrial dietary resources were utilized. The results obtained in this study suggest that nearly all dietary protein was derived from terrestrial C3 cultivated plants in the Waikato region during the period following the intensification of horticulture. This finding is interesting in terms of understanding human dietary adaptation. The manuscript is written with care and attention to detail, the methodology is robust, and the interpretations are appropriate. Most importantly, the research was conducted in healthy collaboration with indigenous communities, and respect for their presence and culture is evident throughout the study. I believe this study represents an important milestone in the promotion of more ethical bioarchaeological research.\nHowever, I believe there are several major points that require improvement.\n1) Significance within history, archaeology, or biology\nOne of the highlights of this manuscript is the respectful and close collaboration with indigenous communities. However, setting this aspect aside, the historical, archaeological, or biological significance of the findings remains somewhat unclear. It may be beneficial to clarify and emphasize, throughout the manuscript, what constitutes the “important advances of significance” that would appeal to a broad readership beyond the scope of mere regional studies, as is the aim of Nature Communications.\n2) Representativeness of the skeletal samples\nThis study discusses the dietary practices of the Māori and Aotearoa as a whole based on stable isotopic data from seven individuals derived from a single site characterized by the \"rare, but not entirely unique\" mortuary features. It is difficult to determine what constitutes a sufficient sample size, but for isotope analysis of relatively recent remains, this study may fall into the category of having a small sample size. I would like to see a thorough discussion of how representative the data obtained in this study actually are. For example, is it possible that the individuals buried at this site belonged to a particular social class or status who might have had a different diet? Furthermore, is it not possible to obtain analytical results from ancient human remains from other sites? If such analyses are not feasible, it would be good to provide the reasons. Doing so would, in turn, indirectly demonstrate the distinctiveness of this study.\n3) Insufficiency of reference data for C3 plants\nThe central argument of this study is that sweet potato and taro were important food resources for the people of Waikato during the Traditional Period, and that their consumption is strongly reflected in the isotopic ratios. Personally, I find this claim reasonable based on the stable isotope ratios of the human remains. However, I must point out that the data on the food resources supporting this claim are poor. According to the reference data for food resources, only four samples of sweet potato are included among C3 plants, and there are no samples of taro or any other plants. Also, if I have overlooked something, I apologize, but in the original paper from which the sweet potato data are obtained (Leach et al. 2003), there is no description of the conditions under which the samples were cultivated. It is well known that the d15N of plants can vary greatly depending on the type of fertilizer used (e.g. Szpak 2013, Front Plant Sci 5:288), and when using modern plants as a baseline for pre-industrial diets, this point should be clearly addressed. With the current situation, where only sweet potato of unknown origin represents the C3 plants, it is not possible to determine from the isotopic ratios whether sweet potato and taro were indeed the main sources of protein for the people of Waikato, nor can one strongly assert that their protein came from C3 plants at all. In order to strengthen the core claims of this study, I believe that the dataset of C3 plants relevant to human diets should be further expanded.\n4) Interpretation of the age at the end of weaning\nThe use of the punching method for dentine, rather than horizontal sectioning, which greatly reduces time resolution, is excellent. However, I believe there is room for discussion regarding the interpretation of the end of weaning. While a sharp decrease in d15N can be interpreted as a reduction of the breast milk protein consumption, the subsequent fluctuations in values require careful interpretation. If foods with lower d15N than those consumed at later ages were provided immediately after the end of weaning, d15N values would continue to decrease in a manner similar to the reduction in breast milk intake, potentially leading to an overestimation of the age at the end of weaning. I would suggest either clearly defining the point considered to represent the end of weaning, or modifying the claim to allow for some flexibility or range. Even so, it is certain that the breastfeeding and weaning patterns differ clearly from those of Europeans after the 19th century.\n5) Use of Māori language\nIncluding Māori terminology demonstrates respect for indigenous languages; however, it may reduce the readability of the manuscript as a paper written in English. I would suggest considering the replacement of Māori terms with standard English equivalents throughout the manuscript, except where the concept cannot be expressed in English. If the true aim is to return research findings and show respect for indigenous languages, I recommend a more fundamental approach, such as including a full translation in the Supplementary Information.\n6) Data sharing\nPlease consider uploading the proteomics data to a public repository such as ProteomeXchange. The stable isotope ratios are already included in the Supplementary Information.\n7) Other minor points\nL95: It would be better to distinguish between amino acid notation for peptide sequences and for post-translational modifications, to avoid confusion. For example, the latter could be written in superscript or placed in parentheses.\nL109–117: Compound-specific stable isotope analysis of amino acids would likely yield interesting results (I am not requesting inclusion in this manuscript).\nFigure 2: Please indicate how the ellipses representing the range of food values were drawn. If they were drawn freehand, I suggest considering the use of objective tools such as SIBER (Jackson et al. 2011, J Amin Ecol 80: 595–602) or rKIN (Eckrich et al. 2019, J Anim Ecol 89: 775–771); the latter does not assume normal distributions.\nFigure 3: It may be helpful to also indicate the values for bone collagen as a comparison.\nTakumi Tsutaya", "reviewer_3": "This article is a great example of collaborative research between developers, archaeologists, and the indigenous community. While it is regrettable that the human remains were unexpectedly encountered and disturbed, since they had to be moved, it provides an opportunity to generate information relevant to many communities, including the descendant community, modern scientific archaeologists, and the general public. Our human ancestors have important stories to tell and lessons to teach us. These kind of collaborative ventures are to the benefit of everyone, and are a valuable way to commemorate and celebrate those who came before us.\nThe scientific component of the research is excellent. The researchers use several state-of-the-art techniques, including isotopic, proteomic, and radiocarbon techniques to show that the 7 individuals here ate very little marine food, surprisingly, but instead consumed mostly C3 plant foods. Relatively late estimated ages of weaning show significant investment and parental care on the part of ancient Maori people, when compared to European colonists from the 1800s. These are significant finds and should be of general interest to readers of Nature Communications. I have only one minor comment below, and I recommend publication.\nTable 1 should include results from all 7 individuals, not just the averages. There are only 7 people, so this would not take up significant space.", "reviewer_4": "This study presents isotopic and peptide analyses of seven individuals from the Tamahere archaeological site in the Waikato Basin, Aotearoa New Zealand. The focus of the study is the stable carbon and nitrogen isotope analysis of bone collagen to reconstruct diet, which provides direct evidence of predominantly plant-based diets in pre-contact Aotearoa. Specifically, the isotopic signatures indicate that all seven individuals consumed diets consisting primarily of C3 plants, which, based on ethnohistoric evidence, were likely cultivated kūmara (sweet potato), taro, and other root crops. Animal protein consumption appears to have been minimal, if any. The authors position this as evidence for \"primarily vegetarian\" diets among Traditional Period Māori, contrasting with the broad-spectrum foraging documented at earlier sites like Wairau Bar.\nThis finding is contextualized by additional analyses: enamel peptide analysis was used for sex determination for two individuals only, both children--one found to be female and one male; the sex of other individuals is not discussed. Strontium isotope analysis tests whether the studied individuals grew up locally--yes, they were local to the Waikato region. The stable isotope analysis of tooth dentine provides evidence of extended breastfeeding periods, as expected for cultures reliant on horticulture without easily available weaning foods, followed by weaning onto plant foods.\nStrengths\nThe study is well-designed in its multi-proxy analytical approach. The integration of stable isotope analysis with enamel peptide sex determination and strontium isotope mobility studies represents methodologically rigorous bioarchaeology. The quality control measures, including collagen quality indicators and analytical precision standards, meet current best practices. The use of dentine micropunch sampling to track weaning patterns provides fine-grained temporal resolution, offering insights into Traditional Period childcare practices.\nThe collaboration with Māori communities through the Tangata Whenua Working Group is important. The researchers followed appropriate cultural protocols, obtained proper permissions, and involved descendant communities as co-investigators and co-authors. This approach assuages longstanding concerns about extractive research on Māori ancestral remains and represents good practice in indigenous archaeology.\nSignificant Limitations\nThe most fundamental issue is sample size and geographic representation. All individuals originate from the same burial, dating to approximately AD 1700-1780, likely represent a single point in time. A small number of individuals from a single locale and likely a single point in time cannot reasonably support claims about broader Māori dietary patterns during the Traditional Period. The authors acknowledge this limitation but perhaps understate its significance for population-level inferences.\nThe burial context presents additional interpretive challenges. These individuals were found as commingled secondary burials in a borrow pit, representing a specialized mortuary treatment rather than typical community burials. We cannot determine whether these particular individuals represent typical community members or a specific subset selected for this unusual burial practice. This potential sampling bias undermines claims about broader dietary patterns.\nGeographic isolation further limits the study's implications. The Tamahere site is located inland, approximately 2 kilometers from the Waikato River, with limited/no access to marine resources. The predominantly plant-based diet may simply reflect geographic constraints rather than cultural preferences or widespread dietary patterns. The lack of marine foods is expected in this context rather than indicative of \"dietary adaptation\" as the authors suggest. Was this in any way different from what was expected based on food availability in the region?\nThe interpretive framework also contains questionable elements. The authors' reasoning for why the strong positive correlation between δ¹³C and δ¹⁵N values suggests specific animal protein sources (rats, dogs, freshwater resources) is puzzling (lines 113-114). This correlation could indicate various trophic relationships without necessarily pointing to those particular sources.\nLimited Novelty and Impact\nPerhaps most significantly, the study's core findings largely confirm rather than challenge existing knowledge. Intensive horticulture in the Waikato Basin has been documented through oral histories, ethnohistorical accounts, and archaeological evidence. The region contains some 500 garden sites, 200 pā (fortified settlements), and thousands of borrow pits, clearly demonstrating the importance of cultivation. While the quantitative isotopic confirmation provides valuable validation, it does not alter or expand our understanding of Traditional Period subsistence strategies.\nThe comparative framework is also limited. The primary comparison with Wairau Bar individuals from 500+ years earlier demonstrates diachronic change but provides no insight into contemporaneous variation across different regions or communities. Without comparative data from other Traditional Period sites, particularly coastal communities, we cannot assess whether the Tamahere pattern represents local adaptation or broader cultural trends.\nThe archaeological context receives little attention in the main text. Until I read the supplementary materials which provide more detail, I had difficulty understanding why the study was designed the way it was: for example, what happened to the teeth, why no sex determinations beyond Kōiwi 2 and Kōiwi 4, with no reference to individual bone pathology until reading the supplement, and so on.\nThe apparent absence of inland-coastal food trade networks, if confirmed, would be significant but requires more systematic investigation.\nContextual Significance\nDespite these limitations, the study makes important contributions within its constrained scope. It provides direct biogeochemical evidence for predominantly plant-based diets in pre-contact Aotearoa, offering quantitative validation of ethnohistorical accounts. The documentation of extended breastfeeding with plant-based weaning foods provides insights into Traditional Period childcare practices that would be difficult to obtain through other methods, albeit not unexpected given the cultural context.\nThe technical demonstration of combining stable isotope analysis with enamel peptide sex determination represents good research design and methodological advancement. The cultural collaboration model also provides an important template for respectful indigenous archaeology that other researchers should emulate.\nConclusion\nThis study represents competent, culturally sensitive research that provides valuable quantitative data within a limited scope. However, the broader claims about Traditional Period Māori dietary patterns are not well-supported because of the limited sample size and spatial and temporal constraints.\nThe authors' claim that this represents \"the first time\" primarily vegetarian diets have been documented in Aotearoa overstates the significance of confirming already known patterns through isotopic analysis. While biogeochemical confirmation has scientific value, the limited sample size, geographic constraints, and specialized burial context prevent broader generalizations about Traditional Period subsistence strategies.\nFuture research should prioritize larger, more geographically diverse samples from typical burial contexts to test whether the Tamahere pattern represents local adaptation or broader cultural trends."}, "author_response": "Response to Reviewers (Kinaston et al)\nReviewer 1\nComment 1: General comments\nThis study is an important contribution as it documents the first direct evidence that some\nWaikato Māori had a diet that was primarily plant-based, and the authors present a compelling\ncase. The archaeological evidence, Māori oral histories, and ethno-historical accounts are\nreconciled with the results of the isotope analysis to show how important horticulture was during\nthe Traditional Period in Aotearoa in the middle Waikato Basin. The collective efforts of the\narchaeologists, bioarchaeologists, and the affected iwi and hapū, along with the resulting\ncollaboration with descendant communities represented by the Tangata Whenua Working\nGroup, are greatly appreciated.\nResponse:\nWe sincerely thank the reviewer for their positive and thoughtful feedback. We greatly\nappreciate their recognition of both the interdisciplinary approach and the collaborative nature of\nthis research with iwi, hapū, and the Tangata Whenua Working Group.\nComment 2: Weaning\nThis study is a great start in establishing baseline data to infer weaning practices in Aotearoa\nduring the 18th century AD. Sweeping generalisations on weaning practices based on two cases\ncannot be made, because, as you note, there are unknowns including food preference,\navailability of resources, and differential access to existing resources. Please clarify how you\ndetermined 5 years of age was the likely age of weaning for Kōiwi 2 and Kōiwi 4, as opposed to\nanother age such as 4 years.\nResponse:\nWe agree with the reviewer that generalisations cannot be drawn from such a small dataset, and\nwe have clarified this point in the revised manuscript. The inference of weaning age for Kōiwi 2\nand Kōiwi 4 was based on the δ15N values reaching to adult levels by that age. We acknowledge\nthat this estimate may vary, and have now rephrased the text:\n“Although only two individuals, both children, had first molars available for analysis the results\nare the first-time patterns of breastfeeding and weaning have been investigated for Māori tūpuna.\nThe isotopic results clearly show that for Kōiwi 2 (a female), there was a ~4 ‰ drop in δ15N\ndentine\nvalues between birth and 2.5 years of age. This pattern indicates that breastmilk gradually\ndecreased as supplemental foods (from a lower trophic level than breastmilk) increased over this\nperiod. However, there was a further, gradual, ~2 ‰ decline in δ15N values between 2.5 and\ndentine\n5 years of age, which may suggest breastfeeding continued over this period. Alternatively, this\ncould be related to another higher trophic level food being eaten in gradually reduced amounts at\nthis time and/or changing nitrogen balance during periods of growth (Henderson, 2014). For\nKōiwi 4, there was a ~3.5 ‰ drop in δ15N values between birth and 3.2 years of age and no\ndentine\nfurther gradual decline in δ15N values, indicating complete weaning likely occurred at this\ndentine\nage. The supplementary foods and childhood diet of both individuals were likely C3 plant foods,\nsimilar to the diet of the Tamahere adults.”\nThis wording better reflects both the limitations of the data and the range of possible\ninterpretations.\nComment 3: Health and non-metric traits\nIt may be of interest to the reader to note if you were able to determine the general health of the\nindividuals based on the skeletal remains that were recovered (besides the caries you\ndocumented in 3 individuals). Furthermore, was there enough present to infer any familial\nconnections between individuals (e.g., a suite of cranial/dental nonmetric or unusual traits in\ncommon that might suggest a familial relationship)? I am not asking you to add this to your\nstudy, I leave it up to you if you want to clarify further for the reader (I admit I want to satisfy my\nown curiosity).\nResponse:\nWe thank the reviewer for this thoughtful question. We not clarify in the supplementary data:\n“BH recorded any observable pathological and non-metric traits present, which are reported in\ndetail in the publicly available final report for the site (Keith, 2022). However, the fragmentary\nnature of the skeletal material and the small sample size limited the ability to assess general\nhealth or to use non-metric traits as reliable indicators of familial relationships. Four individuals\nhad linear enamel hypoplasia (LEH) present on their dentitions: Kōiwi 1 (FDI 18), Kōiwi 2 (FDI\n11 and 12); Kōiwi 3 or 4 (FDI 37); and possibly Individual A (FDI 18), suggesting periods of ill\nhealth or malnutrition during childhood (Hillson, 2014; Kinaston, 2019). It is difficult to\ndetermine if the LEH was related to the plant-based diet of these individuals because of the non-\nspecific nature of the aetiology of LEH development.”\nComment 4: Figure suggestions\nThe figures are helpful, especially Figures 2, 3, and 4. However, Figure S3’s key is unclear –\n“Not likely” is not shown on the map and is represented with the same key as “Coastal &\nTerrestrial Boundaries.” I enjoyed reading your manuscript.\nResponse:\nWe thank the reviewer for drawing attention to this oversight. We have revised the figure legend\nto ensure that “Not likely” is clearly represented with a distinct key symbol, separate from\n“Coastal & Terrestrial Boundaries.” This correction improves the clarity and readability of the\nfigure. We are very pleased you enjoyed reading out manuscript.\nReviewer 2\nGeneral comments:\nThis manuscript presents a multi-element stable isotope analysis and peptide-based sex\ndetermination of indigenous Māori skeletal remains from New Zealand’s North Island, dating\nfrom the mid-17th century to the terminal 18th century, in order to elucidate their dietary\npractices. Previous studies have demonstrated that, in the early period (13th–15th centuries), a\nwide range of both marine and terrestrial dietary resources were utilized. The results obtained in\nthis study suggest that nearly all dietary protein was derived from terrestrial C3 cultivated plants\nin the Waikato region during the period following the intensification of horticulture. This finding\nis interesting in terms of understanding human dietary adaptation. The manuscript is written\nwith care and attention to detail, the methodology is robust, and the interpretations are\nappropriate. Most importantly, the research was conducted in healthy collaboration with\nindigenous communities, and respect for their presence and culture is evident throughout the\nstudy. I believe this study represents an important milestone in the promotion of more ethical\nbioarchaeological research.\nHowever, I believe there are several major points that require improvement.\nComment 1: Significance within history, archaeology, or biology\nOne of the highlights of this manuscript is the respectful and close collaboration with indigenous\ncommunities. However, setting this aspect aside, the historical, archaeological, or biological\nsignificance of the findings remains somewhat unclear. It may be beneficial to clarify and\nemphasise, throughout the manuscript, what constitutes the “important advances of\nsignificance” that would appeal to a broad readership beyond the scope of mere regional\nstudies, as is the aim of Nature Communications.\nResponse:\nWe thank the reviewer for this valuable suggestion. We have revised the introduction and\ndiscussion to more clearly emphasise the significance of this study within history, archaeology,\nand biology. Specifically, we highlight that this is one of the first isotopic studies of Māori\nancestors at a pivotal time in history—directly before colonisation, during the Traditional Period,\nwhen Māori culture was at a distinctive period in terms of art, architecture, cosmology, and\nwhakapapa {Anderson, 2016 #3731;Anderson, 2018 #3846}. We now more explicitly frame these results in the introduction and state :\nIntroduction\n“This study is among the first isotopic investigations of Māori ancestors during the Traditional\nPeriod, immediately prior to colonization, when Māori culture was highly distinctive in art,\narchitecture, cosmology, and whakapapa {Anderson, 2016 #3731;Anderson, 2018 #3846}. Our\nresults provide the first direct evidence that the diets of some Waikato Māori were likely almost\nentirely plant-based underscoring not only the centrality of horticulture in Māori society at this\ntime, but also contributing to a broader understanding of the importance of plant foods to\ntraditional diets globally. The significant dietary changes that occurred from the time of initial\nEast Polynesian settlement of Aotearoa to the Traditional Period reflect cultural innovation\nalongside environmental adaptation over a period of ~500 years. Our findings advance\nunderstanding of Māori lives in the past, including cultural dietary practices, and are of ongoing\nrelevance to descendant communities seeking to record, revitalize, and restore traditional\nfoodways and cultural practices.”\nDiscussion\n“Our findings provide direct evidence of dietary practices and cultural behaviours which have\npreviously been inferred only indirectly from archaeological contexts (e.g., storage pits, garden\nsoils) and provide the first direct evidence for patterns of breastfeeding and weaning.”\n“The stark contrasts between the diets of the first East Polynesian settlers at Wairau Bar and\nLagoon Flat, the later Mōriori at Waihora, the Traditional Period Māori near Lake Rotoiti, and\nthe Tamahere tūpuna reveal the extraordinary dietary and cultural changes that took place within\n500 years across Aotearoa and Rēkohu.”\nComment 2: Representativeness of the skeletal samples\nThis study discusses the dietary practices of the Māori and Aotearoa as a whole based on stable\nisotopic data from seven individuals derived from a single site characterized by the \"rare, but\nnot entirely unique\" mortuary features. It is difficult to determine what constitutes a sufficient\nsample size, but for isotope analysis of relatively recent remains, this study may fall into the\ncategory of having a small sample size. I would like to see a thorough discussion of how\nrepresentative the data obtained in this study actually are. For example, is it possible that the\nindividuals buried at this site belonged to a particular social class or status who might have had\na different diet? Furthermore, is it not possible to obtain analytical results from ancient human\nremains from other sites? If such analyses are not feasible, it would be good to provide the\nreasons. Doing so would, in turn, indirectly demonstrate the distinctiveness of this study\nResponse:\nWe acknowledge the reviewer’s concern and have expanded the supplementary data to clarify\nthe representativeness of the sample and have also included comparative isotope information\nfrom Māori and Moriori, in addition to Historic European and Chinese individuals. We didn’t\ninclude the Māōri and Mōriori individuals earlier because the collagen quality indicators were\nnot reported by Leach et al (2003). We have noted this as a possible caveat to using these\ncomparative samples. We have also added Colonial Period European and Chinese individuals.\nAlthough these people had different diets compared with pre-Contact Māori, they were still\neating locally grown C3 plants and have been interpreted as mainly eating C3-based terrestrial\nresources. We agree with the reviewer that the inclusion of these comparative samples\nstrengthens the interpretations that the Tamahere tūpuna were eating a plant-based diet.\nWe note in the discussion that :A major question is whether the people interred in the borrow pit\nare local to the site and representative of the wider population that lived in the Tamahere area\nduring the 18th century AD.\nWe also note that secondary burial was a widespread practice during the Traditional Period,\nundertaken in varied ways (e.g., reinterment, exposure and collection, cave or tree burials) and\ntherefore is a ‘normal’ burial context for the time:\nMain text: Secondary burial was commonly undertaken to hide kōiwi in caves, rock shelters and\nunderground so enemies could not steal the mana (lifeforce) of an ancestor (13) and, as a result,\nsecondary burials are not commonly found in archaeological contexts. Hapū approval to\nundertake the current research provides a rare opportunity to analyse the lives of tūpuna who\nwere interred in secondary burial context.\nSupplementary text: “Post-burial removal of the skull is a documented practice throughout\nPolynesia (48:59), and there are ethno-historic accounts of traditional Māori burial practices that\ninvolved retrieval and, often, cleaning (44: 64) of skulls recovered from graves and caves for\npurposes of ongoing mourning rites or display (e.g.45: 177). Additionally, in the Waikato region\nand elsewhere across Aotearoa, the Māori-era tradition of exhumation of kōiwi to secret away\nbones in caves, rock shelters is well documented, especially during the later Traditional Period\n(ca. AD 1650-~1800) (13). Although reburial of exhumed kōiwi in secondary burial contexts is\nnot as well-known as secondary burial in caves, the practice has been recorded in many regions\nacross Aotearoa (43).”\nBecause such practices deliberately concealed remains, skeletal assemblages are often\nfragmentary or inaccessible due to their sacred status as wāhi tapu. These constraints explain the\nscarcity of comparative samples and reinforce why this study represents a rare opportunity to\nanalyse well-contextualised remains. We have clarified these points in the manuscript to\nstrengthen our justification of the sample’s distinctiveness.\nComment 3: Insufficiency of reference data for C3 plants\nThe central argument of this study is that sweet potato and taro were important food resources\nfor the people of Waikato during the Traditional Period, and that their consumption is strongly\nreflected in the isotopic ratios. Personally, I find this claim reasonable based on the stable\nisotope ratios of the human remains. However, I must point out that the data on the food\nresources supporting this claim are poor. According to the reference data for food resources,\nonly four samples of sweet potato are included among C3 plants, and there are no samples of\ntaro or any other plants. Also, if I have overlooked something, I apologize, but in the original\npaper from which the sweet potato data are obtained (Leach et al. 2003), there is no description\nof the conditions under which the samples were cultivated. It is well known that the d15N of\nplants can vary greatly depending on the type of fertilizer used (e.g. Szpak 2013, Front Plant Sci\n5:288), and when using modern plants as a baseline for pre-industrial diets, this point should be\nclearly addressed. With the current situation, where only sweet potato of unknown origin\nrepresents the C3 plants, it is not possible to determine from the isotopic ratios whether sweet\npotato and taro were indeed the main sources of protein for the people of Waikato, nor can one\nstrongly assert that their protein came from C3 plants at all. In order to strengthen the core\nclaims of this study, I believe that the dataset of C3 plants relevant to human diets should be\nfurther expanded.\nResponse:\nWe agree with the reviewer that reference data for C3 plants are limited, and we have clarified\nthis limitation in the text. To address this, we have now compare the kūmara values with C3\nplants in temperate environments from published datasets, and we provide environmental context\nby describing the non-arid climate, rainfall, and temperature of the Waikato region in the\nsupplementary data. We also note the Auckland market origin of the modern kūmara samples\nused in previous research. While further sampling of traditional C3 resources (particularly taro)\nis needed, the available evidence strongly suggests that horticultural crops were the main\ncontributors to dietary protein in the Waikato during the Traditional Period. In the supplementary\ntext we note:\n“We included only edible C3 plants that would have been available in Aotearoa during the\nTraditional Period. Four samples of kūmara (Ipomoea batatas) collected by B.F. Leach from an\nAuckland market were used as reference material (Leach, 2003). These kūmara were likely\ngrown locally in Auckland, a region with rainfall (~1100–1200 mm annually) and mean\ntemperature (15.5 °C vs. 14.0 °C) similar to Tamahere, suggesting minimal regional differences\nin δ¹³C values of C3 plants grown in each area. The average δ¹³C value of the kūmara (-26.7‰)\naligns with global averages for C3 plants (–26‰ to –27‰), though values can range between –\n20‰ and –37‰ depending on aridity and canopy effects (Dawson et al 2002; Koch 1998). The\naverage kūmara δ¹5N values (4.0‰) are comparable to non-N -fixing plants ranging from 0 to +\n2\n6‰ but average 3‰ (Pate, 1994), although factors such as animal fertilizers and\nburning/swidden cultivation can increase plant δ¹5N values (Szpak 2014). The kūmara δ¹³C\nvalues used are also consistent with those modern potatoes (Solanum tuberosum), pumpkin\n(Curcurbita spp.) and peas (Pisum sativum) (n=6, -25.6‰) grown in Aotearoa, but slightly\nhigher than the average δ¹5N values for the non N2-fixing vegetables (potatoes and pumpkin)\n(n=4, and 2.8), which may be related to environmental factors (Rogers 2008).”\nComment 4: Interpretation of the age at the end of weaning\nThe use of the punching method for dentine, rather than horizontal sectioning, which greatly\nreduces time resolution, is excellent. However, I believe there is room for discussion regarding\nthe interpretation of the end of weaning. While a sharp decrease in d15N can be interpreted as a\nreduction of the breast milk protein consumption, the subsequent fluctuations in values require\ncareful interpretation. If foods with lower d15N than those consumed at later ages were provided\nimmediately after the end of weaning, d15N values would continue to decrease in a manner\nsimilar to the reduction in breast milk intake, potentially leading to an overestimation of the age\nat the end of weaning. I would suggest either clearly defining the point considered to represent\nthe end of weaning, or modifying the claim to allow for some flexibility or range. Even so, it is\ncertain that the breastfeeding and weaning patterns differ clearly from those of Europeans after\nthe 19th century.\nResponse:\nWe thank the reviewer for raising this important point. We have revised the text to clarify that\nthe sharp decline in δ15N is interpreted as the end of breastfeeding, while acknowledging that\nsubsequent minor fluctuations may reflect dietary variation rather than extended breastfeeding.\nWe clarified the weaning interpretation (see comment 2 to Reviewer 1 above) .This revision\nensures that our interpretation is cautious and reflects both the data and alternative possibilities.\nComment 5: Use of Māori language\nIncluding Māori terminology demonstrates respect for indigenous languages; however, it may\nreduce the readability of the manuscript as a paper written in English. I would suggest\nconsidering the replacement of Māori terms with standard English equivalents throughout the\nmanuscript, except where the concept cannot be expressed in English. If the true aim is to return\nresearch findings and show respect for indigenous languages, I recommend a more fundamental\napproach, such as including a full translation in the Supplementary Information.\nResponse:\nWe appreciate the reviewer’s suggestion. However, in line with guidance from the Editor, we\nhave retained the use of Māori terminology throughout the manuscript. We believe this is\nessential both for accuracy (certain terms do not have precise English equivalents) and for\nreflecting the cultural values of our hapū partners. To support readability, we provide definitions\nat first use and in a ‘Glossary of Māōri and Moriori Terms’ the supplementary text. We\nrespectfully submit that retaining these terms is consistent with both the collaborative ethos of\nthe research and current best practice for indigenous scholarship.\nComment 6: Data sharing\nPlease consider uploading the proteomics data to a public repository such as ProteomeXchange.\nThe stable isotope ratios are already included in the Supplementary Information.\nResponse:\nWe agree and have now deposited the proteomics data in the ProteomeXchange. The stable\nisotope data are already available in the Supplementary Information. The data availability\nstatement has been updated accordingly.\nComment 7: Other minor points\n L95: It would be better to distinguish between amino acid notation for peptide sequences\nand for post-translational modifications, to avoid confusion. For example, the latter\ncould be written in superscript or placed in parentheses.\n L109–117: Compound-specific stable isotope analysis of amino acids would likely yield\ninteresting results (I am not requesting inclusion in this manuscript).\n Figure 2: Please indicate how the ellipses representing the range of food values were\ndrawn. If they were drawn freehand, I suggest considering the use of objective tools such\nas SIBER (Jackson et al. 2011, J Amin Ecol 80: 595–602) or rKIN (Eckrich et al. 2019, J\nAnim Ecol 89: 775–771); the latter does not assume normal distributions.\n Figure 3: It may be helpful to also indicate the values for bone collagen as a\ncomparison.\nResponse:\n We have corrected the notation for peptide sequences and amino acid side chain\nmodification. The modified sequence in single letter code now reads: SM(ox)IRPPY.\n We appreciate the suggestion regarding compound-specific isotope analysis and note\n“Future research employing compound-specific stable isotope analysis of amino acids\ncould provide deeper insights into past dietary practices.”\n We have clarified in the supplementary information and figure legend that ellipses were\ncalculated in Excel using standard 95% confidence ellipse equations.\n We can’t add bone collagen δ13C and δ15N values as the we need the x and y axes to plot\nthat type of data and Figure 3 has only two y axes for the type of data presented\n(incremental biopsy dentine samples).\nReviewer 3\nGeneral Comments:\nThis article is a great example of collaborative research between developers, archaeologists,\nand the indigenous community. While it is regrettable that the human remains were unexpectedly\nencountered and disturbed, since they had to be moved, it provides an opportunity to generate\ninformation relevant to many communities, including the descendant community, modern\nscientific archaeologists, and the general public. Our human ancestors have important stories to\ntell and lessons to teach us. These kinds of collaborative ventures are to the benefit of everyone,\nand are a valuable way to commemorate and celebrate those who came before us.\nThe scientific component of the research is excellent. The researchers use several state-of-the-art\ntechniques, including isotopic, proteomic, and radiocarbon analyses to show that the seven\nindividuals ate very little marine food, surprisingly, but instead consumed mostly C3 plant foods.\nRelatively late estimated ages of weaning show significant investment and parental care on the\npart of ancient Māori people, when compared to European colonists from the 1800s. These are\nsignificant findings and should be of general interest to readers of Nature Communications. I\nhave only one minor comment below, and I recommend publication.\nResponse:\nWe sincerely thank the reviewer for their very supportive comments and recommendation for\npublication. We particularly appreciate their recognition of both the collaborative framework of\nthis research and the scientific significance of the findings. We have aimed throughout the\nmanuscript to highlight the cultural importance of this work alongside its broader contribution to\nunderstanding human dietary adaptation and childcare practices in the Pacific.\nReviewer 3 Specific Comment: Table 1 should include results from all 7 individuals, not just the\naverages. There are only 7 people, so this would not take up significant space.\nResponse:\nWe agree with the reviewer and have revised Table 1 to include the results from all seven\nindividuals, rather than presenting only the averages. We have also retained the summary\naverages for adults and children and added this to the new table of the averages for the\ncomparative populations (Table 2). This revision ensures transparency and provides readers with\na clearer view of the dataset.\nReviewer 4\nGeneral (positive comments)\nThis study presents isotopic and peptide analyses of seven individuals from the Tamahere\narchaeological site in the Waikato Basin, Aotearoa New Zealand. The focus of the study is the\nstable carbon and nitrogen isotope analysis of bone collagen to reconstruct diet, which provides\ndirect evidence of predominantly plant-based diets in pre-contact Aotearoa. Specifically, the\nisotopic signatures indicate that all seven individuals consumed diets consisting primarily of C3\nplants, which, based on ethnohistoric evidence, were likely cultivated kūmara (sweet potato),\ntaro, and other root crops. Animal protein consumption appears to have been minimal, if any.\nThe authors position this as evidence for \"primarily vegetarian\" diets among Traditional Period\nMāori, contrasting with the broad-spectrum foraging documented at earlier sites like Wairau\nBar.\nThis finding is contextualized by additional analyses: enamel peptide analysis was used for sex\ndetermination for two individuals only, both children--one found to be female and one male; the\nsex of other individuals is not discussed. Strontium isotope analysis tests whether the studied\nindividuals grew up locally--yes, they were local to the Waikato region. The stable isotope\nanalysis of tooth dentine provides evidence of extended breastfeeding periods, as expected for\ncultures reliant on horticulture without easily available weaning foods, followed by weaning\nonto plant foods.\nStrengths\nThe study is well-designed in its multi-proxy analytical approach. The integration of stable\nisotope analysis with enamel peptide sex determination and strontium isotope mobility studies\nrepresents methodologically rigorous bioarchaeology. The quality control measures, including\ncollagen quality indicators and analytical precision standards, meet current best practices. The\nuse of dentine micropunch sampling to track weaning patterns provides fine-grained temporal\nresolution, offering insights into Traditional Period childcare practices.\nThe collaboration with Māori communities through the Tangata Whenua Working Group is\nimportant. The researchers followed appropriate cultural protocols, obtained proper\npermissions, and involved descendant communities as co-investigators and co-authors. This\napproach assuages longstanding concerns about extractive research on Māori ancestral remains\nand represents good practice in indigenous archaeology.\nComment 1: Sample size and temporal constraints\nThe most fundamental issue is sample size and geographic representation. All individuals\noriginate from the same burial, dating to approximately AD 1700-1780, likely represent a single\npoint in time. A small number of individuals from a single locale and likely a single point in time\ncannot reasonably support claims about broader Māori dietary patterns during the Traditional\nPeriod. The authors acknowledge this limitation but perhaps understate its significance for\npopulation-level inferences.\nResponse:\nWe understand the reviewer’s concern. While the sample is small, the wider archaeological\ncontext—hundreds of hectares of garden soils, thousands of storage pits, and numerous fortified\npā—demonstrates intensive horticultural use of the Waikato Basin during the Traditional Period.\nThe fact that all seven individuals show primarily plant-based diets reinforces the centrality of\nhorticultural crops in this horticulturally rich zone. As opportunities for isotopic analysis of\nMāori human remains are rare, this dataset provides a crucial first step toward directly\ndocumenting diet in this region. We have clarified these limitations and contextualised the\nfindings more explicitly in the revised manuscript. We have also added comparative assemblages\n(see comment to Reviewer 1, Comment 2).\nComment 2: Burial context and representativeness\nThe burial context presents additional interpretive challenges. These individuals were found as\ncommingled secondary burials in a borrow pit, representing a specialized mortuary treatment\nrather than typical community burials. We cannot determine whether these particular individuals\nrepresent typical community members or a specific subset selected for this unusual burial\npractice. This potential sampling bias undermines claims about broader dietary patterns.\nResponse:\nWe acknowledge this issue and have expanded our discussion of mortuary context. Secondary\nburial was a widespread practice during the Traditional Period, particularly in regions of\nintensive horticulture where conflict and the need to protect resources were prevalent. Urupā\n(formal cemeteries) were less typical in this period, as tribes often sought to protect their dead\nfrom desecration. While the specific form of secondary burial at Tamahere (commingled remains\nin a borrow pit) is uncommon, secondary and commingled burials are well-documented across\nAotearoa, with considerable regional and hapū variation. This context suggests that these\nindividuals are not anomalous but may represent broader community practices. We have clarified\nthis distinction in the manuscript and responded in depth to this in our response to Reviewer 2,\nComment 2.\nComment 3: Geographic isolation and dietary implications\nGeographic isolation further limits the study's implications. The Tamahere site is located inland,\napproximately 2 kilometers from the Waikato River, with limited/no access to marine resources.\nThe predominantly plant-based diet may simply reflect geographic constraints rather than\ncultural preferences or widespread dietary patterns. The lack of marine foods is expected in this\ncontext rather than indicative of \"dietary adaptation\" as the authors suggest. Was this in any\nway different from what was expected based on food availability in the region?\nResponse:\nWe respectfully disagree that this outcome was entirely expected. The site is situated near major\ntributaries of the Waikato River, which served as transport routes for people and foodstuffs.\nMāori were highly adept navigators of waterways, and rivers are considered living beings in\nMāori culture. Archaeological evidence from earlier sites and regional middens indicates that\nanimal protein—fish, shellfish, birds, dogs, and rats—was typically consumed. Therefore, the\nexpectation prior to this study was that Tamahere individuals would have diets rich in both\nhorticultural and protein resources. Our finding that plant foods dominated is significant,\nespecially given that collagen isotopes tend to over-represent protein consumption. The inclusion\nof the comparative Māori Era and Colonial Era individuals assist with the interpretations and\nshow that a people similar inland site (Rotoiti) were eating freshwater and marine foods.\nComment 4: Interpretation of δ¹³C–δ15N correlations\nThe interpretive framework also contains questionable elements. The authors' reasoning for why\nthe strong positive correlation between δ¹³C and δ¹⁵N values suggests specific animal protein\nsources (rats, dogs, freshwater resources) is puzzling (lines 113-114). This correlation could\nindicate various trophic relationships without necessarily pointing to those particular sources.\nResponse:\nWe thank the reviewer for raising this point and have clarified the explanation. Freshwater\nresources typically plot directly above terrestrial foods, producing strong positive correlations\nbetween δ¹³C and δ¹⁵N. Marine foods plot in a different isotopic range with a less positive\ncorrelation (as shown, for example, at Wairau Bar). Dogs and rats would only plot above humans\nif consuming the same cultivated foods, and only then if they were part of the human diet. We\nhave revised the discussion to explain this more explicitly:\n“The low δ13C and δ15N values indicate that the majority of dietary protein was from\ncollagen collagen\na low trophic level, terrestrial ecosystem, notably C3 plants. However, the statistically\nsignificant, strong positive association between the δ13C collagen and δ15N collagen values\n(Spearman’s rs (7) = 0.94, p < .01) hints that a very small amount of animal protein may have\nbeen consumed. This protein intake was likely sporadic rather than a consistent dietary\ncomponent, most likely from terrestrial animals or freshwater resources. A weaker positive\ncorrelation would be expected if marine fish, shellfish, or mammals formed a greater component\nof the diet, as observed for the Wairau Bar kōiwi (Spearman’s rs (27) = 0.70, p < .01), consistent\nwith higher marine protein consumption at this site (3, 42). “\nComment 5: Limited novelty of findings\nPerhaps most significantly, the study's core findings largely confirm rather than challenge\nexisting knowledge. Intensive horticulture in the Waikato Basin has been documented through\noral histories, ethnohistorical accounts, and archaeological evidence. The region contains some\n500 garden sites, 200 pā (fortified settlements), and thousands of borrow pits, clearly\ndemonstrating the importance of cultivation. While the quantitative isotopic confirmation\nprovides valuable validation, it does not alter or expand our understanding of Traditional Period\nsubsistence strategies.\nResponse:\nWhile horticulture in the Waikato Basin is well established, this study provides the first direct\nconfirmation that horticultural foods dominated diet in this region. Previous absence of midden\nevidence created uncertainty about whether marine and forest foods contributed substantially.\nOur results show that despite availability, these resources were not the main dietary focus. We\nemphasise that this represents the first direct dietary evidence for primarily plant-based diets in\npre-contact Aotearoa, which is an important step in refining understandings of Traditional Period\nsubsistence. We have rephrased claims to more clearly frame the novelty as direct confirmation\nrather than discovery of an unknown pattern. The inclusion of comparative samples from the\nMāori and Colonial Eras show that the Tamahere diet is very different than Māori and Moriori\ndiet elsewhere in the country.\nComment 6: Comparative framework\nThe comparative framework is also limited. The primary comparison with Wairau Bar\nindividuals from 500+ years earlier demonstrates diachronic change but provides no insight into\ncontemporaneous variation across different regions or communities. Without comparative data\nfrom other Traditional Period sites, particularly coastal communities, we cannot assess whether\nthe Tamahere pattern represents local adaptation or broader cultural trends.\nResponse:\nWe agree that comparative data from other Traditional Period sites would strengthen the\nframework and have now added kōiwi and kōimi from another published study (Leach et al\n2003). This data was not initially included because collagen quality indicators were not reported\nby Leach et al (2003) in addition to Colonial period individuals. There is a new section in the\nSupplementary data on the Comparative human stable isotope results and these data are\ndiscussed in the text and included in the tables and figures.\nComment 7: Lack of archaeological detail in the main text\nThe archaeological context receives little attention in the main text. Until I read the\nsupplementary materials which provide more detail, I had difficulty understanding why the study\nwas designed the way it was: for example, what happened to the teeth, why no sex\ndeterminations beyond Kōiwi 2 and Kōiwi 4, with no reference to individual bone pathology\nuntil reading the supplement, and so on. The apparent absence of inland-coastal food trade\nnetworks, if confirmed, would be significant but requires more systematic investigation.\nResponse:\nWe appreciate this observation. While word limits constrained the amount of contextual\ninformation included in the main text, we have now incorporated brief explanations regarding\nwhy only two peptide sex determinations were undertaken. We note that oral pathology is\nincluded in the main text as directly relevant to the dietary discussion but skeletal pathology is\nreported primarily in supplementary data as it was not essential to the dietary interpretations. We\ncan only comment in the text that the lack of inland-coastal food trade networks is apparent at\nTamahere from the stable isotope information and complete lack of marine faunal remains in the\nwider site complex.\nComment 8: Contextual Significance\nDespite these limitations, the study makes important contributions within its constrained scope.\nIt provides direct biogeochemical evidence for predominantly plant-based diets in pre-contact\nAotearoa, offering quantitative validation of ethnohistorical accounts. The documentation of\nextended breastfeeding with plant-based weaning foods provides insights into Traditional Period\nchildcare practices that would be difficult to obtain through other methods, albeit not unexpected\ngiven the cultural context.\nThe technical demonstration of combining stable isotope analysis with enamel peptide sex\ndetermination represents good research design and methodological advancement. The cultural\ncollaboration model also provides an important template for respectful indigenous archaeology\nthat other researchers should emulate.\nResponse: Thank you for these observations.\nComment 9: Overstatement of significance\nThis study represents competent, culturally sensitive research that provides valuable quantitative\ndata within a limited scope. However, the broader claims about Traditional Period Māori\ndietary patterns are not well-supported because of the limited sample size and spatial and\ntemporal constraints.\nThe authors' claim that this represents \"the first time\" primarily vegetarian diets have been\ndocumented in Aotearoa overstates the significance of confirming already known patterns\nthrough isotopic analysis. While biogeochemical confirmation has scientific value, the limited\nsample size, geographic constraints, and specialized burial context prevent broader\ngeneralizations about Traditional Period subsistence strategies.\nResponse:\nWe have included comparative samples that strengthen our interpretations. We understand that\nthe sample size is small, but the homogeneous nature of the diets, the context within a\nhorticultural zone and the fact the burial practice likely represents local people provides a\nimportant contribution to our understanding of Traditional Period lives in Aotearoa. We have\nrevised this statement to clarify that our study provides the first direct isotopic confirmation of\nprimarily plant-based diets, rather than claiming novelty in identifying horticultural subsistence\nitself. We believe this nuance strengthens the manuscript by accurately representing the\ncontribution of biogeochemical evidence.\nComment 10: Future research\nFuture research should prioritize larger, more geographically diverse samples from typical\nburial contexts to test whether the Tamahere pattern represents local adaptation or broader\ncultural trends.\nResponse:\nWe agree that broader geographic sampling would be valuable. However, as noted above\n(Reviewer 2 , Comment 2), human remains are only recovered in Aotearoa when disturbed by\nnatural or construction activity, and excavation for purely research purposes does not occur.\nFurther, burial traditions during the Traditional Period were highly variable, with no single\n“typical” context across Aotearoa (see response to Reviewer 2 , Comment 2). As noted above in\nthe our response to Comment 6- we have included the comparative samples and feel this\nsignificantly strengthens the manuscript.\nSummary Response to Reviewer 4:\nWe are grateful to the reviewer for their detailed and constructive comments. We have clarified\nthe limitations of the study more explicitly, burial context and geographic scope, while\nemphasising that this work represents the first direct isotopic confirmation of plant-dominated\ndiets in the Waikato Basin during the Traditional Period. We have revised the text include\ncomparative samples and to improve explanations of isotopic interpretations. We acknowledge\nthat future research with larger and more geographically diverse datasets will be valuable, but\nreiterate that opportunities for such work are necessarily constrained by cultural protocols in\nAotearoa. Within these limits, we believe our study makes an important contribution to\nunderstanding Māori life during the Traditional Period, while also serving as a model for\nculturally respectful, collaborative bioarchaeology."}, {"round": 2, "reviewer_comments": {"reviewer_1": "I have reviewed the revised manuscript and am satisfied that the authors have successfully addressed all of my comments regarding the estimated age of weaning, sample limitations (general health and familial relationships), and figure S3 legend revisions.", "reviewer_3": "This is a second revision of this paper. The authors have addressed all of my concerns to my satisfaction, and from my reading, have addressed concerns of other reviewers as well. I recommend publication."}, "author_response": ""}]

Decision letter