Australopithecus anamensis

Australopithecus anamensis is a species of Australopithecus.Gosh, Pallab 2019. 'All bets now off' on which ape was humanity's ancestor. BBC News Science & Environment.   Its scientific name is abbreviated as A. anamensis. 

A. anamensis is the earliest known australopithecine species.Haile-Selassie, Y (27 October 2010). "Phylogeny of early Australopithecus: new fossil evidence from the Woranso-Mille (central Afar, Ethiopia)". Philosophical Transactions of the Royal Society B: Biological Sciences. 365 (1556): 3323–3331. doi:10.1098/rstb.2010.0064. PMC 2981958. PMID 20855306.Lewis, Barry; et al. (2013). Understanding Humans: Introduction to Physical Anthropology and Archaeology (11th ed.). Belmont, CA: Wadsworth Publishing. It lived from around 4.3 million years agoLewis, Jason E.; Ward, Carol V.; Kimbel, William H.; Kidney, Casey L.; Brown, Frank H.; Quinn, Rhonda L.; Rowan, John; Lazagabaster, Ignacio A.; Sanders, William J.; Leakey, Maeve G.; Leakey, Louise N. (2024). "A 4.3-million-year-old Australopithecus anamensis mandible from Ileret, East Turkana, Kenya, and its paleoenvironmental context". Journal of Human Evolution. 194. 103579. doi:10.1016/j.jhevol.2024.103579. to around 3.8 million years ago. 

A. anamensis lived in East Africa. Paleoanthropologists have found over 100 A. anamensis fossils in KenyaLeakey, Meave G.; Feibel, Craig S.; MacDougall, Ian; Walker, Alan (17 August 1995). "New four-million-year-old hominid species from Kanapoi and Allia Bay, Kenya". Nature. 376 (6541): 565–571. Bibcode:1995Natur.376..565L. doi:10.1038/376565a0. PMID 7637803. S2CID 4340999. and Ethiopia,White, Tim D.; WoldeGabriel, Giday; Asfaw, Berhane; Ambrose, Stan; Beyene, Yonas; Bernor, Raymond L.; Boisserie, Jean-Renaud; Currie, Brian; Gilbert, Henry; Haile-Selassie, Yohannes; Hart, William K.; Hlusko, Leslea J.; Howell, F. Clark; Kono, Reiko T.; Lehmann, Thomas; Louchart, Antoine; Lovejoy, C. Owen; Renne, Paul R.; Saegusa, Hauro; Vrba, Elisabeth S.; Wesselman, Hank; Suwa, Gen (13 April 2006). "Asa Issie, Aramis and the origin of Australopithecus". Nature. 440 (7086): 883–9. Bibcode:2006Natur.440..883W. doi:10.1038/nature04629. PMID 16612373. S2CID 4373806. from 20 separate individuals.

 Name 
The name Australopithecus comes from the Latin word australo (meaning ‘southern’) and the Greek word pithecus (meaning ‘ape’). 

The word anamensis is based on the word anam, which means "lake" in the Turkana language.Leakey, Meave G.; Feibel, Craig S.; MacDougall, Ian; Walker, Alan (17 August 1995). "New four-million-year-old hominid species from Kanapoi and Allia Bay, Kenya". Nature. 376 (6541): 565–571. Bibcode:1995Natur.376..565L. doi:10.1038/376565a0. PMID 7637803. S2CID 4340999. (This language is spoken in the area where A. anamensis fossils were first discovered.) The word "lake" here refers to how A. anamensis once lived next to lakes.

Together, the name Australopithecus anamensis means "southern ape of the lake."

 Evolution 
In human evolution, Australopithecus anamensis is the intermediate species between Ardipithecus ramidus and Australopithecus afarensis.Kimbel, William H.; Lockwood, Charles A.; Ward, Carol V.; Leakey, Meave G.; Rake, Yoel; Johanson, Donald C. (2006). "Was Australopithecus anamensis ancestral to A. afarensis? A case of anagenesis in the hominin fossil record". Journal of Human Evolution. 51 (2): 134–152. doi:10.1016/j.jhevol.2006.02.003. PMID 16630646. This means that A. anamensis descended from Ardipithecus ramidus, and is the ancestor of A. afarensis.Ward, Carol; Leakey, Meave; Walker, Alan (1999). "The new hominid species Australopithecus anamensis". Evolutionary Anthropology: Issues, News, and Reviews. 7 (6): 197–205. doi:10.1002/(SICI)1520-6505(1999)7:6<197::AID-EVAN4>3.0.CO;2-T. ISSN 1520-6505. S2CID 84278748. 

Even though A. anamensis evolved into A. afarensis, it did not replace it. The two species existed at the same time for at least 100,000 years. 

 Description 
The location of A. anamensis fossils show that this species lived in forests and woodlands that grew around lakes.

A. anamensis had a combination of human-like and ape-like traits. It was bipedal: it regularly walked upright.C.V., Warda (2001). "Morphology of Australopithecus anamensis from Kanapoi and Allia Bay, Kenya". Journal of Human Evolution. 41 (4): 255–368. doi:10.1006/jhev.2001.0507. PMID 11599925. S2CID 41320275. However, its long arms and wrist bones suggest that it also spent time climbing trees. It may have sometimes walked on its knuckles.Richmond, Brian (23 March 2000). "Evidence that Humans Evolved from a Knuckle-walking Ancestor". Nature. 404 (6776): 382–385. Bibcode:2000Natur.404..382R. doi:10.1038/35006045. PMID 10746723. S2CID 4303978.

Based on fossils, scientists estimate that A. anamensis was about the same size as modern chimpanzees. Like in modern gorillas and orangutans, females were much smaller than males. (This is called sexual dimorphism.)

Only one A. anamensis skull has been found. That individual had a small brain, smaller than A. afarensis.Haile-Selassie, Yohannes; Melillo, Stephanie M.; Vazzana, Antonino; Benazzi, Stefano; Ryan, Timothy M. (2019). "A 3.8-million-year-old hominin cranium from Woranso-Mille, Ethiopia". Nature. 573 (7773): 214–219. Bibcode:2019Natur.573..214H. doi:10.1038/s41586-019-1513-8. hdl:11585/697577. PMID 31462770. S2CID 201656331.

 Diet 
Based on analysis of wear patterns on fossil teeth, A. anemensis had about the same diet as a modern gorilla. Their diet stayed the same regardless of what environment they lived in.Ungar, Peter Stuart; Scott, Robert S.; Grine, Frederick E.; Teaford, Mark F. (20 September 2010). "Molar microwear textures and the diets of Australopithecus anamensis and Australopithecus afarensis". Philosophical Transactions of the Royal Society B: Biological Sciences. 365 (1556): 3345–3354. doi:10.1098/rstb.2010.0033. PMC 2981952. PMID 20855308. A. anamensis mostly ate plants, including both fruits and tougher foods like nuts.Estebaranz, Ferran; Galbany, Jordi; Martínez, Laura (2012). "Buccal dental microwear analyses support greater specialization in consumption of hard foodstuffs for Australopithecus anamensis". Journal of Anthropological Sciences (90): 1–24. doi:10.4436/jass.90006 – via Dipòsit Digital de la Universitat de Barcelona.

 Fossils 

 First specimen 
The first fossilized specimen of the species, though not recognized as such at the time, was a single arm bone. It was found in Pliocene strata in the Kanapoi region of East Lake Turkana by a Harvard University research team in 1965. The specimen was tentatively assigned at the time to Australopithecus and dated about four million years old.  

 1987 specimen 
Little additional information was uncovered until 1987, when Canadian archaeologist Allan Morton (with Harvard University's Koobi Fora Field School) discovered fragments of a specimen sticking out of a hillside east of Allia Bay, near Lake Turkana, Kenya. 

 Allia Bay site 
Six years later the London-born Kenyan paleoanthropologist Meave Leakey and archaeologist Alan Walker excavated the Allia Bay site and uncovered several additional fragments of the hominid, including one complete lower jaw bone which closely resembles that of a common chimpanzee (Pan troglodytes) but whose teeth are much more similar to those of a human. In 1995, Meave Leakey and her associates, taking note of differences between Australopithecus afarensis and the new finds, assigned them to a new species, A. anamensis, deriving its name from the Turkana word anam, meaning "lake".

 References 

Category:Australopithecines