Woolly Mammoth

**The woolly mammoth** (***Mammuthus primigenius***) is an extinct species of mammoth that lived during the Pleistocene until its extinction in the Holocene epoch. It was one of the last in a line of mammoth species, beginning with the African *Mammuthus subplanifrons* in the early Pliocene. The woolly mammoth began to diverge from the steppe mammoth about 800,000 years ago in East Asia. Its closest extant relative is the Asian elephant. The Columbian mammoth (*Mammuthus columbi*) lived alongside the woolly mammoth in North America, and DNA studies show that the two hybridised with each other.

The appearance and behaviour of this species are among the best studied of any prehistoric animal because of the discovery of frozen carcasses in Siberia and North America, as well as skeletons, teeth, stomach contents, dung, and depiction from life in prehistoric cave paintings. Mammoth remains had long been known in Asia before they became known to Europeans in the 17th century. The origin of these remains was long a matter of debate, and often explained as being remains of legendary creatures. The mammoth was identified as an extinct species of elephant by Georges Cuvier in 1796.

The woolly mammoth was roughly the same size as modern African elephants. Males reached shoulder heights between 2.67 and 3.49 m (8.8 and 11.5 ft) and weighed up to 8.2 metric tons (9.0 short tons). Females reached 2.6–2.9 m (8.5–9.5 ft) in shoulder heights and weighed up to 4 metric tons (4.4 short tons). A newborn calf weighed about 90 kg (200 lb). The woolly mammoth was well adapted to the cold environment during the last ice age. It was covered in fur, with an outer covering of long guard hairs and a shorter undercoat. The colour of the coat varied from dark to light. The ears and tail were short to minimise frostbite and heat loss. It had long, curved tusks and four molars, which were replaced six times during the lifetime of an individual. Its behaviour was similar to that of modern elephants, and it used its tusks and trunk for manipulating objects, fighting, and foraging. The diet of the woolly mammoth was mainly grasses and sedges. Individuals could probably reach the age of 60. Its habitat was the mammoth steppe, which stretched across northern Eurasia and North America.

The woolly mammoth coexisted with early humans, who used its bones and tusks for making art, tools, and dwellings, and hunted the species for food. The population of woolly mammoths declined at the end of the Pleistocene, disappearing throughout most of its mainland range, although isolated populations survived on St. Paul Island until 5,600 years ago, on Wrangel Island until 4,000 years ago, and possibly (based on ancient eDNA) in the Yukon up to 5,700 years ago and on the Taymyr Peninsula up to 3,900 years ago. After its extinction, humans continued using its ivory as a raw material, a tradition that continues today. With a genome project for the mammoth completed in 2015, it has been proposed the species could be revived through various means, but none of the methods proposed are yet feasible.

[[null|link=https://en.wikipedia.org/wiki/File:Mammoth\_molars\_compared.jpg%7Cright%7Cthumb%7CComparison between the lower molars of a woolly mammoth (above) and a southern mammoth; note the lower number of enamel ridges in the older species (below)]]
Within six weeks from 2005–2006, three teams of researchers independently assembled mitochondrial genome profiles of the woolly mammoth from ancient DNA, which allowed them to confirm the close evolutionary relationship between mammoths and Asian elephants (*Elephas maximus*). A 2015 DNA review confirmed Asian elephants as the closest living relative of the woolly mammoth. African elephants (*Loxodonta africana*) branched away from this clade around 6 million years ago, close to the time of the similar split between chimpanzees and humans. A 2010 study confirmed these relationships, and suggested the mammoth and Asian elephant lineages diverged 5.8–7.8 million years ago, while African elephants diverged from an earlier common ancestor 6.6–8.8 million years ago.

In 2008, much of the woolly mammoth's chromosomal DNA was mapped. The analysis showed that the woolly mammoth and the African elephant are 98.55% to 99.40% identical. The team mapped the woolly mammoth's nuclear genome sequence by extracting DNA from the hair follicles of both a 20,000-year-old mammoth retrieved from permafrost and another that died 60,000 years ago. In 2012, proteins were confidently identified for the first time, collected from a 43,000-year-old woolly mammoth.

Since many remains of each species of mammoth are known from several localities, reconstructing the evolutionary history of the genus through morphological studies is possible. Mammoth species can be identified from the number of enamel ridges (or lamellar plates) on their molars; primitive species had few ridges, and the number increased gradually as new species evolved to feed on more abrasive food items. The crowns of the teeth became deeper in height and the skulls became taller to accommodate this. At the same time, the skulls became shorter from front to back to minimise the weight of the head. The short and tall skulls of woolly and Columbian mammoths (*Mammuthus columbi*) were the culmination of this process.

The first known members of the genus *Mammuthus* are the African species *Mammuthus subplanifrons* from the Pliocene, and *M. africanavus* from the Pleistocene. The former is thought to be the ancestor of later forms. Mammoths entered Europe around 3 million years ago. The earliest European mammoth has been named *M. rumanus*; it spread across Europe and China. Only its molars are known, which show that it had 8–10 enamel ridges. A population evolved 12–14 ridges, splitting off from and replacing the earlier type, becoming the southern mammoth (*M. meridionalis*) about 2–1.7 million years ago. In turn, this species was replaced by the steppe mammoth (*M. trogontherii*) with 18–20 ridges, which evolved in eastern Asia around 1 million years ago. Mammoths derived from *M. trogontherii* evolved molars with 26 ridges 400,000 years ago in Siberia and became the woolly mammoth. Woolly mammoths entered North America about 100,000 years ago by crossing the Bering Strait.

### Subspecies and hybridisation

https://upload.wikimedia.org/wikipedia/commons/thumb/0/0b/Mammuthus\_primigenius\_fraasi.JPG/167px-Mammuthus\_primigenius\_fraasi.JPG

Cast of an intermediate form between *M. trogontherii* and *M. primigenius*; *M. p. fraasi*, Staatliches Museum für Naturkunde Stuttgart

https://upload.wikimedia.org/wikipedia/commons/thumb/d/da/Mammuthus\_jeffersonii.jpg/167px-Mammuthus\_jeffersonii.jpg

Specimen (formerly assigned to *M. jeffersonii*) suggested to be a hybrid between Columbian and woolly mammoths at the American Museum of Natural History

Individuals and populations showing transitional morphologies between each of the mammoth species are known, and primitive and derivedspecies coexisted until the former disappeared. The different species and their intermediate forms have been termed "chronospecies". Many taxa intermediate between *M. primigenius* and other mammoths have been proposed, but their validity is uncertain; depending on author, they are either considered primitive forms of an advanced species or advanced forms of a primitive species. Distinguishing and determining these intermediate forms has been called one of the most long-lasting and complicated problems in Quaternary palaeontology. Regional and intermediate species and subspecies such as *M. intermedius*, *M. chosaricus*, *M. p. primigenius*, *M. p. jatzkovi*, *M. p. sibiricus*, *M. p. fraasi*, *M. p. leith-adamsi*, *M. p. hydruntinus*, *M. p. astensis*, *M. p. americanus*, *M. p. compressus* and *M. p. alaskensis* have been proposed.

A 2011 genetic study showed that two examined specimens of the Columbian mammoth were grouped within a subclade of woolly mammoths. This suggests that the two populations interbred and produced fertile offspring. A North American type formerly referred to as *M. jeffersonii* may be a hybrid between the two species. A 2015 study suggested that the animals in the range where *M. columbi* and *M. primigenius*overlapped formed a metapopulation of hybrids with varying morphology. It suggested that Eurasian *M. primigenius* had a similar relationship with *M. trogontherii* in areas where their range overlapped.

In 2021, DNA older than a million years was sequenced for the first time, from two mammoth teeth of Early Pleistocene age found in eastern Siberia. One tooth from Adycha (1–1.3 million years old) belonged to a lineage that was ancestral to later woolly mammoths, whereas the other from Krestovka (1.1–1.65 million years old) belonged to new lineage. The study found that half of the ancestry of Columbian mammoths came from relatives of the Krestovka lineage (which probably represented the first mammoths that colonised the Americas) and the other half from the lineage of woolly mammoths, with the hybridisation happening more than 420,000 years ago, during the Middle Pleistocene. Later woolly and Columbian mammoths also interbred occasionally, and mammoth species may have hybridised routinely when brought together by glacial expansion. These findings were the first evidence of hybrid speciation from ancient DNA. The study also found that genetic adaptations to cold environments, such as hair growth and fat deposits, were already present in the steppe mammoth lineage and were not unique to woolly mammoths.