400,000-Year-Old Tooth in China Reveals Link Between Homo erectus, Denisovans and Modern Humans

Homo erectus skull. Credit: Emőke Dénes / CC BY-SA 4.0

Ancient proteins extracted from a 400,000-year-old bony person connected 3 chapters of quality prehistory successful a azygous study. Researchers identified molecular grounds linking Homo erectus successful China to the Denisovans and, done them, to modern humans surviving today.

The squad analyzed enamel proteins from six Homo erectus teeth recovered from 3 Chinese sites: Zhoukoudian successful bluish China, Hexian successful the south, and Sunjiadong successful cardinal China.

Researchers besides included a bony from the Harbin skull, a known Denisovan specimen from northeastern China. All six Homo erectus specimens day to astir 400,000 years ago, and 5 were identified arsenic antheral portion 1 was female.

Six teeth, 3 sites, and a uncommon molecular find

Two macromolecule variants stood out. The first, AMBN(A253G), has ne'er been detected successful immoderate different quality oregon primate species. It was absent successful Neanderthals, Denisovans, modern humans, and adjacent different Homo erectus specimens from Dmanisi successful Georgia and Atapuerca successful Spain.

Its beingness crossed each six specimens from 3 geographically abstracted sites suggests it was circumstantial to this peculiar radical of East Asian Homo erectus.

Samples of the Middle Pleistocene H. erectus teeth. Credit: Qiaomei Fu / CC BY-NC-ND 4.0

The 2nd variant, AMBN(M273V), carries bigger evolutionary implications. Researchers already knew this variant existed successful Denisovans. Its beingness successful each six Homo erectus specimens present points to these past humans arsenic the apt archetypal source.

Earlier Denisovan specimens, including Harbin and a astir 200,000-year-old idiosyncratic called Denisova 25, carried this variant successful a mixed form, meaning lone immoderate copies of their DNA had it. Later, Denisovans carried it exclusively.

Fu and colleagues accidental this signifier suggests the variant entered Denisovan populations gradually done interaction with groups related to these Middle Pleistocene Homo erectus.

The bony that puts homo erectus among the Denisovans

Previous genomic probe had already shown that Denisovans received betwixt 0.5 and 8 percent of their DNA from an older, unidentified quality lineage whose ancestors divided from the main quality household histrion much than 1 cardinal years ago. The researchers present place Homo erectus arsenic the astir apt campaigner for that chartless lineage.

Fossil grounds from Hualongdong hints astatine humans and Homo erectus interbreeding. Credit: Bas Kers (NL) / CC BY-NC-SA 2.0

Around 15 percent of that ancient DNA aboriginal passed from Denisovans into modern quality populations crossed Asia and Oceania. Today, the variant appears successful 21 percent of radical successful the Philippines, and astatine little frequencies successful India and Papua New Guinea.

The timing besides fits. Denisovans are believed to person divided from Neanderthals betwixt 380,000 and 470,000 years ago, astir the aforesaid play erstwhile these Homo erectus individuals lived crossed China.

Shared geography and overlapping timelines made enactment betwixt the 2 groups not lone plausible but present molecularly supported. The study, published successful Nature, was led by Qiaomei Fu of the Chinese Academy of Sciences successful Beijing.