Oldest Ever Human Genetic Evidence Clarifies Dispute Over Our Ancestors

(CN) — Researchers have made new discoveries about the earliest history of humanity’s family tree, thanks to a brand-new research technique and an 800,000-year-old tooth.

In a study published Wednesday in Nature, scientists from the University of Copenhagen reveal a new research method that allows them to study some of the earliest genetic histories of humanity. Using this new method, they studied in deep detail a roughly 800,000-year-old dental fossil from the Gran Dolina cave site in Sierra de Atapuerca, Spain, and learned some interesting truths about humanity’s ancient and sprawling family tree.

Reconstruction of Homo antecessor skull (Museu d’Arqueologia de Catalunya, Barcelona, Spain)

The discoveries center around Homo antecessor, an ancient human species believed to have thrived largely during the Old Stone Age. Homo antecessor is widely viewed as an integral part to humanity’s early family tree, but its exact placement and connections with other human species, such as Neanderthals and Denisovans, has never been fully explained.

Wednesday’s study, however, helps to fill in much of those gaps.

Using a chemical analysis method known as paleoproteomics, researchers examined the proteins found within the enamel of the 800,000-year-old dental fossil. After sequencing and breaking apart the chemical data, scientists found the Homo antecessor was much more closely related to early modern humans than previously believed.

Rather than some distantly connected human group, Homo antecessorcarried strong genetic relations with other early humans including homo sapiens. These connections are so strong, researchers say, that Homo antecessorwas essentially a type of sister group to our ancestors, one that is genetically intertwined with ancestral footprint of humanity.

 José María Bermúdez de Castro, scientific co-director of the excavations in Atapuerca and co-corresponding author on the study, said that with more details emerging on Homo antecessor, the more apparent it becomes that they are a group deeply connected to humankind’s family tree.

“I am happy that the protein study provides evidence that the Homo antecessor species may be closely related to the last common ancestor of Homo sapiens, Neanderthals, and Denisovans,” de Castro said with the release of the study. “The features shared by Homo antecessor with these hominins clearly appeared much earlier than previously thought. Homo antecessor would therefore be a basal species of the emerging humanity formed by Neanderthals, Denisovans, and modern humans.”

These new connections are significant breakthroughs for those looking to better understand the complicated tapestry that is human evolution. Considering that the ancestral chain between humans and chimpanzee diverged several million years ago, anthropologists have long sought to piece together the most detailed picture possible on the long and complex web that is humankind’s genetic past.

Frido Welker, first author and a postdoctoral research fellow at the Globe Institute, University of Copenhagen, says one of the biggest takeaways from this research is that it proves just how extensive and far-reaching these scientific efforts have become, and that the new methods used by this study can be incredibly successful.

“The single biggest lesson we learn here is that it is possible to analyze ancient hominin proteomes up to 2 million years old,” Welker said in an email. “This is significantly older than any previously published genome/proteome of a hominin species. We demonstrate we can use such ancient proteomes to resolve the evolutionary relationships of ancient hominins through molecular analysis directly.”

Researchers are hopeful this effort is only the beginning in what could be a bright future for paleoproteomics. Using this research effort as a foundation, the study encourages other scientists to explore more of the countless unanswered questions regarding the homo genus and to continue unraveling the mysteries surrounding humanity’s earliest family history.

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