Scientists have got their hands on some genetic information from an 800,000-year-old archaic human species, the oldest genetic information ever retrieved from an ancestor on the human family tree. The findings from the study are already helping the researchers put together pieces of the human story, such as how humans got their “good looks”.
Reporting in the journal Nature today, researchers obtained their insights from an 800,000-year-old tooth belonging to a hominin species known as Homo antecessor found in the Atapuerca Mountains of present-day Spain.
Researchers typically use ancient DNA analysis to study the genetics of ancient humans, animals, and other creatures from the distant past. However, this genetic material degrades over time, meaning it's often impossible to obtain any genetic information from long-extinct species. So, for this new study, the team used a technique known as mass spectrometry. Instead of gathering direct genetic material, the researchers sequenced ancient proteins from the dental enamel, providing them with insights into the genes that made up the ancient hominin’s genetic code.
“The building blocks of proteins are amino acids. Those amino acids are put together in a specific order, a 'sequence', and that order is largely determined by the DNA sequence of the genes in our genomes,” Frido Welker, study author and postdoctoral research fellow at the University of Copenhagen in Denmark, told IFLScience.
“Protein mass spectrometry allows us to 'read' the order of the amino acids of the proteins preserved in these ancient fossils,” they added. “We can then compare those ancient protein sequences with the protein sequences of living organisms (or extinct ones) that either have their genomes sequenced or for which proteomic data is also available.”
Little is known about H. antecessor, and what we do know is full of disagreement and controversy. The archaic human species was first reported in the journal Science in 1997, which described the species as an unusual blend of human-like and primitive features. Although much more ape-like than more recent human ancestors, the species was said to have a surprisingly modern human-like facial structure.
Scientists also don’t know much about H. antecessors’ relationship to other later hominin species. Based on this new research, however, it suggests the species was closely related to the last common ancestor of Homo sapiens, Neanderthals, and Denisovans.
Given all that we know (or can assume) about H. antecessors, the new findings suggest our modern human features actually have a much longer history in the hominin species. Welker explained: “By providing a molecularly-determined estimate of where Homo antecessor is placed in the human family, we now also know that the ‘modern-like’ face of H. antecessor must have arisen earlier in the human family than previously considered."