Oldest Human DNA Brings Surprises
December 8, 2013
The most ancient human DNA ever recovered has been obtained from a 400,000-year-old fossil thighbone excavated in Spain, European scientists have announced. The bone was found at the Sima de los Huesos cave in the Atapuerca Mountains near Burgos. The DNA recovered from this fossil is, by far, the most ancient genetic material ever obtained from a human ancestor. However, instead of providing answers about the relationships among early human ancestors, the DNA seems to have raised more questions than ever.
In the 1990’s, anthropologists working at the cave site excavated the fossilized remains of more than 30 individuals, including several skulls and examples of most other parts of the skeleton. This cave is known as Sima de los Huesos (Pit of the Bones) because the fossils were found in a shaft about 43 feet (13 meters) deep in the back of the cave. The fossil bones are smilar in many ways to the bones of Neandertals, the physically distinct prehistoric people who lived in Ice Age Europe and central Asia from about 150,000 years ago. Scientists think that the Sima de los Huesos fossils represent the distant ancestors of Neandertals. The scientists had hoped this ancient DNA would help them confirm a suspected evolutionary relationship between the Atapuerca population and the Neandertals.
Upon analyzing the DNA from the Atapuerca fossil, however, the scientists were surprised to see that it did not resemble Neandertal DNA at all. Instead, the Atapuerca DNA was more like that of the mysterious Denisovans, a population that lived about 50,000 years ago in Asia–around the time the last Neandertals roamed Europe. The Denisovans are known only from a handful of fossil remains found in the 2000′s at Denisova Cave, in the Altai Mountains of southern Siberia. Scientists identified the Denisovans as a unique prehistoric human population through DNA analysis alone. Without more fossils, the appearance and lifestyle of the Denisovans remains an intriguing mystery.
The fossil DNA from Sima de los Huesos adds to a growing body of evidence showing that interactions between prehistoric human populations were more frequent and more complicated than the evidence from fossils alone suggests. Denisovan genetic material differs markedly from that of Neandertals. This suggests that the two populations had lived apart for thousands of years. Some scientists now speculate that the Sima de los Huesos DNA may represent a common ancestor of both Denisovans and Neandertals. Although the Denisovans and Neandertals died out, some of their DNA persists among living human populations today. This indicates that ancient human populations met, interacted, and interbred with physically modern humans at some time in the distant past.
Additional World Book articles:
- Atapuerca fossil site
- Cave dwellers
- Dmanisi fossil site
- Homo erectus
- Anthropology (2010) (a Back in Time story)