Oldest African DNA: 50,000-Year-Old Antelope Tooth Shatters Record

Researchers have successfully extracted DNA from a 50,000-year-old antelope tooth discovered in South Africa, setting a new benchmark for the oldest genetic material recovered from sub-Saharan Africa. This groundbreaking finding challenges previous assumptions about DNA preservation in the region, suggesting that genetic material can persist for tens of thousands of years despite the typically harsh, hot climate.

For years, the warm temperatures prevalent across much of sub-Saharan Africa have been considered detrimental to DNA preservation, hindering scientists' ability to study the evolutionary history of countless species, including early human ancestors. While ancient human DNA has been found in cooler climates, such as the approximately 400,000-year-old remains from Spain's Sima de los Huesos, the oldest human DNA previously recovered from sub-Saharan Africa dated back only about 18,000 years. The oldest animal DNA from the region was a mere 9,300 years old.

This new study, published on May 27 in Quaternary Science Reviews, aimed to determine if DNA could be extracted from even older skeletal remains. The research team analyzed over 300 animal teeth, some dating back as far as 110,000 years. They discovered that minuscule amounts of DNA were indeed identifiable in specimens from the Late Pleistocene epoch, the later part of the last ice age. The study successfully extracted DNA from numerous Holocene bovid specimens less than 11,700 years old, and crucially, from four Late Pleistocene bovid specimens aged between 12,000 and 50,000 years.

Ancient DNA Offers New Evolutionary Insights

While many of the tested teeth yielded no usable genetic material, a select few proved to be invaluable. The oldest DNA sample, recovered from a partial molar of a mountain reedbuck (Redunca fulvorufula) found in Boomplaas Cave, South Africa, is approximately 50,000 years old. Additionally, the team identified DNA from three extinct long-horned buffalos (Syncerus antiquus), two of which lived 21,000 years ago, and one that died 12,000 years ago.

"The 50,000-year-old DNA is exciting," stated Deon de Jager, a paleogenomics expert at the University of Copenhagen and lead author of the study. "But I am myself skeptical of it, for two reasons." De Jager elaborated that the reedbuck DNA's age significantly surpasses that of the next oldest sample, the long-horned buffalo. Furthermore, the reedbuck specimen showed signs of human DNA contamination, which the researchers managed to filter out. These factors mean the 50,000-year-old finding, while promising, requires further validation. However, subsequent to the study's publication, the researchers successfully sequenced the genome of a 42,000-year-old wildebeest from Ethiopia, further reinforcing the idea that DNA can survive much longer in African climates than previously assumed.

"There is of course a limit to DNA preservation in Africa, but what it is, is not clear," de Jager commented. "There are certainly parts of Africa where DNA will be preserved even better than from the sites we have surveyed. Deep caves with stable, low temperatures will certainly be good candidates, but also high-elevation sites where temperatures have been very low for a long time." The limited DNA recovered from the Late Pleistocene teeth is still sufficient for identifying evolutionary lineages, according to de Jager. If enough data can be collected, scientists may be able to investigate gene flow and interbreeding patterns among ancient species and populations.

While these results open avenues for understanding animal and human evolution in South Africa over the past 40,000 to 50,000 years, the prospect of extracting DNA from much older hominin species, such as *Homo naledi* (extinct around 240,000 years ago) or *Paranthropus robustus* (died out around 1 million years ago), remains extremely challenging. "I think the chances of obtaining DNA from Homo naledi are very, very low, unfortunately," de Jager admitted. "One would have to get very lucky with an incredibly well-preserved skull with the petrous bone still present, which is the best bone for obtaining ancient DNA. To get DNA from something in Africa nearly 1 million years old would probably be impossible, as the conditions in Africa are just too harsh." This discovery pushes the boundaries of paleogenetics and offers a hopeful outlook for uncovering deeper evolutionary secrets hidden within Africa's ancient landscapes.