Scientists have extracted DNA from a 50,000-year-old antelope tooth, setting a new record for the oldest genetic material ever found in sub-Saharan Africa, new research published on Monday, May 27, revealed. The discovery expands understanding of the durability of DNA in hot climates.
This discovery indicates that DNA can be preserved for tens of thousands of years in sub-Saharan Africa. Previously, the region’s hot climate was considered a limiting factor, which degraded the molecule and made it difficult to study the evolution of several species, including human ancestors, which makes this finding crucial for paleogenomics on the continent.
While other areas, such as Sima de los Huesos in Spain, are known for preserving ancient human DNA for up to 400,000 years, the African climate presented greater challenges. Until then, the oldest human DNA in Sub-Saharan Africa dated back 18,000 years (Tanzania) and animal DNA, just 9,300 years ago (South Africa).
Research evaluated hundreds of teeth to find ancient genetic traces
For the new investigation, scientists sought to determine whether it was feasible to extract DNA from even older skeletons. Analyzing more than 300 teeth from animals up to 110,000 years old, they identified traces of DNA even in remains from the Late Pleistocene, the final period of the last ice age.
Published in the journal Quaternary Science Reviews, the research details the extraction of DNA from dozens of bovids from the Holocene (less than 11,700 years old) and four from the Late Pleistocene (between 12,000 and 50,000 years old). Although many teeth did not contain genetic material, some did. The oldest DNA was taken from a partial molar of an African antelope, the mountain redunca (Redunca fulvorufula), found in Boomplaas Cave in southern South Africa. Other samples included three extinct long-horned buffaloes (Syncerus antiquus), dated between 12,000 and 21,000 years old.
Expert expresses cautious skepticism about older sample
Deon de Jager, lead author of the study and a paleogenomicist at the University of Copenhagen, described the 50,000-year-old DNA as “exciting.” However, he expressed initial “skepticism” for two reasons.
De Jager clarified that the DNA of the reedbuck was much older than that of long-horned buffaloes and had contamination with human DNA, which was removed. These factors made the initial result not entirely conclusive. However, since the study’s publication, scientists have sequenced the genome of a 42,000-year-old wildebeest in Ethiopia, reinforcing the idea that DNA can persist much longer in the African climate than previously imagined.
Limits and future possibilities for the preservation of genetic material
“There is a limit to DNA preservation in Africa, but it is not yet clear,” said De Jager. He added that other regions of the continent may present even better conditions for genetic conservation. Locations such as deep caves with low, stable temperatures, and high-altitude areas with long periods of cold, are considered good candidates for future searches.
The Late Pleistocene teeth examined by De Jager’s team revealed very low amounts of DNA. Although it is estimated that the genetic material has a half-life of 521 years (losing half each period), the small amount found is still significant, as the researcher pointed out.
De Jager highlighted that DNA is sufficient to identify evolutionary lineages. With data in adequate volume, researchers will be able to compare gene flow and crossings between different species and populations.
Challenges in recovering DNA from even older human ancestors
Although these findings open doors to understanding animal and human evolution over the last 40,000 to 50,000 years in South Africa, the recovery of DNA from more distant ancestors is still uncertain. This is the case of species such as Homo naledi, which became extinct around 240,000 years ago, and Paranthropus robustus, which disappeared approximately 1 million years ago.
“The chances of obtaining DNA from Homo naledi are, unfortunately, very low,” commented De Jager. He explained that it would be necessary to find an exceptionally well-preserved skull with the petrosal bone intact, ideal for collecting ancient DNA. Extracting genetic material from samples nearly 1 million years old in Africa is considered “probably impossible” due to the continent’s extreme conditions.
