The discovery of viral DNA in 50,000-year-old Neanderthal bones found in the Sakirskaya Cave in Russia has brought new insight into the extinction of the Neanderthals. The discovery could support the theory that Neanderthals suffered from viral infections, which, although proposed in 2010, is only now beginning to receive more concrete evidence.
Marcelo Briones, a molecular biologist, and Renata Ferreira, an evolutionary geneticist at the Federal University of São Paulo in Brazil, led a team that analyzed DNA from the bones of two Neanderthals. Experts found DNA fragments from three viruses that still infect modern humans today: adenovirus, herpesvirus and papillomavirus. These viruses are known to cause colds, cold sores and genital warts respectively.
The theory that infectious diseases may have caused the extinction of Neanderthals is based on signals found in viral and bacterial genomes that suggest modern humans carried pathogens from Africa to Europe. Mathematical models have been used to simulate how diseases might spread, taking into account differences in immunity between Homo sapiens and Neanderthal species.
However, direct evidence has been limited until now due to the difficulty of extracting and sequencing ancient DNA that has been fragmented for thousands of years. Research by Briones and Ferreira’s team showed that traces of viral DNA could be detected in Neanderthal remains, representing a significant advance. This discovery was preceded by the identification of 31,000-year-old herpesvirus DNA found in the teeth of Homo sapiens in Siberia.
Despite these promising findings, the researchers stress that the results are preliminary. DNA fragments only point to the presence of viruses in Neanderthals and the study has yet to be peer-reviewed.
In addition to viral infections, several theories have been proposed to explain the extinction of the Neanderthals. Some experts suggest that sudden environmental changes or competition with modern humans for resources may have played a role. However, these theories have been called into question as more evidence emerges of Neanderthals’ abilities as hunters, fire users, and social beings.
Other hypotheses include that small populations of Neanderthals disappeared over time, or that humans living in large groups benefited from greater genetic and cultural diversity, which gave them an advantage.
“Probably, a combination of these factors, along with others that are still unknown, contributed to the eventual extinction of the Neanderthals,” Ferreira and colleagues agree.
Investigation Available on the preprint server bioRxivand is awaiting formal scientific evaluation.