50,000-Year-Old Neanderthal Remains Reveal Oldest Human Viruses

Analysis of 50,000-year-old Neanderthal skeletal remains found two years ago in Russia’s Chagyrskaya Cave has revealed fascinating genetic data. Genetic material from three prevalent viruses affecting humans today was discovered: adenovirus (which causes cold symptoms), herpesvirus (associated with cold sores) and papillomavirus (known for genital warts and cancer).

These discoveries mark the oldest human viruses ever found, surpassing a 31,000-year-old virus identified in Homo sapiens teeth from northeastern Siberia. The research was conducted by Marcelo Briones and his team at the Federal University of São Paulo. They have published this groundbreaking research in the latest edition of the journal bioRxiv .

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Briones emphasizes that comparing the ancient viral genetic sequences with their modern counterparts has ruled out the possibility of contamination by contemporary humans or predators who may have interacted with the remains. This opens the door to possible synthesis and laboratory testing of these ancient viruses in modern human cells.

“These Jurassic Park-like viruses could be studied for their reproductive and pathogenic traits and compared to their present-day counterparts,” Briones, lead author of the study, told NewScientist .

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The extinction of our closest evolutionary relatives, the Neanderthals, remains a compelling mystery in anthropology. While factors such as climate change and increased competition from Homo sapiens are often cited, an important aspect that is often overlooked is the role of disease.

In this most recent discovery, the presence of viruses such as adenoviruses, herpesviruses, and papillomaviruses suggests that Neanderthals likely faced health challenges similar to those of modern humans. Adenoviruses, for example, can cause illnesses such as the common cold and gastroenteritis, while herpesviruses are associated with conditions such as mononucleosis and multiple sclerosis. Additionally, papillomaviruses are known for their connection to cervical cancer.

Human papillomavirus (HPV) is the most common virus infecting the reproductive tract, and cervical cancer is by far the most common disease caused by it. ( www.scientificanimations.com/CC BY -SA 4.0 )

This finding raises the possibility that Neanderthals may have been particularly vulnerable to these viruses.

However, concerns about contamination in paleogenetics are valid. In this study, the researchers took precautions to ensure the reliability of their findings, comparing ancient viral sequences with modern ones to rule out contamination. The absence of matches between ancient and recent viral strains reinforces confidence in the authenticity of the viruses discovered in Neanderthal remains.

Pathogen exchange: between Homo Sapiens and Neanderthals

Given the close genetic relationship between Homo sapiens and Neanderthals, evidenced by interbreeding that resulted in approximately 2% of DNA in individuals of European or Asian descent being of Neanderthal origin, it is plausible to consider the exchange of pathogens, including viruses, between these two human species, ZME Science reports .

It is reasonable to speculate that encounters between Homo sapiens and Neanderthals could have facilitated disease transmission. This hypothesis is supported by the ease with which humans can transmit diseases to chimpanzees, our closest living relatives.

It is therefore conceivable that interactions between Homo sapiens and Neanderthals involved the exchange of diverse pathogens, potentially including viruses, contributing to the complex dynamics of health and disease in prehistoric human populations.

A 2021 study published in PLOS Pathogens also found that the human papillomavirus was likely passed from Neanderthals to Homo sapiens.

The interaction between Neanderthals and modern humans probably facilitated the transmission of viruses. ( AkuAku /Adobe Stock)

Misperception: Clinging to the evidence

Since the study of ancient viruses remains an emerging field requiring further exploration, current methods used to authenticate ancient DNA results from humans may not be directly applicable to viruses due to their inherently shorter DNA strands.

Briones has expressed skepticism about the feasibility and goal of reviving ancient viruses. She points to the challenges involved, including an incomplete understanding of how viruses’ DNA is damaged and reconstructing fragmented pieces into a complete viral genome. She also concluded by emphasizing the importance of considering interactions between the virus and the host, particularly in a markedly different environment.

It would be fair to say that the findings were expected, given that modern humans typically experience around 10 diseases over their lifetime, implying a likelihood of viral infections among these ancient ancestors. Among the group of nine individuals studied, genetic analyses revealed familial relationships, with two identified as a daughter and her father, and the father linked to two other men, who potentially shared a common grandmother.

The group, which spans various ages from children to adults, are believed to have died simultaneously, although the cause of their death is unknown as there are no signs of burial. These recent discoveries are expected to provide further insight into the factors that contributed to the extinction of the Neanderthals approximately 40,000 years ago.