Did infection from human viruses contribute to the demise of Neanderthals 40,000 years ago?

It’s hard picturing the brawny and hardy-looking Neanderthals sniffling because of a cold, let alone dying from some pesky illness. But after successfully existing for longer than modern humans have, something took them down. While climate change and competition from the Homo sapiens are many researchers’ go-to theories to explain their disappearance, there might have been more to their mysterious fading — like disease.

Researchers in Brazil have stumbled upon the oldest human viruses ever found in 50,000-year-old Neanderthal bones! This groundbreaking discovery reignites the question: could tiny, invisible pathogens have played a role in wiping out our close evolutionary cousins?

The team sifted through DNA extracted from Neanderthal remains in Chagyrskaya Cave, Russia. Their target? Traces of three notorious DNA viruses — adenovirus, herpesvirus, and papillomavirus. Remarkably, all three were present, shattering the record for the oldest human viruses ever discovered.

These findings hint that Neanderthals battled some of the same viruses we do today. Adenoviruses can cause the common cold or stomach flu, while herpesviruses include the Epstein-Barr virus, linked to mono or even multiple sclerosis. Papillomaviruses are associated with cervical cancer.

Did this mean that Neanderthals were particularly vulnerable to these viruses?

"We know all primates get infected with viruses and bacteria," explains the lead researcher. Diseases readily jump between species, with a recent study showing chimps in Africa catching antibiotic-resistant bacteria from their human vets.

The close connection between Neanderthals and Homo sapiens adds another layer of intrigue, potentially explaining why the Neanderthal numbers began to dwindle once the humans arrived. We share 2% of our DNA with Neanderthals, suggesting they weren't strangers to swapping things — including diseases. Without immunity and today’s medicines, these viruses could’ve been formidable adverseries to the human ancestors.

While not the sole culprit, these ancient viruses could have been a significant factor in their decline. By unlocking the secrets hidden in their DNA, we're piecing together a more complete picture of our ancestors' lives, and their ultimate extinction. The fight for survival, it seems, extended far beyond the physical realm.

Contamination is a worry in such studies, but the researchers are confident. They compared the ancient viral sequences with modern ones, and none matched recent strains, as per the study’s authors.