We are completely used to it: plant and animal species are easily many millions of years old. Homo sapiens is relatively young: the oldest real human bones have been dated to about 300,000 years ago (Nature2017). What about our infectious diseases, such as measles? Were Neanderthals already doing that? What did their ‘virus atmosphere’ look like?
Neanderthals lived among such 430,000 and 40,000 years past. They are not ancestors of modern humans: they form a separate, dead-end branch on the hominin family tree. Our last common ancestor is Homo heidelbergensisand we probably went like that 600,000 years ago parted somewhere in Africa – although we sometimes crossed paths afterwards, including in Europe. As a result, it is estimated that about 2 percent of our DNA can be traced back to Neanderthals.
The ‘Neanderthal DNA’ that we carry mainly serves for defense against viruses, American researchers wrote in the magazine in 2018 Cell. That means that humans and Neanderthals probably shared viruses with each other, and that would make sense: if we apparently lived close enough to have children with each other, we must also have exchanged viruses. Which one, the researchers left open.
In any case, not measles, as a German-Belgian study shows in 2020 Science. The measles virus only evolved from a rinderpest virus around the 9th century BC. The virologists discovered this through a family tree study, in which they were able to calculate when the viruses separated from each other based on the known mutation rates of viruses, or the ‘molecular clock’.
This fits the prevailing theory that ‘modern’ infectious diseases such as measles, rubella and mumps, but also bacterial diseases such as whooping cough, typhoid, cholera and tuberculosis, only emerged during the time of agriculture, so roughly in the last ten thousand years. Then people began to live together in greater densities, and what’s more, they lived closely with their farm animals. This made it easier for diseases to jump from animals to humans, adapt to their new hosts and then spread quickly.
Disastrous for indigenous peoples
Hunter-gatherers, like Neanderthals, did not suffer from ‘hotbeds’ of new infectious diseases: they moved around in small groups and did not live very closely with animals.
This also explains why the infectious diseases of the European colonists were so disastrous for the indigenous peoples of the New World and not the other way around: the diseases that the Europeans brought with them were typical ‘agricultural diseases’ to which the local residents had no resistance.
It is still not well known exactly which diseases Neanderthals carried with them. The pathogens themselves have never been found in their old bones; pieces of virus DNA that appeared as ‘by-catch’ in the genomes of Neanderthals (Viruses2024). This involved herpes, adenoviruses and papilloma viruses – very old virus lines that occur in all kinds of animals, as well as in modern humans.
Most likely, Neanderthals also had plenty of parasitic worms and bacterial stomach ulcers. British researchers write this in American Journal of Physical Anthropology (2016). They also state that the range of infectious diseases was very large long before agricultural times. Modern humans are said to have brought all kinds of diseases from Africa that Neanderthals were not resistant to – something that may have contributed to their extinction.
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