Almost all humans that were born outside Africa have a tiny amount of DNA from some our most distant ancestors: the Neanderthals.
This genetic legacy comes from the interbreeding between Neanderthals and the precursors of the modern humans. But how did the genes survive 40,000 after the Neanderthals faced extinction?
Researchers have discovered that they have a well-established role as they guard us against dangerous infections. Newly found data shows that modern humans encountered some of the most aggressive viruses, for example ancient strains if influenza and herpes and H.I.V. as soon as they left Africa almost 70,000 year ago.
Since Neanderthals had already developed resistance to them, they may have unwillingly contaminated modern humans, which were particularly vulnerable to the infections. Although scientists cannot say for sure if the virus exchange took place, they are exploring the viruses that were involved.
The relationships between the ancestors and Neanderthals became stronger; interbreeding allowed our ancestors to gain immunity to some infections and a better resistance towards other.
An independent source that was not a part of the study notes that the discovery represents a landmark in medical genetics, allowing us to take a look into the medical evolution of our precursors.
Our immune system uses a variety of defensive and aggressive methods in order to protect us from infections, like antibodies and white cells. Researchers where curious to find out if the body also developed ways to prevent the infection in the first place.
Since viruses cannot replicate on their own, they depend on the proteins found in cells. If the proteins adapted in order to prevent the insertion of the viral code, the virus will not spread.
The scientist developed a list of all the proteins found in the human body that were susceptible to viruses. A cross-analysis among several species was also done in order to observe how they changed as time passed.
Neanderthals have reached the other continents long before modern humans, and they had time to develop their immune system. The fact that most of their genes were lost when they disappeared may hint that they were not particularly useful. But those that did may have saved humanity from extinction.