Researchers are suggesting how allergies such as hay fever can be traced back to pre-historic origins, more specifically to extinct Neanderthal ancestors, when allergies first afflicted humans. 

More than ten thousand years ago, modern humans along with Neanderthals and the Denisovans interbred with one another and introduced new genetic variations that improved humans' immune systems however, this also had an unfortunate effect of leading some of  us more prone to allergies, according to this new study.

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After migrating out of Africa, these early modern humans have interacted and interbred with other species of ancient humans dwelling in Europe and Western Asia. The result of this interbreeding led to one to six percent of the modern Eurasian genome to to originate from the Neanderthals and Denisovans.

Scientists now think that the evolution of the Neanderthal DNA from this interbreeding have significantly improved and helped the immune system to adapt and provide a defense system from pathogens.

According to co-author of the study, Michael Dannemann from the Max Planck Institute for Evolutionary Anthropology in Germany, this new evidence is suggesting that this genetic region is pivotal in the contribution of significantly improving the immune system of modern day humans.

However, this genetic inheritance from the Neanderthals can also have some side effects to the modern human immune system, leading to some people more prone to allergies, as further research will be crucial in order to investigate a link.

In a second study, researchers reveal new findings about how there are more Neanderthal DNA still present in modern day humans than previously known.

Apparently, immunity genes of modern day humans also contain more Neanderthal origins as opposed to the rest of the human genome. According to co-author of the study, Lluis Quintana-Murci from the Institut Pasteur in Paris, a huge surprise was this specific region where this immunity gene comes from, also possessing a high Neanderthal ancestry, as this reveals a major biological relevance in pathogen resistance and survival of the host against it.

This new study also highlights the importance of introgression events where genes pass on and move among species, that evolved the immune system in modern day humans.

According to researcher Janet Kelso of the Max Planck Institute, how this ancient DNA was retained in the modern genome also makes sense. She explains that Neanderthals lived in Europe and Western Asia for almost 200,000 years and when modern humans arrived to the region, the Neanderthals were already adapted to local food, climate and pathogens. This interbreeding then paved way for modern humans in gaining advantages when it comes t adaptations. 

These studies are published in the journal, The American Journal of Human Genetics.