Blame Neanderthals for Your Allergies: How Their Genes Impacted Humans

Neanderthal genes may have given humans an immunity boost, but they also gave them allergies. Scientists have found that when modern humans met Neanderthals in Europe and the species began to interbreed, the exchange left humans with gene variations that may have caused allergies.

"We found that interbreeding with archaic humans-the Neanderthals and Denisovans-has influenced the genetic diversity in present-day genomes at three innate immunity genes belonging to the human Toll-like-receptor family," said Janet Kelso, one of the researchers, in a news release.

Earlier studies have shown that one to six percent of modern Eurasian genomes are inherited from ancient hominins, such as the Neanderthals or Denisovans.

These latest studies, though, highlight the functional importance of this inheritance on Toll-like receptor (TLR) genes-TLR1, TLR6, and TLR10. These TLR genes are expressed on the cell surface, where they detect and respond to components of bacteria, fungi and parasites. These immune receptors are essential for eliciting inflammatory and anti-microbial responses and for activating an adaptive immune response.

The researchers relied on massive amounts of data available on present-day people from the 1000 Genomes Project together with the genome sequences of ancient hominins. The researchers focused on a list of the 1,500 genes known to play a role in the innate immune system. Then, the scientists examined patterns of genetic variation and evolutionary change in the regions relative to the rest of the genome.

The researchers found little change over long periods of time for some innate-immunity genes. Most interesting was to find the TLR1-6-10 cluster was among the genes presenting the highest Neanderthal ancestry in both Europeans and Asians.

"What has emerged from our study as well as from other work on introgression is that interbreeding with archaic humans does indeed have functional implications for modern humans, and that the most obvious consequences have been in shaping our adaptation to our environment-improving how we resist pathogens and metabolize modern foods," said Kelso.

The findings are published in the Journal of Human Genetics.

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