When modern humans met Neanderthals in Europe and the two species began interbreeding many thousands of years ago, the exchange left some people more prone to allergies. http://phys.org/news/2016-01-neanderthal-genes-gave-modern-humans.html The discoveries reported in two independent studies in the American Journal of Human Genetics on January 7 add to evidence for an important role for interspecies relations in human evolution and specifically in the evolution of the innate immune system, which serves as the body's first line of defense against infection. http://www.cell.com/ajhg/abstract/S0002-9297(15)00485-1 http://www.cell.com/ajhg/abstract/S0002-9297(15)00486-3
By "first line of defence against infection" you mean the body's moronic idea of "If I kill myself first, the infection can't get me. Who needs oxygen when you have histamine!"
