For those of you who have decided to have genetic testing done to determine your likelihood of certain diseases, please read this article. The study of genetics is amazing, but the truth is that no one really knows what most of those genes do. There are still way too many ‘holes in our knowledge’ that need to be filled in.
http://www.forbes.com/sites/stevensalzberg/2015/05/31/17-of-our-genetic-knowledge-is-wrong/
The now extinct animals that were hunted at the Ravidim site in Israel came from a culture archaeologists call Acheulian, and are famous for their hand axes–a prehistoric Swiss Army knife that could perform many tasks. Would have loved to have seen a Straight-tusk elephant, but species change over time. To adapt to environmental stresses like climate change, species hybridize, pulling the genes they need to survive from other species. This may be happening today with bison and cattle. As the climate warms, bison seem to be selecting for certain cattle genes. There is some evidence to suggest this natural selection favors smaller bison, which probably would be adaptive in a warmer world. Smaller bison would consume less resources and have a greater chance of survival when the grasses they need to survive get scarce. Such a diminution of bison size occurred at the end of Pleistocene Ice Age, as well. Of course, we won’t know if the cattle genes in bison helped them 
adapt to a changing climate for around 10,000 years.
http://www.sci-news.com/archaeology/science-stone-tools-butchered-elephant-bones-revadim-israel-02620.html