The latest research shows that Europeans split off from Africans around 80,000 years ago. All non-Africans have around 2% Neanderthal (an archaic human type which survived for around 400,000 years and died out in most places about 40,000 years ago – surviving the longest in Gibraltar) DNA, which is where Europeans get the trait for our light skin pigmentation – an adaptation which helped in the colder climates outside of Africa. The contribution is equal to having a Neanderthal ancestor six generations ago. But the impact is spread in small pieces throughout our DNA, whereas if we actually had a Neanderthal ancestor six generations ago the impact could be seen in larger bunches. Also, since we all (non-Africans) have this ancestry its impact isn’t being diminished with each generation.
Pacific Islanders have twice as much archaic DNA as we do but over half of theirs comes from Denisovans, another archaic human group which also interbred with Neanderthals. Only Asians (and their American Indian descendents) and Pacific Islanders have this ancestry. Much of the archaic mixing had negative effects (contributing to allergies, diseases and even reproduction problems), science shows, but there were occasional positive results. For example, the Tibetans apparently gained their ability to live at very high altitudes with little oxygen from their Denisovan ancestry. Chinese have a little Denisovan ancestry and Europeans have none.
It is now relatively easy to detect archaic human DNA and to map it out and show on average which races got what and how it affected them. There are other archaic human contributions at the trace level which scientists are working to be able to better identify. Of course, the differences between the races today and the extinct archaic human types are very small. But it takes tiny differences to matter greatly when it comes to DNA. Remember that humans and chimps share 99.8% of the same DNA – and most of what we are comes from our inherited genetics. Nature > nurture, in other words.
If you are interested in this subject don’t miss the following presentation by Dr. Svante Pääbo, a Swedish biologist and researcher who is a leader in the field of evolutionary anthropology.