Are Irish Caucasian

Why human "races" are a made up construct

"Genetics shows that intermingling and displacement have occurred over and over again, and that our ideas about previous 'race structures' were almost always wrong," says David Reich, a paleogeneticist at Harvard University. There are no fixed characteristics associated with specific geographic locations, says Reich. For as often as isolation has created differences between the groups, migration and mixing have blurred or wiped them out again.

Today skin color is very variable all over the world. A large part of the differences are related to latitude. Close to the equator, the abundance of sunlight makes dark skin a useful shield against ultraviolet radiation. Towards the pole, where the problem is more of a lack of sun, lighter skin favors vitamin D production. Multiple genes work together to determine skin tone, and different groups of people can have any number of combinations of different adaptations.

Among Africans, some people, such as the Mursi in Ethiopia, have particularly dark skin. Others like the Khoisan have a more copper-colored skin. The researchers were surprised that many dark-skinned East Africans have the light-skinned variant of SLC24A5. (As in Europe, it appears to have been brought in from the Middle East in Africa.) For their part, East Asians are generally fair-skinned but have the dark-skinned version of the gene. Cheng tried to find out why that is with the help of zebrafish. “It's not easy,” he says.

Why the outside is so often deceptive

When people speak of race, it usually seems to refer to skin color - but at the same time more than that. This is the legacy of people like Morton, who developed the "science of race" according to his own prejudices - and the legacy itself Science completely misunderstood it. Research tells us today that the visible differences between supposed “races” are nothing more than historical coincidences. They reflect how our ancestors handled solar radiation - and not much more.

"We often get the idea that if I know the color of your skin, I'll know X, Y, and Z about you," says Heather Norton, a molecular anthropologist at the University of Cincinnati who studies pigmentation. "That's why I think it can be very effective to explain to people: All these differences that we see only result from the fact that I have an A in my genome and they have a G."