Genetics

[fwc67]

Do races have different DNA? Caucasian, Spanish, African, Arab, Indian and Japanese? Google says they are close, I am hoping for some more clarity. 

[mistermack]

39 minutes ago, fwc67 said:

Do races have different DNA? Caucasian, Spanish, African, Arab, Indian and Japanese? Google says they are close, I am hoping for some more clarity. 

Everyone has different DNA. Even brothers and sisters. Only identical twins have the same DNA as another human. Races have some tiny differences in DNA, of course they do. That's why an Asian looks different to an African. But the differences are very small, in DNA terms. For example, humans and chimpanzees have between 95 and 99% common dna, depending on how you measure it. So the difference between different human races are absolutely tiny, compared to that.

One interesting thing is that most people have a tiny bit of DNA inherited from Neanderthal people. But people from Sub-Saharan Africa don't. So homo sapiens people interbred with Neanderthals, when they came into contact, as they spread out of Africa, but Africans who stayed put never encountered them.

[CharonY]

45 minutes ago, mistermack said:

So the difference between different human races are absolutely tiny, compared to that.

It is important to note that the difference between groups is not larger than within (and depending on which groups you compare, can be smaller, depending on how diverse a population is).

46 minutes ago, mistermack said:

One interesting thing is that most people have a tiny bit of DNA inherited from Neanderthal people. But people from Sub-Saharan Africa don't. So homo sapiens people interbred with Neanderthals, when they came into contact, as they spread out of Africa, but Africans who stayed put never encountered them.

That is not quite accurate. The original assumption was indeed that that during the spread from Africa to Eurasia folks mingled with Neanderthals, and the back-migration would only contribute a tiny amount into African populations. So the estimates were that Europeans and East Asians have about 1-4% (or something in that order) of Neanderthal DNA, and only a small part of the African population had any or close to none.

However, a series of investigations a few years ago have shown a much higher proportion of Neanderthal DNA in African population (though only about a third of non-African populations). https://doi.org/10.1016/j.cell.2020.01.012

The misidentification of part of the Altai Neanderthal genome has interesting implications on why the East Asian population were (potentially wrongly) associated with a higher Neanderthal proportion than European ones (essentially Neanderthals might have picked up DNA from modern humans based on a failed migration from Africa to the Middle East around 100k years ago and thus resulted in misattribution).