is there some sort of cutoff point where scientists decided “everyone in Ireland 100,000 years ago will be considered 100% Irish”?
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Well, the people who stayed in Africa didn’t encounter any other species.
As a descendent of Europeans, I’m proud to say that someone in my lineage is a Neanderthal fucker. It’s about 4% of our DNA
even humans back then in Africa didn’t have 100% identical DNA. so what is 100% African DNA?
Technically you could say we’re all African or just “Homo Sapien” and not bother to subcategorize from there, it’s really down to semantics and how different you decide the DNA has to be (which is arbitrary). Populations around the globe have been separated for enough time that they’ve developed different traits, reflecting slight genetic differences. Being “Irish” vs. “Canadian” is really more of a socio-political and historical argument, based on how populations have moved around and where political borders have been drawn. Based purely on DNA, it is extremely difficult to delineate distinct groups of people, because humans have always been traveling between populations and sharing DNA between them. But you can get a DNA test and it can tell you “your ancestors probably lived in X, Y, Z places within the last 500 years” or something like that. You can imagine human populations and their associated DNA as lots and lot of circles overlapping each other like thousands of venn diagrams.
As a biologist, I caution that we have to be careful when deciding how DNA separates humans into groups because it gets muddled up with a lot of bad historical arguments for racial categorizations.
It is, effectively, arbitrary. Countries are geographical and social, these things lead to small genetic differences accumulating over time, to the point where you can, sort of, label the ethnicity/race of a person by cross referencing it with the typical genetic differences seen in people of that ancestry compared with other ancestries. There isn’t some precise point that a population of humans became genetically irish or english, companies that do ancestry testing like this have to decide how exactly they draw those lines.
Practically speaking we’re all just humans with minor genetic differences that we ascribe more meaning to than we ought.
Great answer below. I learned something today, that’s a good day.
I would like to share a funny yet sad story. I distant cousin and I were having a discssion about ancestry. He did one of the DNA tests to determine his “heritage.” Let me stop here and say he is one of the most racist people I know. Anyhow, when he told me he is pure scandinavian, 100%, I laughed and said he should ask for his money back. He gave me this curious look and asked why. I told him if he went back far enough he would realize there was some African DNA in his lineage. I really thought his head was going to explode. Needless to say, he doesn’t speak to me any more. Not a bad thing really. I still get a chuckle out of it.
You that that bakes your noodle. We share 50% of our DNA with a banana. Are we half banana or are bananas half human?
The “out of Africa” hypothesis is being somewhat challenged, although challenged is probably too strong a word really we could say it’s being modified and tweaked.
It’s now clear there were breeding events with devisonians and Neanderthals who evolved from homo erectus outside of Africa. I guess you could point to the fact Homo erectus itself evolved in Africa before spreading out but these distinct human species didn’t evolve in Africa.
They contribute a small but important % of human dna so while *most* of our DNA originated in Africa an important part of it does not since this comes from non-African devisonians and Neanderthals.
The difference genetically between an Irish, Japanes or African human is very very small. Vast majority of the genes are the same.
What you are really asking or should be asking is when did the gene that is associated with those cultural groups develop and how does that make us different?
We place a lot of emphasis on looks and this can be a great bias in our thinking.
We do all have 100% African DNA in that sense.
However, those people wandered about. As they did, they broke up into smaller groups. You can imagine a village getting large, then one day someone says “I was out hunting east of here and found a nice place 3 days from here with a nice lake, lots of berries, and good hunting, anyone want to head out there?”
A portion of the village breaks off and wanders away and starts a new village. The new villagers have children with others in the new village. Genetically, the new village is “enriched” in variations of genes carried by the relatively people that founded it. The smaller the founding group, the bigger the effect. It’s inbreeding to a degree.
Think of the tiniest break off group: a single man and woman. If the man has a genetic trait that only appeared in 1 in 500 villagers, when he and his wife leave / are separated, then the gene appears in 1 out of 2 of the people in the new group. If they have children and they mix with their children, you may have thousands of people generations later, and may 1 out of every 2 will have that genetic variant. You can use that to differentiate that group from the parent group, and if you tested a person and found that they had the gene, you could give a good guess whether they came from the break away village or not.
Ancestry tests do that, but look at hundreds of thousands of genetic differences. Computers look for clusters of genetic differences and build a hierarchy of genetic variations that correspond to points in human history where groups split and formed new groups with distinct genetic composition (the smaller, more isolated, and the longer separated the group was, the more pronounced). Sometimes the groups also merged (whereby a new group with a reduced variation occurred).
All you need to do afterwards, then, is look at modern groups and their genetic composition to label the ends of the tree and look at historical movements, and you can place names (places, ethnicities) to all the groups (with varying degrees of accuracy).
You can take an individual, look at the gene variants they have, and compute what groups they are most like and the probability of being from that group. Most importantly, every group can be traced back over time through a series of movements of people all the way to Africa.
I am part of an ancestry that traveled through North Africa, into the Arabian Peninsula, through southern Europe, and eventually to the British isles and Scotland and Ireland.
Race is fiction, dude. It’s some shit we made up back in the old days to help get the public on board for nationalism, which is great for helping governments go to war. Going to war was pretty important in the olden times, not just for protecting yourself, but for getting shit you wanted from people who had it and wouldn’t sell, and also for prestige and making your people feel good about themselves and thus be less likely to kill you.
Race is not a scientific concept. Do not conflate race with genetics or DNA. It’s purely arbitrary. Okay sure, it’s a sociological concept, but sciocology isn’t exactly an actual science per-say. Very soft science. One of the ones that tries to predict human behaviors. But by the hard sciences? Math. Genetics. Physics. That kind of thing. Race is bullshit we made up so leaders could other groups and make their subjects cool with killing them as necessary.
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