Is Ancient Admixture the same or different from recent when it comes to considering race?

[Stormer99]

For example, Finns are 1/16 Asian. Is it the same or different when determining someone's race if you have someone 1/16 recently mixed with Asian?

[Carlito's Way]

i would like to know also, good thread

[Smeagol]

Different.

[amerinese]

No, I don't think so. Recently-mixed people, the first generation of siblings, come out looking differently. You can see it in many families. This variation continues over many generations. However, selective pressures, if not environmental then social and sexual, will work to homogenize the population over many generations. They may still be 5-10% whatever, but they won't have the same frequency of "throwback"-looking children appearing, as a more recently mixed group with the same level of admixture.

[Stormer99]

Different.

What makes it different?

[Stormer99]

No, I don't think so. Recently-mixed people, the first generation of siblings, come out looking differently. You can see it in many families. This variation continues over many generations. However, selective pressures, if not environmental then social and sexual, will work to homogenize the population over many generations. They may still be 5-10% whatever, but they won't have the same frequency of "throwback"-looking children appearing, as a more recently mixed group with the same level of admixture.

How often does the scenario you described happen?
Also natural selection is at play in a society. Two groups can be genetically similar but look different because different traits were preferred in different societies.

[Smeagol]

What makes it different?

Read what Anthropologique said in the other thread.

[Swearengen]

it's different.

finns share very ancient, "paleo" asian genes with asians.

someone with recent admixture would share modern genes common with modern asian people.

[Prisoner Of Ice]

When it's ancient it's more homogenous. The other problem is that the population of today is not the same in either case as back then so it can get very hard to come up with sense.

The biggest thing to realize is usually something like african % (especially ancient) comes from some other source and basically says not you are 2% african but 20,30, 40, 50% of something completely different.

Plus you can be measuring mixture the other way too, as I am certain is the case for native americans and north euros.

And that's why haplotypes are usually better when looking at populations, autosomals are more useful for individuals.

[amerinese]

How often does the scenario you described happen?

Which scenario? A group of 4 or 5 first-generation mixed children coming out looking different? Often. A group of ex. Mexican Mestizo siblings coming out looking different? Less often, but still often. A homogenized group with ancient admixture, like say post-Neolithic Europeans? A lot less often.



Also natural selection is at play in a society. Two groups can be genetically similar but look different because different traits were preferred in different societies.

Yes, that's basically what I said. Two groups may be "related", say sharing the same two types of ancestry, at basically the same levels, but based on sexual selection, who is successful at reproducing and leaving offspring, certain traits will be selected for.

[Stormer99]

it's different.

finns share very ancient, "paleo" asian genes with asians.

someone with recent admixture would share modern genes common with modern asian people.

Why does it show up the same on DNA tests?

[amerinese]

Why does it show up the same on DNA tests?

For one reason, because autosomal SNP-based DNA tests like 23andMe only test for "Ancestrally Informative Markers", which are a subset of your entire genome, and do not account for all genes that determine ex. your physical appearance. If you had a full genome test, in theory it would find differences.

[Swearengen]

Why does it show up the same on DNA tests?

It's just composition. It doesn't show which genes you actually share.

If you share only very ancient genes, any recently evolved traits (like for example epicanthic fold assuming it was evolved fairly recently) will not exist in that population.

[riverman]

Both. I think it tends to the same however. If the actual admixture is the same, no real reason for differentiation.

[Stormer99]

It's just composition. It doesn't show which genes you actually share.

If you share only very ancient genes, any recently evolved traits (like for example epicanthic fold assuming it was evolved fairly recently) will not exist in that population.

How long would it take it to evolve differently? Also, why does ancient admixture affect clustering if evolution made it different?

[Swearengen]

How long would it take it to evolve differently? Also, why does ancient admixture affect clustering if evolution made it different?

evolution didn't make it different as the ancient DNA survived. But populations with ancient admixture would not share any recently evolved DNA or traits.

I'm not familiar with the science of DNA plots so I'm not sure. As for how long... I'm not sure either. But a few thousand years is more than long enough to significantly change.

[Prisoner Of Ice]

Evolution doesn't enter into it much for modern mixtures. There is selection going on but human agency doesn't count as evolution and that's most of what we see today.