moore2moore
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I've posted it before: the "science" behind so-called "admixture calculators" can't yet be called that. The validity of the output data is getting there, and will get there eventually, but it's not quite sufficient so that we can call the extant methods, "scientific."
In other words, the calculators exist primarily for fun. They can help identify heritage from a continent very well. And they can give a sense to adopted children of their heritage.
But those who impart precision, science, or much else into the results of calculators are charlatans, and we should all be very wary of such people.
Now comes a study in Genome Biology and Evolution. It turns out that certain alleles on certain segments of the human genome will tie Chinese and Japanese with people from Kenya and Nigeria.
I hope you realize the significance of that statement. If a "calculator" was based in whole or in part on those markers, it would produce a result indicating recent admixture between two populations that haven't mixed for millennia. It might tell a Nigerian that she was part Japanese.
Other similar segments will tie Southern Europeans to Africans. Board posters regularly assume that those would be valid, with little inquiry into methods. That is a sort of confirmation bias toward preconceived notions.
With that in mind, here are the three questions the community must ask of people who rely on a "science" that is still not quite ready for prime time.
1. If a calculator produces such a misleading result with one population, how can you trust it generally? In other words, if a calculator's programmer chooses, as a subjective human, to use the markers that tell a Nigerian she is Japanese, then how can we trust the other markers that this subjective human also chose? Because there is a more plausible connection within pop culture?
2. If 30 different calculators produce 30 different results, which 29 are wrong? Would we trust thermometers that produced such widely disparate results?
3. What is the time frame a calculator purports to predict? Modern, 500 years ago, 2000 years ago, Neolithic, Paleolithic? If a calculator tells a Brit that she is 12.5% "Middle Eastern," does that mean gramma cheated on grandpa? Does it mean a colonial came to England in the 1700s? That a Roman-era soldier settled in her town from the Middle East?
Or does it simply tell her that she is European, and that a certain percentage of European genes came from Middle-Eastern-like Early Farmers? (DUH).
There is a big difference.
There is little value in telling us that human populations all converge as you go farther back in time.
In other words, the calculators exist primarily for fun. They can help identify heritage from a continent very well. And they can give a sense to adopted children of their heritage.
But those who impart precision, science, or much else into the results of calculators are charlatans, and we should all be very wary of such people.
Now comes a study in Genome Biology and Evolution. It turns out that certain alleles on certain segments of the human genome will tie Chinese and Japanese with people from Kenya and Nigeria.
I hope you realize the significance of that statement. If a "calculator" was based in whole or in part on those markers, it would produce a result indicating recent admixture between two populations that haven't mixed for millennia. It might tell a Nigerian that she was part Japanese.
Other similar segments will tie Southern Europeans to Africans. Board posters regularly assume that those would be valid, with little inquiry into methods. That is a sort of confirmation bias toward preconceived notions.
With that in mind, here are the three questions the community must ask of people who rely on a "science" that is still not quite ready for prime time.
1. If a calculator produces such a misleading result with one population, how can you trust it generally? In other words, if a calculator's programmer chooses, as a subjective human, to use the markers that tell a Nigerian she is Japanese, then how can we trust the other markers that this subjective human also chose? Because there is a more plausible connection within pop culture?
2. If 30 different calculators produce 30 different results, which 29 are wrong? Would we trust thermometers that produced such widely disparate results?
3. What is the time frame a calculator purports to predict? Modern, 500 years ago, 2000 years ago, Neolithic, Paleolithic? If a calculator tells a Brit that she is 12.5% "Middle Eastern," does that mean gramma cheated on grandpa? Does it mean a colonial came to England in the 1700s? That a Roman-era soldier settled in her town from the Middle East?
Or does it simply tell her that she is European, and that a certain percentage of European genes came from Middle-Eastern-like Early Farmers? (DUH).
There is a big difference.
There is little value in telling us that human populations all converge as you go farther back in time.