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goose966 OP t1_ja0g5w1 wrote

Reply to comment by Sibaron in How do scientists know where the mutation in a gene originated and how long ago the mutation occured? by goose966

Thank you for your response, but I believe my question was not specific enough. What i am curious about concerns the “history” of genetic mutations. For example, it is believed that humans didn’t develop the “dairy-digesting” genetic mutation until about 6000 years ago. How did they come to that conclusion?

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0oSlytho0 t1_ja0nozm wrote

The way they track these mutations in time is by creating a huge family tree and puzzling the way back up. If a group of people is known to have split up e.g. 5000 years ago and none of them have that mutation, it likely occured less than 5000 years ago in the main population. It's not perfect but with enough samples and meta info we can create accurate philogenetic trees.

It also helps a lot that we have found a couple mummified people with intact DNA from different places and points in time.

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Sibaron t1_ja0h8tr wrote

The appearance of new genes can be tracked by sequencing of populations and the appearance of the gene in the population. It involves looking at the specific genes and homology to other conserved genes in a population. Often it also involves tracing migration and behavior of humans in the past. Then you often see a correlation with human migration and settlement in a environment where such a mutation is beneficial.

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