Re:Did the early medieval era ever take place?
by walnutclosefarm on Wednesday July 06, 2022 @03:35PM
(#32005734)
Of course. Absent recombination, you'd start having ancestors dropping out after only 5 generations. With recombination, it's a few more. I didn't make the argument that way, because when I have in the past, I get a bunch of "yeah, but ..." rebuttal. In addition to the complicated nature of recombination, there is the additional complication that when you get back 6 to 8 or more generations, the same progenitors generally start appearing in multiple branches of your family tree - sometimes in many, many branches. But it is nevertheless the most correct. We all probably have great, great, great, great, great, great grandparents from whom we have no genetic inheritance at all. Add a couple more greats, and it's a near certainty.
When genes are sexually recombined, they don't recombine randomly per-base pair, they're cut and recombined in big strips. The chromosomes actually only 'snip' in a small number of places.
This means that after a relatively small number of generations, it's quite easy to have no genes at all from one of your ancestors.
I don't recall the exact numbers but it's something like 8-12 generations where you start having serious numbers of ancestors with no genetic connection.