10k years isn't a huge amount of time for evolution. If the gene isn't detrimental it will definitely persist in the population that long. It takes a long time

10k years isn't a huge amount of time for evolution. If the gene isn't detrimental it will definitely persist in the population that long. It takes a long time for DNA to completely degrade from accumulated random mutations. We still have genes from our prehuman ancestors that are mostly intact.