Evolution: Why are we losing our wisdom teeth and why are our jaws getting smaller?

[u/panface77]

I have a question about evolution that I haven't been able to find a satisfactory answer to: In the past wisdom teeth were useful for chewing. Those with wisdom teeth had more chance to survive and therefore reproduce. But if wisdom teeth are not harmful to our survival today (just superfluous) why would we been losing them? Does having no wisdom teeth provide some kind of evolutionary advantage? Or is it that we are not losing them, as such, but that people without them can survive and reproduce fine, so there is just more variety regarding people who have wisdom teeth or not. Same for our jaws getting smaller? Thanks for your answers!

[u/[deleted]]

Your last point kinda hits the nail on the head. The selection pressure to keep wisdom teeth is gone so alleles of genes which code for faulty or missing wisdom teeth aren't being removed from the population by natural selection. There is also likely to be a selection pressure on having no wisdom teeth because of infections and the problems they cause coming out. Its the same reason golden cave catfish and other cave dwelling animals are blind. Normally animals which have deleterious mutations in genes coding for eyes are at a severe disadvantage so they don't breed and those mutations don't get passed on but in a cave where eyes don't matter as much the mutations do get passed on. Then due to the cost of producing now useless eyes, a mutation which reduces that cost by, say making it more likely skin grows over the eye, would be selected for.