why do vestigal structures persist in modern organisms??

Answer 1

In evolution, a trait does not simply disappear because it isn't needed anymore. A trait only disappears when it negatively affects the reproduction of the organism.

For example, do people with appendixes reproduce less than people without an appendix? No. There is no selection pressure against having an appendix, so it will persist. This is the case with all vestigial structures.

Answer 2

There is no such thing as a "modern organism."

Vestigal implies that these structures once had a purpose, but there is no evidence that they were ever any different at all.

You see what I mean? They aren't vestigal, they were always that way, and they will always be there.

Answer 3

They persist because they haven't been totally wiped from the organism, for instance, if you were to have a tail then you did not need your tail, it disappears. But however, in vestigal structures, these tails have not completely disappeared, but are disappearing.

Answer 4

evolution is a slow process and humans havaent completely evolved to not needing their vestigial organs