As far as I know they have, but then there's that tendency for scientists/evos to declare that anything that could possibly be used to disprove the ToE is "not science" before hand and therefore is not admissible as evidence.
I've seen too many evos on this forum challenge creationists to that very thing, find evidence to disprove evo, and then laugh and say *if that's possible*.
The mindset is that if it supports evo, it's science, and it it doesn't, it's not really science so it doesn't count.
Automatically writing off anything that would make it look bad is intellectually dishonest. It merely reinforces the observation made by non-evos of .... No dissent allowed.
You're assuming they have but you don't know for sure, and you're basing your assesment of the situation on that assumption.