disrupt the environment. Their adaptation to the environment also isn't necessarily the "best" adaptation possible. It is an adaptation that is simply "good enough".
Yea I guess that's a handy advantage of mass extinctions, it does give it a chance to start over. Loss of dinosaurs gave mammals a chance, and mammals we able to evolve to have higher intelligence than dinosaurs. But then again we weren't able to be as big (small human mammals tend to kill off big ponderous ones). So it's all a bit meaningless to say what's better or worse. Maybe with a human extinction something even more "interesting" might replace us.
headaches. A lot of the physical ails of humans are caused by the fact that evolution never starts over, it just twists things around so they will do the job, and keeps on
A lot of those things won't have a significant impact on survival, so they don't really matter. Those problems might have been worse in the past but now they're at a level where we can still reproduce just about as well despite them. It reminds me of a control system where the error is below the sensitivity level or the noise, so it doesn't get corrected.
There's also the issue that "bad" characteristics can just be more strongly expressed forms of good ones - like nature is still oscillating around the optimum. I saw an article on here explaining that people with some schizoid characteristics have a reproductive advantage over normal people, and that stops schizophrenia from being weeded out. There's a similar theory (maybe not well accepted) about male homosexuality - Being more attracted to males helps women reproduce more, but it also means their male children can inherit the same characteristic and it becomes a fault.
