Don't Humans Adapt Too?

For my last post of the semester, I have more of a question than a post.  Having read and written a little bit on Silent Spring this week, I'm not sure what to do with what seems like an innocuous, but potentially big, question regarding Carson's argument.  To me, it seems she's stating that one reason synthetic pesticides and the like should be strictly regulated, if not banned and destroyed right now, is because poisons "accummulate in the tisssues" and "alter" the "heredity" (8) of living creatures, and in the case of some very adaptable species of insects, this can lead to super-species coming back with a better-equipped immune system and terrorizing us more effectively.  I also get how this creates a demand for the production of even more lethal poisons.  But, this is my question, wouldn't humans adapt to the toxic poisons too?  I mean, shouldn't we be hoping we can adapt, and have adapted, to these poisons?  If insects can and do adapt to these poisons and come back stronger than ever, why can't and don't humans too?  Maybe this is how X-men and -women come into being.  (I'm kidding in that last sentence but, who knows, it could actually lead to a fun and interesting project.)  No, really, I wonder:  if insects adapt to insecticides and pesticides, don't humans adapt too?  And if so, doesn't that potentially lessen or dampen their risk?