The Organ of Meaning

So, as Carrie and I were listening to the NPR game show “Wait, Wait, Don’t Tell Me” they talked about a chemical that was found on Mars’ surface that they are saying would hinder the chances of finding life there. I don’t know what the chemical is and it doesn’t matter when it comes to my question. I’ve read a couple of articles stating that it would indeed be dangerous for life there and would hinder it’s survival; so here’s my question that I think is rooted relatively well in evolutionary theory:

Wouldn’t life on Mars have evolved in such a way that the substance would either end up being beneficial (at best), guarded against or a non issue (worse)? There are plenty of chemicals and compounds here that can be harmful, but life here uses or just ignores (oxygen, carbon dioxide, etc.) would that not also happen with this specific chemical if life were to occur on Mars?

I think the issue lies in the fact that people who hear these things don’t understand how the evolutionary theory is supposed to work – things evolve to adapt to their environment. Life adapted to Earth’s environment would not be able to hand the compound well, but then again life from Mars might find some other substance that we don’t even think about deadly.

There seems to be one article that I’ve found that at least questions these evaluations as well.