That's a pretty lame argument. You could say the same thing about eating meat. As hippies have pointed out, meat is an incredibly inefficient use of land, so it's not really a big part of most diets. UK's royal guards were called "beef eaters" because they had the luxury of a diet high in protein. I don't see many Brits (or Americans who decended from Brits) reacting badly to meat.
Turkey is a perfect example of something new. Turkeys are not native to Europe. The first settlers had never seen them before, yet there's no problem eating them.
How can you say the same thing about eating meat? Meat has been around eaten since the dawn of human existence, which occurred about 200,000 years ago. Before that, our ancestors also ate meat.
Earliest evidence of eating peanuts is a mere 10,000 years ago (source:
http://www.eurekalert.org/pub_releases/2007-06/vu-eeo062507.php). That pales in comparison to eating meat.
Also, we can eat turkeys because we have been eating things similar to turkeys for quite some time, that is, other forms of meat. All meat consists of more or less the same proteins, fats, etc. Peanuts are a legume, which weren't commonly consumed until recently. They have a specific protein that certain people are deathly sensitive to.
Anyway, I was just presenting a theory. I don't think peanuts are awful for people that tolerate them well. It's just silly to say that everyone allergic to peanuts should die because natural selection would kill them in nature when the fact of the matter is that if we lived a "natural" lifestyle, few people would encounter them. They are not a common food unless cultivated to be one by humans.
As to those hippies, how else would we cycle the nutrients in soil without animals? Artificial fertilizers?