I don't doubt one bit that this was part of our evolution. Modern thought: the raw feeding of pet dogs. It terrifies a lot of pet owners. "What! You can't feed dogs raw meat!" I fed my dogs raw after I did my research and was satisfied that dogs' stomachs are more acidic than ours, and that's why we didn't have to worry about meat that, to us, would be 'contaminated.' Did it for years with no problems and only glowing health for the dogs.
As for our modern living, I can see both sides of this. On one hand, I do object to the over-sanitization that Procter and Gamble wants to sell us: buy more bleach! Buy more Lysol! Your kids put everything in their mouths, so decontaminate everything or else you're a bad parent! I have to confess that I'm a terribly lazy hand washer. After I go to the bathroom or if I know there's something yucky on them, and that's it. I could go to the grocery store, handle the grocery cart, doors, cash... and come home and eat something without washing my hands.
I basically never get sick.
OTOH, like NiceKitty, I question my mom's kitchen cleanliness habits. She always kept the house tidy, but there was always a *nasty* dishrag for wiping things up. Perpetually stank. It seems like my brother and I were sick all the time with nausea and vomiting. We missed a ton of school. I don't know, maybe someone can chime in with what's the average number of times a year a typical child gets sick like that these days, but it seems excessive for me when I think back on it.
Maybe we were in that generation where grocery store meats were just starting to become chronically contaminated with E. coli and salmonella, and food safety was becoming an issue. I don't know. All I know is now, when I cook with raw meats, I decontaminate the kitchen like there was a nuclear meltdown. I have a slightly irrational fear of food poisoning because of my childhood. I'd rather have a root canal or be frozen in the Arctic than spend a few days like that.