I don't think small mammals, fish and carrion are hard to come by in the winter.
It sounds like this discussion is not about the fitness of
Homo sapiens as a species for wilderness survival. Our ancestors were so skilled at it that they actually began to modify the environment to suit them.
If you're talking about the ability of a dweller in modern civilization to survive if he were dropped off in a wilderness with no training, no physical conditioning and only Stone Age tools, that's a different issue. I don't know why anybody would care about that. We've spent the past eleven thousand years building a world that's more to our liking and we're very adept at flourishing in it. With the tools ("technology") we've invented, we have become the apex predator despite the existence of tigers, bears, alligators and sharks; we have marginalized or extinguished species with whom we didn't care to share our space; we have enslaved others for food, work and sport and made second-class citizens out of others for sheer frivolous companionship; we have re-shaped the face of the planet, turning forests into farmland, fields into shopping malls and rivers into hydroelectric generators.
In other words, we didn't much like living in the wilderness, so we abolished it. To say that we could no longer survive in the wilderness is simply to acknowledge the unique nature of our species: our survival skills are not merely instincts honed by parental training, but elaborate systems crafted over thousands of years. We've chosen to suit ourselves to the world we made.
People who care about wilderness survival skills put great effort into learning them and apparently they become very good at them. As far as I'm concerned this proves that our species has not lost its natural ability for wilderness survival, merely that we no longer teach our children to exploit it.
Which brings me back to Orly's remark. Orly, are you a resolute outdoors enthusiast? Have you bothered to learn how to hunt and fish? Could you build a trap to catch small mammals? Few of us Americans have.
I wouldn't last a week in the wilderness because I've never learned to do any of those things. But I can play a bass guitar, write publication-quality text, drive a car, play go and teach algebra and three languages. Those are the skills I value. I would not want to live in a world where I could not use them so my inability to survive in that world is by definition of no importance to me.
But I can pretty much guarantee you that 10k years ago people weren't living to an average age of 75.
Actually, at the close of the Mesolithic Era in 9500BCE the life expectancy of an adult human who had survived the rigors of childhood (no mean feat, to be sure) was in the low 50s. The cause of death for the majority of them was violence, since the inability of a hunter-gatherer "economy" to generate surplus food made every tribe an enemy of every other tribe during hard times.
It wasn't tooth decay that brought us down; it was, ironically, agriculture. After the invention of the technology of farming, the burgeoning human population quickly adopted a grain-based diet, which is woefully deficient in many key nutrients. By the Roman Era, that same adult had a life expectancy of about 23.
I dont hunt,fish,or spend time out in the wilderness, but I could if I had to.
That's easier said than done. I hope you don't ever have to test that hypothesis.