Are we more disease resistant - than our ancestors? I don’t mean because of modern science and nutrition. If we were put back into ancient times or the middle ages, would we be more or less likely to get ill or catch whatever disease?
Probably more likely, simply because of our lack of exposure to the relatively unsanitary conditions which existed at the time. The immune system of the people of the Dark Ages is neither "stronger"nor “weaker” than those of people today–they’re practically identical, in terms of overall functionality (we are the exact same species, after all). The difference is experience, so to speak. We live today in conditions which are much cleaner and more sanitary than those of our counterparts 1,000 years ago, so our immune systems haven’t been exposed to as wide a variety of microbes and other nasties. Assuming disease dfidn’t kill him, no doubt a modern human could adapt to conditions back then, eventually.
In addition, of course, in earlier times people died younger. A 70-year-old man used to be a rarity, a 70-year-old woman even rarer.
If you were lucky enough to survive infancy, you probably had a very healthy immune system. If you got to be 50, you were just lucky. Think of everyone you know who’s had appendicitis, for example. Up until relatively recently they would have simply died a painful death. Most women in developed areas now fully expect all their children to survive until adulthood, so they may limit their childbearing to only a few, reducing their chances of dying in childbirth.
On the other hand, there is one theory that we have more allergies today because we are exposed to fewer parasites and ordinary bacteria, so our immune systems have nothing better to do than to attack innocuous substitutes.
I happen to believe the theory that the greater number of allergies is a result of the overuse of antibacterial soap, antibiotics, and obsessive cleanliness. I see all these warnings on nutrition labels that this food contains peanuts, wheat, soy, etc. 50 years ago these warnings were unnecessary because so few people had severe allergies to these foods.
I like George Carlin’s take on it. Don’t wash your fruits and vegetables, don’t cover up public toilet seats, don’t wash your hands, for Christ’s sake, you’re strengthening your immune system.
But yeah, if a modern person were transported to the middle ages, they’d adapt. But they’d get a lot sicker than everyone else for a while.
Hmm…(IANAB)…i dont think it is a very good comparison. Are we more resistant than our ancestors IF exposed to their environment or ours? and how far back?
Suppose we have a time travel machine and we (heartlessly) put an infant from our time into their time. I’ll imagine that s/he’ll be pretty vulnerable to the bugs around.
But similarly, if we put an infant from their time into ours, s/he’ll probably die quite easily from what we would consider our ordinary flue.
The microbes we have around us nowadays have been evolving for the same time span as we did and we are quite ‘adapted’ to most of them. Same goes for the microbes’ ancestors and our ancestors.
I remember vaguely abt this Simpsons episode where homer was transported back to the dino period. And his sneeze ended the dinosaurs 
However if you were to consider our distant ancestors, we now probably have more evolved immunity features than they do.
Take for example, malaria. The sickle-cell anemia(a disease prominent to africans) has recently been discovered to actually offer some kind of protection against malaria. However, it by itself is a disease which is an apparent mutation.
Africans of the past would be quite at the mercy of malaria had not some of them “evolved” sickle-cell syndrome. In this case, these present people are better protected than their ancestors (but this is quite simply because we are dealing with the same disease that is assumed to have not evolved!).
A laymans take~