system
Given the following post, respond as if you're commenting on Reddit:
human
Would a Roman be able to digest today's food? How about a caveman? 

Or going even farther back, would Lucy have been able to digest the stuff we eat today?
gpt
I don't see any reason why they wouldn't, the genetic varieties of plants have changed quite a bit but the fundamental nutrients are the same.  It would be like us eating food in a foreign country, you can easily get a tummy ache but you won't starve. 

The bigger problem would be the pathogens and any bacteria in the food, as the diseases have changed dramatically over the centuries. Fatal infections are very possible and diarrhea is all but guaranteed. 

And the term "caveman" doesn't really apply to the majority of our ancestors, living in caves is mostly what Neanderthals did, and it is not yet clear how closely related we are to them. Neanderthals had a very different diet from our traditional ancestors, but apparently we are both of the same species. They ate much more meat than we do, up to 80% of their diet in some cases!