On Sun, 14 Nov 1999, Hans Kylberg wrote: > Just because we have ancestors who lived in the tundra this does not > mean that that became an optimal environment. This is a good point. In particular, we tend to assume that paleolithic people were robustly healthy throughout all these changes in climate and location. But, as my biologist colleagues are fond of pointing out when we discuss this stuff, we don't know that at all. We know that they *survived* these changes, but that doesn't mean that there weren't health trade-offs. They like to point out to me that there are always trade-offs, and the fact that a species manages to survive on a certain diet doesn't imply that the diet is ideal for that species, in terms of the health and longevity of individual members. It only means that the diet is "good enough" to keep the species going. And of course the obvious proof of this is the Neolithic revolution itself. In evolutionary terms, agriculture is more "successful" than any paleolithic way of life ever was, simply because it supports large numbers of people. It seems that the Inuit achieved a workable trade-off in the form of a ketogenic diet, allowing them to survive and reproduce in good health, but tending to shorten their lives somewhat. In evolutionary terms this is a good deal, even if as individuals we might want to find a better arrangement. Todd Moody [log in to unmask]