Inventing a Wellsian time-machine to take us all back to eighteenth century England would be as good for our health as transporting us to the moon without spacesuits. Our bodies are simply too large to survive on the average food supply then available.
If we were so transported, of course, most of us would adapt quite quickly to meager rations by becoming thinner, but only the short would be able to survive, so that the average height of the population would shrink, though more slowly than average weight. (Emphasis added)
I wonder if this explains the commendable preference women have for tall men. In an environment of chronic food shortages, height (more so than weight, which could vary with circumstances) would be a credible signal that a male has consistently had access to abundant food. In a class-ridden society, the tall men would also be the ones at the top of the social pyramid.
As food shortages become a thing of the past, variation in height will come to be explained more by genes, and less by access to resources. When this becomes the case, will natural selection ensure that height becomes less of a factor in assessing the attractiveness of men?
Note: I know I have been obsessing about signalling, but I find the concept quite fascinating. May post a couple more times about this topic, but shall eventually exhaust myself. :-)
Afterthought: Probably not, at least if this is correct. In the past, the primary constraint on how many descendents a woman had was access to resources. What with plenty of cheap food, and birth control, this is no longer the case. However, preferences have been set by past conditions, and what were indirect indicators of the male's ability to gain access to resources now appear to be primarily "aesthetic". In such a situation, those preferences would probably perpetuate themselves, even if they no longer signal wealth. Or not..