maniacmath17 wrote:I can see how height may be affected by diet changes and other similar factors, but feet size? Seems like if your feet are too small to hold your weight, that could get in the way of breeding.
The only way I could see the change taking place would be those with larger feet were having more success in producing offspring than those with smaller feet since the smaller footed people would be too busy struggling to stay upright on their tiny feet.
Okay, first of all, I totally could have sworn that you'd written something different previously! Is there a way to change a post without that ugly little edit warning at the bottom?
Now, I can understand your line of thinking, in that our specialized and proportional feet are necessary to support bipedal movement. A careful balance definately would be necessary for a person to function in everyday life. I think, though, that you would be very hard pressed to find a single individual in the past century who, barring any particular defect, was unable to breed due to inadequacies in the size of her feet, let alone a significant enough of a portion of the population to affect the overall gene pool.
I think you're misunderstanding the implications of the height study. The study does not suggest that from one generation to the next a population inexplicable increased its average height while maintaining all other bodily dimentions. It states, rather, that due to a change towards a more healthy diet, several individuals in several observed populations have demonstrated increased rate of bone growth
which has lead to the populations' overall generational height increase. This boost to bone development rates effects the subjects' entire bodies, giving them an advantage across every dimention, feet included. Height was just the easiest recordable, and most obvious notable change in the population; it certainly wasn't the only one.
If you really want to examine the underlying mechanics of the change that took place, consider that every member of the population in question's development is influenced by his or her genetic makeup. In the older, dwarfed generation, there existed all of the necessary genetic instruction for a normal-sized, well-adapted human being; this generation never realized its genetic potential, however, due to deficiencies in diet. The next generation, which shared the same gene pool as the previous, did have its dietary needs met, and, as such, grew much taller, thanks to an abundance of the necessary elements in their diet to facilitate bone growth. It's the same gene pool, both producing perfectly functional, non-top-heavy human beings. One generation just experienced an increase in their overall growth and development. In each case, the size of the feet was probably in similar proportion to the body, since both generations' feet and height development were dictated by the same gene pool.