Humans and chimpanzees share a common ancestor. An adult chimpanzee male weighs about 110-115 lbs. I don’t know how large the common ancestor was - how big was it?
Is there an evolutionary reason why humans have become as large as we are? We’d be easier to feed if we were 4 feet tall and adult men weighed 115 pounds.
Well it’s a lot easier at our present size than if we’d gotten the genetic code of a Gorilla…
Teh only answer I can think of is there was evolutionary pressure to up the size a bit. Bigger males got more females…bigger males were more successful hunters (chimps don’t hunt…at least not in as much as they run down a water buffalo or something). You could come up with a variety of reasons for this. Obviously at some point size becomes a liability for a human physiology as well so nature ‘settled’ on what you generally see today (with the occasional extreme thrown but only as a rarity).
Actually humans used to not be so big. For example, Phillip of Macedon was about my height (5’2") and Alexander the Great (his son) was only “as high as his heart” (probably 4’9" or so). If you look at old suits of armor you realize that Knights of old had the stature of today’s 14 year old girls. Even into quite recent times 5’6" was a pretty fair height for a man.
Better nutrition is why we’re so much taller, consequently heavier.
IANAP/A/G (Paleontologist, anthropologist, geneticist)
But the explanation I recall (from one of those PBS evolution specials) was that the early hominids were about the size of modern chimps, but we changed environments. Chimps live in forested areas, while the early human ancestors moved out (or were forced out) to the savannahs of Africa. IIRC, the need to see over tall grass to watch for predators and scavenging opportunities lead to our upright posture, and would probably include being taller.
Google brought up some lecture notes regrading the various hominids, search down for “Evolution of Modern Man”
http://entomology.ucdavis.edu/courses/hde19/lecture6.html
And then of course there is the current improvement in height due simply to better nutrition. I remember seeing somewhere that average height has increased 6-10 inches over the past one or two thousand years.
Another factor that might have kept chimps smaller is the fact that they are more aboreal and humans are primarily terrestrial. Chimps had to stay smaller if they were going to stay in the trees, but without that constraint humans could grow somewhat.
IIRC adult male chimps have a highly variable size range and there are quite a few male “alpha” chimps in the 140-200 lb range. The males are not as small as you might think and they are very dangerous when aggravated.
I sort of doubt that was a major factor.
Although I’ve never been to the savanah in Africa, I DO live in an area that, pre-modern, was one of the great grassland regions of the earth and similar in climate, types (if not species) of animal, and so forth. The native grasses grow 6-9 feet tall (depends somewhat on yearly rainfall). I can’t see over that - can you?
Also there are a lot of savannah critters that aren’t as tall as we are - including primates such as babboons who normally amble about on four feet.
It might have been a factor, but I doubt it was a major one.
This I think is more likely.
Even today, there is a tremendous range in adult size for humans with good nutrition, from some African groups where adults are 4’6"- 5’, to NBA players who regularly top 7 feet, including one of Chinese descent (not a group known for great height)
Not necessarily; the way armor is displayed usually has it “compressed”, so to speak, whereas when it’s worn it has a bit more space between the pieces to allow for movement.