Lumpy has an original idea. There were hominids with much larger jaws at about the time of homo erectus.They died out soon, brains too small…etc.
Neotony is the concept of organisms becoming sexually mature while maintaining juvenile characteristics. Mudpuppy salamanders are the classic example. As an amphibian they have the tadpole stage, then begin to mature (lose the gills, get lungs, live out of water etc.) but they are able to reproduce before they mature physically, and in fact never “completely” mature in the sense that other amphibs do.
Humans are similar in that we maintain the juvenile/infant characteristics of a typical primate which include relatively hairless, larger brainsize, and flattened faces. A part of being more infant like (when compared to other primates) is we get the advantage of prolonged parental care, and an extended period where our brains are developing and able to learn more complex things.
Part of maintaining this infant/juvenile primate appearance in the adult form (neotony) is that our faces don’t protrude past our chins.
The reason we have chins is to distinguish we “common plebleans” from members of the British Royal Family.
Or other primates.(See Chimp reference above)
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Actually, for their body size, humans do have one of the largest penises of all the species. IIRC, either human males have the largest penises (adjusting for body size) or the chimpanzees do. Damn, I’m always forgetting these things.
But human fetuses, as well as others, don’t have as much chin as a young human adult, and an old human adult is more likely to have a more pronounced chin than a young one.
Chins are so they can sell more razor blades or electric shaver combs.
So retire to the laboratory and give people without chins a rough time and see what happens to them that would be less likely to happen to the well-chinned.
Ray (If you didn’t have a chin, what would you take it on?)
I recently read a fascinating book called “The Face,” which postulated that chins (and large noses) are actually on their way out in an evolutionary sense. It’s a great book, it talks about why we have the kind of eyes, ears, etc., that we do, what what kind of faces have been found attrative through the years.
The vanishing chin theory, though, leads me to assume that earth will someday become The Planet of the Liza Minnellis. “A planet where Liza Minnellis evolved from man?” “Get your stinkin’ false fingernails off me, ya lousy Liza Minnelli!” “Oh my god, it talks–isn’t that FABULOUS?”
Well, getting back to taking it on the chin. How about looking at it this way (no pigs, no Beijing phone directories). As an expert at falling on my face, I say:
Homo’s the only mammal that really took to running fast and well on his hind feet, and sapiens honed it up the best,. . .but, if you fall on your face, and you don’t have a chin, you can more easily knock out all your teeth. And if you’re in the jungle, that might mean you don’t eat much anymore. You don’t eat, you don’t proliferate. QED
Lab test: Ran down a trail yesterday. Fell a time or two, but chickened out of falling on my face. So we can still say: “Needs further study.”
Ray (slowly arising and removing the rubble from his stubble)
Please note that the hypothesis of my previous post shall be termed the ‘Roll-Bar Theory’.
Ray (author of the more general (not generic) theory that heads bounced once in a while tend to work better.)
Flora: are we still evolving? I thought we pretty much quit, long before recorded history. There are no special environments anymore, we handle all of them. Other than south american natives that evolved for higher altitudes, I can’t think of much.
Evolution is not something that stops happening; it is comprised of a series of (usually) gradual changes that, through reproduction of the individuals possessing these traits, become normal.
As for special environments and the changes that the environment can bring to the human body, the most dramatic examples are the Inuit and Australian aborigines. From what I have read, the Inuit are so physically adapted to extreme cold that they are able to draw blood away from their extremities to prevent it from cooling excessively. The Australian Aborigines are humans, yet they are able to control their temperature internally without sweating (sweating is an excellent cooling technique for other humans, but to Aborigines, who survive on miniscule quantities of water, it would be devastating to bust a sweat and waste precious fluid).
A lot of features are influenced by our ancestors’ environment. The epicanthic eye fold most Asians have is thought to help protect from cold. Long noses are an evolutionary benefit that allow to humidify dry air, heat up cold air, and filter pollution (dirt, pollen, etc.) by means of nose hair and turbinate filtration. Long noses take the strain off the rest of our breathing apparatus.
Some people have proposed that we are evolving weaker arms, although I don’t know if this is true.
About neotony; isn’t it spelled “neoteny”?
“For what is myth, but the deconstructive prose of a missing literary critic who lisps?”