Straight hair shafts are ( ) round (didn't change from our long ago ancestors that lived and dove for shellfish on tropical pocket beaches), while curly hair was later derived (the hair shaft became oval (curly) or () elliptical, not round) which protected people who lived inside tropical rain forests from lice (which carry typhus disease), lice lay their eggs (nits) in hair, but in very curly hair the eggs can't stay attached. People with curly head hair also have curly body hair (but straight eyelashes).
Beard, armpit and pubic hair are called coarse secondary hair, it is fluffy and developed during the diving era, where it gave a smooth rounded linear hydro-dynamic profile when diving, filling the body voids in places that skin fat couldn't fill. Below there is more info.
----- Original Message -----
From: DDeden
To: AAT@yahoogroups.com
Sent: Monday, August 27, 2007 5:38 AM
Hydrodynamic Head Hair => AAT
There are many arguments that can be made for and against AAT, but the one that convinced me was the long straight/wavy head hair for hydrodynamics. Since no other aquatic animal has very long hair, it is not a comparable trait, but I can think of no other reason for 1+ m long head hair except fluid diving and swimming in a mammal which did not become very tube-shaped (unlike most other aquatics) because of pre-existing sessile plucking during feeding. The plucking had existed
during the LCA H-oid as part of the vertical floating/wading and tree food collection, the brain had hard-wired for that feeding style, allowing the face and jaw to reduce prognathism, compared to monkeys and other primates. Modern humans have even less prognathism, indicating even stronger plucking feeding (and tool use).
Plucking => jaws shrink (Homo) or enlarge (boisie nut cracker).
Long head hair is fine at the shores, ok on the savanna but useless, while in the trees it is a problem. People living in tropical rainforests tend to have frizzy hair and/or cut it short or tie it up in some way.
I've written on the frizzy inland hair re. lice and typhus, the main reason I'm sure it's correct is that people with frizzy/nappy hair have straight eyelashes. How could they have started with curly eyelashes? They are more derived biologically than slightly curled or straight haired people, regarding tropical inland adaptation.
So therefore, I doubt that H aq was a large tropical island dweller, as on Papua or Borneo or Taiwan rich in mangroves and muck.
They weren't on coral atolls (due to mineral deficiency) either.
However small to medium volcanic islands with encircling reefs around, perhaps the archipelagos along the Pacific ring of fire, the Maldives and Andamans and Afar, with reduced large cat predators, with some silt/soil for mangroves and fruit trees but not large swamps which crocs favor, and warm reef-protected lagoons which sharks don't favor.
DDeden
I've written on the frizzy inland hair re. lice and typhus, the main reason I'm sure it's correct is that people with frizzy/nappy hair have straight eyelashes. How could they have started with curly eyelashes? They are more derived biologically than slightly curled or straight haired people, regarding tropical inland adaptation.
DD
Interesting thought but it's possible to select for straight hair in some places and curly in others e.g. pubic hair is curly in straight-haired people.
Elaine Morgan
East Asians tend to have relatively straight hair everywhere, although the beard, axillary and pubic hair is less straight and more kinked (but by no means curly). All other people have beard, axillary and pubic hair of similar kinky/straight texture, which is even less straight than East Asians, but still not curled at all.
Inland tropical people with very curly (frizzy/nappy) head hair have very curly body hair, but their beard, axillary and pubic hair is comparatively much more straight, and their eyelash hair is straight.
This indicates that the LCA Homo had straight head hair, straight eyelash hair, straight mustache hair (like orangs), and straight but slightly kinked (not curled) beard, axillary and pubic hair.
I think that kinked-straight hair in the beard, axillary and pubic areas is a result of hydrodynamic selection, since it fills the voids of the body better than straight hair does during swimming. I don't think it's form is due to better odor release, though maybe secondarily.
Therefore, I'd expect that other apes lack this special beard, axillary and pubic form of hair, or only have it to a slight degree.
AFAIK, all people born with the hyperhirsute super-hairy syndrome have straight/wavy hair, never frizzy/nappy nor blonde hair. This occurs most often in Asians (though still very rare). There's a photo of a Chinese guy with this condition in AAT photos, it is probably similar to the LCA Homo hair condition.
That frizzy/nappy hair was ancestral to Hs fits no data whatsoever AFAIK. Our Homo ancestors may have been (shoreside) African, but did not have frizzy/nappy hair.
I suggest that frizzy hair is a recently derived trait in Hs not older than 200ka and more likely 60ka, resulting from the improvement of dugout boats, nets and weapons allowing people into the interior in relative safety. The Khoisan seem to be an intermediate, I don't know precisely their situation, but since they do no diving, likely they were isolated from coastal living at some point, perhaps they were the
rift descendants. Dugouts are widespread all throughout the tropics, that is how I think the tropical rainforest Africans survived away from the sea, safer from [predators but not against pathogens, making increased eccrine sweat and curled hair very important selective traits. Dry air = wavy hair. Humid air = curly hair. Sea diving = straight hair with kinked straight beard/ axil/pubic hair.
DDeden
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