From my 1st paper (1985):
D. The hair follicles on the human head
In humans, the head hairs are normally shorter in men than in women; a male’s uncut neck hairs, beard & moustache grow as far as his chest. Moreover, humans have unique “sebaceous follicles” (17): in our neck, face & upper torso, there are very
large sebaceous glands that are not connected with terminal hair follicles as in other regions of the body or in other mammals, and that ooze the sebum out of the skin. Pinnipeds also secrete quantities of sebum, and aquatic birds have large oil glands (
16). Like the growth of the beard & moustache, the activity of human sebaceous follicles starts in puberty under androgen influence (dihydrotestosteron DHT) and is more prevalent in boys than girls, as is acne, a typically human disease of inflammated
sebaceous follicles.
It is possible that, because of their location, the sebum of these follicles once kept the neck hair, beard & moustache supple, fatty, waterproof & well-fitting to the body, so that the “manes” were not dispersed by the water while swimming. Sebum &
long head-hairs together made the male’s neck completely streamlined (Figure 1).
The convergent evolution of the integument of male Homo & male Eumetopias (as compared to the primitive Primates or Carnivora) is quite remarkable: both developed body nakedness, thick SC white fat, extensive superficial venous networks in the limbs,
abundant sebum secretion, long coarse neck-hairs & a tendency to nakedness at the top of the skull (& perhaps thermoactive sweat glands, see B).
Morgan (2,6) supposed that women’s head hairs, growing longer than men’s, and not kept together by abundant sebum, once enabled the newborn baby to accompany its mother in the water by grasping her hair. This fits in with other data. The baby’s SC
fat grows rapidly from the 34th fetal week until a few months after birth, so the baby is born with a thick layer of white fat (c 16% of its body weight, see B). As such, it is an exception among land-born mammals; even newborn Cavia has much less SC fat
(21). The human newborn also shows what M.McGraw called “swimming behaviour”: when held in water, the baby makes well-coordinated swimming-movements, and it even stops breathing, and shows a pronounced bradycardia when its head is immersed (2,22).
...
Fig.1 – Reconstruction of a swimming ancestor
If the AAT is true, our ancestors must have been more or less streamlined, in order to reduce water resistance and heat loss. I have tried to reconstruct a side-view of a late-Pliocene male Homo swimming under water. The sketch is based on the picture of
a human skeleton (49), that is modified as follows. The head is dorsiflexed (to set the eyes in the swimming-direction, as in all mammals swimming under water). The brain skull is lower, smaller & shifted dorsally (as in the “platycephalic” Java man).
The jaws are more robust, a chin is missing (as in all extinct hominoids). The foramen magnum lies a little bit more dorsally (as in e.g. A.africanus (50)). Sacrum & coccyx are somewhat less projecting dorsally (as in early hominid pelves: before the
great enlargement of the newborn’s brain, the present-day broad pelvic passage was unnecessary). The knee region is a bit smaller, and the tibia & ankle region is a lot smaller (as in australopiths (51)), but the feet are rel.broader (as in the
Laetolil footprints, see C). Upon this modified skeleton, I have sketched a somewhat thick-bellied man (see B), with baldness, uncut neck-hair, beard & moustache (see D). The dorsally projecting portion of the glutaeus maximus muscle is drawn a little
bit smaller (since only in complete bipedality it became important in fully extending the hip joints (52).)
Op donderdag 8 juni 2023 om 20:38:27 UTC+2 schreef
littor...@gmail.com:
:-DDDDDD
Never seen such an idiotic fanatasy!
That's why all kudus have lots of hair on their heads, and I'm bald and I have to shave my beard+moustache.
And my beard is to protect my belly from sunbeams...
:-DDDDDD
"Humans are unique among mammals in having a functionally naked body with a hair-covered scalp. Scalp hair is exceptionally variable across populations within Homo sapiens. Neither the function of human scalp hair nor the consequences of variation in
its morphology have been studied within an evolutionary framework.
Liars, see my Med.Hypoth., Hum.Evol. etc. papers, or see only my book p.41-48 illustr.
How is it possible that PNAS allows such idiocies???
Enough nonsens!
:-DDDDDD
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