Tuesday, November 10, 2009

Gibbons, Humans, Great Apes


"Early hominid ancestors may have left the trees to take advantage of ground-level foods, a behavioral shift that could have resulted in two of the major defining characteristics of humans: unique teeth and walking on two legs, a mode of locomotion known as bipedalism that is extremely rare elsewhere in the animal kingdom."

No, they started at wetland/woodland edges, eating water lily/lotus/sedge rhyzomes/umbels and bush berries and low hanging fruits and fallen nuts, then apes moved higher in rainforest canopy while human ancestors moved to more coastal seashore areas.

Note folded flanges of adult male reduce sunlight in eyes, give gorilla appearance; balding scalp. Nonfolded flanges are broadly flat faced, very non-gorilla appearance, note clear beard and non-nasal mustache. Bornean and Sumatran orangs separated 1.6ma
flat flange
Very dark furred orangutan
dark orangutan
Male with flanges, eyes near center of face, long hair like mammoth

Human deep larynx vs ape air sacs: apnea/speech vs flotation (de Boer, Boe, Lieberman...)

Humans & gibbons share these traits (unlike great apes):

1) long achilles tendon
2) proportionately long legs (not neandertals)
3) protruding chin (not neandertals)*
4) upright biped primarily
5) no laryngeal air sac (exclude siamangs)
6) more monogamous pair bonding
7) continuous song rather than discrete hoots
8) low sexual dimorphism (teeth)
9) no woven branch nest (also siamangs)

gibbons and great apes share these traits (unlike humans)

1) fur coat
2) grasping big toe
3) very low carnivory
4) large canines, small molars

Chromosomes: Great apes have conserved primitive 48 chromosomes, humans derived 46, gibbons variable per species.

Gait: Gibbons and humans have conserved bipedal upright locomotion (original float-feeding/standing hominoid posture) while great apes have derived terrarboreal quadrupedalism.

Milk composition in hominoids, human milk is unique to all apes and all mammals

"In comparison, type I oligosaccharides predominate over type II oligosaccharides in human milk, whereas nonprimate milk almost always contains only type II oligosaccharides. The milk or colostrum of the great apes contained oligosaccharides bearing both N-glycolylneuraminic acid and N-acetylneuraminic acid, whereas human milk contains only the latter. Great ape milk, like that of humans, contained fucosylated oligosaccharides whereas siamang milk did not."

Neu5Gc in hominoids, malaria susceptibility in humans and NWM Aotus monkeys

Human malaria resistance recent? "Although sickle cell is best known in Africa, there is also an India-Pakistan variant of it that seems to have evolved separately," Hawks explained. "Both variants have evolved very recently, in the last three or four thousand years, and in that time have risen to as much as 10 to 15 percent of the populations.
Surprisingly, based on skull measurements, the human brain appears to have been shrinking over the last 5,000 or so years.

"When it comes to recent evolutionary changes, brains have shrunk about 150 cubic centimeters, off a mean of about 1,350. That's roughly 10 percent," Hawks said. "As to why is it shrinking, perhaps in big societies, as opposed to hunter-gatherer lifestyles, we can rely on other people for more things, can specialize our behavior to a greater extent, and maybe not need our brains as much," he added.

Human salivary amylase multiple of chimp, especially starch-eaters? Digestion begins as soon as you shovel a forkful of those mashed potatoes into your mouth and masticate (or chew) the food. Your mouth secretes saliva (up to 1.5 quarts a day) that moistens your food and also contains enzymes (special kinds of proteins) that help break down the food before it reaches your stomach.

One of these enzymes, called salivary amylase, breaks down starches, and a new study finds that humans carry extra copies of the gene that encodes the enzyme, which may have helped spur human evolution. The study, published in the Sept. 9 issue of the journal Nature Genetics, found that humans have more copies of the gene than their ape relatives. The humans sampled carried as many as 15 copies each, while chimpanzees had only two.

The study also found a correspondence between the number of copies of the gene and the amount of starch in a population's diet. Members of the Tanzanian Hadza tribe, which ate more tubers and roots, had more copies of the gene than their neighbors (the Datog) who mostly raised livestock. The finding supports theories that some change in the diet of early humans fueled the simultaneous increases in the size of human brains and bodies, as well as the expansion of our ancestors' geographic range.

Trade distinguished Hs from others (neandertal, baboon, bonobo)
group inter-trade

Evolving group gene
dance, trance & chance

Slight chin in early Hs man 110ka in China & S Africa?

Toba supervolcano dried and cooled south Asia 73ka
Toba effects

Face & limb traits identify various congenital disorders:

Herbivorous hadrosaur dinosaur: biped, quadruped, hopper or walker?

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