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Origins of Mankind (Somewhat Experimental) (Pre-History)
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DPCrisp


In: Bedfordshire
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Glimpsed a programme that said:

a) Human jaw muscles are puny compared to ape jaw muscles. It's down to a single genetic mutation, which is now present throughout the population. The puny muscles do not encase the top of the skull and we have no pronounced bone crests, which means our braincases were now free to expand.

b) There is a congenital speech defect where a particular allele inhibits the fine control of mouth muscles. "Knowing what to look for", they decided the mutation that enabled our mouths to be dextrous enough for speech arose about 200,000 years ago.

'Course, they bandied about the Single Genetic Mutation as though it were an explanation!

Why couldn't we have even bigger heads with powerful jaws and big brains? Even if brains could expand, why did they? Why have they stopped now? Why didn't brains shrink once skulls didn't need to be so burly? Why is bigger necessarily better? How does a capacity for fine movement become a particular practice of fine movement?

Australopithecus boisei and Homo erectus were contemporary: one with a bone crest and small brain; one with a large, smooth brain box. But is there an inexorable march from Homo erectus to Wernher von Braun?

Would it make any sense to say installing a carburettor on a push-bike paves the way for the development of the motorcycle?

And it was all set on the Savannah.
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Mick Harper
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In: London
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One thing to remember is that the brain case is limited by the size of the birth canal in women. And it sounds like increasing the brain size might require sacrifice of other head functions of which this jaw muscle might be one. Now the introduction of a) fire and b) hand-axes means that jaws don't have to be so big now that food can be processed. And using fire and hand-axes requires more brain power...mmm...something to work out there.
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DPCrisp


In: Bedfordshire
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One thing to remember is that the brain case is limited by the size of the birth canal in women.

Yes and no. Our skulls aren't fused and distort wildly in partum; so they are also free to grow rapidly after birth.

We wouldn't need jawbones and muscles to be huge when suckling, but if the first order of business was to build them up, increasing the forces on the skull plates, would they ever get to fuse? Would it cause the brain case to expand...?

But it doesn't (necessarily) follow that bigger is better.

---

The Aquatic Ape idea entails all sorts of stuff about shellfish: 'brain food', fiddly to get hold of, easy to chew, easy to cook (?) in their shells... Another factor, perhaps: we'd need to develop an extra level of dexterity to handle them because very often they are sharp and we have soft hands.

And it sounds like increasing the brain size might require sacrifice of other head functions of which this jaw muscle might be one.

Come to think of it, the whole geometry of the head and neck differs in us true bipeds. Is there even room for massive masseter muscles after the reshuffle?

Now the introduction of a) fire and b) hand-axes means that jaws don't have to be so big now that food can be processed. And using fire and hand-axes requires more brain power...mmm...something to work out there.

Yes, it's got to be cyclical or interdependent. Something like "trying to do something leads to doing it better". I object to the one-shot character of these single genetic mutations that somehow not only enable such-and-such, but cause it, too.
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Mick Harper
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Come to think of it, the whole geometry of the head and neck differs in us true bipeds. Is there even room for massive masseter muscles after the reshuffle?

I think this theme needs more exploration. One of the weirdest things about 'human' evolution is that Neanderthal has a bigger braincase than us (averaging 1500cc versus 1350cc from memory). Now in every other species comparison, orthodoxy claims that braincase size is proportionate to intelligence...but of course it stays quiet on this particular one.

But if Neanderthal should be compared with other hominids rather than with us (which is my general theme), then it would be permissable to start arguing that while the hominids had ever-increasing intelligence, the architecture of their skulls meant that brain case size is not necessarily proportionate to brain size when compared to us. After all, if you've got a massive jaw and a massive brow-ridge then there is no particular reason to cram the brain into a small braincase since the jaw and the browridge have to get through the birth canal in any case.

[I rather think there is a lack of baby Neanderthals and a tendency to call female Neanderthals 'gracile' rather than 'female"...is this other people's feeling?]
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DPCrisp


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Rocky wrote:
It's interesting because Jewish people are more prone to sphingolipid diseases and it's conjectured that whatever may have caused the genetic disposition towards these diseases may have caused smartness as well:

'If these genes were shuffling randomly,' says Gregory Pastores, director of the neurogenetics unit at NYU, 'then why is it that we see the clustering of four diseases in Jews -- Gaucher, Niemann-Pick, mucolipidosis type IV, and Tay-Sachs --when the genes are in different chromosomes entirely? They're not even next to one another.'

The lysosomal storage diseases are a group of over forty human genetic disorders that result from defects in lysosomal function. The diseases are relatively rare and together they have an incidence of approximately 1 in 7000-8000 live births.

Gaucher's disease is the most common of the lysosomal storage diseases... Fatty material can collect in the spleen, liver, kidneys, lungs, brain and bone marrow. Symptoms may include enlarged spleen and liver, liver malfunction, skeletal disorders and bone lesions that may cause pain, severe neurologic complications, swelling of lymph nodes and (occasionally) adjacent joints, distended abdomen, a brownish tint to the skin, anemia, low blood platelets and yellow fatty deposits on the sclera. Persons affected most seriously may also be more susceptible to infection.

Niemann-Pick Types A and B are caused by the deficiency of a specific enzyme... sphingomyelin cannot be metabolized properly and is accumulated within the cell, eventually causing cell death and the malfunction of major organ systems... Niemann-Pick Type C is very different than Type A or B.... has been initially diagnosed as a learning disability, mild retardation, "clumsiness," and delayed development of fine motor skills... NPC is always fatal. The vast majority of children die before age 20 (and many die before the age of 10).

Most patients with Mucolipidosis type IV show psychomotor retardation (i.e., delayed development of movement and coordination), corneal opacity, retinal degeneration and other ophthalmological abnormalities. Other symptoms include agenesis of the corpus callosum, iron deficiency, and improper stomach pH (achlorhydria).

Tay-Sachs disease is a genetic disorder, fatal in its most common variant known as Infantile Tay-Sachs disease... The disease occurs when harmful quantities of a fatty acid derivative called a ganglioside accumulate in the nerve cells of the brain.
Poorly, weak, retarded... not immediately fatal... the sorts of disease that could/would be perpetuated in a close-knit, supportive community, sufficiently self-defining-and-isolating for "Ashkenazi Jew" to be a concept recognised by geneticists? Also, brain tissue/structure-affecting.

It is weird though they get these 4 similar diseases that are genetically distant from each other.

Praps it's just that we understand genetics far less than we think and there are mechanisms at work that often, because of tinkering in a given area, cause similar problems to the ones they're trying to fix.

On the current understanding, there is no correlation between one mutation and the next, so "they're not even next to one another" should not have passed Mr Pastores' lips. Contrariwise, we do know that DNA and real-time cell processes are interactive, which at least nods in the direction of a 'type' of problem occurring regardless of the locations of the genes on the chromosomes.
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Mick Harper
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that often, because of tinkering in a given area, cause similar problems to the ones they're trying to fix.

Remember the recent programmes about genetic defects in pedigree dogs? The defects arose because selecting for a visual physical trait (that appeals to humans not dogs) virtually guarantees that a price has to be paid in other areas. This has two inferences for this discussion:

1. Human beings always select on 'visual physical traits' and whereas these are mainly useful, the vicissitudes of fashion (not something I think applicable generally in the Animal Kingdom) mean that 'a price has to be paid'.

2. In the special case of minorities like Jews, everybody is a 'pedigree'. These groups tend to be fairly obsessed by family trees and marrying 'in' so they are ipso facto creating a pedigree, and a single pedigree at that.
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Hatty
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Archaeology News Report says an Israeli shaman's grave has been found (Wireloop please note, in a cave in western Galilee)

The skeleton of a 12,000 year-old Natufian Shaman has been discovered in northern Israel by archaeologists at the Hebrew University of Jerusalem. The burial is described as being accompanied by "exceptional" grave offerings - including 50 complete tortoise shells, the pelvis of a leopard and a human foot. The shaman burial is thought to be one of the earliest known from the archaeological record and the only shaman grave in the whole region.

Leopard is interesting. An eagle feather was also found in the grave (eagle feathers are part of a shaman's headdress). Tortoises were food for the afterlife?

According to Dr. Grosman, the burial of the woman is unlike any burial found in the Natufian or the preceding Paleolithic periods. "Clearly a great amount of time and energy was invested in the preparation, arrangement, and sealing of the grave." This was coupled with the special treatment of the buried body.

I wonder why they conclude it's a shamanic grave; not many archaeos in Siberia but presumably there are similarities.

Shamans are universally recorded cross-culturally in hunter-gatherer groups and small-scale agricultural societies. Nevertheless, they have rarely been documented in the archaeological record and none have been reported from the Paleolithic of Southwest Asia.

Oh, so no point of comparison. But they still seem to know despite the lack of an archaeological record.

The Natufians existed in the Mediterranean region of the Levant 15,000 to 11,500 years ago. Dr. Grosman suggests this grave could point to ideological shifts that took place due to the transition to agriculture in the region at that time.

Is shamanism associated with the "transition to agriculture" then?
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Rocky



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We're wrong. The correct theory is: "Out of Africa"-"Then Back into Africa"-"Then Back Out of Africa Again"

Archaeologists now believe that our ancestors left for Europe at least 1.8million years ago, before returning to Africa and developing into Homo Sapiens


http://www.dailymail.co.uk/sciencetech/article-1212060/Ancient-skeletons-discovered-Georgia-threaten-overturn-theory-human-evolution.html

Here's an interesting comment (except for the last sentence) someone made:

Here's what happened (prove me wrong):

The Aquatic Ape Theory is true. Our branch of ape evolved the way it did because at some point we became coastal creatures. We lost a lot of our hair (like all other aquatic mammals [save the polar bear {for obvious reasons}]), became bipeds (better for swimming), became dependent on some seafood in our diet (for iodine), and started developing big brains, thanks to our changing body and lifestyle, that both afforded and required a higher metabolism. We probably did quite well and spread ourselves far and wide.

The reason our ancestors were all undeniably out of Africa isn't because we all went back there (as this article suggests), it's because of the Tobo eruption in Indonesia - a caldera volcano that caused mass worldwide extinctions and reduced the early human population down to the thousands (why there are so few strains of mitochondrial DNA). The tribe(s) that survived was(were) in Africa.

This article overturns nothing.
- Thomas Dixcy, New York, USA, 10/9/2009
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Grant



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The aquatic ape theory is rubbish. The chief problem it superficially appears to solve is that of human hairlessness and subcutaneous fat. The argument, as most will know, is that aquatic creatures lose hair to help them swim better. But only fully sea-going creatures like dolphins and whales which need to swim fast have lost all their hair. Creatures which spend a reasonable percentage of their time on land still have hair - think of water voles and beavers. To have lost all our hair we must have been freaking mermaids!

But suppose the anomalies uncovered by the aquatic ape people are actually evidence of our origins in the ice. The subcuteneous fat is evidence of adaptation to cold not water. And the reason we are hairless is that we moved from a very cold environment to a very warm one in just a few generations. We are hairless for the same reason that elephants are hairless. When we lived in the ice we were hairy - like mammoths.

I shall call this The Freezing Ape Theory (FAT).

That still leaves the question "why did we then have to start wearing clothes?" Any ideas?
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Ishmael


In: Toronto
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Grant wrote:
The aquatic ape theory is rubbish.

That's definitive!

The chief problem it superficially appears to solve is that of human hairlessness and subcutaneous fat.

And bipedalism and...(the list is rather long)...

To have lost all our hair we must have been freaking mermaids!

Like Hippos.

And the reason we are hairless is that we moved from a very cold environment to a very warm one in just a few generations.

So you argue that we had too much hair and lost it to keep cool. But why not just lose a little hair? Why all of it? Other creatures in our climes have not lost their hair.

That still leaves the question "why did we then have to start wearing clothes?" Any ideas?

Move an already hairless creature north.
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Chad


In: Ramsbottom
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Move an already hairless creature north.


And/or take him out of the water so that he experiences wind chill.
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Grant



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Like Hippos.

Hippos live in a hot country, like elephants.

And bipedalism

If you live in the snowy wastes it's pretty useful to stand up tall (like a penguin)

So you argue that we had too much hair and lost it to keep cool.


Yes, just like mammoths/elephants.

Move an already hairless creature north.


That doesn't work as an explanation of clothes-wearing becuase it doesn't explain why we had no hair in temperate/hot climes. No other ape ever did the same.
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Pulp History


In: Wales
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On the question of hairlessness / hairyness.... why are the three hairiest places on an adult male the groin, the armpits and the face / neck? If the hair was lost for reasons of heat, then why not lost here? Surely the groin has to remain cool to reproduce sperm and yet is one of the areas to develop hair to keep warm!
Also we are told that adults develop groin and armpit hair to show fertility... but what other animal exhibits this visible change? Are there any? Why would we need this alleged sign of fertility, surely the development of a pair of breasts is all the signal a male needs to choose a fertile mate?
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Chad


In: Ramsbottom
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On the question of hairlessness / hairyness... Where did hair actually come from?

None of the classes of animal that are (supposedly) directly ancestral to mammals had hair -- fish, amphibians, reptiles -- all are either smooth or scaly, not a hair in sight.

But as soon as hair makes its appearance in the fossil record, there it is.... fully formed, modern hair. There are no examples of scaly proto-hair, just plain old proper hair. If hair evolved from scales (as, I think, is still the orthodox model) where are all the transitional forms?

(Funny how transitional forms always manage not to get themselves fossilised.)

Insects and arachnids have their own form of hair... umm.... maybe a bit a gene splicing going on... nah, forget it.

(Help meee...)
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Chad


In: Ramsbottom
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Grant wrote:

If you live in the snowy wastes it's pretty useful to stand up tall (like a penguin)


I don't think you can attribute the penguin's upright stance to the snowy wastes. It is something it shares with other seabirds (such as the auks) and is rather an adaptation to an aquatic lifestyle, to better enable it to swim under water.

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