Mystery solved. How and why human ancestors became upright.

[Twoflower]

Which did humans do more, fight or gather food?

It's not so much what you do more of, it's what affects your ability to sire offspring.
Fighting and becoming dominant gives a better chance of that. That's why Chimps and Gorillas have huge canines, and long jaws, they are a fighting weapon, which we lost.
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actually the huge canines are used almost solely for intimidation. Rarely are they used for actual fighting.

[mistermack]

Jeepers, can you edit that out? It's gigantic.

Quick response ; This appears to apply to ancestors 21mya.
It's not at first glance relevant to the quick change to bipedality, just to a more upright stance.
But I haven't read through it.
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[Trolldor]

But I haven't read through it.

[mistermack]

actually the huge canines are used almost solely for intimidation. Rarely are they used for actual fighting.

True, but they work, or they wouldn't be there.
If I have a spear, I will be less intimidated by big teeth.
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[Gawdzilla Sama]

actually the huge canines are used almost solely for intimidation. Rarely are they used for actual fighting.

True, but they work, or they wouldn't be there.
If I have a spear, I will be less intimidated by big teeth.
.

If you had a spear I'd be laughing.

[mistermack]

But I haven't read through it.

What a surprise? He's only just posted it. You are gradually getting worse.
It's getting to the point where it's not worth reading. Can't you offer anything of any use?
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[GenesForLife]

They are placing vertebral hox modifications to an ancestor 21 mya and building the rest of the puzzle along the human lineage based on other known variations stemming from other hox gradient modifications.

[Twoflower]

actually the huge canines are used almost solely for intimidation. Rarely are they used for actual fighting.

True, but they work, or they wouldn't be there.
If I have a spear, I will be less intimidated by big teeth.
.

But there weren't spears until after the teeth went away. So the fact that you would be less intimidated by big teeth doesn't matter.

[mistermack]

actually the huge canines are used almost solely for intimidation. Rarely are they used for actual fighting.

True, but they work, or they wouldn't be there.
If I have a spear, I will be less intimidated by big teeth.
.

But there weren't spears until after the teeth went away. So the fact that you would be less intimidated by big teeth doesn't matter.

Do you know that? Or are you assuming it?
I'm proposing that there were. I don't have proof, there is no proof either way.
Wood rots very quickly in Africa, and an all-wooden spear would just end up recycled, like the rest of the wood.
Stone tipped spears didn't appear till the neolithic.
And then, it was usually just the tips that survived.
.

[Twoflower]

actually the huge canines are used almost solely for intimidation. Rarely are they used for actual fighting.

True, but they work, or they wouldn't be there.
If I have a spear, I will be less intimidated by big teeth.
.

But there weren't spears until after the teeth went away. So the fact that you would be less intimidated by big teeth doesn't matter.

Do you know that? Or are you assuming it?
I'm proposing that there were. I don't have proof, there is no proof either way.
Wood rots very quickly in Africa, and an all-wooden spear would just end up recycled, like the rest of the wood.
Stone tipped spears didn't appear till the neolithic.
And then, it was usually just the tips that survived.
.

From my physical anthropology notes:
Key points of humanoid evolution
Small Canine
Large brain
Bipedal/long legs
Neanderthals
120,000-28,000 years BP
Lived during glacial period made spears, fire and clothing

[mistermack]

They are placing vertebral hox modifications to an ancestor 21 mya and building the rest of the puzzle along the human lineage based on other known variations stemming from other hox gradient modifications.

Whichever genes were involved, and whatever mechanism, it's pretty clear that our ancestors did get slightly more upright over a very long period, but then suddenly became fully upright over an extremely short period.
The genes can produce the variants, but it's selection pressures that decide which genes flourish in the population, and which genes become extinct.
So I think if you want the key to why we became upright, you have to find the selection pressure or pressures. And I'm suggesting it was something extreme and unique, because very little has happened to Bonobos, or Chimpanzees, or Gorillas, as far as bipedalism goes. And all of the article you posted applies equally to them.
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[Twoflower]

Also most evidence points towards a change in diet as the reason canines became smaller
http://www.as.ua.edu/ant/bindon/ant570/ ... lyTree.pdf
I doubt you will read that, but it's interesting

[Gawdzilla Sama]

They are placing vertebral hox modifications to an ancestor 21 mya and building the rest of the puzzle along the human lineage based on other known variations stemming from other hox gradient modifications.

Whichever genes were involved, and whatever mechanism, it's pretty clear that our ancestors did get slightly more upright over a very long period, but then suddenly became fully upright over an extremely short period.
The genes can produce the variants, but it's selection pressures that decide which genes flourish in the population, and which genes become extinct.
So I think if you want the key to why we became upright, you have to find the selection pressure or pressures. And I'm suggesting it was something extreme and unique, because very little has happened to Bonobos, or Chimpanzees, or Gorillas, as far as bipedalism goes. And all of the article you posted applies equally to them.
.

Your choice for "extreme and unique" is poor.

[GenesForLife]

They are placing vertebral hox modifications to an ancestor 21 mya and building the rest of the puzzle along the human lineage based on other known variations stemming from other hox gradient modifications.

Whichever genes were involved, and whatever mechanism, it's pretty clear that our ancestors did get slightly more upright over a very long period, but then suddenly became fully upright over an extremely short period.
The genes can produce the variants, but it's selection pressures that decide which genes flourish in the population, and which genes become extinct.
So I think if you want the key to why we became upright, you have to find the selection pressure or pressures. And I'm suggesting it was something extreme and unique, because very little has happened to Bonobos, or Chimpanzees, or Gorillas, as far as bipedalism goes. And all of the article you posted applies equally to them.
.

Finally got close to the point, selection pressures explain why being upright was fixed as a phenotype in human evolution, it doesn't explain why humans became upright alone.

[mistermack]

From my physical anthropology notes:
Key points of humanoid evolution
Small Canine
Large brain
Bipedal/long legs
Neanderthals
120,000-28,000 years BP
Lived during glacial period made spears, fire and clothing

Ok but if modern Chimpanzees can make spears, and hunt bushbabies with them, I think it's fair for me to claim that it was perfectly POSSIBLE for our ancestors to be doing the same, six million years ago. The mental capacity at that time is widely agreed to be similar to that of a Chimpanzee.

Its also very unlikely that wooden items from that period would survive to prove it.
We actually have practically no fossils of Chimpanzee ancestors at all, so there is little hope of fossilised spears.
.