Mystery solved. How and why human ancestors became upright.

[mistermack]

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.

If, as I hypothesise, it was carrying sticks or spears, that enabled them to survive all the DISADVANGES of bipedalism, then it's unlikely that an unarmed ape could survive with poor tree-climbing ability.
Chimps and monkeys can get up a tree in a flash, if a predator chases them.
Human ancestors would need SOMETHING to make up for that loss in ability.

So weapons-using actually explains why other apes didn't go the same way.
If they didn't carry weapons, they would be too vulnerable.
Actually, there were eventually many other upright species, but they seem to have evolved from one initial upright ape.
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[GenesForLife]

could =/= does , how would you test the hypothesis and what is the null hypothesis?

[mistermack]

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

There's rather a lot of it, but I will try to find time.
However, to react to the idea, I find it highly unlikely. Female and male chimpanzees eat the same diet. They have highly different canines. The same applied to our ancestors. The males have the big canines as weapons, and as you say, for intimidation.
I'm pretty sure the diet would change, and the teeth would alter, when our ancestors became upright, but that would be BECAUSE they had a more terrestrial lifestyle, and could occupy less wooded areas, so the available food was different.
So you would expect thicker enamel etc if the proportion of fruit in the diet was lower.
But the canines are a special case, and of course, the declining size-difference between males and females also points to a difference in how dominance was achieved. Not conclusive, but just pointing the same way.
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[mistermack]

could =/= does , how would you test the hypothesis and what is the null hypothesis?

You could test it by LOOKING CAREFULLY at fossilised wood dating from more than 3mya, in the (probably futile) hope of finding a piece that has been worked.
I doubt if that is being actively done at the moment, but I wouldn't hold my breath if it was.
Another way would be to minutely examine the tracks at Laetoli, to see if anything possibly matched a stick being rested on the ground, or dragged at any stage. Again, I wouldn't hold out much hope though, but I would love to give it a go.

The footprints at Laetoli do have lots of other marks around them, but they are currently put down to animal tracks, and that's what they probably are.
I would have to look up Null Hypothesis, so I can't answer that.
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[GenesForLife]

A null hypothesis would be one that explained the patterns you are postulating without invoking the cause-effect relationship of your particular hypothesis, in cases of no competing hypothesis the null hypothesis is chance alone explaining your findings.

[mistermack]

Ok, well, if we take the examples of Chimpanzees, Bonobos and Gorillas, we have a pretty good model for what an ape would end up as, if nothing unusual happened.
So it's not just me, most people are looking for something out of the ordinary to explain bipedality.

The Savannah Hypothesis was actually almost accepted, till it became clear from new fossils that bipedality evolved in a heavily wooded environment, not open Savannah. So if I'm guilty of postulating something without enough evidence, how come Savannah theory actually found it's way into so many textbooks? All they had was an apparent coincidence in the timeing of two events.

Aquatic ape hypothesis is widely discredited, in fact it's never even been credited.

Our ancestors DID become upright, DID lose a good deal of climbing ability, DID lose their biggest weapon, the heavily armed males, and yet DID survive as newly upright apes.

I cannot see how they did that, without some form of protection.
So, no, I can't come up with a good null hypothesis, nor has anybody else, as far as I know.
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[GenesForLife]

I was talking about the null hypothesis for the specific predictions your hypothesis was making, namely that you would expect to find remnants of weapons contemporarous to the transition of the human lineage towards complete bipedality.

[Svartalf]

Weapon finds? what's the likelihood of finding fossilized sticks? I mean, the uprighting of man ancestors happened millions of years before humans mastered flint knapping.

[GenesForLife]

So doesn't that just disqualify Mack's hypothesis as being testable?

[Gawdzilla Sama]

So doesn't that just disqualify Mack's hypothesis as being testable?

He divided by zero in the OP.

[mistermack]

I was talking about the null hypothesis for the specific predictions your hypothesis was making, namely that you would expect to find remnants of weapons contemporarous to the transition of the human lineage towards complete bipedality.

Well, Svartalf is right. The chances of finding fossilised fighting sticks, or spears dating from six or seven million years ago is low. But it's especially low, if nobody is even looking.
Perhaps people looking at sites of more than 3mya should be paying more attention to any spear-sized sticks they find.
I think it's asking a lot, to have solid evidence, to back this up. If I did, I'd be publishing this in Nature, or something similar.
Nobody has ANY hard evidence for how we became upright. So it's perfectly valid to try to interpret what we DO have.

The known facts are that a smallish ape, about 1.5 metres tall, became bipedal, lost it's grasping foot, and so lost it's vital ability to practically run up trees, away from danger. So they spent a lot of time on the ground, with a highly diminished escape strategy.
Bipedal humans are slow. Newly bipedal apes would be even slower. Especially sprinting off the mark.
And just at the time that life apparently got more dangerous, the big males lost much of their fighting prowess.
It all points to some other tactic for defence.
If you think sticks or spears wouldn't save them, remember that their arms were two or three times as strong as a man's.
Have a look at this, to see what you can do with a good stick:
(Link)
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[Gawdzilla Sama]

Have a look at this, to see what you can do with a good stick:
(Link)
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Irrelevant link is irrelevant. First off, he was using a club, not a spear. Second, he's a modern human, not a early hominid.

[mistermack]

Have a look at this, to see what you can do with a good stick:
(Link)
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Irrelevant link is irrelevant. First off, he was using a club, not a spear. Second, he's a modern human, not a early hominid.

Of course it's not a perfect parallel. But early hominids were much more powerful than modern humans. And I've consistently said sticks and spears. They are both useful weapons.
Most of the wood available to our ancestors would be hardwoods, and when I say spear, I'm not talking about a javelin, I'm talking about a shorter, sharpened stick, fairly thick and heavy. Not a throwing weapon, a stabbing and clubbing weapon.
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[Gawdzilla Sama]

Have a look at this, to see what you can do with a good stick:
(Link)
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Irrelevant link is irrelevant. First off, he was using a club, not a spear. Second, he's a modern human, not a early hominid.

Of course it's not a perfect parallel. But early hominids were much more powerful than modern humans. And I've consistently said sticks and spears. They are both useful weapons.
Most of the wood available to our ancestors would be hardwoods, and when I say spear, I'm not talking about a javelin, I'm talking about a shorter, sharpened stick, fairly thick and heavy. Not a throwing weapon, a stabbing and clubbing weapon.
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So, you have proof that hominids used sharpened sticks? No, you don't. So your house of cards is made up exclusively of jokers.

[mistermack]

So, you have proof that hominids used sharpened sticks? No, you don't. So your house of cards is made up exclusively of jokers.

That's true, but it applies to any hypothesis. If you have direct evidence that proves something, it becomes theory.
Hypothesis applies to ideas that are argued, and only supported by circumstantial evidence.
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