Mystery solved. How and why human ancestors became upright.

[mistermack]

Bzzz, a selective advantage doesn't result in the original development of the phenotype that later ends up being selected for.

It may explain why once bipedalism was the norm it could be selected for, it doesn't explain why bipedalism developed in the first place, which would be a function of variation in the developmental plan of the human body.

It's an interesting comment, but it would only apply if bipedalism was an on-off switch.
It's not. Chimpanzees are often bipedal. They run, they drag branches, they even stand up to fight, and kick, and stamp on their victim. Our ancestors would be similar, six million years ago, and bipedalim would be improving, rather than arriving out of nowhere.
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[GenesForLife]

Fail, the anatomical mechanisms of chimp bipedalism and human bipedalism are totally different.

http://books.google.co.in/books?id=LnPe ... sm&f=false


http://www.plosone.org/article/info%3Ad ... ne.0001019

Clusters of homeotic transformations mark the emergence point of mammals in the Triassic and the radiation of therians in the Cretaceous. A cluster of homeotic changes in the Miocene hominoid Morotopithecus that are still seen in humans supports establishment of a new “hominiform” clade and suggests a homeotic origin for the human upright body plan.

The necessary genetic changes effecting a homeotic origin explain the why, your "hypothesis" can only explain why such a biped configuration may have been naturally selected, in no way does the fact that something is selected for a reason mean that it originated for the purpose it was selected for, which is what you seem to be trying to imply.

[mistermack]

Oh? What do weapons have to do with jaw strength? The jaws weren't for fighting, but for eating. A strong jaw was required for the tough vegetation and raw meat, canines are particularly effective at removing meat from bone.
If there was a change in diet - softer, easier to chew foods - then we would expect to see the jaw strength decrease if a heavy set jaw was somehow a disadvantage - such as wasting energy.
As for the reduction in canines, that would only happen when their primary use - eating - was again eased. Weaponry and fighting have nothing to do with it.

No, big canines are just for fighting. For establishing dominance between males.
The canines of the females are much smaller. It's extreme sexual dimorphism, in our ancestors, gorillas and chimpanzees.
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[GenesForLife]

just for =/= selected for <facepalm>

[Gawdzilla Sama]

No, big canines are just for fighting. For establishing dominance between males.
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Solely for establishing dominance between males? Prove that.

[Trolldor]

Oh? What do weapons have to do with jaw strength? The jaws weren't for fighting, but for eating. A strong jaw was required for the tough vegetation and raw meat, canines are particularly effective at removing meat from bone.
If there was a change in diet - softer, easier to chew foods - then we would expect to see the jaw strength decrease if a heavy set jaw was somehow a disadvantage - such as wasting energy.
As for the reduction in canines, that would only happen when their primary use - eating - was again eased. Weaponry and fighting have nothing to do with it.

No, big canines are just for fighting. For establishing dominance between males.
The canines of the females are much smaller. It's extreme sexual dimorphism, in our ancestors, gorillas and chimpanzees.
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How idiotic of a statement, which goes back to my original point of 'science not being your strong point'.

[Svartalf]

I can prove that. I have small teeth, and am dominated and beaten to inside females' panties by most every young male with bigger canines ergo mistermack is right

[Gawdzilla Sama]

I can prove that. I have small teeth, and am dominated and beaten to inside females' panties by most every young male with bigger canines ergo mistermack is right

I blame Darwin.

[mistermack]

Fail, the anatomical mechanisms of chimp bipedalism and human bipedalism are totally different.

Yes, of course they are. We've had six million years of walking upright. Chimps are essentially the same body-plan as an ape from six million years ago.

Clusters of homeotic transformations mark the emergence point of mammals in the Triassic and the radiation of therians in the Cretaceous. A cluster of homeotic changes in the Miocene hominoid Morotopithecus that are still seen in humans supports establishment of a new “hominiform” clade and suggests a homeotic origin for the human upright body plan

Of course the body plan of apes was more upright than their smaller, more monkey-like ancestors. That's documented by the fossils.
That's for different reasons, probably size-related, and certainly helped "prepare" apes, their body plan was quite suitable for the transformation. But the change to outright bipedalism seems to have come extremely quickly, in stark contrast to a slow evolution in apes to a slightly more upright posture.

The necessary genetic changes effecting a homeotic origin explain the why, your "hypothesis" can only explain why such a biped configuration may have been naturally selected, in no way does the fact that something is selected for a reason mean that it originated for the purpose it was selected for, which is what you seem to be trying to imply.

No, I don't think anything is selected for a purpose. They are selected, and that selection has a result. If that result helps eventual reproduction, the genes prosper in the population.
The idea of a purpose would be quite wrong.
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[Gawdzilla Sama]

/thread

[mistermack]

How idiotic of a statement, which goes back to my original point of 'science not being your strong point'.

I don't believe that contains an argument, just an unsupported assumption.
At least I argue my case. Your unsupported opinion is of no value whatsoever.
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[Trolldor]

No, I don't think anything is selected for a purpose. They are selected, and that selection has a result. If that result helps eventual reproduction, the genes prosper in the population.
The idea of a purpose would be quite wrong.
.

Superfluous period aside, you do realise you just shat over your own presumption with this comment?

[Gawdzilla Sama]

No, I don't think anything is selected for a purpose. They are selected, and that selection has a result. If that result helps eventual reproduction, the genes prosper in the population.
The idea of a purpose would be quite wrong.
.

Superfluous period aside, you do realise you just shat over your own presumption with this comment?

[mistermack]

No, I don't think anything is selected for a purpose. They are selected, and that selection has a result. If that result helps eventual reproduction, the genes prosper in the population.
The idea of a purpose would be quite wrong.
.

Superfluous period aside, you do realise you just shat over your own presumption with this comment?

I'm not going to attempt to untangle your silly riddles. But at least you speak your mind. Even when there's nothing in there.
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[Trolldor]

You can't comprehend somethingas obvious as "You shat over your own presumption" and you're attempting to explain evolutionary history?