On evolution of humans and that of other animals: any discrepancy?

'Rapid brain expansion' began after (more than 5-7 million years ago) we became omnivorous - the new, protein-rich diet provided adequate nutrients for brain development, and our brains increased in size. However, we soon hit a brick wall - some scientists believe it was the size of our cranium or the mass of our jaw muscles which stopped our brain expansion. Here is where we were lucky - a mutation (or several) resulted in our jaw muscles shrinking. This allowed for further brain expansion, and the fact that we could not now eat things like hard nuts which require gorilla-like jaw muscles to crack put a selective pressure upon us to get smarter, and so our brains increased in size further.

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And as an 'in between' limiting factor, many believe the size of the birth canal limited cranial expansion.

Dolphins don't build telescopes because they do not have hands

I think that evolution is an ongoing process, however, at times, during periods of stress and especially strong selective pressures, I believe that punctuated equilibrium can 'take over' increasing the speed of phenotypical changes dramatically.

Humans are nothing special. We share over 98% of our DNA with the common chimpanzee, Pan troglodytes whom we are estimated to have shared a last common ancestor 5-7 million years ago. A 2% change is not an unimaginably large amount considering the amount of time between our divergence and the present. Our brains have exactly the same parts as any other mammal - some parts are just bigger. Furthermore, Neanderthal man had a larger brain than we do, so you would expect Homo neanderthalensis to have outsmarted us. However, it seems that the neanderthals preferred smaller social groups and did not have the social skills we possess - where we could trade between populations, they isolated themselves, and eventually became extinct after waves of especially large glaciations.

I would say that language is the key to our success - we can record things, whether orally or by writing them down. This allows our offspring to build upon our knowledge and improve upon it, resulting in technological development. Most animals do not have this benefit, and have to find out about the world by themselves, and / or what little they learn from their mothers. Very limited technological development can be observed in chimpanzees - sometimes an individual will improve upon a tool it has seen being used by another member of the group, although this will usually be done with trial and error. Chimpanzees also possess culture - some tools and foods will only be exploited by one or two groups - the other groups have not learned about them yet.

'Rapid brain expansion' began after (more than 5-7 million years ago) we became omnivorous - the new, protein-rich diet provided adequate nutrients for brain development, and our brains increased in size. However, we soon hit a brick wall - some scientists believe it was the size of our cranium or the mass of our jaw muscles which stopped our brain expansion. Here is where we were lucky - a mutation (or several) resulted in our jaw muscles shrinking. This allowed for further brain expansion, and the fact that we could not now eat things like hard nuts which require gorilla-like jaw muscles to crack put a selective pressure upon us to get smarter, and so our brains increased in size further.

There have also been many experiments where apes have been taught sign language or been taught to communicate with a lexigram. While some of the apes, for example a bonobo named Kanzi could communicate very well, and even made up their own words, none of them ever asked a single question. This, is perhaps the single difference between humans and other animals, and may have been key to our evolution - certainly, religion originated from the question 'why are we here?'

EDIT: I cant recommend any books, but I can give you this link: http://www.youtube.com/watch?v=Qus01tIocdQ
The other two are good as well, but thought you'd be most interested in the brain one

Again, to back up what Chordata has said, there's absolutely no difference between the way humans evolved and the way other animals evolved. If you look at the evolutionary history of H. sapiens sapiens, our level of divergence and speciation occurs along a similar time period to what you'd expect given the selection pressures. I don't think the path from erectus -> sapiens is even the most interesting part of human evolution, I think the off-shooting species and the migration of our early ancestors is far more interesting!

Regarding your intellectual oddities in our evolution, how recently in our evolutionary history did those things occur? Most of the mindblowing stuff didn't happen until the last 100 years, and mathematics has been 3000 years in the making - even those 3000 years only make up a tiny section of Homo sapiens history. The increasing intellectual complexity of our ideas certainly isn't a result of biological evolution between early humans and us, it's a more fundamental biopsychosocial reason. It's a property our brains already have, and it doesn't take anything especially complex to explain how we came about with a brain like that.



And as an 'in between' limiting factor, many believe the size of the birth canal limited cranial expansion.
Also given the hunting and survival strategies of hominini genus, intelligence was a selected for trait.

Regarding neanderthal extinction, would you mind linking me to the sources you've read? The authors I've read have hypothesised more for competitive exclusion by the modern human, as opposed to inability to sufficiently adapt to a changing environment during the last glacial period.

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and anatomical structures related with production of voice ( and the associated parts of the brain ).
Of course, then came the next triggering point. If you can associate some sound that you can produce with parts of your body with a specific thing or action, it would be very valuable, since you can teach your children what to do in a specific situation or how to do it. That should enable one generation of your species pass what you've known in your lifetime to your offspring. And the rest of the story of evolution may only be the consequence of combined sociocultural contribution.

I mean, humans can do what no other animals can do. It has a huge brain capable of solving complex mathematical problems, building giant telescopes to understand better how the universe works and giant machines as big as a city such as Large Hardon Collider. Humans have sent machines on other planets. Humans have a brain that is capable of thinking and communicating in complex languages. None of other animals do have such abilities, at least not at this scale, and none have all of them ( some dolphins, for example, do have language, but use only a few words, and certainly they didn't build telescopes. )

Rose-tinted spectacles much? You're giving human intelligence more credit than it's worth. Tell me, could you build a large hadron collider? Could you send a machine to another planet? No, nor could any other single human being on this planet. These things come about through collaboration and centuries of accumulated knowledge by thousands of people. Arguably that is the single trait that separates us from other animals; the way we pass on knowledge.

As for our ability to master complex languages, yes that is a pretty impressive feat, but humans are by their very nature a social animal. On the face of it, we're pretty unimpressive - we can't swim faster than a dolphin, we can't climb trees with the agility of a squirrel, we can't out-run a cheetah, we wouldn't last very long in a fight one-on-one with a lion ect.....our ace in the hole if you will is our social nature, individually we are weak, together we are strong. We would never had survived if we had not evolved the ability to carry out complex communication with one another.

On the face of it, our "intelligence" is no more impressive than the ability of whales to communicate with one another over vast distances, the ability of a bat to catch prey and avoid obstacles while flying using echolocation alone, the ability of a bee to find its way back to the hive even from many miles away, the colour-changing ability of the chameleon, the ability of the octopus to squeeze itself into spaces far smaller than its own body-size......why are these traits not as impressive as humanities cognitive ability?

As a final point, you really over-exaggerate human intelligence. There are intelligent people amongst us and together, we are able to accomplish extraordinary things but individually, the human brain can be quit a foolish thing, it can be easily tricked, gives in to instinct rather than logic far too often, is swift to give in to mob mentality and falling to peer pressure and is prone to superstitious beliefs despite the lack of evidence.

I didn't get you there. Birds have a syrinx analogous to the human larynx in that it plays a role in sound production. So, I guess the development of these anatomical structures in birds and mammals could have taken nearly simultaneously, when they bifurcated from the common ancestor.

Can you explain to see whether I am right or wrong there?

I didn't get you there. Birds have a syrinx analogous to the human larynx in that it plays a role in sound production. So, I guess the development of these anatomical structures in birds and mammals could have taken nearly simultaneously, when they bifurcated from the common ancestor.

Can you explain to see whether I am right or wrong there?

I'm no expert on this, but aren't the larynx and the syrinx slightly different - I believe that the syrinx is lower down the trachea, near the fork, which allows some birds to vocalise two notes at once, where a mammal can only make one using the larynx.

It's possible that when we diverged from birds, as mammal-like reptiles (or whatever the correct term is now) a primitive larynx existed, which evolved convergently to fill the same function. It's possible that the larynx is even older as some extant reptiles can vocalise.

As far as I know, mammals diverged from reptiles, not birds.

Oh, I'm sorry. I haven't been perfect in using the right words, I guess.

Of course birds can produce sounds. But just being able to produce sounds is not enough for the development of a language.

Language works, I think ( I can be wrong, please let me know if you see any points you don't agree with ) in a multi-step process. For being an animal capable of using language ( in the form of speech ) first you have to be able to associate an image of an object or action with a specific sound ( or set or sequence of sounds ... I will give you an example later ) you can produce with your own body parts, and store that association inside your brain.

Then, if another person wants to learn that system, he first needs to reproduce the same sound with his body. Then if he wants to let another person of the society know that information, you have to first recall that image first, then recall what sound you associated first with that image, and then let the motor system of your brain (which is connected with your neurons that stored the auditory information ) order the muscles of your body to reproduce that sound.

Okay, that was a poor try to express what I really wanted to tell.

Suppose, you see a yellow long thing that is usually eaten by the members of your society. Someone decides to tag this thing with a sound ''Ba'' ( I intentionally avoided using the word ''Banana'' just to make it simple. ) Now all the members of that group, including you and one of your friends tag the image of that fruit with the sound ''Ba'' in memory ( by practising suddenly opening up closed lips which require some facial muscles which are in turn controlled by your motor neurons. Your auditory memory cells have to connect with this motor cells too. ) Now suppose, one day, you and your friend are lost in a jungle and find no edible fruit. Suddenly you see a tree in the middle of a bush with those yellow things hanging up. You decide to let your friend know about the good news. You search in your brain which sound you associated with that fruit, and found that it's ''Ba.'' Your auditory memory cell then send the particular motor neurons responsible for contracting the muscles which can suddenly open up closed lips. And viola! You said it. ''Ba'' One small sound for man, one giant shout for mankind.

Now, you've already understood, for language, you need a complex system. Producing or reproducing a specific sound is only part of it. But the real catch is you have to be able to produce a wide range of sounds which are tagged with a lot of objects which you can manipulate. And humans certainly could manipulate a lot of natural resources once they had opposable thumbs ( For a monkey, maybe knowing which things are edible and which things are not is enough. Many social animals warn their peers about predators by producing specific sounds. But for our ancestors, they had to know how to make a sharp piercing stick out of a branch of a tree. And if you know how to sharpen a stick, you must already know what is a stone, or more specifically, a stone with a side made sharp. )

And to do that, it's very useful if you can pass what you know to your children.

So the summary is, you got to have the ability to produce more sounds individually for more objects or actions ( so more muscles and more motor neurons to do that ), and more space inside your memory, and more synapses within the participant neurons and muscles.

I want to make it clear that this is totally my assumption, not based on any evidence of source. I'd be very grateful if you let me know if you noticed something missing, incorrect, illogical, or impossible.

But one thing is certain. The anatomical structures responsible for language in human is far more complicated than that of any other animals.

I'm no expert on this, but aren't the larynx and the syrinx slightly different - I believe that the syrinx is lower down the trachea, near the fork, which allows some birds to vocalise two notes at once, where a mammal can only make one using the larynx.

It's possible that when we diverged from the reptiles that would later evolve into dinosaurs and then birds, as mammal-like reptiles (or whatever the correct term is now) a primitive larynx existed, which evolved convergently to fill the same function. It's possible that the larynx is even older as some extant reptiles can vocalise.

Edit: fixed it

That would explain it quite nicely. Can you give a few examples of some extant reptiles that can vocalise? I know that some dinosaurs retained the ability to vocalise to a certain extent, but what examples are extant now?
Thanks

I wouldn't be surprised if many dinosaurs vocalised like enormous birds.

Anyway, geckos and chameleons are the only reptiles with true vocal chords - snakes have none, so they can only hiss, and crocodiles have folds in the membrane in their throat which perform a similar purpose, but limit the amount and pitch of vocalisations. Frogs also have vocal folds with the throat sac acting as a resonance chamber to amplify the sound, which suggests that vocalisation had evolved even earlier.

Heres a video of a tokay gecko 'barking'




Interestingly, it seems many mammals also have false or reduced vocal chords, such as whales. Many species of primate can also not close their vocal chords as much has humans can - a chimp or bonobo is physically incapable of human speech because of this.

Interesting. Thanks for the input. I knew that frogs could croak, and that meant that vocalisation had existed in amphibians as well.
I was reading that bonobos can, like MedQ mentioned above, learn to associate sounds with specific objects. This ability is a bit limited compared to humans. The anatomical homology you described may be a cause, although I guess this has more to do with auditory relay centers and "language" centers than anything else.

Speaking of which (pun not intended), it's a bit controversial, but the FOXP2 gene may have had something to do with the evolution of language, but I don't know that much about it, so couldn't tell you any more.

http://en.wikipedia.org/wiki/FOXP2

Also, some animals like vervet monkeys have different warning calls for different predators, and they will react differently to each one, showing that they understand the meaning of the vocalisation by using different strategies to avoid the threat. Although I use the term loosely, you could consider this a very primitive form of language as it's relating a sound to an object.

[video="youtube;KRVxqCo9iW8"]http://www.youtube.com/watch?v=KRVxqCo9iW8[/video]

The snake alarm alerts them to group together and stand up to intimidate the snake.

The eagle alarm is explained in the video

And the leopard alarm results in them them running to the tops of the trees, where a large cat cannot reach them.