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12-06-2013, 10:37 PM
RE: Top of the heap.
(12-06-2013 10:08 PM)ghostexorcist Wrote:  
(12-06-2013 06:25 PM)evenheathen Wrote:  So here's a question that I've had since, well, since I can remember. When I was a believer the faulty answer was actually one of the stronger arguments for god's existence in my mind. Now that the god answer is no longer satisfactory, I've been thinking about it again. Maybe some of you smartypants college edumecated types can help me.

How is it that humans' brains evolved so much more rapidly than other animals? What exactly were the evolutionary mechanisms that allowed for such a rapid leap in brain size and function from our earlier ancestors? It seems to be a Cambrian explosion of sorts, but just for our line of species.

I am under no delusion that we are the only highly intelligent animals on the earth. However I dare say there is a substantial gap between our intelligence and even that of our closest relatives.

I know that philosophers have probably been hammering away at this for ages, but I'm more interested in the hard science. The how, not the why. Are there any solid theories as to what circumstances moved this along?

Primates have the largest brain-to-body ratio (Encephalization Quotient) of any animal. This chart shows the EQ for several different species. The further away one is from the line the greater deviation in expected brain size. Note that male gorillas have a lower EQ simply because they are so darn big. Humans lead the pack.

[Image: brainsizechart.png]

There are several theories as to why primate brains are so big, all of which are connected in some way.

1. Social relationships - It takes a monumental amount of brain power to keep track of an ever-expanding pool of acquaintances--i.e. who is higher ranking then me, who is lower ranking than me, who is my friend, who is my enemy, who owes me favors, who I owe favors to, etc. For example, if you know 6 people, you have to keep track of 15 different interactions...

[Image: socialrelationships.png]

The number of interactions obviously goes up from there. Just ask yourself one question: How many people do I regularly talk to in my daily life and on the internet?

2) Food – Since apes are frugivores (primarily fruit eaters), it takes a lot of brain power to distinguish fruit from a sea of leaves. It also takes a lot to remember annual feeding sites and the various routs taken to get there.

3) Behavioral flexibility – Apes are far too intelligent to be mindless automatons that repeat the same actions day in and day out. Sticking to one set schedule is a good way to get eaten. So being behaviorally flexible and adapting to new situations gives one a survival advantage.

All of these are easily applicable to humans. If you view the fossil record, you will see that the earliest individuals on the lineage leading to humans all had chimp-sized brains. Our brains only started to grow beyond this in the last 2 million years or so. One theory is related to number 3 from above. Africa’s climate began to rapidly change starting after 3 million years ago. It shifted back and forth between lush forest and dry savannah. Being able to adapt in this unstable environment was key to survival. Another theory is that the development of fire made meat far easier to digest, thus introducing more protein into our bodies. This not only made us grow taller, but gave us bigger brains. I’m not too knowledgeable on the number of genetic changes that took place. FOXP2 and a few more recent mutations are the only ones I know of (I see the former has already been mentioned). But all of these took place after our brain grew to its current capacity.

Right on. A bigger brain would definitely be required for more knowledge. However simply gaining bigger amounts of knowledge is not a mechanism for a bigger brain to evolve as I understand things. (correct me if I'm wrong there)

So there must have been random mutations such as the FOXP2 coupled with environmental (societal) changes which made the increased ability for memory and whatnot a favored trait for survival. Am I getting it? Kinda maybe? Consider

But what exactly would trigger the entire head to gain size, skull and all? Would all of that just happen together? I may be asking more than I want to learn at the moment...Blush

But now I have come to believe that the whole world is an enigma, a harmless enigma that is made terrible by our own mad attempt to interpret it as though it had an underlying truth.

~ Umberto Eco
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12-06-2013, 11:18 PM
RE: Top of the heap.
(12-06-2013 10:37 PM)evenheathen Wrote:  Right on. A bigger brain would definitely be required for more knowledge. However simply gaining bigger amounts of knowledge is not a mechanism for a bigger brain to evolve as I understand things. (correct me if I'm wrong there)

So there must have been random mutations such as the FOXP2 coupled with environmental (societal) changes which made the increased ability for memory and whatnot a favored trait for survival. Am I getting it? Kinda maybe? Consider

But what exactly would trigger the entire head to gain size, skull and all? Would all of that just happen together? I may be asking more than I want to learn at the moment...Blush

Just use Darwin's finches as an example. Each were born with varying sizes of beaks. Which one was best suited for their environment with larger seeds? The ones with more robust beaks of course. The size of the beaks were the product of random mutations. Likewise, primates born with larger portions of grey matter were able to process more information. They survived better than their less endowed peers and had more children. Remember that evolution happens at the group level. This resulted in our ever-increasing brain size. The reason our brains didn't grow that much prior to 2 million years ago is because the environment was relatively stable. There was no need to select for more "smarts". When the size of our brains began to skyrocket, the skull responded to this growth. See what I posted here.

As for the protein, I look at it like this: a child may be genetically predisposed to be a certain height or weight, but diet plays a huge part in their development. Not enough protein and they will be small. Lots of protein may help them meet or exceed their potential. Epigenetics may play a role in this.
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12-06-2013, 11:28 PM
RE: Top of the heap.
(12-06-2013 11:18 PM)ghostexorcist Wrote:  
(12-06-2013 10:37 PM)evenheathen Wrote:  Right on. A bigger brain would definitely be required for more knowledge. However simply gaining bigger amounts of knowledge is not a mechanism for a bigger brain to evolve as I understand things. (correct me if I'm wrong there)

So there must have been random mutations such as the FOXP2 coupled with environmental (societal) changes which made the increased ability for memory and whatnot a favored trait for survival. Am I getting it? Kinda maybe? Consider

But what exactly would trigger the entire head to gain size, skull and all? Would all of that just happen together? I may be asking more than I want to learn at the moment...Blush

Just use Darwin's finches as an example. Each were born with varying sizes of beaks. Which one was best suited for their environment with larger seeds? The ones with more robust beaks of course. The size of the beaks were the product of random mutations. Likewise, primates born with larger portions of grey matter were able to process more information. They survived better than their less endowed peers and had more children. Remember that evolution happens at the group level. This resulted in our ever-increasing brain size. The reason our brains didn't grow that much prior to 2 million years ago is because the environment was relatively stable. There was no need to select for more "smarts". When the size of our brains began to skyrocket, the skull responded to this growth. See what I posted here.

As for the protein, I look at it like this: a child may be genetically predisposed to be a certain height or weight, but diet plays a huge part in their development. Not enough protein and they will be small. Lots of protein may help them meet or exceed their potential. Epigenetics may play a role in this.

Aha, yes I should have put that together. I have absolutely no formal education in evolution at all (even though I think I have the concepts down fairly well). This was an obvious one, I was just thinking about it too hard. Forgive me. Sad

So do you think that environmental (not just societal, but climate/geological) factors played a significant role in what necessitated our brain growth? And any thoughts to why it happened so quickly?

But now I have come to believe that the whole world is an enigma, a harmless enigma that is made terrible by our own mad attempt to interpret it as though it had an underlying truth.

~ Umberto Eco
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12-06-2013, 11:55 PM
RE: Top of the heap.
(12-06-2013 11:28 PM)evenheathen Wrote:  Aha, yes I should have put that together. I have absolutely no formal education in evolution at all (even though I think I have the concepts down fairly well). This was an obvious one, I was just thinking about it too hard. Forgive me. Sad

So do you think that environmental (not just societal, but climate/geological) factors played a significant role in what necessitated our brain growth? And any thoughts to why it happened so quickly?

Like I stated in the first post, the environment of Africa started to rapidly shift between dry savannah and lush forest starting sometime around 3 million years ago. Those with larger brains could adapt to the unstable environment better. Another theory is that tool usage may have led to an increase in brain size. This is because making more intricate tools required more brain power and fine motor control. The Oldowan tool complex first appeared around 2.5 million years ago.

[Image: toolbrainbipedalitytoot.png]
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13-06-2013, 12:16 AM
RE: Top of the heap.
(12-06-2013 11:55 PM)ghostexorcist Wrote:  
(12-06-2013 11:28 PM)evenheathen Wrote:  Aha, yes I should have put that together. I have absolutely no formal education in evolution at all (even though I think I have the concepts down fairly well). This was an obvious one, I was just thinking about it too hard. Forgive me. Sad

So do you think that environmental (not just societal, but climate/geological) factors played a significant role in what necessitated our brain growth? And any thoughts to why it happened so quickly?

Like I stated in the first post, the environment of Africa started to rapidly shift between dry savannah and lush forest starting sometime around 3 million years ago. Those with larger brains could adapt to the unstable environment better. Another theory is that tool usage may have led to an increase in brain size. This is because making more intricate tools required more brain power and fine motor control. The Oldowan tool complex first appeared around 2.5 million years ago.

[Image: toolbrainbipedalitytoot.png]

Awesome, thanks! Any insights to my original question as to why we seem to be the the best adapted as far as brain size goes? Seems to me that other species would have also been affected by environmental change as well, given we all were in the same boat, but we sped ahead for some reason. I realize your specialty is primarily primates.

But now I have come to believe that the whole world is an enigma, a harmless enigma that is made terrible by our own mad attempt to interpret it as though it had an underlying truth.

~ Umberto Eco
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13-06-2013, 12:39 AM (This post was last modified: 13-06-2013 12:51 AM by Momsurroundedbyboys.)
RE: Top of the heap.
(12-06-2013 06:25 PM)evenheathen Wrote:  So here's a question that I've had since, well, since I can remember. When I was a believer the faulty answer was actually one of the stronger arguments for god's existence in my mind. Now that the god answer is no longer satisfactory, I've been thinking about it again. Maybe some of you smartypants college edumecated types can help me.

How is it that humans' brains evolved so much more rapidly than other animals? What exactly were the evolutionary mechanisms that allowed for such a rapid leap in brain size and function from our earlier ancestors? It seems to be a Cambrian explosion of sorts, but just for our line of species.

I am under no delusion that we are the only highly intelligent animals on the earth. However I dare say there is a substantial gap between our intelligence and even that of our closest relatives.

I know that philosophers have probably been hammering away at this for ages, but I'm more interested in the hard science. The how, not the why. Are there any solid theories as to what circumstances moved this along?

I haven't read through all the comments, yet, but I seem to recall that our brain development and evolutionary whatever had a lot to do with walking upright or bipedalism (thank goodness my iPad knows that word).

Unfortunately I can't recall how...something about the amount of energy used...or not, helped humans to develop skills, speech centers...We could travel longer distances (albeit slowly), but that I think from an evolutiary standpoint might be a reason. In areas where there are rapid changes, adaptations occur more rapidly.

I would imagine since we tend to keep those adaptations that prove the most useful and are best suited to our environment., our brains developed through millions of years of adapting. I can't say that we did it any faster than other species -- we might have been better equipped to handle the changes.

It's not to suggest there wasn't other human type species that didn't survive that process either and ultimately became extinct. Homo erectis (sp?) was one of the first to leave Africa almost 1.5 million years ago...and it's brain was larger than the very first homo whatever's (lol) which appeared 3 million years ago and significantly larger than its more hominid (sp) predecessor.

And who knows...who says we were the smartest? Or the ones with the largest brain...maybe the really smart one didn't make it.


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13-06-2013, 07:10 AM
RE: Top of the heap.
Bipedalism takes a lot of fine motor control.

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13-06-2013, 09:36 AM
RE: Top of the heap.
(13-06-2013 12:16 AM)evenheathen Wrote:  Awesome, thanks! Any insights to my original question as to why we seem to be the the best adapted as far as brain size goes? Seems to me that other species would have also been affected by environmental change as well, given we all were in the same boat, but we sped ahead for some reason. I realize your specialty is primarily primates.

First, see my first post on why science thinks primates grew large brains. Second, I would say all other animals were smart enough for their respective environments. Third, humans are apex predators. As the chart I posted shows, animals with the highest brain-to-body ratio are meat eaters. Since we ate pretty much everything, our activities may have selected against animals growing more intelligent. Although, I will say that we may not be the "top of the heap." Science is still exploring the concept of intelligence. What we consider to be "smart" may only apply to us. For instance, being able to speak and write doesn't necessarily mean one is intelligent. Some researchers believe that dolphins may be our intellectual superior.
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13-06-2013, 09:41 AM
RE: Top of the heap.
(13-06-2013 09:36 AM)ghostexorcist Wrote:  For instance, being able to speak and write doesn't necessarily mean one is intelligent. Some researchers believe that dolphins may be our intellectual superior.

The dolphins think that it's obvious.

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Science is not a subject, but a method.
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13-06-2013, 09:45 AM
RE: Top of the heap.
(13-06-2013 12:39 AM)Momsurroundedbyboys Wrote:  I can't say that we did it any faster than other species -- we might have been better equipped to handle the changes.

I could have sworn that I've read or seen that the development of our modern brains happened very quickly. Perhaps in evolutionary terms it wasn't all that quicker than normal and I just misunderstood it as being more extraordinary than it actually was.

But now I have come to believe that the whole world is an enigma, a harmless enigma that is made terrible by our own mad attempt to interpret it as though it had an underlying truth.

~ Umberto Eco
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