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Human brain result of 'extraordinarily fast' evolution
Posted: Wed Dec 29, 2004 9:23 pm
by August
Human brain result of 'extraordinarily fast' evolution
Emergence of society may have spurred growth
The sophistication of the human brain is not simply the result of steady evolution, according to new research. Instead, humans are truly privileged animals with brains that have developed in a type of extraordinarily fast evolution that is unique to the species.
"Simply put, evolution has been working very hard to produce us humans," said Bruce Lahn, an assistant professor of human genetics at the University of Chicago and an investigator at the Howard Hughes Medical Institute.
"Our study offers the first genetic evidence that humans occupy a unique position in the tree of life."
Professor Lahn's research, published this week in the journal Cell, suggests that humans evolved their cognitive abilities not owing to a few sporadic and accidental genetic mutations - as is the usual way with traits in living things - but rather from an enormous number of mutations in a short period of time, acquired though an intense selection process favouring complex cognitive abilities.
Evolutionary biologists generally argue that humans have evolved in much the same way as all other life on Earth. Mutations in genes from one generation to the next sometimes give rise to new adaptations to a creature's environment.
Those best adapted to their environment are more likely to survive and pass on their genes to the next generation.
The evolution of a large brain in humans, then, can be seen as similar to the process that leads to longer tusks or bigger antlers. In general terms, and after scaling for body size, brains get bigger and more complex as animals get bigger.
But with humans, the relative size of the brain does not fit the trend - our brains are disproportionately big, much bigger even than the brains of other non-human primates, including our closest relatives, chimpanzees.
Prof Lahn's team examined the DNA of 214 genes involved in brain development in humans, macaques, rats and mice.
By comparing mutations that had no effect on the function of the genes with those mutations that did, they came up with a measure of the pressure of natural selection on those genes.
The scientists found that the human brain's genes had gone through an intense amount of evolution in a short amount of time - a process that far outstripped the evolution of the genes of other animals.
"We've proven that there is a big distinction," Prof Lahn said. "Human evolution is, in fact, a privileged process because it involves a large number of mutations in a large number of genes.
"To accomplish so much in so little evolutionary time - a few tens of millions of years - requires a selective process that is perhaps categorically different from the typical processes of acquiring new biological traits."
As for how all of this happened, the professor suggests that the development of human society may be the reason.
In an increasingly social environment, greater cognitive abilities probably became more of an advantage.
"As humans become more social, differences in intelligence will translate into much greater differences in fitness, because you can manipulate your social structure to your advantage," he said.
"Even devoid of the social context, as humans become more intelligent, it might create a situation where being a little smarter matters a lot.
"The making of the large human brain is not just the neurological equivalent of making a large antler. Rather, it required a level of selection that's unprecedented."
Posted: Wed Dec 29, 2004 10:18 pm
by Prodigal Son
thanks for the posting...it gave me a good laugh!
Posted: Thu Dec 30, 2004 8:18 am
by August
Sorry, I was going to add that I think this is a real problem for evolutionists, in that there was non-physical factors involved in generating mutations. Societal needs are not realy scientifically measurable, are they? The article is from the British Guardian newspaper.
Posted: Thu Dec 30, 2004 11:42 am
by Prodigal Son
if you find the author, title, and date of article, i can share it with my agnostic/atheist friends.
Posted: Thu Dec 30, 2004 12:36 pm
by August
Posted: Thu Dec 30, 2004 3:45 pm
by Anonymous
I think the evolutionist view in this context is "hey, whatever works" - it doesn't really matter if the path is greased as long as it leads in the right direction. If I understand it correctly, the main requirements for evolution are replication, limited mutation and a selection criterion. The emergence of society would have strengthened the first and third of these - larger populations and much greater need for intelligence.
--Edit: which now I come to read it is pretty much what the article was saying
Posted: Thu Dec 30, 2004 4:44 pm
by August
I don't dispute the requirements for evolution, but my understanding is that the genetic mutations used to prove evolution are a physical response brought on by changes to the physical environment, for example Darwins finches. In the case of the human brain, from the statement of this scientist, who may just be misinterpreting the data, societal changes created psycological needs, like the need to outsmart an opponent, work together for the good of society through spoken and written language, and establish right from wrong. Those needs are not physical, i.e. longer and stronger beaks because of harder seeds like in the case of Darwins finches, but changes that are "perceived" necessary by human observation.
My question is how a need to evolve formed from a perception, can lead to a physical genetic mutation over a large enough population so as to become the only living specimen of that mutation? If through speciation, which generally according to the TOE takes a long time, but this happened so quickly, why do we not see humans with big and small brains in the fossil record or alive today, or non-socially adapted humans? Furthermore, evolutionists like to explain that evolution does not mean that the predecessor disappears, the reason they claim man came from an ape and we still have apes. Does Darwins tree not show that too? Where are the small-brained humans then, a necessary intermediary for the human, if all of this happened so quickly? Other homonoids are too old to fit into this discovery, according to ome quick checking I did, which may be wrong. Why did we not see the same happen with the ape species, wolves, baboons, lions, fish and other groups that display societal behavior? Why did other parts of the human body not develop as fast as the brain, if these societal needs were so pressing?
"The making of the large human brain is not just the neurological equivalent of making a large antler. Rather, it required a level of selection that's unprecedented." He is trying to fit this into the TOE, but it does quite seem to want to go.
The scientist also reveals a bit of his underlying bias by saying "Simply put, evolution has been working very hard to produce us humans,". That is giving designer characteristics to evolution, is it not? Probably just a misstatement, but amusing nonetheless.
Sorry for the long post, I'm just seriously enthusiastic.
Posted: Thu Dec 30, 2004 5:16 pm
by Anonymous
My question is how a need to evolve formed from a perception, can lead to a physical genetic mutation over a large enough population so as to become the only living specimen of that mutation?
I'm having trouble parsing this. If I understand correctly, the thrust of your question is how the heck did the brainpower of an entire species take a leap? I'd need to do some research, but I imagine the evolutionary answer is something along the lines of "There were lots of genes capable of increasing the human brain capacity floating around. Suddenly societies started to coalesce and all these genes became very important. The result was that the survivors of the revolution had several of these genes, hence a seriously big brain."
If through speciation, which generally according to the TOE takes a long time, but this happened so quickly, why do we not see humans with big and small brains in the fossil record or alive today, or non-socially adapted humans?
It is believed that speciation doesn't always take a long time. For example, after a mass extinction, there is lots and lots of space to spread into (cos all your neighbours copped it). The result is that mutations which, in the more intense pre-extinction environment, would have been wiped out are suddenly able to flourish. They have time to make something of themselves, as it were. Once the slack is taken up the pressure resumes again, but by that time plenty of odd and useful stuff may have emerged. This is, I believe, the standard explanation for things like the Cambrian Explosion, which is evolution's answer to the dot-com boom
Furthermore, evolutionists like to explain that evolution does not mean that the predecessor disappears, the reason they claim man came from an ape and we still have apes. Does Darwins tree not show that too? Where are the small-brained humans then, a necessary intermediary for the human, if all of this happened so quickly?
Evolution doesn't
necessarily mean that the predecessor disappears. If a species finds itself able to spread into a new evolutionary niche, it will do so - hence, for example, the many species of finch on the Galapagos Islands, with beaks modified for different tasks. However, if a subset of the species becomes more effective within the existing habitat, it will tend to displace the less-effective "predecessor". An example of this would be the antibiotic-resistant "superbugs" often found in hospitals.
Other homonoids are too old to fit into this discovery, according to some quick checking I did, which may be wrong.
As far as I can see, the article doesn't specify what point this surge in brainpower was supposed to have happened at. That makes it quite hard to research
Why did we not see the same happen with the ape species, wolves, baboons, lions, fish and other groups that display societal behavior?
Cos none of them have complex social behaviour and tool usage, apart from the apes, and were thus not able to get much out of any newfound intelligence. Remember that the brain consumes a ridiculous amount of energy and oxygen - if it's not good for much, it won't tend to hang around. Regards apes, the evolutionary argument would be that it
did happen to them, and we're the result. Maybe if it hadn't happened to us it'd have happened to chimpanzees in a few millennia.
Why did other parts of the human body not develop as fast as the brain, if these societal needs were so pressing?
I assume cos none of them particularly needed it. Most of us don't use anything like our full physical capacity in day-to-day life - having more efficient muscles wouldn't have made that much difference to survival when weapons were just being invented.
"The making of the large human brain is not just the neurological equivalent of making a large antler. Rather, it required a level of selection that's unprecedented." He is trying to fit this into the TOE, but it does quite seem to want to go.
I see what you mean. I think he's just saying that cos he's not allowed to use swearwords for emphasis when talking to reporters
The scientist also reveals a bit of his underlying bias by saying "Simply put, evolution has been working very hard to produce us humans,". That is giving designer characteristics to evolution, is it not? Probably just a misstatement, but amusing nonetheless.
Again, I know what you mean. Scientists and atheists both are as guilty of anthropomorphisation as anyone else - I've been known to plead with my computer when it crashes
Sorry for the long post, I'm just seriously enthusiastic.
Me too
Discussion is fun.
I'm aware that in this post I've been very much taking the evolutionist role upon myself. I've mostly been trying to avoid doing this cos it doesn't come across as very openminded. Unfortunately I'm tired and I'm looking back at this and I don't have the energy to rework it to be more impartial - sorry,
Posted: Thu Dec 30, 2004 5:59 pm
by August
No worries about the position you take, it's an interesting debate.
"I'm having trouble parsing this. If I understand correctly, the thrust of your question is how the heck did the brainpower of an entire species take a leap? I'd need to do some research, but I imagine the evolutionary answer is something along the lines of "There were lots of genes capable of increasing the human brain capacity floating around. Suddenly societies started to coalesce and all these genes became very important. The result was that the survivors of the revolution had several of these genes, hence a seriously big brain." "
My question is twofold. One, how can a social need influence the physical, and two, you got it, how did it happen to a large population? Your answer does not quite get to the first part, unless I missed it. As to your response to the second question, that is an awful lot of assumption. The TOE states that very few genes mutate, and even then the "good" mutations are only a few out of thousands. The point the scientist makes is that the development of the human brain does not quite fit with that model, since it happened quicker than that model would allow.
"This is, I believe, the standard explanation for things like the Cambrian Explosion, which is evolution's answer to the dot-com boom"
The Cambrian explosion is not all that well-explained in the literature I read. There are a lot of predecessors missing especially among the phylas. The other assumption about the cambrain explosion is that it was a very fertile time on earth, causing evolution (and speciation) to speed up. That is still a physical environment change, i.e. more water, mild temperatures etc, as opposed to the societal needs described here.
"Cos none of them have complex social behaviour and tool usage, apart from the apes, and were thus not able to get much out of any newfound intelligence. Remember that the brain consumes a ridiculous amount of energy and oxygen - if it's not good for much, it won't tend to hang around. Regards apes, the evolutionary argument would be that it did happen to them, and we're the result. Maybe if it hadn't happened to us it'd have happened to chimpanzees in a few millennia."
I need to consult experts on the issue here, but I believe the animals mentioned display the same societal behavior which could have prompted early man to develop more brainpower. Otherwise we have to assume that humans somehow had to display unique societal behavior, somewhere in between, which prompted the evolution of more brainpower, but then it becomes a circular argument, man needed more brainpower to develop society, to develop the need for more brainpower.
I have some more thoughts, will post later.
Posted: Thu Dec 30, 2004 6:52 pm
by Prodigal Son
on the animal thing--wolves and elephants and dolphins and many other species have extremely complex social behaviors and high intelligence. elephants also use tools.
know the author, name of article?
Posted: Thu Dec 30, 2004 7:05 pm
by August
The original article is linked earlier. It came from the UK Guardian newspaper, apperently compressed from another publication called "Cell", by the science journalist at the Guardian, Alok Jha.
If those animals show highly complex societal behavior, why did their brains not evolve at the same rate as humans, if complex societal behavior was the catalyst for the evolution of the human brain? Elephants use tools, as do apes, but do they make tools? Will they pick up a rock or stick, make it into something else, and then use it, or just use a rock or stick to crack open stuff?
Posted: Thu Dec 30, 2004 7:22 pm
by Anonymous
I'm still reasonably sure that apes were the best candidates we had for developing advanced tool-usage - can't beat those opposable thumbs. Enhanced tool usage - primitive clothes, inanimate objects as weapons, fire and cutting implements for better food processing - would have caused a population boom, and also allowed specialisation. Both of these would have required extra brainpower - those at the bottom of the social heap, or who couldn't grasp this new "trading" thing, would have struggled compared to those who took it all in their stride.
Going back to August's and my discussion:
how can a social need influence the physical?
A social problem is just a psychological one that lots of people share
If physical improvements make survival and breeding more likely then it surely doesn't matter if the danger came from furry things with teeth, high cliffs, or one's fellow men-like creatures.
and two, you got it, how did it happen to a large population? ... As to your response to the second question, that is an awful lot of assumption. The TOE states that very few genes mutate, and even then the "good" mutations are only a few out of thousands.
The TOE, IIRC, doesn't really state much more than "kill off the bad ones, breed the good ones and you'll tend to get good ones." There would be several gene modifications floating that added directly to the raw brainpower of their owners, but, until tool-making became prolific, these wouldn't be much use - sure you'd be able to outthink your neighbour, but it wouldn't really be worth the waste of energy.
Then humanity suddenly gets into tools in a major way, a trend continued to this day by Black&Decker wielding DIYers. Now brainpower is very important - being big and strong isn't worth so much when your neighbour has a very sharp rock. Suddenly all those slightly smarter people have something useful to do with their brains. They profit, they breed, every brain-enhancing gene the species ever happened across and forgot to throw away comes to the fore. In addition, they're better nourished - your brain can afford to grow that extra few grams without cannibalising the rest of you in the process. Consider the amount of weight people managed to pile onto innocent farmyard animals during the Industrial Revolution. Now consider the same effort going into increasing brain size.
I get what you're saying - the scientist's comments about genes appearing all at the same time is a little misleading - but I think that effectively all he's saying is that humans utilise their "good" brain-related genes far more effectively, and are less likely to discard them, than macaques and rats.
Posted: Thu Dec 30, 2004 7:45 pm
by Mastermind
Lifewish, natural selection is no longer a factor in human evolution, and hasn't been for a long long time. We will always need strong warriors who don't need a brain as well as weak brainiacs. The vast majority of humans, no matter what group they belong to, are smart enough to ensure their survival to a much higher extent than any other animal.
Posted: Thu Dec 30, 2004 8:14 pm
by August
"If physical improvements make survival and breeding more likely then it surely doesn't matter if the danger came from furry things with teeth, high cliffs, or one's fellow men-like creatures. "
Those are still physical needs, which were quite well addressed in the earlier specimens, i.e. they survived and bred well. The scientist in this case implies that societal needs was the reason for the evolution of the brain, and now we are back in circular reasoning, society will cause development of intelligent brains, and having many intelligent brains will cause society to develop. If the TOE is applied to this case, then it was indeed a Cambrian explosion of intelligence among humans. But what would cause that? This is what the scientist in this case does not yet understand, from the article, he is merely speculating that societal needs could have caused it. If he is not speculating, what is the scientific proof for it being the only cause?
Societal need describes collective responsibility to the individual, as you stated in the first sentence, which clearly includes the consideration of others and concepts of right and wrong, in order for society to grow and prosper. Then why would the human brain evolve faster and better than those of socially complex animals?
"The TOE, IIRC, doesn't really state much more than "kill off the bad ones, breed the good ones and you'll tend to get good ones." There would be several gene modifications floating that added directly to the raw brainpower of their owners, but, until tool-making became prolific, these wouldn't be much use - sure you'd be able to outthink your neighbour, but it wouldn't really be worth the waste of energy."
So you are saying that what was essentially damaged brian genes would have been neutral, or fulfilled another function until called upon to raise intelligence? That is more than I can grasp at this point, I need to ponder that, again against the background of what could have caused that to happen.
Posted: Thu Jan 06, 2005 2:07 am
by Anonymous
Hey,
I don't know if it's already been referred to, but one philosophy is that the human brain has now reached its evolutionary capacity - in otherwords, if the brain grows even bigger, we will decrease in knowledge rather than increase. Many modern day philosophers now believe, that our evolution now carries on in society rather than in the brain - through computers and systems etc...
In Christ,
Fr. A