Posted on 12/29/2004 9:14:28 AM PST by aculeus
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."
Guardian Unlimited © Guardian Newspapers Limited 2004
I don't know. When Jesus said "No man comes to the Father but by Me" remember He was speaking to the people around Him. Jesus could have meant that if they do not listen to Him and practice what He is teaching them they won't go to heaven. It is not certain He meant that for generations and generations into the future those who don't believe in Jesus or who have not even heard of Jesus are automatically not going to Heaven. So, I am not certain what was meant by that. I am a Christian, but I have family members who are not. I think the best way to convert people is by setting a good example. What made me go from agnostic to Christian was actually getting to know nice people who were Christians. Hearing Christians talking about others going to Hell actually turns alot of people off. Leave the decision of who is going to Heaven or Hell up to God.
Never heard that term before. The problem is that there are so many variables in biological systems that a difference in gene expression is bound to be correlated to one of them. It's an even bigger problem when there is but one positive data point--here, humans vs all other species.
In that case, any aspect of the human environment that differs from that of other species could be used to 'explain' the difference in gene expression, particularly with evolutionary biology, a very flexible tool for hypothesizing causation retrospectively. So you pick one that suits your preconceptions and write a journal article. I'm not sure what it is; but it's not science.
Once again, my caveat. The posted article is a popular press article, not the journal article. It may be that the author actually has some statistical basis for the claim. With only one data point, that would be hard; but the popular press article may have just left out a whole section of the journal article that contained statistics as uninteresting.
One other caveat, the authors speculation that complexity of society has driven brain mutations may have been just that in the journal article. A speculation about possible future testable hypotheses would be a proper function in a journal article. The reporter could have erroneously picked this up as the whole point of the journal article.
Most textbooks presenting the Theory of Evolution hardly encourage skepticism. Don't you know 150 years of science has established the fact of common descent?
The universe exists, for starters. How does evolutionism explain that? It doesn't, it can't, and it does not want to.
Laws of Nature exist, too. How does evolutionism explain that? It doesn't, it can't, and it does not want to.
Fish have been fish as long as recorded history has been around. How does evolutionism explain that? It tries, it doesn't, much as it would like to.
"In the beginning, God created . . ." only takes five words. Evolutionism takes a mountain of scholarly obfuscation to explain. Occam's Razor should be applied to multiplicity of words in the same manner it is applied to multiplicity of explanations, but Occam isn't God.
Try this link for further illumination.
Here's a question for you - not trying to be argumentative, I'd just like your take on it.
If the development of society is what caused the superfast evolution of human brains, why wouldn't *other* societal animals, like, say, wolves, also undergo a superfast evolution? Wolves have very specific societal organization, and a smarter wolf would almost certainly rise to alpha male status and thus pass his genes along.
Again, *NOT* trying to be argumentative, it just seems to be a gap in the argument, and you seem pretty knowledgeable on the topic.
"Let us make man"...
"Let us confuse their tongues..."
What's with this "us"? To whom is He referring? It seems to imply a "decision by committee".
I don't believe it is angels, because these phrases imply an equality that simply does not exist. In the presence of angels, wouldn't He be more inclined to say, "I will make man in My image", or, "I'll confuse their tongues".
Anyone who has thoughts or ideas on this will be most appreciatively welcomed.
CA....
I don't know, I'm not an evolutionary biologist, but I suppose the answer is that there wasn't the same pressure on wolves or other societial animals to become smart. Are superintelligent male wolves more likely to become alfa-males and pass on their genes or do female wolves seek out other characteristics like strength or even the gloss of their coat? And the other factor, are superintelligent males any better at hunting deer and elk or whatnot than normal wolves and therefore more likely to survive to reproduction? I suspect the answer is no, or otherwise the advantage is not significant enough to lead to much of a change.
Our ancestors couldn't hunt deer with our fangs -- we had to work together and use tools and whatnot because we are so weak and slow, so yes intelligence was an advanatage.
a) the wrong prophecies, and thus the fact that Jesus fulfilled them is irrelevant.
The thing is, most of these 'prophecies' are not prophecies at all. Even from the standpoint of Christianity, the vast majority of these are 'typologies' rather than 'prophecies'. That is, they are verses or brief passages read and interpreted to bring out a Christological meaning, without regard to the surrounding context.
A good example of this is:
This was to fulfil what the Lord had spoken by the prophet, "Out of Egypt have I called my son." (Matthew 2:15)
The passage this refers to is:
When Israel was a child, I loved him, and out of Egypt I called my son. (Hosea 11:1)
Considering that the passage is in the past tense, it is clearly not "prophetic" in the ordinary understanding of the term -- e.g. "And I will make of you a great nation" (Genesis 12:2). From the Christian perspective, these typologies infuse the Hebrew scriptures with Christological significance. From the Jewish perspective, Christians are taking scripture out of context and reading their own preexisting beliefs into the text. If you read the whole of Hosea 11, it is clear that the entirety cannot be referring to Jesus. It is only the first verse to which Christians ascribe Christological significance (rightly, in their view; wrongly, in the Jewish view).
b) an incomplete set of prophecies; Jesus fulfilled some but not all.
There are only a dozen or so passages in the Hebrew scriptures which are generally agreed by Jews to be messianic prophecies. Generally, these are prophecies which Christians believe will be fulfilled at the 'second coming'.
c) we're incorrectly interpreting events as fulfillment.
I think it's less a matter of interpreting events than it is of differences in the ways in which we interpret scripture.
Since you bring up the topic of 'fulfillment', though, I'd like to ask you a question. It makes sense to speak of fulfilling a prophecy -- the events foretold come to pass. But what does it mean, in your understanding, to "fulfil the law" (Matthew 5:17)?
The Wolves that became dogs certainly went through superfast evolution. Plus there are 32 subspecies of wolf in the world so they are varied.
If that is the case the author is arguing then I don't it can be called Darwinian evolution.
I'm no scientist but my understanding of DE is random mutations and/or gene duplication is the mechanism for DE. The beneficial random mutations are then selected and become heritable.
This guy seems to be saying that the these mutations are directed by the environment which would seem to mean that some optoisolator in the genome turned on and requested an algorithm for a larger brain.
Perhaps he's an ID guy. :-}
I'm sure if I misstated anything Darwinian the wrath of the Darwinians will soon be showering down on my blue collar but there you have it anyway.
Here's a post I made in March 2002 explaining punk eek to someone who didn't understand it at the time. (I'll refrain from speculating how much has changed since then.)
I saved it under the heading "My personal punk-eek example." Note the particular hypothetical I chose for illustrative purposes. I mention it now because you seem to be crowing over catching us "once again changing our story."
Still, way to go! You've discovered punk-eek! Someday you may know something about evolution. (Of course, you'll probably go to Hell for it.)
I remember that post very clearly, despite it not being addressed to me. When I see a reference to punk-eek, I pull up your explanation in my mind. I will say you are an effective communicator considering I still clearly remember your summation.
I can see how this idea is attractive to those who are confined to a materialistic explanation for reality. It attempts to explain the unexplainable, couched in scientific terms.
I still don't understand why you choose to confine yourself in that way, considering the supernatural evidence that surrounds us.
Some night's I'd pursue that but I'm old and cynical and out for this one.
AMEN - YEC INTREP
First of all, I'm not preaching but discussing and answering questions and posing some of my own. But, with that said, people come to Christ through a variety of means and motivations. Some through love and example. Some through desperation from having hit bottom. And LOTS through fear of hell. And there is utterly NOTHING wrong with quoting the Bible; it's exactly what we're commanded to do. Nor is there any ambiguity whatsoever about he meaning of the verse under discussion. As for people who never hear from others about Christ, I believe the Spirit ministers directly to them, but that certainly doesn't mean we as Christians are supposed to ease around with our mouths shut and eyes closed.
MM
True, but the intelligence difference between dogs and wolves is miniscule compared to that of chimps and humans. Another way to state my original question is this: if participation in a society is what caused human brains to undergo superfast evolution, why didn't other species undergo similar superfast evolution to similar levels as humans?
It still is. See below.
I'm no scientist but my understanding of DE is random mutations and/or gene duplication is the mechanism for DE.
That's the *source* of variation in Darwinian evolution, but it's only *one* part of the *mechanism*. As you mention in your next sentence, selection is also part of the mechanism:
The beneficial random mutations are then selected and become heritable.
Without selection, there is no evolution. Without heritable variation, there is no evolution. Without reproduction, there is no evolution. With any two of the three, there still isn't evolution. It's only when all three are present that Darwinian evolution kicks in as a process (or "mechanism", if you prefer that term).
This guy seems to be saying that the these mutations are directed by the environment which would seem to mean that some optoisolator in the genome turned on and requested an algorithm for a larger brain.
No. What you're missing is that changes in any (or all) of the *three* components of Darwinian evolution can affect the rate of evolution. Faster reproductive rates result in faster evolution, for example, which is why bacteria and viruses evolve much faster than, say, fruit flies, and fruit flies evolve faster than horses, etc.
Up to a point faster mutation rates also can drive evolution more quickly, but there's a point of diminishing returns, where the mutation rate is so large that successful reproduction at all becomes difficult, or cancer rates skyrocket, etc.
What the current article is discussing, however, is when *selection* is particularly intense on a population. This can happen for many reasons. For example, when famines become common in a particular region, the species which face multiple starvation events will cause selection which "weeds out" more quickly individuals with genes that make them less tolerant of periods without food, and will enhance the reproductive success of the individuals who have genes which keep them alive longer during periods of starvation, and/or enable them to still breed and reproduce successfully on low food supplies, etc. Note that in this example, unless there is always an overabundance of food, even during times of adequate but sparse food, evolution could also select for better lack-of-food tolerance, because most animals go hungry for at least short periods at times even when a full-out famine isn't occurring. However, the effect of selection at those times would be much *slower* than in times of famine, because the amount of reproductive differential that the different genes provide will be much less during times of occasional hunger than they will during times of "half-the-population-dies" famines.
In short, selection occurs more quickly (often *MUCH* more quickly) -- that is, it has a faster, more extreme effect of eliminating "worse" genes from the population and concentrating "better" genes in the population -- when conditions are such that the amount of help/harm the genes contribute to their "owner's" reproductive success is largest.
The point of the article is that at the time when modern humans were evolving from their common ancestor with the other apes (and contrary to popular belief, we're *still* technically apes/primates), something about the conditions we were in at the time strongly favored the survival rate (actually, "reproductive success", but you can't reproduce if you don't survive, although raw survival is only part of the larger picture) of individuals who were smarter than their peers.
In short, our proto-human ancestors found themselves in an intense mental "arms race" with each other, where the guys/gals with the higher intelligence were much more "favored" by selection than their denser cousins.
There could be a lot of factors which would lead to such a condition (and most likely several were probably at play to at least some degree, not just one exclusively). But like the authors, I think that a good possibility to do more research on (to confirm or eliminate it as a potential factor) is the advent of "society" as we know it. Once proto-humans began to band together into groups larger than extended families (as is the case for most of the great apes), having the smarts to figure out your "competition's" plans and work out your own plan to come out ahead of them (e.g., "court intrigue", "politics", call it what you will), and how best to form and keep alliances, while blocking opposing alliances, not to mention winning wars against rival social groups, etc., would provide a HUGE selective pressure for the "most cunning". And as the species as a whole got smarter over generations as a result, it would just up the ante in the "intelligence arms race" yet again, continually providing evolutionary pressure for bigger and bigger brains. Outwitting your "political rivals" requires a hell of a lot more smarts than "outwitting nature", which is all that most other species need to do brain-wise.
This is not a new idea. Several years back I saw a program on the Discovery Channel (IIRC), which pointed out that the smartest species in their own animal familes are the ones which are the most *social*. Dolphins are very social and form shifting social alliances within their pods. Dogs/wolves are very social and have a heirarchical social structure, and need to hunt as teams. Parrots are the smartest birds, and live in social groups. Elephants are quite intelligent, and live in very social groups. And humans, needless to say, are both the smartest animal, and live in the largest, most complex societal groups of all.
Another factor (which would be intimately intertwined with social interaction anyway) would be the advent of grammar-based language. Gorillas and chimpanzees use language as well (and can learn quite a bit of ours, actually, through sign language or fat-fingered "word keyboards"), yet don't seem adept at using language in ways where subtle changes in word order or sentence structure can result in significant changes in meaning. They can impart simple messages to each other (e.g. "Lion, run!"), but can't easily express more complicated concepts. If the early proto-humans achieved a breakthrough in being able to use even a primitive grammar-based language, it would again provide a *huge* incentive for improvements in the brain which to capitalize on the enormous possibilities of the new "tool" (to pass on accumulated tribal knowledge, to better coordinate hunts/wars and other tasks, to agree on tribal laws, to work out differences, etc. etc.) This too would quickly cause a "brain arms race" -- and would simultaneously make human-type societies possible as well, since they are highly dependent upon the ability to exchange ideas.
Any/all of these factors would have greatly accelerated the Darwinian selection of increased intelligence, and cause evolution to "grab on to" (i.e. quickly select for) any incremental increase in mental ability as minor mutations of various kinds slowly built up "human-type" brains from "ape-like" brains.
Perhaps he's an ID guy. :-}
No, he's not, nor is there any need to invoke ID.
I'm sure if I misstated anything Darwinian the wrath of the Darwinians will soon be showering down on my blue collar but there you have it anyway.
Nah, as long as you ask nicely, we'll explain nicely. :-)
It's only when someone barges in and tries to "tell" us why we've all allegedly been completely and "obviously" wrong for 140+ years because of something they read a few years ago in a pamphlet, that we get a little testy.
I'm no Biblical scholar, but the explanation I've always heard is that the plural is a reference to the Trinity, or the Triune Godhead. In other words, God the Father was speaking to God the Son and God the Holy Spirit. Don't know if that's the 100% correct solution, but it makes sense to me.
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