Human brain result of 'extraordinarily fast' evolution

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."

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.

Okay, I'll pose my question to you too, since you seem to be pretty knowledgeable. Why would the mental arms race confine itself only to humans? It seems like other highly social animals (wolves specifically come to mind) would reap huge benefits from being a little smarter than their peers. Like I told Alter Kaker, I'm not trying to argue, I really don't get it.

Okay, first, I concede the point that prophecy is not the best choice of words when referring to a lot of these conditions we believe have been met. I guess the best word is, uh, er, CONDITIONS. :-) Some prophecy. Some conditions and/or characteristics and circumstances that we believe were referring to a Jesus who had not yet been born.

And yes, I see double meaning in Hosea 11: A literal discussion of Israel, and a Christological meaning in parts of it.

Matthew 5:17 -- great passage, and from my perspective, a clearcut reminder to Christians that ALL of the Bible is important. There is indeed a tendency among many Christians to focus only on the New Testament, which I believe to be a grave error. I realize you disagree, but I believe the Bible to be an incredibly complex (both in text and structure) INTEGRATED message, sixty-six books written by over forty different penmen over thousands of years. And I think M5:17 goes right to the heart of the issue; I think Christ's message here about fulfillment was layered, as His messages often were. I think He was warning us not to see Him as something separate and disconnected from the events of the Old Testament, but as an EMBODIMENT thereof, a parallel extension of God's love for Israel. (You've probably heard the expression that the Old Testament is the New Testament concealed, while the New Testament is the Old Testament revealed.) Does this answer your question?

What are your thoughts on Daniel 9, specifically 9:25?

As is often the case with questions about evolution, it's amazing how often Darwin himself had enough foresight to conceive of the question and suggest possible answers, way back in the 1800's, long before the anyone even knew that DNA existed, and when the fields of paleontology, geology, etc. were in their infancies:

But every one who admits the principle of evolution, must see that the mental powers of the higher animals, which are the same in kind with those of man, though so different in degree, are capable of advancement. Thus the interval between the mental powers of one of the higher apes and of a fish, or between those of an ant and scale-insect, is immense; yet their development does not offer any special difficulty; for with our domesticated animals, the mental faculties are certainly variable, and the variations are inherited. No one doubts that they are of the utmost importance to animals in a state of nature. Therefore the conditions are favourable for their development through natural selection. The same conclusion may be extended to man; the intellect must have been all-important to him, even at a very remote period, as enabling him to invent and use language, to make weapons, tools, traps, etc., whereby with the aid of his social habits, he long ago became the most dominant of all living creatures.
A great stride in the development of the intellect will have followed, as soon as the half-art and half-instinct of language came into use; for the continued use of language will have reacted on the brain and produced an inherited effect; and this again will have reacted on the improvement of language. As Mr. Chauncey Wright (1. 'On the Limits of Natural Selection,' in the 'North American Review,' Oct. 1870, p. 295.) has well remarked, the largeness of the brain in man relatively to his body, compared with the lower animals, may be attributed in chief part to the early use of some simple form of language,--that wonderful engine which affixes signs to all sorts of objects and qualities, and excites trains of thought which would never arise from the mere impression of the senses, or if they did arise could not be followed out. The higher intellectual powers of man, such as those of ratiocination, abstraction, self- consciousness, etc., probably follow from the continued improvement and exercise of the other mental faculties.
-- Charles Darwin, "The Descent of Man", 1871

Elsewhere in "The Descent of Man", Darwin writes of the obvious connection between language and complex society, since as I mentioned in an earlier post, you can't have one without the other. So his view was similar to that of the authors of the current study -- that at some point the development of a sufficiently complex degree of language/culture, there was a "snowball effect" (like a snowball rolling downhill and growing in size and momentum), where each stepwise advance opened the door to even greater survival advantage, and drove even further advances.

These type of "tipping points" are reasonably common in evolution -- once a species begins to "specialize" in a particular trait to a certain degree, it can hit a point where its success in that area increases selection pressures for even greater successes, evolutionarily. For example, the success of a predator cat depends on applying many factors to the hunt, like stealth, brains, cooperation, speed, strength, etc. But if a species of cat begins to succeed primarily through a moderate advantage in speed, evolutionary pressures will likely accelerate its specialization in its speed advantage, often abandoning most other strategies in order to extend the speed advantage to the point where the other factors become of minor importance in comparison, resulting in for example the Cheetah, which can chase down prey at 70mph. Once its ancestors began succeeding more through speed than through other methods, evolutionary selection would kick into high-gear on increasing their speed even further, relative to improvements on their already secondary attributes (stealth, etc.).

Finally, often a species will achieve a functional "breakthrough", which makes many more advancements now possible to evolve. For example, in reptiles the jaw is hinged at the very back of the jawbone (which in reptiles consists of a few different bones fused together), and incidentally is also instrumental in the resonance and function of their ears. In the descendants of reptiles which eventually became mammals, however, the hinge-point of the jaw migrated to a more forward location, leaving the rearmost components of the multi-bone jaw performing only the hearing-assist functions, instead of the dual hearing/hinge function of the reptilian jaw.

This alone was a relatively minor change, and just helped the early mammals articulate their jaws in a somewhat more flexible manner. HOWEVER, this change had a fortuitous side effect, which is that once the rearmost bones in the jaw no longer had to continue to work as the jaw hinge, they were "free" to evolve into greater specialization as resonators in the improvement of hearing. And thus they rapidly (relatively speaking) separated from the jaw and evolved into the three inner-ear bones of the specialized mammalian ear, better known as the Hammer, the Anvil, and the Stirrup. One seeminginly inconsequential change (the shift in the jaw-attachment point) happened to "open the door" to a sequence of evolutionary changes which dramatically improved the function of the early mammal's hearing -- and that of its descendants, including us.

And *yes*, there *are* transitional fossils showing the steps in this evolutionary progression, along with DNA sequence evidence of the change itself, and its evolutionary origin.

Similarly, early man may have achieved some seemingly inconsequential evolutionary change (perhaps biochemical, or structural, or in neuron functionality, or whatever), which by our good fortune happened to set the stage for the rest of our great leap forward in mental ability, making the rest possible. And once possible, made evolution able to achieve it by subsequent accumlated changes.

The full human and chimp genomes have now been sequenced, and a huge amount of research is being done on the differences (and similarities) between them. There are dozens of ways that evolutionary histories can be extracted from DNA comparisons (see for example these former posts of mine: 1, 2), and within the next decade most of the exact sequence of evolutionary changes between man and the other apes will be brought to light. Then we'll finally understand exactly which changes, and when, mankind underwent on our journey from our non-human ancestors, and how those changes brought us to where we are today.

...and even then the die-hard creationists will keep chiming in to assert, "there ain't no evidence at all for evolution, none!"

Once again the media blows the reporting of a scientific study big time. This story way over exaggerates the findings.

Here's the link and abstract to the actual study.

Accelerated Evolution of Nervous System Genes in the Origin of Homo sapiens

Human evolution is characterized by a dramatic increase in brain size and complexity. To probe its genetic basis, we examined the evolution of genes involved in diverse aspects of nervous system biology. We found that these genes display significantly higher rates of protein evolution in primates than in rodents. Importantly, this trend is most pronounced for the subset of genes implicated in nervous system development. Moreover, within primates, the acceleration of protein evolution is most prominent in the lineage leading from ancestral primates to humans. Thus, the remarkable phenotypic evolution of the human nervous system has a salient molecular correlate, i.e., accelerated evolution of the underlying genes, particularly those linked to nervous system development. In addition to uncovering broad evolutionary trends, our study also identified many candidate genes—most of which are implicated in regulating brain size and behavior—that might have played important roles in the evolution of the human brain.

I have a Science Direct account and read the whole study.

A couple of things

1) This 'extraordinarily fast' evolution they are talking about occurred over 25 million years!!!!!

2) In the actual study, They compared only human and macaques and not humans & chimps because as they put it

Quote "To obtain evolutionary rates in primates, we compared sequences between human and the Old World monkey, macaque. We note that even though much discussion of human evolution has focused on human-chimpanzee comparisons, the strong sequence similarities between these two species results in high stochastic uncertainty in the estimation of evolutionary rates".

So they are basically talking about the whole ape line not just humans. If they did this study with chimps or gorillas and macaques they would have gotten the same results. So despite the sensational headlines of this article there is nothing in this study to suggest that somehow humans evolved (for lack of better words) in a more "special way" (thus hinting at some sort of ID) than any other ape.

3) They only compared the evolution of human/Macaque vs mouse/rat brains, who knows if other families might have actually had more brain evolution (i.e. elephants, dolphins, etc)

4) Interesting thing in the study: The Human(ape) line split from the Macaque line and the rat line split from mouse line both about 25 million years ago. But despite the "fast" evolution of the Human brain, Humans overall are still more genetically similar to macaques than rats are to mice. So for all this talk about 'extraordinarily fast' evolution, rats still over all evolved much faster/more than humans did over the same time period. (which since they breed so darn fast is to be expected under the T.O.E.)

"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.

Actually, you haven't explained anything. You've merely taken 5 words to assert something. Now, please explain how God does his creating. For starters, what's his methodology, what kind of "stuff" does he manipulate to create what we know as matter and energy, is there such a thing as "time" to God, and is his timeline the same as ours, or is it orthogonal to ours? Is God truly omniscient & omnipotent, or does it just seem that way to us? Is there just one God in his world, or is he actually a supernatural high-school science student who created our universe as a class project? If so, did his dad help him with anything? Has the teacher judged his project yet, and after that happens will he throw us into the trash or store us in his closet? You say that God can do anything, but is he able to change the past in our timeline? (Presumably he wouldn't be going back in his time, just ours, so it shouldn't cause any problems for him. Unless his timeline is the same as ours.) If so, how many times has he gone back in time and changed our timeline? If so, how would we know? How many alternate timelines have we already played out? What's God's criteria for deciding that a timeline needs to be tweaked one more time? When God tweaks the timeline, does he immediately see all the consequences happen at once, or does it take time in his world for time in our world to play out as well?

These are off the top of my head. Needless to say, there are hundreds more questions that your theory needs to explain. I suspect that if you actually tried to adequately explain these implications of your 5-word theory, you'd end up with a pretty long book yourself!

Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.