Evolutionary increase in size of the human brain explained

Researchers have found what they believe is the key to understanding why the human brain is larger and more complex than that of other animals.

The , with its unequaled , evolved rapidly and dramatically.

"We wanted to know why," says James Sikela, PhD, who headed the international research team that included researchers from the University of Colorado School of Medicine, Baylor College of Medicine and the National Institutes of Mental Health. "The size and cognitive capacity of the human brain sets us apart. But how did that happen?"

"This research indicates that what drove the evolutionary expansion of the human brain may well be a specific unit within a protein – called a protein domain -- that is far more numerous in humans than other species."

The protein domain at issue is DUF1220. Humans have more than 270 copies of DUF1220 encoded in the genome, far more than other species. The closer a species is to humans, the more copies of DUF1220 show up. Chimpanzees have the next highest number, 125. Gorillas have 99, marmosets 30 and mice just one. "The one over-riding theme that we saw repeatedly was that the more copies of DUF1220 in the genome, the bigger the brain. And this held true whether we looked at different species or within the human population."

Sikela, a professor at the CU medical school, and his team also linked DUF1220 to brain disorders. They associated lower numbers of DUF1220 with microcephaly, when the brain is too small; larger numbers of the protein domain were associated with macrocephaly, when the brain is too large.

The findings were reported today in the online edition of The American Journal of Human Genetics. The researchers drew their conclusions by comparing genome sequences from humans and other as well as by looking at the DNA of individuals with microcephaly and macrocephaly and of people from a non-disease population.

"The take home message was that brain size may be to a large degree a matter of domain dosage," Sikela says. "This discovery opens many new doors. It provides new tools to diagnose diseases related to brain size. And more broadly, it points to a new way to study the human brain and its dramatic increase in size and ability over what, in evolutionary terms, is a short amount of time."

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baudrunner
1.7 / 5 (11) Aug 16, 2012
I see only two possibilities as to how the human genome came to be possessed of so many copies of the DUF1220 protein domain: 1. normal evolutionary pathways encountered by choice or chance as necessary adaptations to the environment, and 2. genetic tinkering by the "gods". Don't discount the second possibility. There is just too much evidence in the accounts from ancient Egyptian to pre-Babylonian civilizations that explain human development via genetic engineering.
TheGhostofOtto1923
4.4 / 5 (19) Aug 16, 2012
"The take home message was that brain size may be to a large degree a matter of protein domain dosage,"

-The existence of this protein may have been what enabled the brain to enlarge, but its functional abilities were WHY larger brains were continually selected for. They provided advantages in communicating, remembering, anticipating, synthesizing, and planning, which all gave them decisive advantages in conflict with others.
TheGhostofOtto1923
4.1 / 5 (19) Aug 16, 2012
There is just too much evidence in the accounts from ancient Egyptian to pre-Babylonian civilizations that explain human development via genetic engineering.
We are a product of domestication as are our animal and plant creations. Human traits were artificially selected for using cultural, as opposed to environmental, influences.

No need to invoke genetic engineering; husbandry offers sufficient explanation.
R2Bacca
2.9 / 5 (7) Aug 16, 2012
2. genetic tinkering by the "gods". Don't discount the second possibility. There is just too much evidence in the accounts from ancient Egyptian to pre-Babylonian civilizations that explain human development via genetic engineering.


Someone has been watching too much StarGate. It's a great show, but... really?

Human traits were artificially selected for using cultural, as opposed to environmental, influences.


I think you're over-crediting this a bit. You're saying our brain size is a result of nurture as opposed to nature? Isn't that a bit of a chicken-and-egg argument?
Sonhouse
4.7 / 5 (3) Aug 16, 2012
I wonder what that # would be in Dolphins? Wouldn't that be a good test of the effect?
TheGhostofOtto1923
4.2 / 5 (18) Aug 16, 2012
I think you're over-crediting this a bit. You're saying our brain size is a result of nurture as opposed to nature? Isn't that a bit of a chicken-and-egg argument?
'Nurture' is really a misnomer. Weapons use is cultural. Those who could make the best weapons and use them most effectively in the field against the competition, would be expected to prevail.

"There can be no doubt that a tribe including many members who, from possessing in a high degree the spirit of patriotism, fidelity, obedience, courage, and sympathy, were always ready to give aid to each other and to sacrifice themselves for the common good, would be victorious over most other tribes; and this would be natural selection." Darwin, 1871, i, p. 166
http://rechten.el...RID2.pdf

-TRIBALISM is a cultural phenomenon. Those who can thrive in such an environment have to behave in ways contrary to their animal natures.
cavhealth
2.4 / 5 (5) Aug 16, 2012
What does this finding about DUF1220 have to do with evolution? So we have more copies of DUF1220 than other mammals. That does not lead to the conclusion that evolution is the reason.
animah
4.8 / 5 (4) Aug 16, 2012
The study indicates a statistical correlation between this protein and micro & macrocephaly. There is clearly a benefit to this discovery in terms of predicting these conditions at birth or even genetic predisposition among parents.

However to link this protein to intelligence via brain size throughout the animal kingdom is overextending the argument I think. Sperm whales have 7kg brains (5 times larger than us). Elephants are at 5kg, dolphins 2kg - but they are not smarter than us. Conversely, an octopus's brain is much smaller but has the largest neurons in nature. Even though it has much fewer neurons, octopuses have been shown to be as smart as apes.

Intelligence in evolution is one of the most complex issues in biology and just cannot be boxed in so simply.
gpkoz
5 / 5 (2) Aug 16, 2012
animah has a good point to say the protein argument linked to evolution is overextended. Not only do octopi have giant neurons but the squid axons are the basis for many electrophysiological studies by many neuroscientists like Kandel but even in goldfish there are neurosecretory neurons so large that capillaries penetrate them as reviewed by Bargmann and Scharer in the '60's.
Torbjorn_Larsson_OM
5 / 5 (4) Aug 16, 2012
Actually it isn't our brain that is "dramatically" increased, but the other homininae whose brains haven't scaled with increased body mass as other monkeys - but we do "the monkey routine". So we stand out more than different species of elephants do (also big-brained, but all of them.) But it is neat to find simple regulatory mechanisms behind that.

Creationists shouldn't comment on science, it is hilarious to see.

@ cavhealth:

1. Evolution is the process behind biology, so it is "the reason" for biological changes.

2. We don't need genomics to see how evolution has worked here, if you take all hominid fossil finds you can draw a smooth line through increased cranial capacity.

3. But with genomics you see evolution at work, since we split of from first rats (rodents), then marmosets (monkeys), then gorillas (apes). "The closer a species is to humans, the more copies of DUF1220 show up." That increase on the lineage to us: it is evolution.
malapropism
5 / 5 (3) Aug 16, 2012
... to link this protein to intelligence via brain size throughout the animal kingdom is overextending the argument I think. Sperm whales have 7kg brains (5 times larger than us). Elephants are at 5kg, dolphins 2kg - but they are not smarter than us. Conversely, an octopus's brain is much smaller but has the largest neurons in nature. Even though it has much fewer neurons, octopuses have been shown to be as smart as apes.

You're right and one would hope that they used brain mass to body mass ratios rather than a straight brain mass comparison. Unfortunately the paper isn't available to check (that I could find, anyway.)
cavhealth
1 / 5 (6) Aug 16, 2012
@ cavhealth:

1. Evolution is the process behind biology, so it is "the reason" for biological changes.


It is an unproven theory, and there are competing theories.

2. We don't need genomics to see how evolution has worked here, if you take all hominid fossil finds you can draw a smooth line through increased cranial capacity.


If you take all hominid fossil finds that exist, you will find nothing of the sort. You cannot even find a complete skull of one hominid fossil, without a lot of assumptions about what the skull looked like.

3. But with genomics you see evolution at work, since we split of from first rats (rodents), then marmosets (monkeys), then gorillas (apes). "The closer a species is to humans, the more copies of DUF1220 show up." That increase on the lineage to us: it is evolution.


More theory, but that's all it is. The same evidence is consistent with alternative theories.
animah
5 / 5 (4) Aug 16, 2012
Sorry which competing theories (your plural)? Specifically: That meet the minimum framework standard for "theoretical" (presenting to formal peer review for public scientific testing) in say the last 20 years?
Shabs42
5 / 5 (6) Aug 16, 2012
Sorry which competing theories (your plural)? Specifically: That meet the minimum framework standard for "theoretical" (presenting to formal peer review for public scientific testing) in say the last 20 years?


Beat me to it. I really wish the word theory was better understood by the average citizen. Just coming up with an explanation that fits the evidence isn't good enough. "God did it" always fits the evidence no matter what, and is therefore not a theory in the scientific sense.

You are right that evolution is a theory. It is about as sure of a thing as the theory of gravity. There are aspects to both that we don't fully understand, but we have the basics worked out for both.
Shabs42
5 / 5 (6) Aug 17, 2012
cont'd

At this point, evolution should be easily accepted by anyone with even a high school understanding of biology. The amount of evidence in fossils, genetics, lab work, and field work is each staggering on its own. Taken as a whole the evidence is far beyond any reasonable doubt.
vega12
5 / 5 (2) Aug 17, 2012
I wonder what that # would be in Dolphins? Wouldn't that be a good test of the effect?

That's an interesting question. Although dolphins are not as closely related to us as the great apes, so they might have other protein factors at work controlling brain size. If it was the same gene controlling size for dolphins too, that would be a very interesting find.
blazingspark
5 / 5 (4) Aug 17, 2012
That's an interesting question. Although dolphins are not as closely related to us as the great apes, so they might have other protein factors at work controlling brain size. If it was the same gene controlling size for dolphins too, that would be a very interesting find.

I wouldn't be too surprised to find similar mechanisms at work in dolphins. They are still mammals after all. Mammalian brains have quite a bit in common.
cavhealth
1 / 5 (5) Aug 17, 2012
... At this point, evolution should be easily accepted by anyone with even a high school understanding of biology. The amount of evidence in fossils, genetics, lab work, and field work is each staggering on its own. Taken as a whole the evidence is far beyond any reasonable doubt.


I disagree. I have more than a high school science education, and I am not aware of any un-fabricated fossil evidence that proves that we evolved from non-organic matter. Genetics show similarities but no proof of evolution from one species to another. I'm not sure what lab work and/or field work you have in mind.
DarkHorse66
5 / 5 (2) Aug 17, 2012
[q I disagree. I have more than a high school science education, and I am not aware of any un-fabricated fossil evidence that proves that we evolved from non-organic matter. Genetics show similarities but no proof of evolution from one species to another. I'm not sure what lab work and/or field work you have in mind. O for crying out loud.That's because the first organisms were not only single cell, but as a result of being 'soft'cell, preserved poorly.But there is some fossil evidence.
http://www.fossil...tion.htm
http://en.wikiped...volution hint: see 'hadean eon',last entry
http://en.wikiped...organism
Here is your dividing line between organic&non-organic:
http://en.wikiped...emotroph (mentioned in the above-mentioned'last entry')I suggest everyone read these,in case he has issues accepting them as evidence for"un-fabricated fossil evidence"ie that they were the first to exist.Regards to allDH66
DarkHorse66
5 / 5 (3) Aug 17, 2012
@cavhealth: Also, you haven't been clear in what you meant. So, just exactly what DO you mean by "un-fabricated fossil evidence"? A fossil that has been faked in someone's lab? Or are you saying that someone invented details for the sake of 'pretending' to have evidence? Even genetic evidence does not fit the definition of 'fabricated evidence', since they do know how to distinguish between the amounts of time a gene will have been present in a particular pool. If you are intending to have a genuinely serious discussion about this topic, you need to make sure that everyone understands just what it is you are trying to say. Or else you will be practically inviting certain people to become dismissive at best and abusive at worst towards you. That's no longer communication. Not a way to really learn more. Not a good look. Regards, DH66
cavhealth
1 / 5 (2) Aug 17, 2012
To avoid getting into the various possible meanings of un-fabricated, just tell me what "fossils [are] staggering on its own. Taken as a whole the evidence is far beyond any reasonable doubt."

I am not aware of any fossil evidence that proves that we evolved from non-organic matter.
DarkHorse66
5 / 5 (3) Aug 17, 2012
To avoid getting into the various possible meanings of un-fabricated, just tell me what "fossils [are] staggering on its own. Taken as a whole the evidence is far beyond any reasonable doubt."I am not aware of any fossil evidence that proves that we evolved from non-organic matter.

Not all fossils are direct or full imprints of animals or vegetation.Not all evidence is found in the 'classic' fossil! You should have read the links that I gave you, before asking that question.Your question gives you away.The most detailed description of both the type of evidence & why that is so, is clearly described in the Fossilmuseum link(1 easy page).It is the 1st link provided.It is not that hard to read.If you do want a genuine discussion, at least do the courtesy of reading the material that gets provided&if you don't really understand it THEN ask about it,else your sincerity begins to be doubted.I don't mind a healthy discussion but I don't want to waste my time if you refuse to engageDH66
cavhealth
2.5 / 5 (2) Aug 17, 2012
Pardon me, DarkHorse66, but I was directing my previous post to "Shabs42", whom I had quoted.
Tausch
not rated yet Aug 17, 2012
Is the density of biochemical pathways worth considering?
Is there an 'optimal' or 'advantagous' size vs. density (of pathways)? - (For the 'selection' (of size) ensueing from evolution?)
Is there an organic, molecular 'Morse' law?
Doesn't DUF1220 have to 'handle' the size 'difference' between the sexes?
Shabs42
5 / 5 (1) Aug 17, 2012
Pardon me, DarkHorse66, but I was directing my previous post to "Shabs42", whom I had quoted.


Well, first off you're confusing (possibly deliberately) evolution with abiogenesis. I also believe in abiogenesis (which admittedly has much less evidence than evolution), but that is a different debate; and one that evolution does not really attempt to answer.

I have to go to work in about ten minutes, so this will be an incomplete post; but for lab work I was thinking specifically of one experiment where yeast strains were subjected to different environments. They changed into new species over time, and some of the newer species were lost out to older species that were reintroduced, showing that they were adapting to their current environment; not just progressing on a straight line of progress.

As for field work, one example are the ring species. There are others, but I have to go. I'll trust DH or any of the other usual suspects to continue on with my arguments.
cavhealth
1 / 5 (3) Aug 17, 2012
Well, first off you're confusing (possibly deliberately) evolution with abiogenesis. I also believe in abiogenesis (which admittedly has much less evidence than evolution), but that is a different debate; and one that evolution does not really attempt to answer. ...


I think you need to pin down abiogenesis AND evolution. Without confirming how evolution got its start, it remains just an unproven theory.
Shabs42
5 / 5 (4) Aug 17, 2012
I think you need to pin down abiogenesis AND evolution. Without confirming how evolution got its start, it remains just an unproven theory.


Sorry, but you're wrong on this one. I hope one day we can show how life started; but I think the best we'll be able to do in the foreseeable future is give multiple reasonable scenarios. As someone else pointed out earlier, the earliest forms of life did not leave any fossils behind, so showing exactly how the earliest species evolved will likely always remain beyond reach barring a time machine.

We can still show how evolution has worked for the last several hundred million years, we can show how it is working today, we can force it to happen in a lab. Evolution IS a theory in this sense, quoted directly from wiki:

A scientific theory is "a well-substantiated explanation of some aspect of the natural world, based on a body of facts that have been repeatedly confirmed through observation and experiment."
cavhealth
not rated yet Aug 17, 2012
... We can still show how evolution has worked for the last several hundred million years, we can show how it is working today, we can force it to happen in a lab.

Evolution IS a theory in this sense, quoted directly from wiki:

A scientific theory is "a well-substantiated explanation of some aspect of the natural world, based on a body of facts that have been repeatedly confirmed through observation and experiment."


What factual evidence of macro-evolution is there from earliest life to the human?

I find wiki unreliable for controversial subjects such as evolution. Often one side controls the page, and therefore only that one viewpoint is expressed.
Shabs42
5 / 5 (3) Aug 17, 2012
In general I agree with you on avoiding wiki, it's just so damn easy though. Also, in this example I was simply using it for the definition of a scientific theory, not as evidence for evolution.

I'm not going to sit here and type out every bit of evidence that exists, but if you are truly interested there are literally thousands of websites and books that can meet your needs. One very good and succinct one:

http://www.nature...gems.pdf

My personal favorite is talk origins, but the website can be a bit difficult to navigate due to the sheer amount of information they have, some of which is repetitive. I would start here:

http://www.talkor...ead.html

And just read whatever catches your eye. As a warning, some parts of that site are devoted to arguing against creationism, I would just stick to the evolution parts. Thank you for keeping this conversation civil by the way. I hate when these threads turn into people trading insults.
TheGhostofOtto1923
4.6 / 5 (12) Aug 19, 2012
I'm not going to sit here and type out every bit of evidence that exists, but if you are truly interested there are literally thousands of websites and books that can meet your needs. One very good
If these websites were written by honest people they would include all the definitive evidence which debunks all their claims.

Archeology has given us the one indisputable body of evidence which thoroughly reputes your god; the major biblical settings and people in your book never existed. People have searched for hundreds of years and have found only contrary evidence for the exodus, the joshuan rampage, the kingdoms of Solomon and David, and the ministry of Jesus Christ.

We can conclude that, if they did exist then your god made all the evidence evaporate and he replaced it with evidence which disproves them. So how could we believe either of the 2 contrary creation stories in his book? Either he lied or he tampered with the evidence. Either way he is untrustworthy.
Shabs42
5 / 5 (3) Aug 20, 2012
Umm...you know I'm on your side of this one, right? The sites I linked to list evidence for evolution. Talk origins even has a huge section listing common Creationist arguments and responses to them. Most are pretty good, some are unconvincing on their own.
TheGhostofOtto1923
4.7 / 5 (12) Aug 21, 2012
Umm...you know I'm on your side of this one, right? The sites I linked to list evidence for evolution. Talk origins even has a huge section listing common Creationist arguments and responses to them. Most are pretty good, some are unconvincing on their own.
Sorry my antireligion cannon has a hair trigger. I do find it easier to discredit the books their gods wrote, which is after all where they get their creation and ID notions from.