Monkey skull study suggests brain evolved in spurts

February 9, 2016 by Bob Yirka report
Credit: Leandro Aristide, doi: 10.1073/pnas.1514473113

(Phys.org)—A small team of researchers from Brazil and Argentina has found via skull analysis and modeling that a kind of new-world monkey appears to have undergone changes in individual parts of its brain during evolutionary periods which led to advances in cognitive development. In their paper published in Proceedings of the National Academy of Sciences, the team describes their study and results and why they believe what they found might apply to humans as well.

For many years, believed that superior intelligence in humans was attributable to our size—that the large size of our brain relative to the size of the rest of our body was what set us apart. But subsequent studies found that other animals had ratios that were even more pronounced than ours, suggest thing it must be something else. In this new study, the researchers propose that it was changes to the size of certain parts of the brain that led to increases in cognitive abilities, and that it happened in spurts.

The team came to these conclusions by studying the skulls of 179 adult platyrrhines (which included 49 species and samples of both genders)—a type of new world monkey. The researchers added data from the skulls into modeling software that was also able to take into account evolutionary changes. In studying the models, the researchers found that the brains of the monkeys underwent two distinct periods of evolutionary change. The first came about as the monkeys began moving around on the ground more, allowing them to obtain new types of food. That led, the researchers assert, to an enlarged neocortex, which forced the brain to shift on its axis, pushing the brain stem farther down. The next spurt came about, they believe when the monkeys became more social—that led to a less expanded prefrontal area. The models showed that the brain changed to meet changing circumstances, the team suggests, eventually leading to the shape the monkeys have now.

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Brain shape changes associated with PC1. Credit: Leandro Aristide, doi: 10.1073/pnas.1514473113

Because humans are also primates, the researchers suggest that it seems reasonable to conclude that our brains grew in spurts as well during similar situations of our history, and because of that suggest that it was not just growth in overall brain size that led to our superior intellect, but the growth of certain parts that were used heavily as we evolved.

Explore further: Recognizing the basic structure of language is not unique to the human brain

More information: Brain shape convergence in the adaptive radiation of New World monkeys, Leandro Aristide, DOI: 10.1073/pnas.1514473113 , http://www.pnas.org/content/early/2016/02/04/1514473113

Abstract
Primates constitute one of the most diverse mammalian clades, and a notable feature of their diversification is the evolution of brain morphology. However, the evolutionary processes and ecological factors behind these changes are largely unknown. In this work, we investigate brain shape diversification of New World monkeys during their adaptive radiation in relation to different ecological dimensions. Our results reveal that brain diversification in this clade can be explained by invoking a model of adaptive peak shifts to unique and shared optima, defined by a multidimensional ecological niche hypothesis. Particularly, we show that the evolution of convergent brain phenotypes may be related to ecological factors associated with group size (e.g., social complexity). Together, our results highlight the complexity of brain evolution and the ecological significance of brain shape changes during the evolutionary diversification of a primate clade.

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11 comments

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BartV
1.4 / 5 (9) Feb 09, 2016
If you don't buy in to the unfounded theory of evolution (like I don't) then this article is a piece of crap. It does nothing to prove or disprove evolution. So evolution shouldn't even be a part of it. Junk science.
antialias_physorg
4.1 / 5 (14) Feb 09, 2016
If you don't buy in to the unfounded theory of evolution

Well,, since there is no 'unfounded' theory of evolution I don't know what you're griping about, here.

There's gazillions of papers with evidence (historical records as well as experimental) on evolution. It's like you're saying "I don't buy into the theory of gravity". Fine. But if you expect anything to happen by such an attitude except people looking at you with incredulity then you're in for a bit of a surprise.
jeffensley
2.3 / 5 (3) Feb 09, 2016
Like the moment in "2001:A Space Odyssey" when the monkey figures out how to use a bone as a weapon. Nature tries new things all the time. Some are failures, some successes but what is most interesting is we don't know exactly how or why these moments of creation occur.
Vietvet
3.9 / 5 (7) Feb 09, 2016
They are not "moments of creation", it's evolution and innovation.
someone11235813
not rated yet Feb 10, 2016
...suggest thing it must be something else.


Probably fingers and opposable thumbs with large brain areas devoted to them, after all no matter how big a porpoise's brain I can't ever see them even building a rudimentary crystal receiver, let alone exploring Mars.
bschott
1 / 5 (2) Feb 10, 2016
They are not "moments of creation", it's evolution and innovation.


It's actually called adaptation, an innovation improves an objects performance for the same task the object is used for. Evolution as theorized requires a change from one form to another more efficient or better suited one. The monkey just did something different with the bone....pretty creative.

Monkey click one star GO!
Torbjorn_Larsson_OM
5 / 5 (4) Feb 10, 2016
bschott, more precisely evolution has no direction so it doesn't "require" adaptation, and there are indeed mechanisms like near neutral drift (no adaptation) and extinction (failure to adapt).

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"unfounded". "prove or disprove".

How do you know a religious lies? He/she opens the mouth: https://en.wikipe...volution . (O.o)
bschott
not rated yet Feb 10, 2016
bschott, more precisely....


More precisely than describing it as a change? I didn't claim any "directionality", although I may have implied a "forward" direction by suggesting that to evolve was to become more efficient or better, but I would use the term "de-evolve" should the physical change make the subject less capable or suited to it's environment. Traditionally we do not see external forcings cause something to make an evolutionary change for the worse...

Agreed about religious activists, although spiritualists cannot be included as they do not make claims about God's will and generally suggest to everyone to find their own ways to connect to their beliefs.
yep
5 / 5 (3) Feb 11, 2016
If you don't buy in to the unfounded theory of evolution (like I don't) then this article is a piece of crap. It does nothing to prove or disprove evolution. So evolution shouldn't even be a part of it. Junk science.

Again, how does a bacteria develop a resistance if not through evolution?
jeffensley
1 / 5 (1) Feb 11, 2016
They are not "moments of creation", it's evolution and innovation.


It's actually called adaptation, an innovation improves an objects performance for the same task the object is used for. Evolution as theorized requires a change from one form to another more efficient or better suited one. The monkey just did something different with the bone....pretty creative.

Monkey click one star GO!


Yeah but how did that connection in the brain happen the way it did? That to me is creation... you suddenly have a tool from something that moments before was just a remnant piece of body structure. Imagination, mutation = creation.
FESTtheory
1 / 5 (1) Feb 12, 2016
BECOMING HUMAN / INTELLIGENCE : FINALLY SOLVED. NEW COMPREHENSIVE THEORY starts from the end by establishing the working theory of functioning of the human brain-IQ. This is the only way to solve this puzzle and here is the only picture/story that makes sense. The human evolution (7 million years ) must perform / accomplish the evolution of intelligence, but I have found only "the evolution of emotions". These three processes intersect at one point - baby / human infant that is incapable for independent survival for many years. That is not an evolutionary mistake, on the contrary, that is the key element of my research. https://evolutionofhumanintelligence.wordpress.com/

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