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Can culture explain why brains have become bigger?

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From ScienceDaily:

Humans have extraordinarily large brains, which have tripled in size in the last few million years. Other animals also experienced a significant, though smaller, increase in brain size. These increases are puzzling, because brain tissue is energetically expensive: that is, a smaller brain is easier to maintain in terms of calories. Building on existing research on learning, Muthukrishna and colleagues analytically and computationally modeled the predictions of the cultural brain hypothesis and found that this theory not only explains these increases in brain size, but a variety of other relationships with group size, learning strategies, knowledge and life history.

The theory relies on the idea that brains expand to store and manage more information. Brains expand in response to the availability of information and calories. Information availability is affected by learning strategies, group size, mating structure, and the length of the juvenile period, which co-evolve with brain size. The model captures this co-evolution under different conditions and also describes the specific and narrow conditions that can lead to a take-off in brain size — a possible pathway that led to the extraordinary expansion in our own species. The authors called this set of predictions the cumulative cultural brain hypothesis. These theories were supported by tests using existing empirical data. Taken together, the findings may help explain the rapid expansion of human brains and other aspects of our species’ life history and psychology.

“This is a brand-new theory to explain the evolution of the human brain as well as brains more generally. It shows how various characteristics of a species are actually intrinsically connected through a common evolutionary process,” says Muthukrishna. “The limits to larger brains is our ability to birth them, but as this theory suggests, this process is ongoing — we’re now expanding our juvenile period, hitting a new biological limit in our ability to reproduce at an older age.” Paper. (open access) – Muthukrishna M, Doebeli M, Chudek M, Henrich J. The Cultural Brain Hypothesis: How culture drives brain expansion, sociality, and life history. PLoS Comput Biol, 2018 DOI: 10.1371/journal/pcbi.1006504 More.

Humans have certainly expanded the amount of information available to us explosively in the last few decades, and significantly in the last few thousand years. But it’s unclear that the amount of information a chimpanzee or a crow living in the wild needs has changed much at all. Thu7s, the theory might be easier to consider if we left non-humans out of the account for now.

To the extent that this is a theory intended to account for the evolution of the human brain, it has a lot of competition:

Some say we evolved large brains alongside small guts, but another research team found no such correlation. Alternatively, fluid societies (relative to chimps) explains it. And, according to some, mental illness helped. Chimpanzees’ improved skills throwing excrement are also said to provide hints about human brain development. (The ability to throw projectiles at very high speeds is apparently unique to humans.) Our ancestors had to grow bigger brains anyway, we are told, to make axes and hunt something besides elephantsCollective intelligence (“ideas having sex”), whatever that means, has been really important to human evolution as well.
The obvious problems with all of these disunited and discordant theses can be summed up for convenience as: 1) If some aspect of chimpanzee behavior explains matters, why didn’t it produce the same result in chimpanzees? 2) If mere advantage (which every primate seeks) explains a development like the human mind, why did only humans experience it?

The above is only a selection from the claims advanced for one isolated hook or another on which key parts of our fragile humanity are said to suspend. A vast, interlocking pattern of timed hooks forming a design would better account for the evidence, but it wouldn’t be Darwin. Darwinian theory, by its very nature, demands this zealous emphasis on isolated, randomly generated characteristics or events — warring trivia, basically. And we haven’t even got to language or society yet. More.

Just about anything that a theorist thinks is righteous or plausible or defensible can be said in polite company to promote the evolution of the human brain. So the answer to the title question (“Can culture explain why brains have become bigger?”) is: Yes. Your ticket is #17.

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See also: Do big brains matter to human intelligence?

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3 Replies to “Can culture explain why brains have become bigger?

  1. 1
    Silver Asiatic says:

    Denyse O’Leary

    Darwinian theory, by its very nature, demands this zealous emphasis on isolated, randomly generated characteristics or events — warring trivia, basically.

    Yes that was an amazing catalogue of unscientific conjectures in the name of Darwinian theory.

    Now we have “brains became bigger because of an increase of information”. It doesn’t explain why more information is needed or where the information came from in the wild. Food, reproduction, survival – no information required. Sea urchins survive well without brains. As do bacteria.

  2. 2
    bornagain77 says:

    Anyone who would confuse this paper with real science would also be gullible enough to confuse monopoly money with real money.

    This is a shining example of “virtuosity in invention” instead of real science.

    Sociobiology: The Art of Story Telling – Stephen Jay Gould – 1978 – New Scientist
    Excerpt: Rudyard Kipling asked how the leopard got its spots, the rhino its wrinkled skin. He called his answers “Just So stories”. When evolutionists study individual adaptations, when they try to explain form and behaviour by reconstructing history and assessing current utility, they also tell just so stories – and the agent is natural selection.
    Virtuosity in invention replaces testability as the criterion for acceptance.
    https://books.google.com/books?id=tRj7EyRFVqYC&pg=PA530

    First off, brain sizes have been shrinking, not growing larger as they presupposed in their ‘just so story’

    Are brains shrinking to make us smarter? – February 2011
    Excerpt: Human brains have shrunk over the past 30,000 years,
    http://www.physorg.com/news/20.....arter.html

    If Modern Humans Are So Smart, Why Are Our Brains Shrinking? – January 20, 2011
    Excerpt: John Hawks is in the middle of explaining his research on human evolution when he drops a bombshell. Running down a list of changes that have occurred in our skeleton and skull since the Stone Age, the University of Wisconsin anthropologist nonchalantly adds, “And it’s also clear the brain has been shrinking.”
    “Shrinking?” I ask. “I thought it was getting larger.” The whole ascent-of-man thing.,,,
    He rattles off some dismaying numbers: Over the past 20,000 years, the average volume of the human male brain has decreased from 1,500 cubic centimeters to 1,350 cc, losing a chunk the size of a tennis ball. The female brain has shrunk by about the same proportion. “I’d call that major downsizing in an evolutionary eyeblink,” he says. “This happened in China, Europe, Africa—everywhere we look.”
    http://discovermagazine.com/20.....-shrinking

    Cro Magnon skull shows that our brains have shrunk – Mar 15, 2010 by Lisa Zyga
    Excerpt: Using new technology, researchers have produced a replica of the 28,000-year-old brain and found that it is about 15-20% larger than our brains.
    http://phys.org/news187877156.html

    Human face has shrunk over the past 10,000 years – November 2005
    Excerpt: Human faces are shrinking by 1%-2% every 1,000 years. What’s more, we are growing less teeth. Ten thousand years ago everyone grew wisdom teeth but now only half of us get them, and other teeth like the lateral incisors have become much smaller. This is evolution in action.”
    http://www.stonepages.com/news.....01604.html

    Scientists Discover Proof That Humanity Is Getting Dumber, Smaller And Weaker By Michael Snyder, on April 29th, 2014
    Excerpt: An earlier study by Cambridge University found that mankind is shrinking in size significantly.
    Experts say humans are past their peak and that modern-day people are 10 percent smaller and shorter than their hunter-gatherer ancestors.
    And if that’s not depressing enough, our brains are also smaller.
    The findings reverse perceived wisdom that humans have grown taller and larger, a belief which has grown from data on more recent physical development.
    The decline, said scientists, has happened over the past 10,000 years.
    http://thetruthwins.com/archiv.....and-weaker

    “Neanderthals are known for their large cranial capacity, which at 1600cc is larger on average than modern humans.”
    – per wikipedia

    Secondly, intelligence does not correlate with brain size as is presupposed in this paper:

    “The intellectual capability and brain structure of ravens, crows, and jays is much more similar to humans than they are for chimpanzees, orangutans, and gorillas.”3 – Hugh Ross
    3. Johan J. Bolhuis and Clive D. L. Wynne, “Can Evolution Explain How Minds Work?” Nature 458 (April 2009): 832–33, doi:10.1038/458832a.
    http://users.ecs.soton.ac.uk/h.....Nature.pdf

    Discrepancy Between Cerebral Structure and Cognitive Functioning: A Review – 2017
    Excerpt: The aforementioned student of mathematics had a global IQ of 130 and a verbal IQ of 140 at the age of 25 (Lorber, 1983), but had “virtually no brain” (Lewin 1980, p. 1232).,,,
    This student belonged to the group of patients that Lorber classified as having “extreme
    hydrocephalus,” meaning that more than 90% of their cranium appeared to be filled with cerebrospinal fluid (Lorber, 1983).,,,
    Apart from the above-mentioned student of mathematics, he described a woman with an extreme degree of hydrocephalus showing “virtually no cerebral mantle” who had an IQ of 118, a girl aged 5 who had an IQ of 123 despite extreme hydrocephalus, a 7-year-old boy with gross hydrocephalus and an IQ of 128, another young adult with gross hydrocephalus and a verbal IQ of 144, and a nurse and an English teacher who both led normal lives despite gross hydrocephalus.,,,
    Another interesting case is that of a 44-year-old woman with very gross hydrocephalus described by Masdeu (2008) and Masdeu et al. (2009). She had a global IQ of 98, worked as an administrator for a government agency, and spoke seven languages.,,,
    ,,, , people who grew up with only one hemisphere developed all the neuronal foundations
    needed for ordinary cognitive and most motor skills. Even so, it seems additionally surprising that one hemisphere can accomplish this after the other has been removed or was isolated anatomically and functionally from the rest of the brain, as it is the case of surgical hemispherectomy.,,,
    It is astonishing that many patients can lead an ordinary life after this drastic procedure, having only minor motor disabilities that result from mild hemiplegia.,,,
    McFie (1961) was astonished that “not only does it (one hemishere) perform motor and sensory functions for both sides of the body, it performs the associative and intellectual functions normally allocated to two hemispheres” (p. 248).,,,
    ,,, most patients, even adults, do not seem to lose their long-term memory such as episodic
    (autobiographic) memories.,,,
    https://med.virginia.edu/perceptual-studies/wp-content/uploads/sites/360/2017/12/Discrepancy-between-cerebral-structure-and-cognitive-functioning-JNMD.pdf

    Long-term memory: scaling of information to brain size – Donald R. Forsdyke* – 03 June 2014
    Summary
    The material bases of information—paper, computer discs—usually scale with information quantity. Large quantities of information usually require large material bases. Conventional wisdom has it that human long-term memory locates within brain tissue, and so might be expected to scale with brain size which, in turn, depends on cranial capacity. Large memories, as in savants, should always require large heads. Small heads should always scale with small memories. While it was previously concluded that neither of these predictions was invariably true, the evidence was weak. Brain size also depends on ventricle size, which can remain large in some survivors of childhood hydrocephaly, occupying 95% of cranial volume. Yet some of these have normal or advanced intelligence, indicating little impairment of long-term memory. This paradox challenges the scaling hypothesis. Perhaps we should be looking further afield?
    http://journal.frontiersin.org.....00397/full

    Thus both of their foundational presuppositions, i.e. that brain sizes have been increasing, and that intelligence correlates with brain size, are shown to be wrong. (as far as the scientific evidence itself is concerned.)

  3. 3
    vmahuna says:

    I’m kinda confused here. Are the “pro-culture brain” guys actually saying that Neanderthals (a human sub-species) had bigger brains than modern chimps and gorillas?

    That is, humans appear POOF! without ancestral species. And the first humans had all the modern human accessories, like a really nifty voice box and a nice big brain. We also got truly opposable thumbs, the precision grip AND the power grip (Gorillas ONLY have the power grip), and this endlessly useful fully upright bipedal motion thing.

    Note that human babies are REALLY excited about Learning to Walk. It frees their hands for more dexterous grabbing and holding, and it gets their eyes way above the ground clutter of stuffed animals and coffee tables.

    So, again, which non-human species are they using to compare brain sizes? As far as I know, human culture also appeared POOF! along with humans. And baby humans have ALWAYS learned to talk by endlessly reciting “ma-ma” and “da-da” and watching the proud smiles from Mama and Dada. “Do it, again, Baby! Do it again!”

    See also the authoritative documentary “Caveman” starring Ringo Star, which shows not only the development of vocabulary for the new Language, but also the invention of drumming by pounding on rocks.

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