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Mathematical model says humans’ larger brains evolved via food, not culture


From ScienceDaily:

Animals with high cognitive ability also have relatively large brains, but the factors that drive evolution of big brains remain unclear. Scientists have hypothesized that ecological, social, and cultural factors could each play a role. Most of these hypotheses have not been formalized mathematically, but doing so would allow scientists to refine their tests.

To address the issue, Mauricio González-Forero of University of Lausanne, Switzerland, and colleagues developed a mathematical model that predicts how large the human brain should be at different stages of an individual’s life, depending on different possible evolutionary scenarios.

The model relies on the assumption that the brain expends some energy on cognitive skills that allow an individual to extract energy from the environment (food), which in turn helps the brain grow. Given natural selection, it predicts how much energy is used to support brain growth at different ages under different biological settings.

The researchers used the model to test a simple scenario in which social interactions and cultural factors are excluded, revealing the influence of ecological factors alone. In the scenario, a human must hunt or gather food alone, but may receive some help from its mother while it is still young.

Under those specifications, the hypothetical human brain grew as big as ancient humans’ brains are thought to have grown, and the slow growth rate matched that of modern human brains. This runs counter to prevailing thought, which holds that social and cultural influences are required to achieve these sizes and growth rates. (public access) Paper. – Mauricio González-Forero, Timm Faulwasser, Laurent Lehmann. A model for brain life history evolution. PLOS Computational Biology, 2017; 13 (3): e1005380 DOI: 10.1371/journal.pcbi.1005380More.

One difficulty with the model is that it is hypothetical. At each stage that enabled a gain in intelligence, ecological, social, and cultural factors would become more evident and important. Whether brains could get larger in the absence of these factors may amount to answering a question that isn’t part of the overall puzzle. Still, interesting.

See also: Faster metabolism enabled larger brains?

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mahuna, you are correct, 'no chimp offspring or gorilla offspring', could grow a human-sized brain as they are not human, they are a different species, albeit one very closely related to us. "Again with the 'evolved' thing." Of course, it is a science site. One that I visit often. For them the 'evolved thing' is not controversial, merely science. If you don't like the 'evolved thing', don't visit science sites. rvb8
Again with the "evolved" thing. Humans have an extra large hole in our skulls to allow an extra larger artery to pump extra large quantities of blood to our extra large brains. Among other things, our extra large blood supply is needed to COOL our extra large brains. As with many other Irreducibly Complex bits of human anatomy, no chimp offspring or gorilla offspring can grow a human-sized brain in their old style animal skulls, which lack the proper plumbing. Humans appeared POOF! There were no intermediate species. Humans always had overly large brains, AND a hand made to use the Precision Grip as well as the Power Grip. And a dozen other options not available on other models in our line. mahuna
[...] food processing alone could indeed have been sufficient to allow for a substantial brain expansion. In addition, food processing may help satisfy at least two of the three key conditions identified for large-brain evolution listed in the first paragraph of the Discussion. First, a shift in food-processing technology (e.g., from primarily mechanical to cooking) could create a steeper relationship between energy-extraction skill and competence by substantially facilitating energy extraction (relating to condition 1). Second, food processing (e.g., by building the required tools or lighting a fire) is a challenging feat to learn and may often fail (relating to condition 2). Yet, there are scant data allowing to judge the metabolic expense for the brain to maintain tool-making or fire-control skills (condition 3). Our results are thus consistent with the hypothesis of food processing as being a key factor in human brain expansion.
Does such a 'brilliant' conclusion imply that my brain has remained so undeveloped, compared to my wife's, because she can easily make delightful meals that our relatives and friends enjoy, while the best I can do is wash the dishes? Does that mean that with every yummy recipe she creates -using different tools and machines in the kitchen- her brain develops further, making her much smarter than her lazy husband? Assuming she continues to do so, is there a possibility that her brain might someday outgrow her skull? Did I understand this right? The above quoted conclusion seems an example of the term 'bzdura' in Polish language or of the Spanish words "idiotez", "imbecilidad" and "estupidez". As Professor John Lennox has said, nonsense remains nonsense regardless of who says it. Oh, well. What else is new? Dionisio

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