Scientists at Duke University, UC Berkeley, Stanford, Yale and more than two-dozen other research institutions collaborated on this first large-scale investigation into the evolution of self-control, defined in the study as the ability to inhibit powerful but ultimately counter-productive behavior. They found that the species with the largest brain volume — not volume relative to body size — showed superior cognitive powers in a series of food-foraging experiments.
Moreover, animals with the most varied diets showed the most self-restraint, according to the study published April 21 in the journal of the Proceedings of the National Academy of Sciences.
“The study levels the playing field on the question of animal intelligence,” said UC Berkeley psychologist Lucia Jacobs, a co-author of this study and of its precursor, a 2012 paper in the journal, Animal Cognition.
This latest study was led by evolutionary anthropologists Evan MacLean, Brian Hare and Charles Nunn of Duke University. The findings challenge prevailing assumptions that “relative” brain size is a more accurate predictor of intelligence than “absolute” brain size. One possibility, they posited, is that “as brains get larger, the total number of neurons increases and brains tend to become more modularized, perhaps facilitating the evolution of new cognitive networks.”
Maybe. But a number of factors might be at work. What about the ease with which a given type of animal (everything from bonobos to squirrels was represented) learns a specific type of behaviour?
Note that “animals with the most varied diets showed the most self-restraint.” That might matter more in the long run. They have already learned a variety of food gathering skill sets. The food reward test is just another one. They have learned how to learn.
The last quoted paragraph is just Darwinian tale-spinning. Not only don’t we know that larger brains “become more modularized, perhaps facilitating the evolution of new cognitive networks”, but if it were true, elephants and whales should be dramatically smarter than smaller intelligent animals, and they aren’t.
One of the problems with Darwinism is that it encourages people to state things on the strength of sheer belief in the system of thought that are almost certainly untrue in the world.
Here’s the significance/abstract (paywall):
Although scientists have identified surprising cognitive flexibility in animals and potentially unique features of human psychology, we know less about the selective forces that favor cognitive evolution, or the proximate biological mechanisms underlying this process. We tested 36 species in two problem-solving tasks measuring self-control and evaluated the leading hypotheses regarding how and why cognition evolves. Across species, differences in absolute (not relative) brain volume best predicted performance on these tasks. Within primates, dietary breadth also predicted cognitive performance, whereas social group size did not. These results suggest that increases in absolute brain size provided the biological foundation for evolutionary increases in self-control, and implicate species differences in feeding ecology as a potential selective pressure favoring these skills.
Cognition presents evolutionary research with one of its greatest challenges. Cognitive evolution has been explained at the proximate level by shifts in absolute and relative brain volume and at the ultimate level by differences in social and dietary complexity. However, no study has integrated the experimental and phylogenetic approach at the scale required to rigorously test these explanations. Instead, previous research has largely relied on various measures of brain size as proxies for cognitive abilities. We experimentally evaluated these major evolutionary explanations by quantitatively comparing the cognitive performance of 567 individuals representing 36 species on two problem-solving tasks measuring self-control. Phylogenetic analysis revealed that absolute brain volume best predicted performance across species and accounted for considerably more variance than brain volume controlling for body mass. This result corroborates recent advances in evolutionary neurobiology and illustrates the cognitive consequences of cortical reorganization through increases in brain volume. Within primates, dietary breadth but not social group size was a strong predictor of species differences in self-control. Our results implicate robust evolutionary relationships between dietary breadth, absolute brain volume, and self-control. These findings provide a significant first step toward quantifying the primate cognitive phenome and explaining the process of cognitive evolution.
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