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In a humbling moment for our species, the following large news has just been published: When it comes to the frontal lobes, we're not so special later on all.

Comparing of the frontal lobes among human and other not-human primate species. The connecting lines indicate the evolutionary relationships among the species. Katerina Semendeferi and colleagues institute that the frontal lobes in humans are not disproportionately larger than expected for a primate brain of its size. Figure and caption adapted from Passingham (2002).

For years, scientists take attempted to pinpoint the $.25 of our brain that might assist explain our uniquely homo intelligence. The frontal cortex, which resides toward the front of the brain, has often been singled out as large relative to other species. But the results accept been mixed, with some researchers arguing for a disproportionate expansion, other researchers arguing for no expansion relative to bang-up apes, and still other researchers arguing that information technology depends on which species are beingness analyzed.

Why the mixed findings? 1 potential reason is that some researchers based their conclusions on unscaled measurements, such as accented encephalon size or total encephalon volume. By these measures, our frontal cortex does announced larger than other species. Only if we take unscaled measurements seriously, then things go really absurd. By this metric, chihuahuas and several species of fish have bigger brains proportional to their trunk than we do! Even merely looking at the frontal cortex, bounding main lions have a larger frontal cortex than several "higher primates,"such equally baboons and gibbons, whereas llamas exceed macaque monkeys. Every bit Robert Barton and Chris Venditti so eloquently point out in their recent paper,

Unless one is willing to have seriously the hypothesis that lemurs have more than of the qualities bestowed by frontal cortices than practice humans, or that llamas possess more than monkeys, information technology must exist concluded that testing the hypothesis that any species is specialized for frontal cortex functions, every bit opposed to functions mediated by more extended networks, requires scaling to be taken into account.

To help us out of this cool paradox, Barton and Venditti analyzed five independent data sets, taking into business relationship two important facts most brain development:

  1. The volumes of unlike brain regions develop at different rates equally both encephalon and body size evolves.
  2. While it's true that the total volume of the neocortex-- the outer layer of the cognitive cortex-- increases with brain size faster than the cerebellum, the number of bodily neurons in each of these two encephalon structures stays about the same.

Their issue? The size of our frontal lobes, including specific frontal regions such as the prefrontal cortex, is zip special relative to the size of our other brain structures. Even more than humbling for humans, they likewise found that once nosotros diverged from chimpanzees about half dozen million years agone, the speed with which our frontal cortex volume increased relative to our other brain structures was "unremarkable". In fact, other species showed faster rates of change than united states!

And then what gives? How come we can compose beautiful, lyrical poesy and play breathtaking cello sonatas, and gorillas tin barely go on a tune? Allow's consider some possibilities. For i, it's possible that nonfrontal brain regions expanded unduly during our evolution. In other words, maybe nosotros've been focusing on the wrong encephalon regions. In that location'southward some tentative show of a relative expansion of temporal lobe structures afterward taking into account differences in brain size. But information technology gets tricky, because all else being equal, if there really were specific brain regions that underwent greater expansion relative to the rest of the brain, frontal regions should appear relatively small in humans. Just they don't.

A more than probable caption is that carve up areas of our brain increased their advice with each other. In contempo years, neuroscientists have discovered a big-calibration brain network disquisitional for novel and complex goal-directed problem solving. According to Aron Barbey and colleagues, a major function of this network is the manipulation, integration, and control of distributed patterns of neural activity throughout the encephalon, including lower-level sensory and motor modules. This neural architecture typically involves efficient and reliable communication between the outer layer of the frontal cortex (lateral region) and areas toward the back (posterior) of the parietal lobe.

But other researchers such as Vivek Prabhakaran and colleagues have argued that the neural footing of human general intelligence is better characterized by frontal-posterior integration. According to this emerging view, the posterior regions of the parietal lobe are just one of the many posterior brain regions that are controlled by the frontal cortex.

Even so posterior the integration, the frontal cortex doesn't only communicate with other areas of the cerebral cortex. I believe a hugely overlooked function of our uniquely human brain wiring is the stiff connectivity we see betwixt the frontal cortex and the cerebellum , a non-cortical region of the brain. The cerebellum plays a crucial function in our motor control and the learning of complex, well-rehearsed routines. Researchers accept recently argued that throughout the past million years of human evolution, the prefrontal cortex coevolved with encephalon support systems—such as the cerebellum—to help store, implement, and smooth out tried and true routines and solutions. This offloading would accept given much needed relief to an overburdened working retention.

It has fifty-fifty been suggested that the increased cultural demands in but the past x,000 years have put such an extraordinary burden on our working memory that it has driven an expansion of the cerebellum relative to the neocortex, contributing to the emergence of child prodigies. In our consideration of the neural causes of our uniquely homo intelligence, we might be seriously underestimating the extent to which our ability to simplify and automatize our immediate experiences, and access a deep knowledge base on need, contributed to our extraordinarily intellectual and innovative accomplishments.

Along these lines, Liane Gabora has argued that the "man revolution"* seen in the Middle-Upper Paleolithic era betwixt sixty,000 and 30,000 years ago was due, non to new brain structures per se, just to better use of the structures nosotros already had through the very gradual acquisition of the ability to switch betwixt different modes of idea depending on the context. According to this account, the fundamental to our uniquely human being intelligence is not any unmarried kind of mind, but mental flexibility. In back up of this argument, Gabora and colleagues accept shown through calculator simulations that the ability to identify things in context, and see things from dissimilar perspectives, can lead to more than creative and highly-seasoned cultural products.

Some of this perspective taking, especially when it involves mentally simulating the minds of others, thinking about deeply personal memories, and imagining the future, recruits the default manner brain network. This network involves areas deep within the frontal cortex and temporal lobe (medial regions), along with communication with some outer and inner regions of the parietal cortex.

Of class, our brain doesn't create culture in isolation from the outside earth. Allow's not forget: we could accept had all the brain connectivity in the world, but without human being connectivity, nosotros would have displayed very piffling cultural flourishing. As Gabora and I debate in a book affiliate for The Cambridge Handbook of Creativity,

The creative process is compelling and our creative achievements unfold with scenic speed and complexity in part because we are fortunate enough to alive in a world that offers infinite possibilities for exploring non only the realm of "what is" only the realm of "what could exist."

Clearly, there is much nosotros still don't know near the evolution of our heed, brain, and behavior. Nevertheless, 1 affair is clear: the more than we understand the evolutionary origins of human intelligence and creativity and their development inside our lifetime, the better we volition be in a position to directly the future evolution of our species and our planet.

For more on the development of intelligence and inventiveness, come across my forthcoming book "Ungifted: Intelligence Redefined," coming this summertime from Basic Books.

© 2013 Scott Barry Kaufman, All Rights Reserved

* I put "man revolution" in quotes because more recent archeological evidence has seriously challenged this story. Well-nigh of the claims for a revolution involve a "Eurocentric bias"— based on the European Paleolithic record and ignoring the African record. The truth is, most of the artifacts associated with the rapid transition to behavioral modernity constitute twoscore,000 and l,000 years ago in Europe are also found in the African Middle Rock Age tens of thousands of years earlier. These include blades and microliths, bone tools, increased geo- graphic range, specialized hunting, the use of aquatic resource, long-distance trade, fine art and ornament, the Berekhat Ram figurine from State of israel, and an anthropomorphic figurine of quartzite from the Middle Acheulian site of Tan-tan in Morocco about 400,000 years ago. If Sally McBrearty and Alison Brooks are correct that mod human being behaviors were gradually assembled starting as early as 250,000 to 300,000 years ago in Africa, this would mean that our cultural flourishing would have been more of a trickle than a outburst, and would be consistent with Liane Gabora's idea that our cultural flourishing in Europe was the result of a gradual use of the mental structures that already existed.

Gorilla image credit: iStockphoto; Cerebellum image credit: theAbysmal; Integrative Architecture paradigm and Default Network image were illustrated by George Doutsiopoulos.