Scientists have detected the brain network that gives humans superior reasoning skills over other primates such as chimpanzees.
Researchers found mounting brain evidence that helps explain how humans have excelled at "relational reasoning," a cognitive skill in which we discern patterns and relationships to make sense of seemingly unrelated information, such as solving problems in unfamiliar circumstances.
The findings suggest that subtle shifts in the frontal and parietal lobes of the brain are linked to superior cognition.
Among other things, the frontoparietal network plays a key role in analysis, memory retrieval, abstract thinking and problem-solving, and has the fluidity to adapt according to the task at hand.
"This research has led us to take seriously the possibility that tweaks to this network over an evolutionary timescale could help to explain differences in the way that humans and other primates solve problems," said University of California, Berkeley neuroscientist Silvia Bunge, the study's principal investigator.
"It's not just that we humans have language at our disposal. We also have the capacity to compare and integrate several pieces of information in a way that other primates don't," she added.
In reviewing dozens of studies - including their own - that use neuroimaging, neuropsychology, developmental cognitive and other investigative methods, Bunge and fellow researchers concluded that anatomical changes in the lateral frontoparietal network over millennia have served to boost human reasoning skills.
"Given the supporting evidence across species, we posit that connections between these frontal and parietal regions have provided the necessary support for our unique ability to reason using abstract relations," said Michael Vendetti, co-author of the study and a postdoctoral researcher in neuroscience at UC Berkeley.
The researchers found that "synaptic pruning," which usually takes place in adolescence when white matter replaces gray matter and signals between neurons speed up, was more evident in the inferior parietal regions of the brain.
While human and non-human primates were found to share similarities in the frontal and parietal brain regions, activity in the human rostrolateral prefrontal cortex differed significantly from that of the macaque monkey's frontal cortex, researchers found.
Humans were also found to use higher-order strategies to guide their judgement while non-human primates relied more heavily on perceptual similarities and were slower at reasoning and problem-solving.
The study was published in the journal Neuron.
