Many people think our large brain is what makes us humans. The shape of the brain andlobes may be important.

The way the different parts of the human brain evolved separates us from our primate relatives, according to the results of a study. Our brain doesn't grow up. The Neanderthals are the only primate that shares this syndrome.

Our findings give insight into what makes us, but also narrow the distinction between ourselves and our ancestors.

Tracking the evolution of the brain

Each of the four regions of the brain has a specific function. The temporal, occipital, and parietal parts of the brain help to integrate sensory inputs.

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Labelled diagram of the four main parts of the brain that form the cerebral cortex.

The four main parts of the brain form the cerebral cortex. (Image credit: The Conversation, CC BY-ND (http://creativecommons.org/licenses/by-nd/4.0))

We wanted to know if the brain's lobes evolved independently of each other or if the evolution of the lobes is tied to changes in others.

We wanted to know how human brains differed from other primate's.

One way to address this question is to look at how the different lobes have changed over time among different species.

The degree to which the brain's lobes are integrated with each other can be measured.

Is a shape change in one part of the brain related to changes in the rest of the brain? Evolutionary steps can be retraced through an animal's growth. The fact that we can trace our evolution back to fish is a common example.

Both methods were utilized. Hundreds of living and fossil primate models were included in our first analysis. The map of brain evolution was made possible by this.

Living ape species and humans at different growth stages allowed us to chart integration of the brain's parts in different species as they mature. The brains were based on scans of skulls. A good approximation of the brain's shape can be obtained by filling the brain cavities.

A surprising result

We were surprised by the results of our analysis. We found that humans had high levels of brain integration between the parietal and frontal lobes.

We are not unique. Neanderthals had similar levels of integration between the lobes.

Integration between the brain's lobes is similar to that of humans until they reach adolescence, according to research.

Integration falls away in the apes but continues into adulthood in humans.

Left: a chart shows the degree of integration between the brain’s lobes, with cooler colours indicating higher integration. Right: translucent skulls of a human, Neanderthal, chimp and gorilla, showing the digitally reconstructed brains within.

Left: a chart shows the degree of integration between the brain’s lobes, with cooler colours indicating higher integration. Right: translucent skulls of a human, Neanderthal, chimp and gorilla, showing the digitally reconstructed brains within. (Image credit: Gabriele Sansalone and Marina Melchionna)

Neanderthals were sophisticated people

This all means something. What distinguishes us from other primate is not just that our brains are larger. Unlike any other primate, we retain the integration of the different parts of our brain through adulthood.

A higher capacity for learning is associated with young people. The evolution of human intelligence could be traced back to this Peter Pan syndrome.

When did humans begin speaking? The language evolved in Africa.

Another implication is present. Neanderthals, known as brutish dullards, were capable and sophisticated.

The development of sophisticated technologies, from the earliest known evidence of string to the manufacture of tar, continues to be supported by archaeological findings. Neanderthal cave art shows a lot of symbolism.

Us and them

Any dividing line between us and them is blurred by our results. Many believe that some innately superior intellectual quality gave us a competitive advantage that allowed us to drive our cousins to extinction.

There are a lot of reasons why a group of people can dominate. The early Western scientists wanted to understand why Europeans dominated the world. Skull shape didn't have anything to do with it.

Humans may have come perilously close to extinction in the past.

It is not because we were dumb. If we had gone extinct, the descendants of Neanderthals would have a hard time figuring out how their superior brains gave them the edge.

The first-ever genetic analysis of a Neanderthal family paints a fascinating picture.

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