It’s surprising how many people offer the common throwaway line, “We share 98.8 percent of our DNA with chimps!” without stopping to consider something rather obvious: If so, that demonstrates beyond reasonable doubt that not everything we need to know about a life form is found in its DNA.

Fortunately, some neuroscientists have been examining the question of human–chimp differences more seriously. At BBC’s ScienceFocus, science writer Tom Howarth looks at a study done by Oxford neuroscientist Rogier Mars and colleagues, comparing human brains to those of chimps and macaques. And they found some surprises:

According to Mars, most studies comparing human brains to those of other animals tend to focus on factors like overall size, the size of specific regions or the number of neurons. “But our philosophy is that if you want to truly understand what’s happening, you need to examine how the brain is organised,” he said.

With that approach in mind, Mars and his team set out to investigate. Using publicly available MRI data — similar to the scans used in hospitals — they created “connectivity blueprints” of the brains in the three different species. These blueprints essentially map how much different regions of the brain talk to one another. 

“We’ve finally discovered how your brain differs from a chimp’s: new study,” March 17, 2025

The Researchers Didn’t Find What They Expected

They thought the big physical differences would be in the prefrontal cortex, associated with “complex thought, planning and decision-making.” They did find more connectivity in this “personality centre” but they also found significant human–chimp differences in other areas as well:

“The prefrontal cortex is where researchers tend to look when searching for something uniquely human,” Mars said. “But we found differences in lots of places, particularly in the temporal cortex, which is just above your ear. These seemed to be much more wired up to the rest of the brain in humans than in any other species.”

The temporal cortex plays a key role in processing sensory information — particularly sight, sound and language. Given our highly social and cooperative nature, it’s perhaps no surprise that these areas are more intricately connected in the human brain.

“Your brain differs”

Howarth observes, “All of this suggests that there isn’t a single defining switch that makes humans, well, human. While some believe that a pivotal evolutionary event propelled us to dominance, the reality is likely more complex.”

The paper is open access.

Cross-posted at Mind Matters News.