Chimps can be three to five times stronger than humans.
That means a really strong chimp could, in theory,
lift around sixteen people over its head.
But, can eating bananas and swinging around in trees
really account for this difference?
After all, aren't we supposed to share 99% of our genes?
Studies have shown differences in the way our muscles are built
but muscle control may be a much more important factor
Chimps seem to have less control over how much muscle they use at once.
While this may sound counter-intuitive, this can account for the difference in strength.
Let's take a look at why.
Compared to humans, chimps have less gray matter relative to body weight.
Gray matter is the part of the nervous system
that contains the nerves responsible for controlling motion.
These branch out from the spine into the muscles
to control individual muscle fibers.
Some neurons can contact many muscle fibers at once.
Activating these neurons causes all of the muscle fibers that touches
to contract at once.
Creating a lot of force.
This combination of neurons and muscle fibers
is called the large motor unit.
And these are used for gross motor skills
like jumping and climbing.
Some neurons contact only a few fibers
making a small motor unit.
These don't have a lot of power
but they are a lot more precise.
Small motor units let us do delicate complex tasks
like playing a video game or plucking a ukulele.
Things that we can do and
chimps can't.
So chimps who have less gray matter
have fewer motor neurons.
Therefore, their motor neurons are more likely
to be dedicated to large motor units.
This means when they do engage their muscles
it's an all-or-nothing response which we see as strength.
Unlike chimps, our neurons control smaller bundles
so we have more specific muscle control.
So keep this in mind the next time you think of challenging a chimp in a pub;
You might want to try thumb wrestling instead.
For Scientific American, I am Yasmin Tayaq.