Have you ever trawled the internet for amusing videos and come across the gorilla in a zoo throwing poo at people? Perhaps it’s just me. Anyway, apart from the fact it is vaguely amusing, the interesting thing really is just how awful they are at throwing! How can one of our closest living relatives, a species that we share 98% of our DNA with, be so bad at throwing? And, probably more importantly, why do you have a shoulder surgeon blogging about it? Well you’ll have to bear with me as I take you down a brief history of human and shoulder evolution.
Gorillas can’t throw at all well.
The main difference between humans and monkeys is the fact that we walk on 2 legs. This change happened around 2 million years ago, in the time of Homo Erectus. The reasons why this happened remain somewhat of a mystery but seem to coincide with a change in our diet towards eating more meat and consequently, scientists conclude, must coincide with an increase in hunting. The ability to throw a spear became crucial and the human body evolved to improve both power and accuracy at throwing.
The main adaptations that occurred were at the shoulder blade, which retracted around the torso (moving backwards towards the spinal column) to allow a wider arc of shoulder rotation. This allows the modern human to throw at velocities in excess of 90mph. The next fastest thrower is the chimpanzee at a pedestrian 20mph. It really is a remarkable feat and something that sets us apart from our primate relatives.
Humans are well adapted for throwing.
So why is a shoulder surgeon bothered about how gorillas throw?
Well, evolution continues and human beings are starting to get into bad habits and consequently experience more shoulder problems. It has been a few hundred years (at least) since we threw a spear to catch our next meal. Those shoulder blades that were sitting nicely further back are starting to drift forward due to worsening posture, sitting at computers, mobile phones, and driving. In fact, during most activities we do seem to have our arms in front of us. Our shoulder blades inevitably have started to wander and, with a more protracted (forward) position, shoulder pain and impingement become more common. You can try it yourself now. Move your shoulder blade into a forward position and then try to lift your arm up. It doesn’t like it.
Human shoulder evolution – a modern problem?
So, I apologise if I start sounding like your mother, but shoulders back! Find that lost hunter gatherer within you!