Walking vs Running

Runner's high - it's that sensation of well being that you get from intense physical effort, like endurance running. It's apparently due to the hypothalamus and the pituitary gland releasing endorphins. It's a way of injecting oneself with internally secreted stimulants. No wonder the pleasure generates by intense sports is akin to 'excitement, pain and orgasm' - dixit Wikipedia. And while this effect was baptized "runner's high" it's experienced in a whole range of sport disciplines - from boxing to swimming.

Anyway, the main subject is running - an activity which is typical to humans among primates. It distinguishes us from our cousins great apes. The chimpanzees, orangutans and gorillas are not capable of jogging like we do.

The First Runner's High: Jogging Separated Humans from Apes
by Robert Roy Brit - on LiveScience.com

This article was an eye-opener and a source of wonder for me. I was taught in biology class that the distinctive attributes of humans among primates were

1. the upright posture
2. articulate speech
3. work / the use of tools

I didn't give it much thought back then but now the question resonates to me clearly:
In what order ? Did the ancestors of homo sapiens start chatting with each other while they were still living in the trees ? Were their first conversations about how to use weapons or tools ?
How did the whole process of evolution take place ?

And one answer that particularly resonated with me is given in the article above:

The conventional thinking has been that running was a mere byproduct of upright walking, known as bipedalism.

But the ape-like species Australopithecus is thought to have gone bipedal 4.5 million years ago while continuing to climb trees, too. It took another 3 million years or more for Homo sapiens to evolve from Australopithecus.

"So is walking going to be what suddenly transforms the hominid body?" Bramble asks. "No, walking won't do that, but running will."

[...]

Importantly, the food that early humans could catch by simply outlasting their prey -- meat -- would have changed everything.

"What these features and fossil facts appear to be telling us is that running evolved in order for our direct ancestors to compete with other carnivores for access to the protein needed to grow the big brains that we enjoy today," Lieberman said.

So part of what make us so special - as animals - is running ! The need to outrun their prey made our human ancestors descend from the trees and evolve features that helped maintain an upright posture and excel at track and field ! They started to catch little mammals and reptiles that they could beat in an endurance challenge. This in turn provided the proteins which helped their brains grow. Apes, in comparison, could'n do that so they continued to rely of a predominantly vegetarian diet, and remained an arboreal species. With the increase in size of their brain, our ancestors started to figure out how to forge tools, which further helped them in their hunting, fishing, harvesting activities. Acquiring articulate speech was probably a subsequent evolutionary step.