The human brain is a hefty thing. Weighing well over a kilo, its an electrified lump that’s been compared by neuroscientists to the texture of silken tofu, and yet within its innumerous connections is coded everything that we are. 

That wasn’t always the case, however. In fact, among the earliest lifeforms, eyes actually evolved before the brain. It makes you wonder: How exactly did we get to the human brain? And why are we so much more cognitively advanced than other mammals?

I wanted to find out, and with his latest series Secrets of the Brain set to air on BBC Two on September 29, Professor Jim Al-Khalili was an obvious person to ask. His mission? To dive into the history of the brain, and the pivotal changes that led to humans and our close relatives becoming so advanced at things like problem-solving and socializing.

Survival of the brainiest
The search for those answers led to Prof Al-Khalili, highly respected science communicator that he is, hanging from a tree in a less-than-comfy harness for several hours. It might not have been the most relaxing way to demonstrate how hard the primate brain had to work to be able to forage in the treetops while keeping an eye out for predators, but it's a good reminder of what a lot of our intelligence is attributable to: struggle.

“Like a lot of people, I assumed the human brain evolved because we're smart and it’s doing all this data processing and analysing because we develop language, and because we have opposable thumbs,” Al-Khalili told IFLScience. “What I hadn't appreciated was that this evolution, it's a story that is continuous.”

Our ancestors had to cope with challenges, to survive, to find food, and that required more brain power.
- Professor Jim Al-Khalili

“It wasn’t that animals were stupid and then humans turned up and became very smart. There were all these steps along the way, and a lot of them are just completely fortuitous.”

“You have mass extinctions, and then the organisms, the creatures, the animals that are left behind, they have to cope. Our ancestors had to cope with challenges, to survive, to find food, and that required more brain power.”

“So, the brain is growing because these creatures need to be able to adapt to their environments, and because this is evolution, those that brains don't grow, don't survive. It's only the smart ones that survived, but they developed their smartness because they needed to, it wasn’t that they survived because they were already smart.”