The Social Leap summary

Here’s a question: If the average chimpanzee’s brain weighs about 380 grams, how much do you think a normal human brain weighs? 500 grams? 800 grams? Nope. Plop an average human cranium on a scale and it will weigh in at 1,350 grams. Quite the difference. 

So, what accounts for this stark divide in brainpower? About six million years of evolution. You see, while a chimp’s ancestors stayed in the trees, ours spent several thousand generations adapting to life on the ground. 

It’s 12,000 BCE and your hunter-gatherer tribe has a choice. You can continue as always, moving from place to place, feasting on whatever you happen to catch each day. Or, you can settle down, sew some grain, and await the harvest. 

The choice actually isn’t so easy. Sure, quitting your nomadic lifestyle for an agrarian existence provides some extra stability and lets you store more material goods. However, as a farmer, your diet will be less varied, your work will be more strenuous, and if you hate your neighbors, you’re still stuck sharing the same land.

Imagine you’re dropped off in the middle of the forest completely naked and utterly alone. How long do you think you’d last before becoming dinner to some hungry tiger or bear. Probably not too long. 

Now, imagine a similar scenario. You’re still dropped naked into the woods, but this time you’re accompanied by 100 other humans in the same condition. How long do you last under these circumstances? 

Today, you probably woke up and checked your email on your smartphone. This simple act relies on countless technological inventions – from the chips in your phone, to the electricity in your home, to the satellites currently orbiting the Earth. 

Clearly, humans love innovating. It’s one of the qualities that sets us apart from other animals. But, consider this: The rolling suitcase wasn’t invented until 1970. 

April, 1994. After decades of political activism, Nelson Mandela is elected as South Africa’s first post-apartheid president. He uses his power to guide the country toward greater peace and equality, then retires after one term.

December, 1987. Robert Mugabe is elected president of Zimbabwe. He also makes much-needed reforms. However, in contrast to Mandela, he runs a corrupt regime that brutalizes his opponents, he enriches himself, and he clings to power for decades. 

Fantastic news; you’ve just won the lottery! In an instant, you’ve gone from a life dedicated to stressful scrimping and saving to having more money than you can even imagine. Surely, as a newly-minted millionaire, you'll be ecstatically happy from this point on.

If only it were that easy. Incredible as it sounds, people who hit the jackpot don’t end up significantly happier. Sure, the first few weeks of lavish spending and luxury living give winners a temporary mood boost. But, studies show that after a year or two, almost all these lucky individuals return to their baseline levels of contentment. 

What makes a happy animal? Well, due to evolution, most critters are happiest when they act in ways that prolong their lives and pass on their genes. In the wild, this means there’s a simple road to satisfaction. Just spend your days hunting prey, avoiding predators, and working on your mating call.

For humans, it’s not so straightforward. We just have too many options to choose from. After all, what’s better for our survival – practicing tennis or taking up tai chi? What will help us attract a mate – spending cash on clothes or dropping a few dollars on a new haircut?