You and I started out as little spermies, lost in a mess looking for home. In a feat that I am still trying to wrap my head around, we were each gold medal winners in a wilderness trek against 300 million of our closest siblings.
We were Mother Nature’s biggest double-or-nothing gamble at life yet: a HUMAN. Never has so much collective order been leveraged into one birth. But life moves forward when the Search to bond with the Other is stronger than the risk of death. So every animal since the eukaryotes has really pretty much gone crazy about this thing called sex.
Case: I give you the American Oyster. She is the reproductive champ of the animal kingdom. This lady lays 500 million eggs EVERY YEAR.
She is also the worst mother of the animal kingdom. Only 2-3 of her 500 million eggs, on average, will survive to reproduce.  (Moms, if you ever get down on yourself about your parenting, just know it could be worse.) Oysters are an extreme r-selected species, which means they are horribly inept and have to produce millions of copies so that a couple can survive.
It also means that, in baby Oyster World, you’re on your own, pal. Gooood LUCK with that life thing.
R-selected = least mothering and least parental investment.
K-selected = most mothering and most parental investment
Being K-Selected also means we all start out as the weakest, most helpless ‘little thangs’.
Through social connection, though, something magic happens – the most helpless, needy balls of tissue on the planet somehow transform into the toughest, smartest, most creatively adaptive species on earth. Now, we put lions in zoos for our toddlers to walk by and point at. All the other animals are under our control.
The ancient Genesis narrative told how the Gods created humans as animals, and then gave them the power to rule and subdue the earth and have dominion over the other organisms. In fact, humans became so powerful so quickly, that we started accidentally destroying the other organisms like crazy. In the ancient mythic stories from all around the world, the gods flooded the earth in an attempt to kill humans because we were so destructive.
Obviously, our power comes from working together. This is Metcalfe’s law. More relationships = more communication = more awareness = faster growth = more collective power. Not just a little more, but exponentially more. And over time, this compounds and spirals.
…Well, up to a point.
See, because 5,000 wildebeests are pretty dumb, right?
TOO MANY in a single network comes at the cost of deep individual relationships. Collective power isn’t JUST lots of us in one place, but it’s also about how deeply the individuals are connected in a common narrative.
In a wild world, this requires individual trust, something wildebeests don’t have.
Trust grows in felt safety, the idea that your investment of attention is worth it with that individual. If I pour out my attention to her, will she reciprocate it one day by giving me hers?
So a trust relationship, like a healthy human, can only grow in homeostasis. Give and take. Over time, reciprocity builds trust.
Trust is the ability to throw your raw emotions and full self into the chaos of the other’s possession. It enables us to lend others our power. The collateral for trust is our observational experience with that person. So trust takes deep observational skills with deep brains over time. With each individual, it has to be grown and, once grown, maintained. Like a happy vine.
Relationships are living things.
Invisible, but alive nonetheless.
Trust opens the door for deeper information transfer – power transfer. It tells our conscious Will that the other person is okay to share some gold with.
Much more than for a wildebeest, each relationship becomes like a living organism to grow and maintain. Trust is like a watered plant, as we must regularly revisit other’s stories and rekindle the flame as we update ourselves with their lives. It’s like keeping up with the latest episode of the Gilmore Girls.
As you might imagine, it takes an incredible amount of neural energy to tend to even a few deep relationships. Multiply that by many friends, and this costs a lot of energy.
These connections were expensive. Evolution had to select strategies:
Even though these connections were expensive, the return on investment would be worth it, because of what we could achieve together. So primate evolution answered the call. Our brains began to spend a crapton of energy to observe individual distinctions among other primates. We began to classify, sort, rank, and file observations as a way to build trust and co-operational abilities. Our brain grew.
For each 1 billion neurons, it takes about 6 calories (kCal) of energy per day just to operate. So this 3 pounds of flesh is only 2.5% of our body mass, but consumes 25% of our energy.
Our brains became more and more dense as we became more and more social.
The only way to drive up both number and depth of relationship would be more brainpower.
One million years ago, we were likely consuming about 1600 calories per day, similar to modern chimps.
That’s 8-10 hours a day wasted foraging for raw food, just to keep the lights on upstairs. Since that’s pretty much eating all the time, we primates finally hit an upper social limit. We couldn’t eat more, couldn’t evolve more brainpower, and couldn’t evolve to be any more social than that.
So we stopped evolving there, right?
One day, another breakthrough – we learned to control fire and cooked some food. 
Fire and cooking meant hitting the energy lottery in places where food was abundant. Now, instead of grazing all day (which I may/may not still occasionally be guilty of), we could free up hours a day for juicy gossip and fun things, enabling trust and extending our social group. Over time, our brains evolved until nature presented us with this graph:
Brain size and social group size co-evolved to become larger, having more energy pumped into our bodies. Thanks to cooking, we can now eat 2,000 calories in 10 minutes, and our brain reigns supreme of the social connectors – all without sacrificing relationship depth.
If there is any trait of the human brain that makes it an evolutionary unicorn, it is our ability to observe and remember tiny distinctions among others in our species. This leads to cooperation and trust.
Thus, we became the most prolific socializers, ever.
Selection pressures within our own human tribes came to demand that only the most cooperative of us would be most likely to reproduce.
Do you really want to make babies with a loser? No, you don’t.
Nature selected for the most socially skilled, empathic humans, with the largest neocortex (wrinkled part). This selection compounded, and our snowball kept rolling.
We finally broke through in number and depth of relationships:
Wildebeest never individuated their relationships and grew trust. Other primates, like chimps and orangutans learned to individuate, but never grew the brainpower to expand their social circles.
But more energy gave us the break we needed, and the snowball rolled until one day, we discovered the next hack, and the snowball would only speed up more.
 Imagine every single person in the entire United States lined up in a race. That’s the race you WON, you badass spermie, you. *Fistbump* Note, this is the very male version of the story. Some might identify better with the discretionary wisdom of the egg, tidying up your little eggy home. You wisely turned all the bad guys away and only let the RIGHT one in. *Fistbump for providing MUCH needed discretion.*
 Next time your kids are going bonkers in a restaurant and you’re feeling like a failure, just remember Ms. Oyster and think, “At least I’m not her”. She puts out 2 functioning adults while the other 499,999,998 of her kids literally die. Spaghetti on the floor might not be so bad.
 UN estimates the Global Total Fertility Rate to be 2.5 children per woman in 2015, while global life expectancy was 72 years in 2015. 72/2.5 = 28.8. Does NOT mean you can only have kids at ages 29 and 58.
 Also, if youre in the subspecies Whitis Suburbananis, you have like 1.3 kids and live to be 95.
 Okay, THEY do. I don’t.
 Ask someone born between 1975-1985.
 Suzana Herculano-Houzel, “What’s So Special About the Human Brain.,” TEDGlobal 2013. Fantastic talk, Suzana!