[cellis]

This is one of the primary takeaways I got from reading Sapiens. Our big brains didn't pay off for millenia, until they did, and in a big way. Most times, innovation isn't enough to beat the competition...you have to survive long enough for it to give you an edge.

[fivedogit]

> Our big brains didn't pay off for millenia, until they did, and in a big way.

That's not how evolution works. Each step along the way must produce a net benefit or it gets discarded. Just as insect wings served as propulsion for water skimming before actual flight, big brains paid off, then got bigger and paid off some more, etc. The only hiccup is the benefit has to outweigh the cost (eg big brains need more calories).

Side note: I think our wide array of modern mental disorders are costs of our brains' continuing enlargement. I.e. brains are trying to figure out how to get even bigger and more powerful without also having OCD or schizophrenia.

[dragonwriter]

> Each step along the way must produce a net benefit or it gets discarded.

More precisely, each step must not impose a net fitness cost or it gets selected against to a degree positively linked to the degree to which it imposes a net cost. But that's, more importantly, each genetic variation taken in total, not actually each individual phenotypic effect of the genetic variation (e.g., sickle cell trait was preserved not because sickle cell anemia is not a net negative, but because the malaria resistance that comes even when an individual is heterozygous for the trait is a strong benefit that manifests more often than sickle cell disease which occurs when an individual is homozygous for it.)

[racer-v]

Each step along the way must produce a net benefit or it gets discarded.

Maybe so, but the benefit could have just been individual fitness signalling (like a peacock's tail) without providing any advantage to the species as a whole until the big "payday".

[dkural]

A peacock's tail can be seen; how do you propose the other sex fell in love with the brainier homo sapiens? It's a lot more likely that intelligence provided a net benefit.

[racer-v]

"That man that hath a tongue, I say is no man,

If with his tongue he cannot win a woman."