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.
> 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 calor…
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.)