> humans are weird outliers—we’re the shortest sleeping primates, yet we pack in the most REM sleep relative to this short duration
Isn't that sort of the point? Sleep is a detrimental necessity and the more efficient an organism is in needing less of it, the more effective it can be because it simply has more time to get ahead of the others?
It's still very odd that no species has ended up evolving a continuous maintenance system that can run while conscious, the benefits when hunting other animals that need sleep would be enormous, so there has to be significant evolutionary push for it. I suppose the single hemisphere sleep some marine mammals do is part of the way there, but it is at most a lazy workaround. Practically all other organs have evolved to run 24/7 for up to a century without a single break, what makes brains so universally different?
> It's still very odd that no species has ended up evolving a continuous maintenance system that can run while conscious
- will gains of 24/7 hunting/foraging offset the extra energy costs? Lions sleep 16-20 hours a day, according to the internet.
- do continuous maintenance systems imply duplicate systems? If so, I have a hunch that even a mere 40% increase in energy expenditure would quickly undo the gains in waking hours.
I disagree. Endurance hunters walk an animal down throughout a single day. Sleep isn't the bottleneck. Efficient bipedalism and sweat are enough.
Instead of going to Tanzania you could’ve asked a sleep scientist. Sleep length has no known correlation to brain size and is known for drastic within family variation. What’s more sleep has a high within species variation too, some sleepers can survive 4 hours, others need 8. Collectively we used to sleep 9 hours in the 20th century, but it appears shorter sleep is fine too. TLDR: no one has any idea why sleep length varies and he won’t find his answers in antrophological studies in Tanzania, though luck, buddy