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I have an alternative answer to that question. Mammals evolved to sleep because those young that gave their parents a rest survived childhood. Seems obvious to

I have an alternative answer to that question. Mammals evolved to sleep because those young that gave their parents a rest survived childhood. Seems obvious to any parent. :-) Imagine a puppy that never stopped. Its mother would abandon it.

carsongross 11y ago
Cute, but just turn the darwinian crank: the mother that didn't abandon it would then have super-puppy offspring that would be able to secure far more resources for themselves and their offspring. The obvious advantages of not sleeping indicates to me that there is a deep connection between sleep and our waking performance. If there weren't why the hell would it have persisted across so many creatures for so long. I am confused by the fact that human young keep parents awake so much: it seems like a delicate time to be introducing poor cognitive performance into the mix. But then a lot of things confuse me when I apply straight forward darwinian thinking.
- zyrthofar 11y ago
  I like to think that we evolved sleep because it's better, in the wild, to be still and silent in the dark, than move around and make noise. Since we can barely see in the dark and can't do anything anyway, wouldn't it be preferable to minimize the time spent defenseless against predators with better night vision? Staying still seems like a good strategy a lot of times, when most animal visions, night vision or not, is based on movement. It doesn't answer, though, why the top of the food chain need to sleep too.
  - ricree 11y ago
    It also doesn't explain why the effects of sleep are so strong, when an instinct for watchful stillness would have been every bit as effective for that purpose.
  - jqm 11y ago
    Maybe if we hadn't been sleeping we would have evolved the ability to see in the dark by now.
- logfromblammo 11y ago
  Toothed whales (incl. dolphins) can apparently sleep with just half their brain at a time, while remaining alert with the other half. Thus, there exists a solution in nature wherein the creature experiences the benefits of both regular sleep and continuous alertness. The rarity of the solution suggests that sleep is more important for most mammals, except in niches where a prolonged loss of consciousness could lead to drowning, or being eaten by sharks. Also recall that as social, tribal animals, modern humans relied on aunts and grandmothers to relieve exhausted mothers for all of prehistory. Separate homes for smaller family units and wider geographic dispersal of family members are relatively recent developments. I wouldn't expect biological adaptations to the practice to appear any time soon. I think the most likely event is that we will discover and use a pharmaceutical remedy for sleep deprivation in parents, possibly by studying dolphin brains.
  - kayman 11y ago
    Similar to meditation perhaps.
winternewt 11y ago
That doesn't explain why the parents need to sleep, though.
- simonsquiff 11y ago
  It does, it's the vestigial remnants of whatever makes the baby sleep...
  - ars 11y ago
    There are plenty of neonatal behaviors that stop as the child gets older. Why would sleep be the exception?

carsongross 11y ago

Cute, but just turn the darwinian crank: the mother that didn't abandon it would then have super-puppy offspring that would be able to secure far more resources for themselves and their offspring. The obvious advantages of not sleeping indicates to me that there is a deep connection between sleep and our waking performance. If there weren't why the hell would it have persisted across so many creatures for so long. I am confused by the fact that human young keep parents awake so much: it seems like a delicate time to be introducing poor cognitive performance into the mix. But then a lot of things confuse me when I apply straight forward darwinian thinking.

zyrthofar 11y ago
I like to think that we evolved sleep because it's better, in the wild, to be still and silent in the dark, than move around and make noise. Since we can barely see in the dark and can't do anything anyway, wouldn't it be preferable to minimize the time spent defenseless against predators with better night vision? Staying still seems like a good strategy a lot of times, when most animal visions, night vision or not, is based on movement. It doesn't answer, though, why the top of the food chain need to sleep too.
- ricree 11y ago
  It also doesn't explain why the effects of sleep are so strong, when an instinct for watchful stillness would have been every bit as effective for that purpose.
- jqm 11y ago
  Maybe if we hadn't been sleeping we would have evolved the ability to see in the dark by now.
logfromblammo 11y ago
Toothed whales (incl. dolphins) can apparently sleep with just half their brain at a time, while remaining alert with the other half. Thus, there exists a solution in nature wherein the creature experiences the benefits of both regular sleep and continuous alertness. The rarity of the solution suggests that sleep is more important for most mammals, except in niches where a prolonged loss of consciousness could lead to drowning, or being eaten by sharks. Also recall that as social, tribal animals, modern humans relied on aunts and grandmothers to relieve exhausted mothers for all of prehistory. Separate homes for smaller family units and wider geographic dispersal of family members are relatively recent developments. I wouldn't expect biological adaptations to the practice to appear any time soon. I think the most likely event is that we will discover and use a pharmaceutical remedy for sleep deprivation in parents, possibly by studying dolphin brains.
- kayman 11y ago
  Similar to meditation perhaps.

winternewt 11y ago

That doesn't explain why the parents need to sleep, though.

simonsquiff 11y ago
It does, it's the vestigial remnants of whatever makes the baby sleep...
- ars 11y ago
  There are plenty of neonatal behaviors that stop as the child gets older. Why would sleep be the exception?