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Not only how difficult labor is, but how helpless a child is for so long. Years before they can walk, for example. Compare that to a fawn, which stands up and f

Not only how difficult labor is, but how helpless a child is for so long. Years before they can walk, for example. Compare that to a fawn, which stands up and follows its mom after just a few minutes into the world.

war1025 9y ago
Babies start crawling at about 6 months, and walking somewhere between 9 months and a year. I have a two year old, and she is far from helpless.
- matt_wulfeck 9y ago
  That’s just a personal anecdote. Some babies never crawl at all and some toddlers don’t start walking until much later than 12 months. And your 2yo toddler is still nothing compared to the mobility and world-awareness of a two-month-old fawn, which has already learned to recognize and outrun predators at this age. The fact that there’s such a spread for these otherwise extremely important life stages in humans shows a lack of maturity in their development compared to other mammals, not the inverse. Something is a little different about us.
  - jriot 9y ago
    If we were to compares ourselves to actual animals. Personal anecdotes wouldn't matter as fatality rates would increase without modern comforts not afford to animals. The child doesn't crawl or start walking for another year, child would die as the parents wouldn't care for weak off-spring. It sounds harsh when discussing humans but the differences in development occur because our death rate is low compared to wild animals. Thus allowing weak genes to be passed e.g., not being able to crawl or walk for 3 years double or triple the normal would not be tolerated in the animal kingdom.
    - Tenhundfeld 9y ago
      Not necessarily. It depends on why the offspring couldn't crawl or walk for longer. If it's associated with something that increases survival in mature members of the species, it might be tolerated, even selected for. For example, if the child is delayed in walking because more metabolic resources are being channeled to larger brain development, that could be a survival benefit. I use that example, because that's essentially the theory of what happened in humans, in comparison to chimpanzees. (Obviously not 1 child randomly taking 2x or 3x to develop, but a slow evolutionary process.) Chimps are relatively helpless when they are born too, relative to most species. They nurse for years, stay with parents for years, are totally reliant on them for survival, etc. But they are not so helpless as humans. It's estimated human gestation would have to be about 18 months for newborns to be at a comparable stage of cognitive development as newborn chimps. So, from this perspective, we do take 2x the time in comparison to chimps, and yet it was tolerated. I guess my overall point is that evolution is more complicated than how quickly an offspring can crawl or walk or be independent.
twobyfour 9y ago
If we carried our children until they were sufficiently physically developed to stand, they'd kill the mothers in childbirth 19 times out of 20. As our brains became more advanced, our crania became larger and more dangerous to birth at full term. But as our intelligence increased, so did our ability to care for infants that were essentially born premature. So now even our full term babies are born so early that they need another 3 months (sometimes referred to as the "fourth trimester") just to be mature enough to sleep properly, among other things. But as intelligent humans, we're able to care for them and devise ways to carry them with us and protect and nurture them despite their extreme helplessness. FWIW, the offspring of carnivorous mammals, though not born quite as "premature" as humans, are often as underdeveloped at birth as a 3-month-old baby. I mean, have you ever seen a newborn kitten or puppy? Eyes closed, barely able to crawl to its mother's teats? The need for a prey animal - especially one that depends on speed for self-preservation - to be able to escape from within minutes of its birth is very different from the survival requirements for a carnivore or even a prey animal that gives birth in a hidden den (like many rodents).

war1025 9y ago

Babies start crawling at about 6 months, and walking somewhere between 9 months and a year. I have a two year old, and she is far from helpless.

matt_wulfeck 9y ago
That’s just a personal anecdote. Some babies never crawl at all and some toddlers don’t start walking until much later than 12 months. And your 2yo toddler is still nothing compared to the mobility and world-awareness of a two-month-old fawn, which has already learned to recognize and outrun predators at this age. The fact that there’s such a spread for these otherwise extremely important life stages in humans shows a lack of maturity in their development compared to other mammals, not the inverse. Something is a little different about us.
- jriot 9y ago
  If we were to compares ourselves to actual animals. Personal anecdotes wouldn't matter as fatality rates would increase without modern comforts not afford to animals. The child doesn't crawl or start walking for another year, child would die as the parents wouldn't care for weak off-spring. It sounds harsh when discussing humans but the differences in development occur because our death rate is low compared to wild animals. Thus allowing weak genes to be passed e.g., not being able to crawl or walk for 3 years double or triple the normal would not be tolerated in the animal kingdom.
  - Tenhundfeld 9y ago
    Not necessarily. It depends on why the offspring couldn't crawl or walk for longer. If it's associated with something that increases survival in mature members of the species, it might be tolerated, even selected for. For example, if the child is delayed in walking because more metabolic resources are being channeled to larger brain development, that could be a survival benefit. I use that example, because that's essentially the theory of what happened in humans, in comparison to chimpanzees. (Obviously not 1 child randomly taking 2x or 3x to develop, but a slow evolutionary process.) Chimps are relatively helpless when they are born too, relative to most species. They nurse for years, stay with parents for years, are totally reliant on them for survival, etc. But they are not so helpless as humans. It's estimated human gestation would have to be about 18 months for newborns to be at a comparable stage of cognitive development as newborn chimps. So, from this perspective, we do take 2x the time in comparison to chimps, and yet it was tolerated. I guess my overall point is that evolution is more complicated than how quickly an offspring can crawl or walk or be independent.

twobyfour 9y ago

If we carried our children until they were sufficiently physically developed to stand, they'd kill the mothers in childbirth 19 times out of 20. As our brains became more advanced, our crania became larger and more dangerous to birth at full term. But as our intelligence increased, so did our ability to care for infants that were essentially born premature. So now even our full term babies are born so early that they need another 3 months (sometimes referred to as the "fourth trimester") just to be mature enough to sleep properly, among other things. But as intelligent humans, we're able to care for them and devise ways to carry them with us and protect and nurture them despite their extreme helplessness. FWIW, the offspring of carnivorous mammals, though not born quite as "premature" as humans, are often as underdeveloped at birth as a 3-month-old baby. I mean, have you ever seen a newborn kitten or puppy? Eyes closed, barely able to crawl to its mother's teats? The need for a prey animal - especially one that depends on speed for self-preservation - to be able to escape from within minutes of its birth is very different from the survival requirements for a carnivore or even a prey animal that gives birth in a hidden den (like many rodents).