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Old 08-24-2013, 08:54 PM
 
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Quote:
Originally Posted by Wild Colonial Girl View Post
Different strategies in terms of investment in few strong offspring vs many weak ones. You also have to work with what you have, not what you'd like to have. We couldn't fit the head of a more developed foetus through the pelvis, so they're born relatively helpless and have a relatively long childhood. The advantages of bipedalism obviously outweigh the disadvantage of immature newborns.
This has been the dominant theory and seems reasonable . . . but a more recent theory suggests it is the metabolic demands on the mother that determine it.It is our big brain that is the major problem. Absent the pelvic restrictions, a mother would have to carry a baby for 18 to 21 months to have a baby with the neurological and cognitive development and abilities of a newborn chimp. A newborn child has less than 30% the size of an adult brain.The metabolic requirements of two brains . . . one adult and one rapidly developing . . . place enormous demands on the energy requirements of the mother causing her to deliver before it is fully developed. Actually it is very difficult to suggest a plausible evolutionary driver for our big brains . . . but they are what create this early birth problem to begin with.
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Old 09-01-2013, 12:14 PM
 
Location: Somewhere out there
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Default All Glory to Man The Wunnerphull!

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Originally Posted by Thinking-man View Post
Wouldn't it make more evolutionary sense as far as survival if we had evolved into not needing much after being born? Why do we have fewer of the 'instincts' i mentioned, than the next animal?
Many other species besides "man the magnificent God-image!" () , indeed, require and benefit from a longer post-birth training period. It promotes better long-term survival and is therefore more prevalent in those species that have longer lives. See: "Evolution for success"

Apes, monkeys, elephants, dolphins, whales, and so on. It's not just limited to some Godly entities (pun intended. We're so arrogant!)

Btw, when properly tested, humans do indeed carry over some instant survival instincts, but they don't show up until the offspring are about 2 - 4 years old, since before that, we could not possibly pull them off physically!

PS: Check on the human anti-looming fear response, the drop and hold still response (as with most all newborn ungulates...), and keeping quiet response, when faced with an imminent predatory invasion. Not ever taught by anyone!
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Old 09-01-2013, 01:06 PM
 
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Originally Posted by Thinking-man View Post
hello friends....
i was thinking this morning about a topic and i wasn't able to figure out a possible answer to it......thought i'd try my educated friends on here.....

Why do some animals have "Animal instincts" when they're born (like hunting, fighting predators, flying, walking, etc.) while other animals (ie. humans) do not? (Strictly from an evolutionary standpoint.)
It appears to be some sort of evolutionary trade-off -- the more complex a social species is, the less they are born knowing and the more they have to learn before they can make it as adults. The only instincts a human baby is born with are: sucking nourishment, gripping mom's hair and holding our breath underwater. If we are allowed to be near water regularly starting before the age of 10 months, we will teach ourselves to be competent swimmers. In that same year we are starting to teach ourselves to stand, walk and climb. We also have the instinct to imitate the sounds and behaviors we hear and see others performing. There is not much else -- we are so stupid that we will crawl off cliff's edges and into fires if allowed to, pet angry alligators, eat anything that is sharp or poisonous -- you know all the trouble a small child gets into. No newly-hatched iguana would do any of those dumb things.

It seems to be that the more steep our learning curve got to be, the more we tended to depend completely on elders to teach it to us. It seems like the better our language capacity got, the more we depended on it (rather than instinct) to learn from and the more the instinctive knowledge fell away.
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Old 09-01-2013, 01:13 PM
 
Location: SW Missouri
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I don't believe that animals have the instincts you describe when they are born. Cats, bears, elephants and other animals must be taught by their mother to hunt, kills, forage, etc. Even baby birds are taken out by a parent and taught how to fly.

The only "instinct" that most animals have at birth that humans do not is the instinct to stay quiet and hide if approached by a predator.

Now I will grant you that animals LEARN many behaviors much sooner than humans do, but that is because their life span is much shorter so they have evolved the ability to do this out of necessity. For instance a horse, which lives only 20 or 30 years can run within a couple of days of being born, whereas a human, who lives 70 or 80 years usually cannot run until a year or so after birth. But it is all proportionate, or nearly so.

20yrsinBranson
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Old 09-01-2013, 01:22 PM
 
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Originally Posted by 20yrsinBranson View Post
I don't believe that animals have the instincts you describe when they are born. Cats, bears, elephants and other animals must be taught by their mother to hunt, kills, forage, etc. Even baby birds are taken out by a parent and taught how to fly.

The only "instinct" that most animals have at birth that humans do not is the instinct to stay quiet and hide if approached by a predator.

Now I will grant you that animals LEARN many behaviors much sooner than humans do, but that is because their life span is much shorter so they have evolved the ability to do this out of necessity. For instance a horse, which lives only 20 or 30 years can run within a couple of days of being born, whereas a human, who lives 70 or 80 years usually cannot run until a year or so after birth. But it is all proportionate, or nearly so.

20yrsinBranson
But you're only underlining my point! Cats have an instinct to stalk and leap on smaller animals, but they are social creatures and you can watch their moms teach them how to climb trees, catch and kill the moles and mice they play with and so on. Cats not taught to hunt will not learn how -- they will just play with the mice and sometimes never learn that they are good eating. Frogs, who are not social, eat whatever moves that is small enough to get their lips around, and nobody teaches it to them. They just know. Elephants have a close, complex social structure and so do dogs, and they have a much longer dependency period -- more like humans than frogs, which have no dependency at all on their parents.

It's humans who had to slow down their development, starting from a much quicker schedule like the one followed by birds and rodents. So much teaching needs to go into the development of a human that the ones who grew more slowly and stayed dependent longer learned more and ultimately did better. Which made them even more social with each generation. And the beat goes on.
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Old 09-01-2013, 03:23 PM
 
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There is a difference btw mammalian and reptilian instinct development.
Most mammal newborns are very vulnerable and at first lack the sort of instincts that would allow them to survive in the wild without parental protection. Reptile newborns break from their eggs with an already well developed set of instincts that allow them to navigate the wild, find food and avoid predators.
Of course, reptiles dont have the capacity to ever learn or become "trained". They will never be anything but biological machines that react instinctively to various stimuli. Mammals are a far more complex and advanced type of animal and possess the capacity to be taught and remember and have emotional attachments to other animals.
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Old 09-03-2013, 01:57 AM
 
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Originally Posted by Thinking-man View Post
Wouldn't it make more evolutionary sense as far as survival if we had evolved into not needing much after being born? Why do we have fewer of the 'instincts' i mentioned, than the next animal?
I think the difference between animals and humans you are looking for is the fact that the evolution of the human mind has necessitated that more of our development occurs after birth than before it.

This is actually a varying continuum across the animal kingdom. It is not that animals are at one end and we are at the other. The off spring of some creatures basically enter this world and set off as if they have been always in it. While others are born and require much more development before they become self sufficient in even the smallest degree.

You suggest it makes more "sense" to have most of the development done before one is born. But one has to remember that the womb, egg sac, or whatever, is limiting. Evolution is the art of compromise, not the art of "making sense". It might make "sense" that an off spring pop out with the full ability to fight and run... but one has to consider A) The birth canal aspects of that such as fitting arms and legs with fully usable muscles out of a vagina and B) the energy requirements on behalf of the mother in sustaining such an internal development.

Limitations on energy inputs and head:hip width ratio, along with many other factors, simple place a large limitation on the developments that occur before, and after, birth.
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