I think I remember my mother pointing out a "soft spot" on the head of a newborn. I think the plates can deform during birth and it isn't till after that they "solid up".
One thing for sure. A newborn stands no chance alone. On Jul 20, 7:22 pm, rigsy03 <[email protected]> wrote: > The birth canal can handle 14 pound infants whose bones are still soft > therefore I disagree with you. > > On Jul 20, 1:42 pm, GarrieMushet <[email protected]> wrote: > > > Jim, > > > Yes, 1,400 cubic centimetres is the average volume a fully adult human > > brain. I should have made this distinction. > > > However, human beings have larger brains than their ancestors did at > > all stages in life. So which an infant's brain isn't quite 1,400 cubic > > centimetres, it is still a hell of a lot larger than those of our > > ancestors at the time of birth. > > > The baby's head is usually the widest part of its body at the time of > > birth. You are right to propose that the shoulders would also cause > > considerable difficulties, but it may be interesting to note that one > > of the physiological changes that would be necessary to accommodate a > > larger head, heavier head (which is necessary to accommodate a larger, > > heavier brain), is wider shoulders. > > > Regards, > > > Garrie > > On Jul 20, 5:57 pm, retiredjim34 <[email protected]> wrote: > > > > Garrie - again, many thanks for your thoughtful, thorough reply and > > > observations. > > > I think the only one I would question is the brain size - I > > > believe you are citing the size of the adult brain. An infant's brain > > > size is much smaller. So delivery of the infant at birth might not be > > > nearly the problem you think. Also, at birth is the head the largest > > > object, or is it the shoulders or the hips? > > > You are quite right about natural selection preferring nothing - > > > it has no preference. It just describes the result of a natural > > > process, as you point out. Jim > > > > On Jul 19, 12:52 pm, GarrieMushet <[email protected]> wrote: > > > > > Jim, > > > > > In evolutionary terms, the most important goal is to hand down your > > > > genes. The prerequisites to this goal are reproduction and survival. > > > > Therefore, there is NOTHING more important than survival in > > > > evolutionary terms. > > > > > So no, I wouldn't say that sleep serves a purpose more important than > > > > survival. I would say that sleep serves the purpose of survival, in > > > > fact. > > > > > You are entirely right that sleep makes the sleeper vulnerable to prey > > > > that is not asleep. But natural selection does not know this. > > > > > Many people see evolution and natural selection as independent > > > > conscious agents who constantly and actively refine the organism to > > > > make it better and better at surviving. This just isn't the case. > > > > Natural selection and evolution aren't 'aware' of anything. They do > > > > not know that sleeps makes up vulnerable. I daresay that if evolution > > > > and natural selection were conscious creative agents, then sleep would > > > > have been abolished long ago. > > > > > It hasn't though. Why? This is your question, I believe. Why haven't > > > > we evolved to not require sleep, when in fact, it is a danger to the > > > > organism to be a sleep. > > > > > Well first of all, let me say that sleep is not the only phenomenon of > > > > living creatures which would seem to be a disadvantage to individual > > > > survival. Let me introduce to you a few of them within our own > > > > species: > > > > > 1) The human brain. > > > > > Around 2 to 2.5 million years ago, our ancestors had brains with a > > > > volume of only 400 cubic centimetres. Around that period, it bloomed > > > > to about 650 cubic centimetres. Around 500,000 years ago, it jumped to > > > > 1,200 cubic centimetres. And then around 150,000 to 200,000 years ago, > > > > when the first 'homo sapiens' walked the plains of africa, it jumped > > > > to its current volume of around 1,400 cubic centimetres. > > > > > But the problems that came from the increase in the volume of the > > > > brain were quite substantial. For starts, millions upon millions of > > > > women have died in the last 200,000 years because their pelvises have > > > > been unable to pass the head of a baby needed to house this massive > > > > organ. Quite a lot of the time, the baby perished too. > > > > > Not only that, but the brain takes up one fifth of the entire human > > > > energy reserve. So 200,000 years ago, our ancestors found themselves > > > > having to hunt and eat a lot more food than they had to when their > > > > brains were only 400 cubic centimetres. > > > > > Our heads are now so heavy that the risk of a human suffering from a > > > > broken neck is massive compared to that of our chimpanzee cousins. > > > > > 2) Walking on 2 legs. > > > > > Humans still haven't adapted to walking to 2 legs as fully as they > > > > could be. Walking on two legs is a relatively recent practice among > > > > the species, and as such, we haven't quite had the chance to > > > > assimilate to it. The statistics for the number of humans with chronic > > > > back problems are enough to convey this, and almost every single human > > > > will have personal experience of it at one point in their lives. Going > > > > back 200,000 years, the notion of back trouble was even more daunting > > > > than it is today. For us it means annoyance when rising from our > > > > chairs, but for our ancestors it was the difference between escaping > > > > predators and being gored to death. It was the difference between > > > > catching the extra prey necessary to provide the energy that our > > > > brains required and lying on the african plains, dying from > > > > starvation. It was the difference between between being sexually > > > > attractive and sexually selected, and being cast aside to die without > > > > ever passing on their genetic codes. > > > > > So why oh why has natural selection not ridded us of these burdens? > > > > > Well, because Natural Selection really doesn't care. Natural selection > > > > is indifferent to what makes us vulnerable. Natural selection has no > > > > inclination to remove the characteristics which cause us great pain > > > > and discomfort. Natural selection doesn't care if we live or die. > > > > Because natural selection isn't capable of caring, or thinking, or > > > > realising what characteristics are beneficial, and which are > > > > burdensome. > > > > > The reason we continue to sleep, walk on 2 legs, and have massive > > > > brains is the NET effect they have on us, as a species, is a > > > > beneficial one. So although, if you look at sleep from one angle, it > > > > seems to be a great disadvantage, if you look at it from another > > > > angle, you see that the benefits we gain from it far outweigh the > > > > disadvantages. > > > > > Afterall, sleeping for 8 hours a day only makes us vulnerably for 1 > > > > third of our lives, but it keeps us fresh and awake and able to escape > > > > predators and catch prey for 2 thirds of our lives. If we never slept, > > > > the nature of our physiology would make us vulnerable for 100% of our > > > > lives (and short lives they would be!). > > > > > In conclusion: > > > > > Yes, many organisms have died from being asleep at the wrong time, > > > > having massive brains, and attempting to walk on two legs. But many > > > > more organisms have USED their brains to aid their survival, have USED > > > > their walking habits to benefit their survival, and used a good > > > > night's rest to make them must more 'fit' for an overwhelming majority > > > > of their lives. > > > > > On the whole, these characteristics have been beneficial enough to > > > > allow the majority of the organisms that have these characteristics to > > > > survive, reproduce, and hand those characteristics down to their > > > > offspring. And the humans who refused to walk on two feet, didn't have > > > > as big brains, or didn't get enough sleep perished in the competition > > > > of their smarter, faster, and more energised rival humans. > > > > > Natural selection doesn't refine us until we are perfect. It just gets > > > > rid of the specimens whose genes do not allow them to survive to pass > > > > them on. > > > > > Regards, > > > > > Garrie > > > > > On Jul 19, 7:51 pm, retiredjim34 <[email protected]> wrote: > > > > > > Garrie - on further reflection, is seems to me self-evident that sleep > > > > > makes the sleeper vulnerable to a predator that isn't sleeping. So > > > > > since virtually all living forms sleep, sleep must be needed for some > > > > > reason more important than survival. Does that sound right? Jim > > > > > > On Jul 18, 10:24 am, retiredjim34 <[email protected]> wrote: > > > > > > > Garrie - Excellent point. Thank you. Jim > > > > > > > On Jul 17, 4:45 am, GarrieMushet <[email protected]> wrote: > > > > > > > > If sleeping was dangerous enough to kill all animals that need > > > > > > > lots of > > > > > > > sleep, then indeed, those animals would have died out. But they > > > > > > > didn't. > > > > > > > > The fact of the matter is that most animals who sleep did NOT die > > > > > > > out, > > > > > > > and therefore they WERE able to survive and reproduce. > > > > > > > > So rather than thinking that the theory of evolution is wrong > > > > > > > based on > > > > > > > your hypothesis that sleep isn't compatible with naturally > > > > > > > selected > > > > > > > highly evolved beings, I would tend to think that your hypothesis > > > > > > > that > > > > > > > sleep isn't compatible with naturally selected highly evolved > > > > > > > beings > > > > > > > is flawed. > > > > > > > > There are many examples of features and characteristics that have > > > > > > > evolved that increase the risk of death. But as long as this risk > > > > > > > of > > > > > > > death does not kill people too early, then they have time enough > > > > > > > to > > > > > > > reproduce, and their traits will be passed on. > > > > > > > > These are not exceptions to the theory of evolution, they are > > > > > > > simple > > > > > > > traits that, whilst they may decrease the quality and length of > > > > > > > life, > > > > > > > they do not do so enough to reduce the chances of reproducing. If > > > > > > > they > > > > > > > did, those characteristics WOULD have died out. > > > > > > > > On Jul 14, 6:35 pm, > > ... > > read more » --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups ""Minds Eye"" group. 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