Firstly, evolution is not about increased productivity, it is about increased survival chances. Secondly, how can a woman have two children if the first child killed her?Quote by: Night
What I really don't get, evolutionarily, is why humans have such bad vision.
We don't know the life expectancy of early man. Just because the average lifespan was lower doesn't mean their weren't still plenty of outliers dieing older and younger. And maybe menopause happened earlier on in life for earlier cultures and has changed since.
No, it's not. You seem to have terribly confused the mechanisms that cause the process of evolution with the process. Evolution is about change (or sometimes stasis) in the heritable makeup of populations of organisms over time. One mechanism of that change is natural selection, which may be what you think you are talking about. Natural selection is most simply stated as differential reproductive success. In other words, certain beneficial characters give an organism a reproductive advantage. While that may mean that such an organism has survived to reproduce, it also means that such an organism tends to be more successful in leaving offspring. A further point that is implied is that the offspring must also have increased reproductive success. A good example was given by Jonathan Weiner in his Pulitzer Prize winning book, The Beak of the Finch. Peter and Rosemary Grant spent 20 years studying Darwin finches on a small island in the Galapagos. They successfully trapped and tagged every bird on the island for those 20 years (and more). They were able to recognize each bird on sight. In those years, two male ground finches both survived much longer (by years) than any other finches on the island. They were also quite successful 'producers', as you state it. Their broods were, on average, larger and, of course, they produced more over the years. If evolution is all about survival, then you might think that these two birds might have been significant in the evolution of ground finches on the island. That's not the case. Actually, their effect was zero since not a single one of their offspring lived to reproduce.
@Night:
Actually, just because a characteristic is universal does not necessarily mean that it has an evolutionary advantage. Especially in the case of menopause. What is evolutionarily significant is whether the woman survived to reproduce. You don't know it, but you answered your own question when you mentioned that in early mankind, there were probably few women that lived long enough to go through menopause.What I'm asking is, why would menopause happen in woman everywhere (meaning it had to be very important evolutionarily) when most woman never got old enough to go through menopause?
You are also looking at this from a very limited viewpoint. Some years ago, in the days of extended families, the elderly assisted in raising the offspring of their children. Thus, they assisted in passing on their genes to further generations. There are examples of such activity in many species, where non-reproductive females assist in the caring of the young born of other females, usually a close relative.
I wonder, if menopause occurs even in egg bearing species/birds and fruit bearing trees !!!!
Aging seems to be only reason !! Since at older age it won't be possible to rare their (older specie's) young ones, nature has put an automatic check in reproduction!!!!
Come to think of it, chickens can't lay once they're really old. I have no knowledge of trees.
The more you complain, the less I care about your problems.
To my knowledge even fruit bearing trees stop fruit bearing after a particular time period ! A botanist can tell us better !
Again, I'm going to disagree. Evolution is not about increased productivity, it is about increased chances of survival, which can include a decrease in productivity to sustain a population on a shortened food supply for example. I'm not sure if your study disproves me either, you need to go into detail about the contradiction between "They were also quite successful 'producers', as you state it" and "Actually, their effect was zero since not a single one of their offspring lived to reproduce." The first two finches are proof that the result of evolution is better chances of survival. Their non-reproductive offspring could've been a victim to a number of contingencies you haven't gone into.
There are variety of essential factors - already posted by others, within this thread.
I believe that DNA coding could supply us with some additional (and maybe the most crucial) answers.
I provided the answer. It is not simply a matter of the woman surviving, but her children surviving as well. Her children's survival is increased if she stops having children. This also comes up in the abortion issue. The primary reasoning for killing infants, is the survival of the mother and her living children. A child at the wrong time, is dangerous liability, so nature helps us out by reducing our child bearing years.
Long lived women played an important role in the survival of humanity.
I speak controversy so we have something to talk about. Don't take me too seriously.
Oh dear Athena, this seems to be ideal logic. I do not know how I missed this post for a month or so. In fact, I was out of station and then my system was also down.
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