Is it true that Nature always maintains the man,woman ratio nearly 50,50?

Question

I have heard that after a war when lage number of men are killed more boys than girls are born

Answer 1

There is some debate on weather certain environmental stressors affect the male production of x or y spermatozoa. The biggest "missing link" to evolution theory is a mechanism which would alter the expression of genetic material based on the experience of an individual. As an example, how is a child's skin color at birth determined based on the experience of his or her ancestors? Exposure to the sun darkens the skin as a defense mechanism. How does that experience affect the skin color of the offspring?, I believe that the same type of mechanism would be at work to alter the chromosomal makeup of reproductive cells. And the global ratio would not apply. I would want to analyze the birth rate in geographical segments, say a comparison to the birthrate in South Africa -vs- Sudan, or Kurdish Iraq -vs- Central Iraq. If the mechanism is present, those contrasts would show it. This isn't to say there is doubt of evolution of species or gender balancing, just that we do not know how it is expressed. If mutations and natural selection were the only sources of change, then the process would take too long to account for the adaptive diversity we see today. Skin colors are estimated to have emerged less than 20,000 years ago.

Answer 2

In humans, the ratio is not exactly the same because the motility of sperm with a y chromosome is slightly better than the motility of a sperm with an x chromosome, so more of the y sperm win the race to the egg cell. There is no evidence that either male or female sperm are given some sort of "handicap" when the population goes out of balance, though. It's difficult to get a 'true' figure because there is some selection that goes on, for instance in decisions whether to carry a pregnancy to term or how hard to try to keep a sick baby alive, and that might reflect social pressure.

In other animals, the ratio is not necessarily the same. In ants, almost all are female, and the sex is determined by the queen. And frogs can choose (remember Jurassic park?)

Answer 3

In the short term, no. There are many factors (environmental, genetic, social, economic, etc.) that influence gender imbalances, but natural selection will tend to even it out if it gets too unbalanced in the long run.

If there were a significant imbalance, then there would not be enough of one gender to go around, and there would be a lot of people not bearing & raising children. But among those who do, there would still be a statistical balance of children's genders nearing 50/50 (~105 F / 100 M).

Answer 4

This is a myth, and not a modern Urban one.

Evidence to the contrary is available throughout recorded history. Usually the birth rates remain very close to 50-50.

Recent studies have reported the current world-wide birth ratio is 100 males to every 105 or 106 females. However other data is available.

Answer 5

Nope...there are more woman on the planet today than there are men. And we hardly live in a natural environment anymore, so don't think nature works for people that way anymore.

Answer 6

not actually. sex of a person is determined by X and Y chromosomes. Male haveX and Y. females have X and X. According to recent studies the no. of Y chromosome is decreasing. that means one day there will be no male. BUT this rate is very very slow and it will take thousands of years for this to happen

Answer 7

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Answer 8

Bonjour

Answer 9

It may try to, but we manage to kill off our men in war

Answer 10

Wouldn't surprise me. Nature is well clever isn't it. Nature's powers rule.