The human population is roughly 50/50 male and female. Could it ever dramatically veer either way?

Answer 1

It is extremely unlikely. Although, as previous answers have eluded to, the global ratio of males to females is 53 percent female to 47 percent male, the actual birth rates are rather different. At bitrth 51% are male and 49% female, however the higher death rate of males, in developing countries especially where manual labour is more prevalent, means that a greater percentage of females survive in to old age than males of the same generation.

The sex of a child is based entirely on the genetic make up of the embryo. if the embryo is xx then it is female, if it xy it is male. This would be expected to occur in a 50:50 ratio as the sperm is the deciding factor to the sex of the child (all female gametes are x, males may be x or y), however it has been found that sperm carrying the y chromosome can 'swim' to the egg faster than female chromosome carrying sperm, perhaps because the y chromosome is lighter meaning the sperm can out compete sperm carying the x chromosome..

So in summary, the male sperm are more likely to fertilise an egg - this explains the fact that more males are born than females, however due to the higher death rate of males more females live to old age resulting in a ratio of 53 percent female to 47 percent male in the general population. As dangerous industries become more automated it is likely that the global male female split will become more equal.

The future may allow for genetic selection of embryo's however I do not know whay more of one sex may be selected than of another.

Answer 2

From an evolutionary standpoint, this can only happen over the long term in a society that practices polygamy or incest.

Consider a society in which there are twice as many men born as women. In that society, women are at a premium: many men will be unable to find a mate, while almost all women will be able to find a mate. So if, for genetic reasons, all your children are female, you will have many more grandchildren than you would if all your children are male -- because many of the male children won't reproduce at all.

Therefore, in such a society, anyone who is able to produce girl children reliably has fabulous genes, and those fabulous genes will be selected for, and gradually work their way through the gene pool, until the sex ratio is restored to 50/50.

The same logic applies the other way in female-rich societies, but not quite to the same extent, because of the possibility of polygamy by males soaking up the excess females. But male polygamy is a two-edged sword, because it's more than likely that more than just the excess will be soaked up by an alpha male, resulting in an apparently male-rich society again. That's why human populations are slightly female-rich, because of male polygamy.

The balance can also be tipped (and even more radically) in societies that routinely practice incest.

Answer 3

Probably only if there was a certain incurable disease that affected either gender.
During times of war etc men often went to fight and so the ratio of women to men in a country's population increased.
Some societies have created a gender imbalance. In China for example, because of the government's One Child Policy there is now a shortage of females. 20 or 30 years ago families could only have one child and so much importance was placed on having a boy, many female babies were aborted as foetuses, killed or dumped soon after birth. So the current generation of young men in China do not have enough women to 'go round' so to speak.
Also, increasing numbers of people are deciding on the gender of their baby through IVF and other fertility treatments - maybe this will also have an impact on the ratio of males to females (?) These treatments are becoming more common as the rate of peoples' infertility rises.

Added 1pm - CustomDreamMachine you are talking bigoted crap. Altering the number of gay people in the world would have no impact on the male to female ratio of babies being born. What is the connection?

Answer 4

Selective abortion of male or female foetuses, or infanticide (leaving to die at birth) of boy or girl babies could have a major impact on the male/female ratio. It appears that this is happening in countries where boy babies are preferred, particularly in Asia. In China, where in many areas families are only allowed one child, there is particular evidence that the number of boys is greatly exceeding that of girls. Potentially, artificial means of conception could produce similar results. So it is actually quite likely that there will be a dramatic increase in the number of males compared to females in the world's population in the coming decades.

As most members of the world's armed forces are men, war can potentially increase the proportion of women in the population.

Medical advances could change the sex ratio in the population if medical techniques are developed that address problems specific to, or mainly affecting one sex, e.g. brest cancer. Medical advances generally increasing life expectancy will tend to increase the number of women in the population as they generally live longer.

Conceivably, a virus could emerge that differentially affects men and women.

I believe, although I do not know enough biology to give you the details, that environmental factors, e.g. chemical pollutants, can affect the likelihood that a woman will conceive a boy as opposed to a girl.

In short, there are a number of reasons why the sex ratio in the human population may veer away from 50/50, and one why it is probable that it will.

Answer 5

There are slightly more females than males (52/48) which may be due to prevelence of sex-linked genetic deficencies in males (darn Ychromosome!) If some sort of sex-linked genetic deficency arose for some reason, there could be a shortage of males. Technically, it is more evolutionarily sound to have a lot more females than males and do away with monogamy. This is because females can only produce the ability for offspring every 9 months while males can.. a lot quicker. If we wanted to make the largest population boom, we would need a lot more females than males.

Answer 6

There has been a lot of research on this subject. Generally, scientists believe that evolution would take control, to stop anything to drastic happening.

The world population is actually 53% women and 47% men. It is believed that this is the result that men can make many more babies much more quickly than women can. It takes a woman 9 months. It takes a man less than 9 seconds.

Answer 7

Actually most recent studies show it to be more like 53 percent female and 47 percent male. Any sudden change to the overall population such as famine or disease will lead to more females being born in order for the population to rebuild. This is the same for most vertebrates. BTW I've read that Canada is 61 percent female.

Answer 8

!Apparently Guildford Surrey is the most dramatically veered place towards the male of the species. So if you are a single female make your may down there to make up the balance!

Answer 9

During times of war in world history the ratio of male to female has been unbalanced. Nature seems to take care of this though, as can be witnessed by the higher number of boys born after WWII. Nature is a balance, and left alone it will always balance itself.

Answer 10

I think it has in some countries where girl babies are left to die or aborted. India and China in particular have populations where there are more males than females. You'd think it would make girls more special, but not so. Apparently they are just made to do more . Of course this is selective, not through breeding.