Friday and population data

Let’s talk about anything but the virus today. I was looking around to see what was there, and I got excited about a paper that I read looking at sex ratios in Asian countries. The paper can be found here.

I want to set it up properly.

The problem: the number of young males in Asia is skewed. At birth, the human species produced about 105 males to women. It falls over time, because women generally are healthier than men and live longer.

But in some Asian countries, the ratio is decidedly skewed to males. In China at birth there are 111 males to females, 6 extra males per 100 females.

Impact: It is very negative for a country to have so many more young men than women (more about the elderly later):

Source: CIA factbook

The consequences of having too many men, now coming of age, are far-reaching: Beyond an epidemic of loneliness, the imbalance distorts labor markets, drives up savings rates in China and drives down consumption, artificially inflates certain property values, and parallels increases in violent crime, trafficking or prostitution in a growing number of locations.

Short summary: it’s really bad to have a skewed ratio.

Why? Social scientists have tried to look at why it is happening. There are a few hypothesis:

Policies: For example, in China, maybe the one-child policy is the reason why it is so off? This is probably true, but it can’t be the whole story, because India is also really bad.

Patriarchy: Is it because of a society being male-dominated? Then why does Egypt have a ratio of 1.06 males to females at birth? Saudi Arabia is even lower at 1.05 (but other figures for Saudi are very weird, so it is likely an outlier for some reason).

Economics: Is it because of economic reasons? If so, why do the richer parts of India have a worse imbalance than the poor ones?

Culture/religion: Some posit that the skewed sex ratio is because of culture and/or religion. Unless there is some prohibition against infanticide, cultures that value boys more than girls, will see an imbalanced ratio.

Looking at Vietnam: As can be seen in the chart above, it has similar issues to China, although less severe. It is actually the worst in SE Asia, with 1.09 males to females at birth and 1.11 males to females age 0-14.

So this study tried to figure out how much is due to policy, patriarchy, economics and how much of it is due to culture or religion. It looked at immigrants to Canada. In Canada, economic reasons for having a boy are moot, and it is fairly easy to get an ultrasound and abortion, so policies aren’t an issue. If that was the case, then all immigrant groups and those that have been in Canada for more than 2 generations, should all have a similar sex ratio.

Well, it turns out that immigrants from Asia have a very different sex ratio than the rest of Canada (1.05 males/female at birth).

In the study, they found that there were a few things that determined an imbalance sex ratio:

• Religion: Muslims and Christians from Asia did not show the same skew, probably because both religions have strong prohibitions to infanticide.

• Generations: First generation immigrants are more likely to resort to sex selection overall. But second generation immigrants are more willing to go the route of sex selection on their second child (if the first is a girl) than first generation, which wait until the third child.

• Sikhs are the group that has the biggest skew among immigrants in Canada. This is most clearly shown in the third child (after 2 girls), where there are 2 males to every female born.

• Indian immigrants have the greatest imbalance (again for the third child) with almost 2 males per female, probably driven by Sikhs.

So it seems that culture is a big part of this, and so is religion. Because Christianity and Islam have negative views on abortions, you don’t see the same sex ratio imbalance for followers of these faiths. Although they may have more children to get a boy.

A fun thing is that even if everyone keeps having children until they have a boy, the sex ratio will still remain in balance (at that 1.05 or so at birth). Why? Well, you can do it in Excel pretty easily

[Just set it to come up with a random number between 0 and 1. Assume 1 is a boy, so if 1 does not comes up, then run the random number generator again as many times as needed to get a 1. Then average all of these. It will approach 0.50 as more and more tests are run.]

The idea is that if 100 people have children, 50 will have boys and 50 will have girls. Then those 50 with girls will have 50 more children, 25 girls and 25 boys. Then those 25 will have more, 12.5 girls and 12.5 boys. Then those will have 6.75 girls and 6.75 boys. Then keep going down until the numbers get so small that any additional boys at the very end are statistically meaningless.

Source: CIA Factbook

Where Vietnam stands now: It will be very interesting to see what happens in Vietnam with the excess men. Right now for ages between 25-54, there are 1.03 men to women, which isn’t too bad. This falls drastically as the cohorts get older (a sizable majority of people over 65 are women), probably because of the war.

But we are entering a period when lots of Vietnamese men are getting to marrying age. Remember, under 25, there are approximately 110 men for every 100 women.

If there aren’t enough couples, then lots will be left to bachelorhood. The Washington Post article above has lots of scary details.

There is a small COVID-19 tie in, which is unlikely to materialize in Vietnam, because cases are under control. More men than women die of COVID-19:

In Italy, men have accounted for 71% of deaths and, in Spain, data released on Thursday suggests twice as many men as women have died.

If deaths get much, much higher, then we could see changes in the sex ratio, but that’s going to take hundreds of thousands of deaths. And we are nowhere near that now. Thank goodness.

Anyway, so there is a demographic time bomb coming up (already here for India and China), and it will be difficult to get through. Cheery thoughts for a Friday.