Can I call you Father?

There is a lot of noise being made by the recent report that up to 4% of all fathers are raising another man's child. I'll quote before commenting:

"Professor Mark Bellis and his team said that the implications of so-called paternal discrepancy were huge and largely ignored, even though the incidence was increasing.

In the US, the number of paternity tests increased from 142,000 in 1991 to 310,490 in 2001.

Vital information is being delivered to people without very much thought about how it is going to affect them

Lead researcher Professor Bellis

Demand for testing has grown by a factor of 10 in the last decade in the UK, according to University Diagnostics, Teddington.

The current level in the UK is somewhere between 8,900 and 20,000 tests per year.

About 5,000 of these tests are instigated at the demand of the Child Support Agency to resolve who should be paying child maintenance.

Others are done to investigate inherited health disorders and others for social reasons.

The Liverpool team found that rates of cases where a father was not the biological father of his child ranged from 1% in some studies to as much as 30%.

Experts have generally agreed that the rate is below 10%, with a 4% rate meaning that about one in 25 could be affected.

However, increasing use of genetic testing is likely to boost the rates of paternal discrepancy, say the authors."

Medical statistics, especially those that make news headlines, are often the result of very limited studies. These statistics are often lacking the sort of controls we'd expect to see in modern linear regression within the social sciences. In fact, a simple correlation is often enough to make the front page of a newspaper.

It is worth noting that this number: 1 our of 25 fathers, cannot apply to the population of the UK, nor any other country. The sample that the fraction was derived from is the sample of all people who have either chosen to have paternity tests or have been ordered to by the Child Support Agency.

If we really wanted to know whether or not this statistic applied to the overall population, it would have to be a result of a study with random sampling. There is too much self selection with the current sample as parents who already concerned enough to get fertility testing are more likely to have been victims of infidelity. It is even arguable that people fighting over child support are more likely to have experienced an 'illegitimate' birth.

Rantings over statistical accuracy aside, I don't see many ramifications resulting from a 4% rate of false fatherhood. This is pure conjecture, but I'd imagine that this number is at a historical low, as the existence of modern contraception and the disincentive to infidelity of paternity tests have undoubtedly reduced this occurrence.

However, on a case by case basis, I can see how earth-shattering a discovery could be.

No more children, please

Some of you might not be familiar with China's one-child policy. Adopted in 1979 it is an attempt by the Chinese government to reduce both urban and rural fertility rates by legally restricting the amount of children a couple can have. It is most effective in China's cities, as in the rural areas, couples are often allowed to have a second child after a number of years.

China has good intentions, as curbing population growth in a country with over a billion citizens is incredibly important. However, their enforcement of such a policy has had a variety of negative repercussions on the Chinese population.

This BBC News Article by Francis Markus, which I've been meaning to link for quite some time now, highlights some of the more recent problems:

""Nowadays many rural families don't want to send their children to work in the factories because they have only have one child and they regard that child as their insurance policy for old age," said Feng Shengping, senior researcher at a Communist Party think tank in southern China. "

While some economists and demographers would argue that old-age security isn't an important factor in fertility decisions, others, including yours truly, believe that it is one of the most important incentives for having large families in developing countries. In the absence of a proper pension system (China has one, but usually fails to deliver), parents will optimize their fertility in order to improve their chances of having a surviving child (preferably a son) to take care of them.

In the absence of a proper pay-as-you-go pension system and with an upper bound on fertility, it is hardly surprising that families do not want to let go of the few children they have, as it is of the utmost importance that the child does not default on his/her responsibilities. There are a few benefits to this situation: this creates incentives for parents to invest heavily in child quality, often seen as a staple of demographic transition.

However, the negatives far outweigh the positives. As would be expected, a son is far more useful to a family than a daughter, so many daughters are aborted or removed through infanticide in order to make room for more men. As a result, the sex ratio in China has taken a drastic turn (with numbers as high as 117 men for every 100 women).

It might also be noted that population growth is not always a bad thing. The growth of dependency-aged populations (children and seniors) usually has a negative effect on a country's economy, as neither group actually produces anything, and instead only consumes. Early on in demographic transition, as child mortality falls, we usually see youth dependency rates skyrocket, as suddenly we have a lot of children being born.

China's policy, the in face of lower child mortality rates, is now hurting the growth rate of China's working population, which is much more essential to economic growth. At the same time, the restriction is inflating average age, so as China's population gets older and older, they are finding less and less children to be there for them.

A little bit of population growth, like inflation, is good for an economy. Let's hope that China comes around before they wind up with a large dependent senior population before they've moved from being a developing country to a developed one.

A change of pace

Evidently, the relative lack of fresh population-related information has hampered my post count. Either that or I've been too busy to do the research myself. In the meantime, I think I'll post some musings on the subject


It has been claimed before that there is no limit to the human life span, but I wonder how realistic this is?

Note that life span is the total number of years a human being is physiologically able to live; not to be confused with life expectancy which is the expected number of years out of his/her life span. Researchers claim that since life span has been climbing for the past 200 years (probably a little less than a year a decade) that there is no tail end to it. Yet I might note that life expectancy has also been on the climb during this time, and at a much faster rate. If we considered one of the highest life expectancies in the world, like that of Japan (81.15), to be the mean of the age distribution, we should be seeing the right outliers moving out at a further rate, one more comparable to the growth of life expectancy.

I had a teacher once that said that life expectancy was just going to keep growing and growing and growing, but as the income/technology effect on life expectancy appears to have diminishing returns, I think we'll find that we'll cap out at 115, which I presume to be our life span.

A slight delay

I apologize for a lack of posting this week. I found out yesterday that I've been accepted into the MSc in Economics for Development program at Oxford University, so resulting jubilation took up most of my time yesterday!

The Dragon Stirs

"A century ago, the French scientist Gustav Le Bon pointed to the smaller brains of women - closer in size to gorillas', he said - and said that explained the "fickleness, inconstancy, absence of thought and logic, and incapacity to reason" in women.

Overall size aside, some evidence suggests that female brains are relatively more endowed with gray matter - the prized neurons thought to do the bulk of the brain's thinking - while men's brains are packed with more white matter, the tissue between neurons."

This is taken from a recent NYT article on the differences between men and women that may affect perceived aptitude.

Many of you may have heard of the comments made by Harvard president Lawrence H Summers at a recent economics conference. Summers suggested that there might be innate differences in intelligence between men and women on a genetic level, which could explain for the lack of female involvement in science and mathematics.

In Summer's defense, he certainly wasn't defending the position, just merely trying to stir up debate on the subject. However, in the politically correct world of today, he might have gone about it a better way.

However, it is still an interesting question. Is it even possible to account for all the environmental factors that could explain this discrepancy? Many women that I have talked to have felt like they were discriminated against in the (high school) classroom. Are women actively discouraged to enter the science or maths? If there were innate differences between men and women in terms of intelligence, and either party came out on top, would the other be discouraged from participating in study that requires a high level of cognition?

I think it's an interesting, but perhaps superficial debate. Shouldn't we be talking more about the wage gap than about a minor intelligence gap?

Oh, and if you don't have a Nytimes.com account and wish to see the articles I link, use

username: kargos@rocketmail.com
password: demographer

The Reds and the Blues of having children

This is an interesting New York Times Op-Ed piece by David Brooks that was forwarded to me by my thesis adviser. It describes an interesting divide on the Red State/Blue State border: a difference in desired number of children. This relationship is most evident in this passage:

"You can see surprising political correlations. As Steve Sailer pointed out in The American Conservative, George Bush carried the 19 states with the highest white fertility rates, and 25 of the top 26. John Kerry won the 16 states with the lowest rates."

It's a pretty interesting article, although it seems to be written from the point of view of a natalist, as it does a lot to lavish goodwill. From the point of view of an economist, having experience studying the relationship between female income/rights and fertility, I find this passage to be the most important:

"Natalists resist the declining fertility trends not because of income, education or other socioeconomic characteristics. It's attitudes. People with larger families tend to attend religious services more often, and tend to have more traditional gender roles."

I would like to see research on this issue which takes into account the mother's income as opposed to a more tradition family income. What could be shrouded in this is a situation where we have well-educated mothers who assume "traditional roles" as housewives, and so have no obvious opportunity cost to having lots of children. The income effect is shrouded by a well-off husband. Of course, we'll be able to find examples to the contrary (many of my friends, for instance), as there are plenty of women who desire to have a high paying job AND lots of children (the feasibility of which may be questionable). However I bet the shrouded income effect dominates in the Red States.

Low-fertility Europeans more fertile?

According to a New York Times article by Nicholas Wade, Icelandic researchers may have isolated a portion of DNA on the 17th chromosome that may cause Europeans to be more fertile than the rest of the world.

"The region is not a single gene but a vast section of DNA, some 900,000 units in length, situated in the 17th of the 23 pairs of human chromosomes. In some Icelanders, the Decode team found, the section runs in the standard direction but in others it is flipped. Looking for any physical consequence, the Decode researchers found that women carrying the flipped or inverted section tend to have slightly more children."

In turns out that 1 in 5 Europeans have this chromosome inversion. I think this is an interesting find, because, in recent years, Europe has been known for it's dramatic depopulation, which is due partially to emigration, but also to a sharp decline in its fertility rates. We should be thankful that this gene is most common in an area of the world where people have already decided to have less children and rare in places like Africa and Asia, where they are struggling to keep population under control.

Welcome to The Demographer

Many of you, my well-read friends, may be familiar with The Economist, the UK-based news magazine which covers a broad range of topics from economics and finance to politics and science. It is easily read by any with an open mind, whether or not you are interested in their political analysis or their famed 'Big Mac' index, which can often be found on the back page.

Why bring up The Economist when the title of this blog is The Demographer? For a start, I've always believed that what truly makes The Economist interesting isn't the subject matter, but the way it addresses the various topics. I believe the title of the magazine conveys its perspective in its analysis, as it attempts to maintain a voice of reason and rationality. Because of this, it is hard to place The Economist's political base. The paper has at times supported Thatcherite conservatives, and yet endorsed Senator Kerry in the last presidential election. Its own self-assessment may shed some light:

"It is to the Radicals that The Economist still likes to think of itself as belonging. The extreme centre is the paper's historical position."

I digress from an introduction to my own blog. My reason for titling it as such isn't just to convey its intended topic: the study of population in the world today. I want to convey the same sense of perspective that The Economist does. Not only will you read posts and articles on this site about demography, but you will also read every day articles looked at from the intended perspective of someone interested in demography. I might also note that the title is not my own; I am nothing but a soon to be graduate student in economics who likes to apply his abilities to the study of people's most basic human choices and constraints.

Enough with this introduction, I'll go ahead and post the first article I stumbled across recently. Enjoy.