What makes Australians happy?

Lately I’ve been exploring demographic and social data, including looking at the Australian data in the World Values Survey. Of particular interest are data on self-reported happiness. Among women, financial stress and poor health contribute to unhappiness, as might be expected. Socially conservative women report being happier, and single women report being less happy. Finally, women who attend religious services once per week or once per month are happier than those who do not attend religious services, or those who attend religious services more than once per week. This is broadly consistent with literature on the effects of religion on mental health.

Among men, financial stress and poor health act in the same way as for women. In terms of marital status, however, it is separated men who are the least happy. Male happiness is also closely tied to employment status, with unemployed (and, to a lesser extent, self-employed) men reporting more unhappiness.


Gender and Health

Lately I’ve been exploring demographic data related to women’s health. Among other things, this involved looking at the Australian data in the World Values Survey, which includes a self-reported measure of health. For women, this depends on a number of other variables, including age:

For men, the age effect is weaker:

Presumably, this is because male health problems are more likely to be fatal, which is why there is an excess of women amongst the elderly, as indicated by Australian census data:

Why vaccinate?

Why do we vaccinate children? To prevent some horrific diseases that have haunted the human race for centuries. These diseases have not gone – they are still lurking in the darkness, and have already started to reappear in towns with low vaccination rates. Here is a brief reminder of five diseases that no sane person would want to see return.


Diphtheria is caused by a toxin-producing bacterium. It kills between 50 and 200 out of each thousand people who catch it.


Measles is caused by a virus. In the US, it kills about 2 out of each thousand people who catch it (in the rest of the world, more like 7 out of each thousand). However, it can also cause brain damage, deafness, blindness, and other complications in the survivors. It is extremely infectious – far more so than Ebola or the flu. And cases are trending upwards in the USA as a result of non-vaccination.


Rubella (German measles) is of concern not only because of the harm it can do to those who catch it, but because it also causes miscarriages and birth defects in pregnant women.


Pertussis (whooping cough) can leave children weak for a long time. It is particularly deadly in young infants, and low vaccination rates are responsible for the deaths of babies in some areas. See here for a rather disturbing video of a baby in intensive care.


Poliomyelitis (polio) is caused by a virus, which can cause permanent paralysis of various muscles. The 1950s saw serious epidemics that have now been largely forgotten. Unfortunately, attempts to eradicate polio have stalled in certain parts of the world.

Polio survivors (photo: RIBI Image Library)

Worldwide, each minute of every day and night, three children under five die from vaccine-preventable diseases like these. So “jab for life,” mums and dads!

The dose makes the poison

Some time ago, someone pointed me at a “natural health” site which expressed shock that “Big Pharma” was putting “toxic copper” into baby formula. Those poor babies! Now the copper was there, all right, but only because copper is an essential mineral. Indeed, copper is present in human breast milk, at a concentration of about 0.36 milligrams per litre, and inadequate copper intake has terrible consequences, especially in premature babies. The copper was necessary. The key idea here, which the diagram below is intended to capture, is sola dosis facit venenum (“the dose makes the poison”).

Many essential vitamins and minerals, like copper, transition from a “no effect” dose (blue) to a beneficial dose (green) to a toxic dose (red). In the upper three bars of the diagram, the black dot indicates the recommended daily intake (which we should ingest), and the white bar marks the recommended upper limit, which we should not exceed (disclaimer: this diagram may contain inadvertent errors; please take your medical advice from official sources).

Something similar happens with medicines, like paracetamol (acetaminophen). Small amounts do nothing for your headache; in adults, one or two tablets (0.5–1 gram) safely ease mild pain; but exceeding the dosage indicated on the packet can cause liver failure and death.

Paracetamol tablets (photo: Mateus Hidalgo)

For toxic heavy metals like mercury, cadmium, lead, or silver, there is no beneficial level – the transition is from a “no effect” dose (blue) to progressively greater harm, up to and including death. In the lower four bars of the diagram, the white dot indicates the daily intake of the average person (which generally seems to have no observable effect), and the white bar marks the recommended upper limit.

When people are exposed to levels above the white bar, health authorities start to get worried. For example, shark meat can contain 1 mg of mercury per kg or more. Australian authorities recommend that if shark meat is eaten by pregnant women or children, it should be limited to 1 serve per fortnight (with no other fish eaten that fortnight). But even there, it is the dose that makes the poison.

Mercury and formaldehyde in vaccines?

The anti-vax community runs regular scare campaigns regarding “toxins in vaccines.” Mercury and formaldehyde are the two most often mentioned. Mercury occurs in the form of the antibacterial thiomersal (thimerosal), but not in vaccines routinely administered to children. Thiomersal is present in multi-dose vials (not in single-use vials) of influenza vaccine, typically at a level of 25 micrograms (0.025 milligrams) per dose. For comparison, though, the normal mercury intake is about 2410 micrograms (2.41 milligrams) per year, so an annual “flu shot” adds very little extra. And even that exaggerates the risk, because thiomersal breaks down into ethylmercury, which is less dangerous than other forms.

Formaldehyde, though toxic in moderate to large quantities, is naturally produced and consumed as part of human metabolism, with a turnover of about 50 grams of formaldehyde per day for a person weighing 50 kg. Formaldehyde occurs naturally in blood at levels of about 2.6 milligrams per litre. Even for a 3.5 kg newborn baby (with 85 mL/kg of blood), that comes to 0.77 milligrams of formaldehyde (and there’s more in body tissue). Vaccines contain at most 100 micrograms (0.1 milligrams) of formaldehyde, and so add very little to the blood (and that is very quickly eliminated). That’s even more true for older children, with their much greater blood volume.

Part of the problem here, I suspect, is widespread confusion between grams, milligrams, and micrograms. At the other end, of course, some people also have problems in economics with understanding the difference between millions, billions, and trillions.

BMI revisited

One of the more infamous datasets floating around the Internet is the set of body measurements of Playboy centrefolds. Wired magazine reported on this dataset in 2009 and again last year, although I found their analysis a little disappointing.

Playboy has been around since 1953, and has influenced attitudes to women in a number of (largely negative) ways in that time. However, the numeric data has a life of its own, as Wired points out (and, in a complex system, tracking one component over time sheds light on the system as a whole). Of particular interest, in the light of my previous post about BMI, is the way Playboy sells a certain “ideal” female body shape. Playboy influences and is influenced by the general Zeitgeist in this regard (e.g. the fashion industry), but is also presumably influenced by inherently biological male preferences.

I’ve taken the 2009 dataset used by Wired, added more recent data screen-scraped from Wikipedia, and done my own analysis (all in R, of course). The chart below shows the results. These numbers may, as Wired points out, not be entirely accurate – but even if they are not, Playboy is still selling the body shape which those numbers describe.

The first thing to note is that 52% of Playboy centrefolds had a BMI (body mass index) below the healthy green zone on the chart. Like the fashion industry, Playboy is selling an unhealthily underweight female body shape. However, the average fashion model has a BMI of 17.6 (blue line on the chart), and the mean BMI of Playboy centrefolds has always been higher than that. This may be a case of inherently biological male preferences moderating the Zeitgeist’s drive towards ever thinner models.

The black line on the chart shows the smoothed mean BMI values (using 1st degree loess smoothing). There are some interesting temporal variations here. The mean BMI of Playboy centrefolds was stable at a healthy 19.4 up to early 1965, but then dropped steadily to an unhealthy 17.9 in early 1986. The mean BMI then increased again to 18.5 in early 2009, and then dropped sharply again to 18 in early 2016 (the last three trends are statistically significant at p = 0.00000000003%, 0.12%, and 0.53% respectively). The two minima show up again if we look at the lowest BMI values – those 16 or less. The table below shows that there were two of these around 1980, and four others after 2009. These changes may reflect a movement from the Twiggy generation to the Cindy Crawford generation to the Kate Moss generation. Whatever lies behind the numbers, however, it is disturbing to think that the 1970’s pressures on women to become unhealthily underweight may have returned stronger than ever.

Month Height Weight BMI
July, 1978 168 cm 43 kg 15.3
October, 1982 173 cm 48 kg 16.0
February, 2010 170 cm 46 kg 16.0
September, 2013 160 cm 39 kg 15.1
July, 2014 173 cm 48 kg 16.0
August, 2015 173 cm 45 kg 15.2

For comparison, the chart below shows the estimated BMI for some winners of the Miss World and Miss Universe beauty pageants (in the absence of weight data, BMI is estimated from body measurements, where these are available, using a regression equation derived from a standard anthropometric database). Here 57% of the women are underweight. The mean estimated BMI is roughly steady at 18.7 (just inside the healthy range) up until the year 2000, but from 2000 onwards there is a significant decline (p = 4%). More data would be useful here, but it does seem that (in spite of bans on underweight fashion models in some countries) there are indeed renewed pressures on women to become unhealthily underweight. Furthermore, the post-2009 downturn in the mean BMI of Playboy centrefolds seems to have been in reaction to a more global trend that had already begun a decade earlier.

The words of the fictional demon in C. S. Lewis’s 1942 book The Screwtape Letters still seem relevant today (although Lewis clearly did not foresee the current industry in silicone breast implants, which Wired also comments on):

It is the business of these great masters [of the Lowerarchy] to produce in every age a general misdirection of what may be called sexual ‘taste.’ This they do by working through the small circle of popular artists, dressmakers, actresses, and advertisers who determine the fashionable type. … The age of jazz has succeeded the age of the waltz, and we now teach men to like women whose bodies are scarcely distinguishable from those of boys. Since this is a kind of beauty even more transitory than most, we thus aggravate the female’s chronic horror of growing old … We have engineered a great increase in the licence which society allows to the representation of the apparent nude (not the real nude) in art, and its exhibition on the stage or the bathing beach. It is all a fake, of course; the figures in the popular art are falsely drawn … As a result we are more and more directing the desires of men to something which does not exist – making the rôle of the eye in sexuality more and more important and at the same time making its demands more and more impossible.


I love my daily shot of caffeine, preferably in the form of a good espresso. Caffeine is a stimulant and vasoconstrictor. It can increase alertness, and will sometimes alleviate headaches (although a rebound effect means that withdrawal from caffeine may temporarily cause headaches). Alfréd Rényi famously said that “A mathematician is a device for turning coffee into theorems,” and that does seem to be true. In addition, moderate coffee intake seems to have minor health benefits, including a slight protective effect against some cancers.

There are, however, good reasons to limit caffeine intake to 400 mg day (and half that for pregnant women). That leads to the limits in the table below (data from here and here). I intend to keep on enjoying my coffee responsibly, within those limits!

Drink Volume Caffeine Max/day
Espresso 1 shot (30 ml) 60 mg 6
Brewed coffee 1 cup 200 mg 2
Starbucks coffee “venti” 400 mg 1
Black tea 1 cup 40–80 mg 5–10
Green tea 1 cup 30–60 mg 6–13
Coca-Cola 1 can 35 mg 11
Red Bull 1 can 80 mg 5