Falling birth rates may not just reflect changing choices. They may also reflect changing human biology, and the evidence deserves far more attention than it receives.
Australia's birth rate isn't collapsing by accident. It's the result of decades of economic, cultural and political choices that have made family formation harder than ever.
Labor’s under-16 social media ban has failed to deliver what was promised. Its answer is to give Julie Inman Grant more power over private records, online identities and people beyond Australia.
Falling birth rates may not just reflect changing choices. They may also reflect changing human biology, and the evidence deserves far more attention than it receives.
We have built a society that delays family formation, rewards consumption over commitment, and makes children harder to afford than at any point in living memory. Those choices have consequences.
George Christensen
Money and culture are only part of the story. Fertility also depends on whether people are physically capable of having children.
A major systematic review and meta-analysis in Human Reproduction Update found significant falls in sperm concentration and total sperm count across several continents. The authors said the decline appeared to be continuing and may have accelerated after 2000. An earlier analysis covering North America, Europe, Australia, and New Zealand estimated a fall of roughly 50 to 60 percent among men not selected on the basis of fertility between 1973 and 2011.
The causes are still being argued over. Obesity, smoking, alcohol, poor diet, metabolic illness, inactivity, heat exposure, stress, and sleep problems may all play a role. Older fatherhood matters too, even if male fertility usually declines more gradually than female fertility.
Men are also delaying stable relationships and children. Sperm quality, hormone levels, and reproductive outcomes can worsen with age, and older fathers carry higher risks for some pregnancy and child-health outcomes. The idea that men can postpone family indefinitely without consequence is another comforting story that biology has declined to honour.
Researchers have also reported age-adjusted declines in testosterone in several male populations over time. Obesity, metabolic illness, inactivity, poor sleep, medication use, diet, and exposure to endocrine-disrupting chemicals have all been proposed as contributors.
Endocrine disruptors deserve more attention than they usually receive. Phthalates, bisphenols, pesticides, PFAS, and similar chemicals can interfere with hormonal signalling. Animal studies, laboratory research, and epidemiological studies have linked various exposures with altered testosterone, poorer semen quality, impaired sperm function, and abnormal reproductive development.
While folks laughed at Alex Jones’ claim that “they’re turning the fricking frogs gay,” he was right. Atrazine, a widely used herbicide, has been shown in studies of African clawed frogs to demasculinise genetic males. Researchers reported hermaphroditic development in exposed frogs, and a later experiment found that some genetic males developed functioning female reproductive characteristics, mated with males, and produced viable eggs.
Methylmercury has also altered reproductive behaviour in birds. In a controlled study involving 160 white ibises, exposed males performed fewer of the normal courtship displays directed at females and formed more male-male pairs as mercury exposure increased. In one breeding season, about 55 percent of males in the highest-exposure group paired with other males. Females receiving the highest dose produced about 35 percent fewer fledglings than the control group.
Now, frogs and birds are not people, and animal mating behaviour is not the same thing as human identity. But those studies do tell us something important. Chemical pollutants can interfere with sexual development, hormone signalling, courtship, mate selection, and reproductive success in vertebrate animals.
Humans are exposed to endocrine-disrupting compounds before birth, throughout childhood, and during puberty, often as mixtures rather than one chemical at a time. Yet suggesting that such exposure might affect human sexual development, reproductive behaviour or fertility is treated as socially dangerous before it is even treated as a scientific question.
That is backwards. The animal evidence does not give us the final answer. It gives us a reason to investigate.
And investigate we should, because we do not know exactly how much these chemicals have contributed to Australia’s fertility decline. Human beings are exposed to mixtures, not neat laboratory doses, and separating one chemical from diet, age, weight, occupation, and lifestyle is difficult.
That difficulty seems to have become an excuse for complacency. Regulators examine substances one at a time, find that no single exposure has been proven to explain a national demographic trend, and carry on as though the combined chemical load cannot matter.
The Murdoch Children’s Research Institute and other groups have established the Australian Male Infertility Exposure study to investigate lifestyle and environmental factors associated with unexplained male infertility. That alone tells us these concerns are not confined to internet speculation. At least some Australian researchers consider the problem serious enough to study formally.
Then there is plastic. A 2024 study found microplastics in all 23 human testes and all 47 canine testes examined. The average concentration reported was 328.44 micrograms per gram in the human samples and 122.63 micrograms per gram in dogs. Some polymers were linked to lower testicular weight in the dogs, although the preserved human samples could not be used to measure sperm production.
Look at where the argument has reached. Researchers are no longer asking whether plastic pollution surrounds us. They are asking what it is doing inside human reproductive organs. Nothing to worry about, presumably. Just plastic in the testicles. It may turn out to be largely incidental. It may turn out to matter a great deal. Nobody yet knows. What we do know is that human beings are being exposed to a chemical environment with no precedent in our evolutionary history, while several measures of male reproductive health appear to be moving in the wrong direction.
That all ought to stir some urgency. Instead, it usually produces another round of bureaucratic throat-clearing.
To be continued on Monday...
“Nature, to be commanded, must be obeyed.”
― Francis Bacon
Australia's birth rate isn't collapsing by accident. It's the result of decades of economic, cultural and political choices that have made family formation harder than ever.
Labor’s under-16 social media ban has failed to deliver what was promised. Its answer is to give Julie Inman Grant more power over private records, online identities and people beyond Australia.
NAB may have just given us the first real warning of an impending housing apocalypse in Australia.
The Albanese Labor Government is undermining both the Australian economy and Australian democracy.
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