Contraception and Causality; r/K Selection and Population Growth

Tod’s recent post on contraception contained this thought-provoking segment:

Another note of interest was this argument by Connell:

“Birth control as it is now practised in the United States is bound to bring about a notable decline in our white population in the near future.”

I think in may ways this comment deserves more consideration, and maybe at some point a different post. And not because I think thisargument shows that those that are either anti-birth control or pro-religious freedom today are racists – in fact quite the opposite. No, what I find fascinating about this argument is that of all Connell’s warnings about what would happen should contraception be made available, this is the one that has actually occurred. There are a myriad of factors other than contraception at work, of course, and the reality isn’t so much that the white population has decreased numerically so much as decreased as a proportion to the whole. But the concerns and fear that lie in Connell’s warning have most certainly come to pass.

As I mentioned in the comments to Tod’s post, I think it’s very difficult to infer causality – that widespread use of birth control has resulted in a lower white population rather than the two phenomena being unrelated or sharing the same root cause (condoms have been available for centuries, for instance). When it comes to the question of whether or not the decline in the birth rate of the white American population and the availability of chemical contraception are incidental or epiphenomenal to each other, I find it more interesting to speculate that the two trends share a common root cause. So what is that root cause?

Understanding cause requires an understanding of mechanism. There is something missing from most public discussions of population growth, whether those discussions assert that Great Britain and Japan will continue to decline to nothingness and childbirth will be considered an eccentricity of the past akin to handmade goods and typhus or whether those arguments assert that the Indian subcontinent will someday contain a majority of the world’s population. As far as these population problems are problems at all, they are problems of management: how to manage scarce resources, how to prevent violence from erupting over competition for resources, how to distribute resources from productive groups to vulnerable groups, how to plan cities to minimize congestion, etc.

Luckily, nature provides an automatic stabilizer when it comes to population growth: the logistic sigmoid pictured above, otherwise known as (MacArthur-Wilson) r/K selection theory. r/K selection theory states that – ceteris paribus – population growth for a species follows two general, mathematically-modellable paradigms: r-selection – the exponential growth area of the sigmoid function – dominates in unstable environments, such as might be experienced by vulnerable or marginalized populations like immigrants or the poor. K selection – the logarithmic (flat) area of the sigmoid at the upper right – dominates in stable or predictable environments, such as those experienced by comfortable classes.

Population growth is a sigmoid function.

Some speculate that it is “culture” that causes fewer children as a function of wealth, but this is a meaningless explanation. Attributing rising or declining birth rates to culture fails to explain why the phenomenon is so widespread and cross-cultural: as populations have access to more resources, as their needs progress up Maslow’s hierarchy, they produce fewer offspring, whether those populations are American yuppies, middle-class Japanese or Koreans, members of the European upper class, chimpanzees, elephants, or penguins, despite having access to more resources.

So what is the cause of such counter-intuitive behavior? I’d hypothesize that the sudden exponential growth in the global population around 1900 has something to do with modern technologies – specifically solutions to the various problems of disease and security – allowing higher than usual populations to exist in many places. What we’re seeing now with the rise of urbanism is the end stages of the effective neutralization of the capacity of communicable diseases to ravage human populations in close proximity to each other. As a corollary, I’d hypothesize that the inflection point of the graph at the left – sometime in the late nineties it seems (earlier for industrialized countries) – corresponds to a certain critical global saturation of these nature-fighting technologies.

What happened in Rwanda, what happened with World War II (notice the ever-so-slight “dip” on the graph above), and what is happening in many other places where wars are fought over resources, is a new kind of war. Whereas war historically – during the r phase of global population growth – was a natural check on growth and a driving factor of r selection, war now is an anomaly, a failure on our part to fully understand the implications and unintended consequences of our own cleverness.

As for what is truly driving the sigmoid function – as opposed to an immediate adjustment and stabilization corresponding to a flat or linear growth rate –  I’d imagine it has to do with a “lag” in information, or a kind of “sticky perception” of one’s situation. Families many centuries ago gave birth to many children, and relatively few of them made it to adulthood to produce their own children. The pattern – through the natural cullings of disease, war, famine, and many other basic problems that we have solved in much of the world – tended towards self-replacement. Around the beginning of the Twentieth Century, we made great progress as a species and developed technologies to allow a significantly higher percentage of children to survive to adulthood. Despite there having been a paradigm shift, people continued reproducing at levels to allow self-replacement under the old paradigm. Eventually – typically after one generation – we acquired the ability to plan for self-replacement under the new paradigm, which is represented by the area of K growth at the upper right of the sigmoid (which, for the graph of global population, above assumes continued global diffusion of technology).

Inasmuch as we seem to analyze this phenomenon in the United States specifically in racial terms – probably because we are obsessed with race – it is more a function of the wealth that comes with being the established power culture that the white population has declined relative to the populations of various minority groups. Not only has the above pattern affected whites disproportionately on account of (1) whites historically having access to more wealth in this country; (2) the category of “white” being continually and historically redefined and rather arbitrary; (3) the huge wealth gap of the American economic mode; but there has also been a trend towards diversity in the immigrant pool – i.e. a higher proportion of “non-white” immigrants relative to overall numbers of immigrants – even as our immigration policy on the whole has become increasingly hostile, since the time Father Connell wrote those words in the Atlantic.

I suspect that, if chemical contraception is to be blamed for causing a decline in the white population, it is only because chemical contraception – among many other things – has come to gradually replace disease and poverty as an equilibrator, first for the white population, then for everyone else.