Slow Road To Extinction

Over at Mangan’s, our friend Dennis links to a post by Bruce Charlton about the cratering birthrates of the developed, Westernized world. That there is something maladaptive about secular modernity has been apparent for some time, and I’ve written about this myself; most of the discussion to date, however, has focused on social and cultural influences, with particular emphasis on religion.

Unsurprisingly, the penetrating intellect of Alexis de Tocqueville descried this hazard of secularism two centuries ago. In Democracy in America, Tocqueville wrote:

Religions give men a general habit of conducting themselves with a view to futurity: in this respect they are not less useful to happiness in this life than to felicity hereafter; and this is one of their chief political characteristics.

But in proportion as the light of faith grows dim, the range of man’s sight is circumscribed, as if the end and aim of human actions appeared every day to be more within his reach. When men have once allowed themselves to think no more of what is to befall them after life, they readily lapse into that complete and brutal indifference to futurity, which is but too conformable to some propensities of mankind. As soon as they have lost the habit of placing their chief hopes upon remote events, they naturally seek to gratify without delay their smallest desires; and no sooner do they despair of living forever, than they are disposed to act as if they were to exist but for a single day. In sceptical ages it is always therefore to be feared that men may perpetually give way to their daily casual desires; and that, wholly renouncing whatever cannot be acquired without protracted effort, they may establish nothing great, permanent, and calm.

If the social condition of a people, under these circumstances, becomes democratic, the danger which I here point out is thereby increased. When everyone is constantly striving to change his position – when an immense field for competition is thrown open to all – when wealth is amassed or dissipated in the shortest possible space of time amidst the turmoil of democracy, visions of sudden and easy fortunes – of great possessions easily won and lost – of chance, under all its forms – haunt the mind. The instability of society itself fosters the natural instability of man’s desires. In the midst of these perpetual fluctuations of his lot, the present grows upon his mind, until it conceals futurity from his sight, and his looks go no further than the morrow.

What Bruce Charlton is suggesting, though, is not a social, cultural, or psychological mechanism, but a biological one. He wonders if there may be some environmental cue, or combination of cues, that is causing humans to adopt a “slow-life-history-speed” breeding strategy.

From Dr. Charlton’s post:

Life history speed refers to the reproductive strategy on a scale from FASTER – with rapid maturation, focus on mating effort, and a priority of achieving earlier and more frequent reproduction with less individual care (resources) per child; to SLOWER – with delayed sexual maturation, a long-termist socio-economic plan taking priority over reproduction, fewer offspring, and each child provided with more parental resources.
The decision between faster or slower life history strategy is probably ‘set’ in childhood in response to environmental stimuli which (under ancestral conditions) have signaled what was likely to be the most adaptive reproductive strategy (that which is most likely to lead to the greatest number of viable offspring).

Signals of instability (perhaps experiences of starvation or disease, absent father, chaotic environment) lead to a perceived risk of earlier death; and therefore more rapid sexual maturation and early mating efforts implicitly aimed at parenting a larger number of offspring – on the expectation that not children all will survive to adulthood.
In contrast, signals of a stable environment trigger a slower life history, because under stable conditions a slow maturing individual with higher parental care can build the ability to exploit specialized niches in a situation of high competition.
(For example, delaying reproductive effort and instead embarking on a long apprenticeship to become a high status and economically secure specialist craftsman; or delaying sexual maturation to ‘build’ a more beautiful and long-lastingly attractive face and body.)
It is possible that extreme prosperity/ comfort/ lack of hunger/ lack of disease stress/ unprecedented security and stability (or some other aspect of modernity) is acting as a supernormal stimulus to the ‘mechanism’ of life history calibration in early childhood.
So that an environmental signal (of a type unprecedented in human evolutionary history) may be triggering such a slow life history that (in the real world) it is incapable of replacing the current population – and is therefore maladaptive.

Humans, and large mammals generally, are what evolutionary theorists call “K-strategists” — they breed as though the selective environment is in a stable equilibrium, in which conditions are unlikely to change, and offspring are more likely to survive. This favors having few offspring, and investing heavily in each one. A relevant factor in K strategies, however, is age-related mortality, which affects how much time prospective parents will have to bear children and raise them to self-sufficient maturity. When average age at death is lower (which correlates with, and presumably is indicated to the organism by, various types of environmental stress), this time-span is compressed, so females should space their offspring more closely together (and vice versa).

Our unprecedented control of our habitat means that we’ve now got all sorts of “supernormal stimuli” yanking the behavioral levers that selection installed in us to optimize our survival in long-gone environments. (Examples abound: sweet/fatty foods, artificial lighting, mass communication, pornography, motion pictures, video games, high-speed travel, etc.) Dr. Charlton’s idea — that collapsing birth rates in modern societies may be a biological response to some as-yet-unidentified supernormal stimulus that tricks our bodies into thinking they have forever to reproduce — is very interesting. As Dennis said in the comment thread to Dr. Charlton’s post, I wish I’d thought of it myself.

Read the original post here, and Dennis’s remarks about it, over at his own place, here.

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One Comment

  1. Kevin Kim says

    “Signals of instability (perhaps experiences of starvation or disease, absent father, chaotic environment) lead to a perceived risk of earlier death; and therefore more rapid sexual maturation and early mating efforts implicitly aimed at parenting a larger number of offspring – on the expectation that not children all will survive to adulthood.”

    Fascinating insight. This might explain explosive reproduction in poor, violent neighborhoods, or reproduction among members of a religion that sees itself as beleaguered and on an urgent mission.

    Posted February 22, 2013 at 12:08 am | Permalink