Animals living in harsh conditions respond with early and closely spaced births and so too humans, writes WILLIAM REVILLE
WE ARE ALL familiar with the social problems common in the poorest and most underprivileged sectors of society – higher crime rates, higher incidence of teenage pregnancies/ mothers, absent fathers, and more dangerous patterns of living.
There is no consensus as to the cause of these phenomena, but evolutionary biology suggests that it is a survival strategy that is automatically generated in populations that live in harsh and unpredictable environments. Research in this area is reviewed by Mairi Macleod in July's edition of New Scientist.
The appropriate biological evolutionary strategy for a mammal living in hard and unpredictable circumstances, susceptible to disease and with a high probability of early death, would be to grow up fast, have offspring early and closely spaced in order to leave viable progeny before becoming incapacitated or dying. This happens in many animal species, and humans seem to follow a similar pattern.
Mcleod cites studies across countries showing that the shorter the life expectancy of women the earlier they have their first child. And, in developed countries, women in the most deprived areas have babies earlier and in quicker succession, have smaller babies and breastfeed less (making an early next pregnancy more probable) than women in better-off areas. Women in very deprived areas also experience ill-health much earlier in life than women in better-off areas.
Everything is foreshortened for women in deprived areas, including time of having first babies – at around 20 years of age compared to 30 in the better-off areas.
Teenage pregnancy rates are similar in poor and in better-off communities, but teenage girls are more likely to have abortions in better-off areas, thereby facilitating career development and being able to invest more effort in the children they have later on.
The absence of fathers in many cases in poor areas when children are growing up also causes problems – Mcleod cites evidence to show that when the father is present daughters tend to start sexual relations with boys later, to score higher on IQ tests at age 11 and to display increased upward social mobility in adulthood.
Fathers are more likely to be absent in deprived areas because they have a higher tendency to engage in risky activities such as violent behaviour, crime and gambling. This reduces involvement of fathers with children and militates against remaining with the same woman for long periods.
The “fast living” strategy adopted by males results from a similar evolutionary strategy to that which underpins the early female child bearing.
If these behaviours are largely a biological response to a harsh environment, the only solution to the behaviours is amelioration of the environment. The widespread assumption that much progress could be made if only people in these poor areas could be persuaded to adopt middle-class habits is mistaken.
Therefore, interventions such as sex education, healthy eating and exercise programmes, and so on, can only have very limited effectiveness. The poor general atmosphere in such deprived areas – crime rates, poor housing, air pollution, traffic accidents, etc – triggers a downward spiral of fast living and a casual attitude to health.
Why invest lots of time developing a healthy body when you hear that the healthy boy down the street is in intensive care in hospital after being attacked on the street last night? And why take time choosing a healthy balanced diet, including expensive fruit and vegetables, to supply your daily calorie requirement when you can easily and cheaply get these calories from the local high calorie fast food takeaway?
I agree that the only solution to the problem behaviours that correlate with poverty is to eliminate poverty. When people feel economically secure and see real prospects ahead, they behave differently. But it is also important to damp down income inequality between groups, thereby encouraging social cohesion.
Countries with the highest levels of income inequality also have the lowest life expectancy, the highest level of teenage mothers and a wide range of social problems. And everyone does not have to become equally well-off for the positive effect to kick in. Reducing income inequality within a country has a very positive effect on the poorer sectors.
However, many vocal social commentators give the impression that they will never be satisfied until everybody has pretty much the same income. This can never happen and history shows that such utopian islands can only be approached, although never reached, across a sea of blood.
William Reville is UCC’s professor of biochemistry and public awareness of science officer – understandingscience.ucc.ie
I agree that the only solution to the problem behaviours that correlate with poverty is to eliminate poverty