The puzzle of small families

Lesley Newson

People living in modern Western societies have no problem understanding why we don't have as many children now as people did in the past. Raising children is a lot of work and requires a huge commitment. And it often gets in the way of us having what we have come to see as the good and important things in life.
But this is a problem for Darwinists to explain. According to Darwinian Theory, producing offspring is the purpose of life. Animals of other species living in the wild produce as many offspring as possible and so do people living in traditional societies. But members of modern societies and developing societies seem to have abandoned the pursuit of what Darwinists call "reproductive success". Why have other things become more important for us?

Humans are cooperative and communicative to an extent not even approached by other animals. Human groups generate a culture - a set of beliefs, values, rules, technology, punishments and rewards which its members participate in - some with enthusiasm and some with more reluctance. Having culture has enabled humans to be very successful. Because members of the same culture follow the same rules (formal or informal) and share a language, they can cooperate and coordinate their activities.


And yet, in the case of modern Western societies, our culture provides us with beliefs and values that prevent us from behaving in ways that would be most efficient from the biological perspective. Our lives are full of concern for career, travel, relationships and leisure pursuits.

We are more prosperous than we have ever been before - in all of human history and pre-history. We could afford to raise huge families. Yet birth rates are lower than ever before.

Humans are no longer efficiently investing their time and resources in the production of offspring. Instead we are increasing our own fun and comfort and indulging our taste for consumer goods. Why has our behaviour changed in this way?


An important part of the explanation is that humans are "cooperative breeders". In other great apes, a mother receives no help in caring for and feeding her young. This severely restricts how many children she can have because she cannot get pregnant again until her child is ready to be independent. Human babies are born even more helpless and mature even more slowly than the babies of the other great apes but human mothers often get pregnant again when their previous child is only a toddler. This is because she can rely on others to help her. In many cases, the child's father provides help but so to other family members and friends. I believe that understanding the cooperative nature of human reproduction will bring important insights into human behaviour. This is an exciting area of research that is just beginning to become established. Other people interested in cooperative breeding include Sarah Hrdy, Ruth Mace, Rebecca Sear and Carel van Schaik.


All human groups have cultural norms - rules of behaviour - and some of the most powerful and complicated norms are those that govern reproductive behaviour - everything from whom you can have sex with to how you raise your children. This is not surprising when you think that in the small close-knit groups that humans evolved in, the whole group was involved in the reproduction of each of its members. Everyone helped, if only in a small way, in looking out for youngsters. If reproduction is a group activity, members need to follow rules or they might abuse the good will of the group and find that no one wants to help look out for their children.


It may be that many of the cultural changes that follow economic development are linked to this - including our low fertility and consumerism. Economic development doesn't just make people richer; it changes the structure of their societies. No longer are people surrounded by their relatives and people they know.


We know from research in social psychology that groups of people develop and constantly adjust their group norms. It may be that the much larger groups and less closely knit communities of economically developed societies are bound to have norms that are different from those of the kinds of communities in which human behaviour evolved. This may explain why humans in modern societies don't behave as evolutionary theory predicts.


I am currently testing some hypotheses based on this basic idea and looking at how cultures are likely to evolve in the future.


The University of the Third Age (U3A) has helped me to carry out some of my research and they have published on the web a non-academic explanation of some of my recent research.