Ian Wilmut: Filling up a world of limited capacity

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As the global population expands and competition for resources increases, steps need to be taken to offset the impacts – both at home and abroad

THE continuing rapid increase in the human population has been a cause of anxiety for many years because of its profound effect upon the world and our own well-being. Fifty years ago it was a major topic of public concern, informed by the writing of people like Paul Ehrlich in his book The Population Bomb and Don R. Arthur in Survival: Man and his Environment.

Today it takes a singular event such as the prediction that the global population will pass 7 billion this week for population growth to be a major news item. By contrast, at present, public concern is focused upon the effects of our profligate consumption of energy and other resources. In reality our fate will be determined by the multiple of these two factors and there are good reasons for us to be concerned about them both.

Global population is expected to reach ten billion by the end of this century and may be even more if the predicted reduction in family size does not occur. It is inevitable that there is a very considerable margin of error in these estimates. There is extensive experience to show that, as countries become more affluent, the number of births in each family falls to a level that merely maintains population. This effect can be seen clearly in Europe where it is believed that the population has peaked and may even decline in the future, depending partly on the extent of immigration into Europe.

Similarly, it is predicted that there will be only a relatively small increase in Asia during the rest of this century. Africa is expected to be the last continent to make this change, with the continent’s population predicted to treble by the end of the century. That is a huge increase that will have indirect effects in many other parts of the world, for example because the people will consume food that otherwise could be exported. There is considerable variation in the estimates of population growth in different regions of Africa, with the greatest increase being expected in eastern Africa.

Any such increase will pose a real challenge to those seeking to deliver the Millennium Development Goals. At their very minimum these goals include eradication of extreme poverty and hunger and a reduction in child mortality rates. At present large numbers of people do not have adequate food and water and lack basic health care. Life expectancy is particularly low in Africa, reflecting a very high incidence of infant mortality at present. It is proving very difficult to provide effective healthcare even with the present population so it seems likely this will be even more difficult to overcome as the population increases.

Thousands of children die of infectious diseases that could easily be prevented despite the contribution made by organisations such as the GAVI Alliance whose specific aim is to provide vaccination and immunisation. The situation is at its worst in regions such as the Horn of Africa where there is political instability and conflict on top of the apparent impact of climate change. The effect of schemes to promote effective agriculture could be negated by continued population growth.

As population increases elsewhere and countries become wealthier, there is expected to be increased competition for food on the international markets. In response to this change, plans are being developed already to achieve significant increases in food production here in the UK. The aim is to replace the food which at present we import from overseas. These plans include the introduction of new methods of agricultural production including genetic modification.

It is also likely that we will be encouraged to eat less meat because it requires more land to produce than for an equivalent volume of vegetables. This is particularly the case for animals that are fed an intensive diet of grain. Modification to land use will change the countryside and put increased pressure on biodiversity in this country.

Most people now accept that human activity is having an effect on global climate. This may be associated with the extraordinarily high rainfall and flooding such as that in Pakistan last year and Thailand at present. If the increase in temperature causes thawing of a significant proportion of the polar ice then we can expect sea level to rise over large areas of fertile, but low lying land. Naturally, in these circumstances, fear of poverty and starvation will prompt people to try to move to areas that are not at risk and this has other social and political consequences.

So what can be done to help limit population growth? Ready availability of simple effective contraception is clearly a major requirement and there are millions of women who do not have this opportunity despite international agreements over the past decade. Sadly this results in a large number of back street abortions, often with tragic consequences. Further research is being carried out in this country and elsewhere to improve contraception.

There is still no effective male contraceptive. The condom comes nearest to meeting the needs of ready availability, but suffers from its great inconvenience when it is being used. Trials are underway with male “pills” which can interfere with sperm development in a reversible manner, but further research is required.

In addition, new biological understanding of the hormonal control of female reproduction has led to the development of simpler hormonal regimens that are now being assessed. It is possible to develop a pill for women that would be taken once a month and act by preventing conception. In these circumstances the hormone is far less likely to have side effects than the conventional pill. In addition to the biological efficacy of these new treatments it is also essential that the method should be socially acceptable in the countries concerned.

Finally there should be promotion of the notion that population control is essential and beneficial even in countries like our own. After all this is a relatively crowded island and there are obvious effects of human activity upon the rural environment already.

The trends in population and increased agricultural production that are predicted to occur will only increase these pressures. An alternative opportunity for those who want more children is to adopt children, and there are many children who need a home. This also offers a means of having a child of the gender that you most wish for.

At some times in our history governments have encouraged people to have large families to restore the nation’s population and create adequate numbers of people in each generation. As a society we have always recognised by providing financial support that children have the right to a good and healthy start to life and it would be perverse to remove that support.

What is needed now is government promotion of the fact that having more than two children is imposing unacceptable demands upon the environment. Furthermore there should be social encouragement for those who choose not to have children or have only one child, although anything approaching the enforced single child policy of China would be inappropriate and unacceptable.

• Professor Sir Ian Wilmut is director of the Scottish Centre for Regenerative Medicine at the University of Edinburgh