The AIDS epidemic in sub-Saharan Africa should be a warning to us all (Aids researchers fear Mbeki is putting lives at risk, 11 July 2000; Catholic Church is hindering Aids battle, says Short, 12 July 2000).

What we are witnessing is evolution in action, nature destroying those who do not learn to adapt their behaviour to changed circumstances. 

Unlike any other species, man is capable of cultural evolution, which gives him the ability to consciously adapt his behaviour to altered circumstances, and thus increase his chances of survival. 

The behavioural changes required to stop AIDS in its tracks are well known: for people to refrain from unprotected promiscuous sex - whereby the qualifying adjective "promiscuous" needs to be emphasised.

Contrary to those who claim that it is not, AIDS is very much a "moral" problem, in the sense that morals means no more than "accepted forms of behaviour".

In all societies incest is an unacceptable - and thus immoral - form of behaviour because it is detrimental to the survival of the species. For the same reason, unprotected promiscuous sex needs to become an unacceptable, immoral form of behaviour.

Those who accept this will be rewarded with a greatly increased chance of survival; those who do not will eventually die out. That is the way evolution works.

This reasoning does not only apply to AIDS. 

There is another virus that is even more of a threat to us: the non-sustainability of current economic philosophy and activity, as well as our excessively materialistic orientation and life styles.

AIDS is particularly pernicious because it attacks and destroys the very system that normally protects us from infection.

The virus - if I can call it that - of non-sustainability is also particularly pernicious, because it is ingrained and rooted in the long accepted, and thus perfectly moral, values and modes of behaviour that up until now have brought us such great success. Bill Gates, for example, is celebrated as the richest and thus most successful man in the world, although the values and aspirations that drive him and most economic development are non-sustainable and must necessarily lead to disaster on a finite planet with vulnerable life-supporting ecosystems and a limited carrying capacity.

Not only Africans must learn to live up to their scientific name of "Homo sapiens" by adapting their behaviour, if they are to survive. We all must. And not just in respect to AIDS.