It is interesting to look at why species become extinct. There are two basic reasons, firstly a key component necessary to their survival is removed, such as warmth, as in the asteroid created global winter that probably lead to the extinction of the dinosaurs. The other reason is the introduction of a predator to the environment and man is probably the most pervasive predator of all. The introduction of man to New Zealand saw the extinction of the giant moa. In Australia a range of megafauna went extinct with the arrival of the first Australian Aboriginals.

Of course a new predator does not usually drive a species to extinction, the typical outcome is that initially population numbers plunge as the species adapts to the presence of the predator. Over time the population recovers as it evolves strategies for coping with the predator's presence, although often they do not recover to what they originally were because of the changed dynamics of the environment.

It is easy to overlook the fact that these fundamental laws of nature apply equally to humans as to any other species. For humans, however, predators are not now large carnivores, we have long since developed ways to manage our interaction with these animals. The predators that we have never fully conquered are microscopic, bacteria and viruses. A great predator facing the human species at the moment is AIDS, although interestingly malaria rivals AIDS in deaths and infections, causing more than 300 million acute illnesses and at least one million deaths annually.

Next week, over 15,000 delegates will converge on Bangkok for the XV International AIDS conference. Taking a dispassionate view of this pandemic it is interesting to speculate why there is no similar body for malaria. The answer is probably that we understand and have a cure for malaria. In other words we can control it in areas where people are wealthy enough to do so. AIDS is the bogey man because we do not know how to control it. Even the wealthy are susceptible to this virus and no amount of money can cure it at this stage. When the wealthy feel their mortality, that is when there is some real action.

We can overlook the poor starving to death or dying of a curable disease. On the other hand their death by a disease that could also strike us is completely unacceptable because it reminds us that we are a vulnerable and mortal animal that is at the mercy of nature, the same as all the rest.

If you are interested in following the AIDs conference visit Nature who is covering it.
If you would like to find out more about malaria and its impact on the human population then visit The World Health Organisation.