At London University's Queen Mary and Westfield College Professor William Keatinge and his team have found that

At London University's Queen Mary and Westfield College, Professor William Keatinge and his team have found that blood thickens in hot weather because water is lost by sweating. The majority of heat-related deaths are caused instead by a lethal assault on the blood's chemistry. Whenever there are extremes of temperature, tens of thousands of people - particularly the elderly - die as a result. Scientists are only now beginning to discover that the body reacts in surprising ways to both heatwaves and extreme cold.

Their findings overturn a few cherished myths about the conditions that kill us and our defences against them. We usually imagine, for example, that old people die of heat stroke (in which the body simply overheats). In fact, heat stroke in this country is extremely rare, and is mostly suffered by young people doing heavy exercise in too much clothing, such as during army manoeuvres. Yet despite the May chill, there is every chance that this summer will be one of the hottest and driest on record. An absence of westerly winds, the meteorological trademark of our islands, has created eccentric conditions and a weather forecaster's nightmare. Two weeks ago, icy winds were still blasting British shores; trees and shrubs blossomed late; there was unseasonal ground frost and a marked absence of rain.

And how wrong they would have been.! Lewis Wolpert of University College, London, is chairman of Copus (the Committee on the Public Understanding of Science). His book 'Triumph of the Embryo' is published by Oxford University Press at pounds 7.50.. The idiosyncracies of the British climate are well enough known and constantly discussed - perhaps more than ever in recent weeks, when the spring weather hasn't behaved at all as it should. Mutations in such genes can provide misinformation; a recently- discovered gene in the fly is capable of initiating eye development even on legs. This same gene probably underlies the development of all known eyes, including ours.Modern animals have evolved many genes that buffer them from change Precision and reliability of development are paramount. I think I can make an argument that no interesting new animal forms could ever evolve Evolution of form is largely over But the dinosaurs might have come to the same conclusion.

There are lots of them - more than 10,000 control our own development.The genes in the embryo do not provide a blueprint for the organism that wall develop There are no genes that provide a plan for the arm or eye. Rather the genes provide a programme for how to make an arm or eye. Origami is just like development, for the instructions on how to fold the initially featureless piece of paper are just what genes do. The final result of the folding bears no simple relation to the instructions. We are often surprised when after the final fold and tug we find we have constructed a bird or a boat. Evolution of animals can thus be seen as the modification of the embryo's developmental programme.