Letter: Modified food

Sir: When I lecture to my students on plant biotechnology I try to capture their attention by asking the question, "Why do you suppose the coca bush produces cocaine?" The answer is that it is probably an insecticide. Plants, like any other living organism, have evolved defences against their predators. These are animals, mostly insects, but also including us. This is why out of the hundreds of thousands of species of plants on the planet we can safely eat very few. Even these are the outcome of thousands of years of breeding to partially eliminate the components that do us damage. On the other side we, the survivors, have acquired immunity to some of them. Those who did not are no longer with us.

We now have much more powerful methods of removing undesirable components from our food plants by gene manipulation, and to reject what is by far our best chance of dealing with this situation because it makes a few people feel uneasy is lunacy.

The possibilities are far-reaching. One that is particularly intriguing for the ruling classes is that it may now be possible to go back to pre- phylloxera vines. The European vine was virtually wiped out in the last century by phylloxera. It was only saved because an American root stock was found that was resistant to it, and grafting continues to this day. It is potentially possible to transfer the gene for resistance to phylloxera into the European vine and, we must hope, to do away with the need for grafting. I cannot wait to see what wine buffs make of this.

Professor MICHAEL P TOMBS

Pavenham, Bedfordshire