I've already mentioned the GE potatoes that can resist serious diseases. That's one example of how genetic engineering might be useful in the future (for people, that is). And here's another interesting idea: glowing fish. Scientists have added a selection of genes from humans, rats, trout and fireflies (insects that have tails that glow) to a fish called a zebra fish[1]. Why?

This special mix of genes means that the modified fish glows in the dark when the water it's living in is polluted. It turns out that, like other fish (or flesh-eating animals), zebra fish tend to 'collect' - to bioconcentrate - pollutants like PCBs and dioxins in their flesh. (This is why it can be very dangerous to eat fish from polluted lakes, rivers or sea.) If these modified fish are put in a cage in polluted water, the glow soon switches on. Long ago, coal miners used to take canaries down the mines they worked in. The poor birds would keel over and die before poisonous or explosive gases built up to danger levels for miners. They were the first 'pollution sentinels'. The zebra fish, like the canaries, are so sensitive that they show even tiny traces of poisons by glowing - traces which scientists would only be able pick up with the best equipment they have. Another advantage is that the fish are quite similar to mammals (including humans) in the way their bodies process food and poisons. So if you ever catch a glowing zebra fish, don't eat it or drink the water!

Of course, none of this would be necessary in the first place if humans hadn't made such a terrible mess.

1. New Scientist, 'The tough get glowing', 12/1/02, 36-37.