Jurassic park risks

Biting insects have been found trapped in amber in Canada and we can be pretty sure that they preyed on dinosaurs.

This is because the number of hairs on the insect's antennae indicates how big the animal it preys on is. This might sound unfeasible but there is a reason - the insect's antennae are used for detecting carbon dioxide (CO2) given off by animals.

Biting insects that parasitize small animals need a lot of hairs on their antennae because the levels of CO2 they are trying to detect are very low. However, some of the insects found in the amber had very few hairs meaning that they preyed on animals like dinosaurs, which, being bigger created a lot of CO2.

It is not likely that a five ton T-Rex or vicious Velociraptor will ever be cloned from DNA preserved in amber.

Even if a DNA sample from the stomach of a blood-sucking insect could be identified as the insect's last supper on the skin of a T-Rex, the odds against ever reconstructing a T-Rex are overwhelming.

Reassembling the complete DNA genome of a dinosaur from gene fragments trapped in amber would be like trying to reconstruct the complete Encyclopedia Britannica from a cupful of letters in alphabet soup.

However, it may be possible to clone ancient viruses and bacteria preserved in amber. Since they have fewer genes, reconstructing the DNA of a virus or single-celled bacterium is within the realm of today's modern biotechnology.

Bringing extinct micro organisms back to life after many millions of years could have some valuable medical implications, such as the origin of present- day disease organisms.

There could also be some frightening consequences equal to those of Jurassic Park, such as bringing back to life a serious pathogen - perhaps an AIDS type virus that killed off the dinosaurs. The latter scenario is reminiscent of another Michael Crichton book, The Andromeda Strain.

The next time you gaze at your favourite amber inclusion, think about the DNA of microbes that it might contain, quietly resting in a harmless abiotic state for the past 50 million years.