Such conditions would have been catastrophic for any living things on the land surfaces or in the water. Sleep estimated that the Earth would have taken 2,000 years to restabilise after each collision. One solution may be provided by a number of unusual microorganisms discovered in places previously thought to be not conducive to life. Known as hyperthermophiles, these microbes survive by metabolising the chemicals produced from the volcanic activity. The international Ocean Drilling Program has discovered another group of organisms deep underground in drill cores from rock samples a kilometre beneath the seabed.
Life seems to be particularly prolific under the seabed as opposed to under land.
Parkes has discovered that population density actually rises from one billion per cubic centimeter just below the surface, to 10 million per cubic centimeter in deeper rock strata. Tommy Gold from Cornell University has found evidence of biological activity seven kilometres down. A myriad of different organisms, now classified into a new Kingdom known as the archaea, have been discovered surviving under surprising conditions, from extreme cold to very high salt concentrations and even exposure to highly corrosive chemicals such as sulphuric acid. Comparative DNA studies indicate that the archaea are the most primitive living things and most likely gave rise to the other Kingdoms such as the bacteria and the eucarya, which include plants and animals. Davies postulates that life evolved deep underground, protected from the constant bombardment by meteorites.