CONCLUSION

Current thought suggest that the “last universal common ancestor” (the hypothetical latest living organism from which all organisms now living on Earth descend, or, in other words, the most recent common ancestor of all current life on Earth) is estimated to have lived some 3.5 to 3.8 billion years ago. However, the actual mechanism for its origination is still far from clear.

While the circumstances that led to life on Earth are no doubt special, there is no reason to suspect that they are peculiar to Earth. As Richard Dawkins points out, if the universe contains a billion billion planets (which some scientists consider a conservative estimate), then the chances that life will arise on one of them is not really so remarkable. If, as some physicists claim, our universe is just one of many in a multiverse, each of which contains a billion billion planets, then the chances that life will arise on at least one of them is almost a certainty.

We are beginning to find evidence that our solar system may not be untypical of other planetary systems throughout the universe, opening up the possibility of other other life “out there”. As recently as 1992, astronomers identified the first planetary system outside our own, but since then one discovery has followed another in an accelerating trend: in 1995, a Jupiter-like planet was found orbiting a sun-like star; the first terrestrial planet outside our own solar system was discovered in 2005, followed by several others; in 2007, the first Earth-sized “Goldilocks” planet was discovered; etc.

Indeed, many scientists believe that it is entirely possible that different forms of life may have appeared quasi-simultaneously in the early history of Earth. Some of these may now be extinct, or they may survive as extremophiles (an organism that thrives in extreme conditions that are detrimental to the majority of life on Earth), or they may simply have gone unnoticed. It is only in quite recent years that living things have been discovered in conditions as unlikely as hot volcanic vents deep beneath the sea and in totally dark and dry lava tubes in the desert.

This remains an area of intense debate and speculation in both scientific and religious circles and, while new discoveries are made almost every year (which may, or may not, throw some light on the subject), no definitive solutions have yet been yielded.