Reply #5: One argument for the extraterrestrial origin of life is chirality. [View All]

All living systems are chiral, meaning that of two possible three dimensional mirror images, only one is found.

It happens that the spontaneous formation of chiral compounds is virtually unknown in the laboratory: Although one can synthesize chiral compounds quite readily, one always needs a chiral starting material or chiral catalyst to do it. In other words, all chirality requires chirality to form. Thus people quite naturally wonder what the first chirally pure example of a compound was and from whence it sprang and how it induced chirality so perfectly in living systems.

This "Chicken and Egg" conundrum represents one of the great unanswered scientific questions and is rather comparable to the question that remained unanswered until the middle of the twentieth century of what the source of energy in stars and our sun was exactly.

Almost all spontaneous processes in the universe are achiral, both mirror images occur. There is two glaring exceptions, radioactive beta decay and plane polarized synchotron radiation from events like supernovae. Beta decay and synchotron radiation from supernovae are asymmetric, one possible mirror image form of these types of radiation is found, and the other is not.

This is a very important clue.

Although the earth is very radioactive, and was very much more so around the time of the origin of life on earth, the effect of achiral induction in molecular structures from beta decay is very small and it not believed that the intensity of radiation on earth was ever high enough to account for the terrestrial induction of chirality by this means.

This suggests that the origins of chirality was extraterrestrial, a likely place for it to have occurred would be the radiation bath surrounding a supernova. It is known that the earth originated from supernovae ejecta since this accounts for the existence of vast amounts of uranium and thorium and many other heavy elements like gold, mercury and iridium. It is likely therefore, that, if supernova account for the origin of chirality, the local environment represents one place where it could of occurred. However, there is no special reason that this chirality would have been limited to the earth. It is completely possible that it was widely distributed not only in the local region, but also in many other regions where supernovae occurred.

With this in mind, coupled with the discovery in the last several decades of extremeophiles, organisms that survive high temperatures, highly acidic environments and even in the cores of nuclear reactors,
there is absolutely no reason to suppose that life needed to form on the surface of a planet and then be ejected into space. Further, an area of active chemical research concerns the self assembly of molecules and molecular recognition. Many experiments suggest the possibility that the very nature of carbon leads to highly organized and semi-self replicating molecular systems.

If I were a betting man, I would guess, though I certainly cannot prove, that something very much like panspermia exists, that the conditions for the formation of life are more broadly found than used to be believed.

This of course is a good thing, because I strongly expect that we are close to wiping this planet out, if only by profound stupidity. It would be nice to think that life somewhere else will do a better job of surviving than we are likely to do.