© 1975-1979, 2008 Robert A. Freitas Jr. All Rights Reserved.

Robert A. Freitas Jr., Xenology: An Introduction to the Scientific Study of Extraterrestrial Life, Intelligence, and Civilization, First Edition, Xenology Research Institute, Sacramento, CA, 1979; http://www.xenology.info/Xeno.htm

8.3  Exotic Lifeforms

What is the bottom line in xenobiochemistry?

It must be admitted that the mere ability of atoms to assemble themselves into polymers, while significant, is yet a far cry from the complex biochemistry needed to sustain a living system. There remains a vast gulf between the simple silicone and polyphosphazine polymers and the orchestrated symphony of life.

While chemists have been vaguely aware of the possibility of exotic life schemes for more than a century, no coherent, well-integrated alternative system has been proposed and none is on the horizon. Without actual specimens of alien organisms to examine, the task suddenly takes on staggering dimensions. Imagine trying to speculatively reconstruct our entire terrestrial biochemical basis, having no prior knowledge of its nature or even of its existence!

The evidence admittedly is against the existence of silicon-based life-forms: The evolutionary mechanisms and planetary conditions appear much too unwieldy. Ammonia life seems far more feasible, if for no other reason than it is so closely analogous to terran biochemistry.

It would also appear that carbon is the backbone element of choice in Earthlike environments, although this should impose no real restriction on diversity. One must agree with Shklovskii and Sagan when they assert: "It is quite premature to conclude that ours is the only, or even the best of all possible, biochemistries."²⁰

In spite of the difficulties, there probably exist many different kinds of life in our Galaxy, including some very exotic forms based on different physical interactions than ours. But we cannot be certain of this until we travel into space and seek them out.

Last updated on 30 December 2008