Self And The Phenomenon Of Life: A Biologist Examines Life From Molecules To Humanity

An Astronaut’s Dilemma 13

“9x6” b2726 Self and the Phenomenon of Life: A Biologist Examines Life from Molecules to Humanity

Notes and References

1. Barlowe WD, Summers I. (1979) Barlowe’s Guide to the Extraterrestrials.
   Workman Pub. New York.


2. Hoyle F. (1957) The Black Cloud. New American Lib. New York; Easton
   Press, Norwalk, CT, 1986.


3. Koshland DE Jr. (2002) The seven pillars of life. Science 295: 2215–2216.


4. Perret M. (1952) New Biology. 12 : 68; cited by Luisi PL (1998) About var-
   ious definitions of life. Origins of Life and Evolution of the Biosphere 28:
   613–622.


5. Earth life is based on long chains of carbon atoms forming covalent bonds.
   As an alternative to carbon, extraterrestrial life may choose to use silicon,
   which, like carbon, has four electrons in the valence shell and can form four
   covalent bonds. Chains of silicon atoms 26-member long are known to exist.
   Arsenic is one row below phosphorus in the periodic table and has bonding
   properties similar to phosphorus. Arsenic is a potential substitute for phos-
   phorus in life chemistry. Strange forms of life may depend on hydrogen
   bonds rather than covalent bonds as their backbone, if their habitat hap-
   pens to have a low temperature (chemical bond strengthens with decreased
   temperature). Extremophiles are microbes on Earth that thrive on extreme
   conditions — very high temperature, very high pressure, or very acidic or
   basic pH. Though unusual to us, they may be the norms of life rather than
   exceptions in other parts of the universe. Extraterrestrial beings may live in

Fig. 2.3. Weak expression of self: a robot starved of power. The limited goal-seeking
function of a robot does not spontaneously occur; it is a mere extension of that of the
programmer. [Permission Bloom County, Cartoonist Group, Berkeley Breathed.]