The Case for Humanoids Is it likely that there are intelligent beings on other planets? Would they resemble us, or would they be totally different in appearance and behaviour?
Many scientists today believe that life will eventually evolve where it is physically possible for it to do so, and given sufficient time and favourable conditions, intelligent being will eventually emerge. New discoveries in biology are taking place almost daily but the question of the origin of life is still controversial. Some experts believe that the origin of life of Earth was a singular event, the result of an extremely unlikely chain of chemical reactions, an event so improbable as to be unlikely to be repeated anywher else in the universe at any time. According to Jacques Monod:
"...the biosphere does not contain a predictable class of objects or events but is a particular event, certainly
compatible indeed with first principles, but not *deducable*
from those principles, and therefore unpredictable." (1)
However, many scientists would argue that it would be possible to predict the occurence of life, if only we knew enough about biology. Those who believe that life is quite common in the universe often say that it is unlikely to be much like life on Earth:
"Some scientists have been especially impressed by the number of individually unlikely events which are together responsible for the development of man and human intelligence. They have emphasised that even if the Earth were starting out again from scratch, and only random factors allowed to operate, the development of anything like a human being would be highly
unlikely." (2)
Such opinions seem very plausible, but they fail to take into account the various constraints imposed by the laws of nature. For example: "...silicon compounds might replace carbon
molecules as structural biochemicals". (3) The notion that there
could be forms of life based on silicon rather than carbon crops
up again and again in the literature. It should not be taken
seriously, as such an idea betrays an ignorance of elementary
chemistry. Some writers assume that because silicon is the
nearest neighbour to carbon in the periodic table and also has a
valency of four, then it can form bolds with hydrogen, oxygen,
etc., to produce compounds analogous to compounds based on
carbon and having similar properties. this is not true. The bond
energies involved in the links between silicon and other
elements, and carbon and other elements, have different values.
the Si-Si bondis weaker than the C-C bond, but the Si-O bond is
stronger that the C-O bond. To see what this means in practice
we can compare the gas that bubbles out of fizzy drinks, carbon
dioxide, with a lump of quartz, silicon dioxide. I maintain that
anyone who takes the trouble to consult the appropriate
chemistry text-books will be readily convinced that a
biochemistry based on silicon is impossible.
So here we have a basic constraint on the nature of any living creature, imposed by the laws of chemistry. Observational evidence indicates that these laws are the same throughout the observable universe, so there would seem to be no way of avoiding this conclusion.
Assuming that intelligent beings have evolved on other planets, what would they look like? It is tempting to speculate that they would look like 'nothing on Earth', but we must not let our imaginations run wild. The laws of nature impose many constraints on the size and shape of living organisms, and even on the social behavior of intelligent creatures.
If we wish to design a hypothetical intelligent being, where do we start? Well, it would need a brain, and a very elaborate one at that. Thus it will need to be big enough to support a large brain, and this delicate organ will need some sort of protection. How about a skill? The brain will also need sensory inputs to tell it what is happening in the outside world. it will need eyes, of only to avoid such disasters as falling off
cliffs or walking under buses. Yes, but would those eyes
necessarily see the same wavelengths as our eyes? Undoubtedly
so, because planetary atmospheres are most transparent to those
wavelengths which we detect as visible light. What about
'seeing' with radio waves? Well, with radio waves:
"In order to have any useful resolution - that is, detection of fine visual detail - the effective collecting area must be enormous. To have the same resolving power at 5cm wavelengths that they eye has at 5000A. wavelength, an extraterrestrial microwave 'eyeball' would have to be roughly half a mile in diameter." (4)
We could go on to fill a full-length book with similar arguments, but the whole question is neatly summed up in the words of Professor M R House:
"Typical gross form associated with ecological habit for a given animal size and mode of life, suggests that there is a 'paradigm' or theoretically appropriate form for given circumstances, and that selection pressures tend to work towards this by eliminating those organisms least approximating to it". (5)
House points to various examples of evolutionary convergence such as gross similarities between swimming reptiles, mammals and fish, and the fact that "sabre-tooth tigers of the Tertiary, of South Africa were marsupial mammals, whilst the present-day tigers are placental mammals".
In other words, where there is an ecological niche it will eventually be filled, by the processes of evolution, with the appropriate animal or plant. Because of the natural constraints imposed by the laws of physics and chemistry, ecological niches on other planets must bear some resemblance to those with which we are familiar on Earth . . .
Harney continues with speculation that extraterrestrial intelligences would also tend to similarities in aspects of social organization and behaviour, concluding that "they would undoubtedly have to face and and find answers to similar problems to ours - technical, economic, political and
philosophical".
1. Jacques Monod, 'Chance and Necessity', translated by Austryn Wainhouse, Collins, London 1972
2. I.S.Shklovskii and Carl Sagan, 'Intelligent Life in the Universe', Dell, NY, 1968
3. Ibid.
4. Ibid.
5. M.R.House, 'Evolution and the Fossil Record', in
'Understanding the Earth', Artemis Press/OU Press, 2nd. ed.,
1974.
It seems to me that much of Swords' speculation can be accepted almost as a given by both ETH advocates and PSH proponents. It has little to do with the reality of whether any potential ET craft has ever visited this planet. For that we are inevitably brought back to the investigation of individual cases, which really is where we came in, with the ten or fifty, (or even one) best cases.
Magonia online
by John Harney
Published in MUFOB
New Series No.6, Spring 1977.
http://www.magonia.demon.co.uk