contingencies are random factors in mutation, such that the process of evolution involves a whole series of non-repeatable accidents. According to Simpson:
The assumption that once life gets started anywhere, humanoids will eventually and inevitably appear is plainly false. The chance of dupli-cating man on any other planet is the same as the chance that the planet and its organisms have a historical identity in all essentials with that of the Earth through some billions of years. Let us grant the un-substantiated claim of millions or billions of possible planetary abodes of life; the chances of such historical duplication are vanishingly small.
(ibid.)
Gonzalo Munévar (1989) has raised questions concerning the assumption in SETI research that extraterrestrial intelligence must be linked to an advanced technology similar to ours. He argues that, while one cannot reject the possibility that an advanced technology could evolve elsewhere, there is nothing necessary about the assumed connection between intelligence and technology. With a different natural history, an intelligence might have evolved without present technology, which relies heavily on human characteristics such as the kind of dexterity afforded by the development of matching thumbs and forefingers among other features. Furthermore, he argues, a technological culture is not an inevitable feature of human evolution. If other cultures had achieved ascen-dancy, then science and technology would not have emerged as a reference point for measuring intelligence. SETI’s requirement for an almost identical technology, although scientifically understandable, is based on an impoverished concept of intelligence.
According to Munévar, the development of a scientific culture, with access to radio communication, is highly contingent, requiring a number of lucky breaks from the environment and human natural and social history. In this context Munévar cites the development of mammalian intelligence. It is widely believed that the dinosaurs were wiped out by the immediate effects of an asteroid or cometary impact or possibly volcanic eruption. But mammals who survived the years of darkness caused by the dust of the impact or eruption then evolved to occupy the niche held by the dinosaurs. If the dinosaurs had survived it seems unlikely that they would have gone on to develop a technological intelligence as they lacked the dexterity necessary for an elementary tool-making phase. But if the dinosaurs had not become extinct as the result of a major catastrophe, then mammals would probably have remained small vermin. In order to develop the size of their brains to facilitate eventual human intelligence they would require larger bodies. But long before their brains could develop enough to outwit the dinosaurs their large bodies would make them an easy prey. The emergence of the ascendant intelligence of humans was contingent upon the extinction of their predators.
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Human ascendancy, Munévar argues, allows us to apply a brake on the development of high intelligence among other creatures. If racoons become increasingly intelligent they will be seen as pests and hunted to extermination (ibid.: 3). Our way of life prevents the emergence of high intelligence in animals that compete with us. Once the first species passed the threshold of tool- and weapon-making it pre-empted the possibility of other species evolving in ways that would compete with its supremacy. There are, of course, limits to our ability to control the development of our competitors. Despite our advanced technology we have not found a way of exterminating rats and mice and combating many forms of viruses and bacteria.
Scientific progress, argues Munévar, requires having the right physical environment. Our scientific breakthrough occurred when Newton unified terrestrial and celestial physics, bringing together astronomy and physics, making it possible for us to expect similarities throughout the universe. ‘But in a planet very similar to ours but perennially covered by clouds,’ argues Munévar, ‘a comparable development of astronomy would be unlikely’ (ibid.: 4). Electricity is essential to radio communication and a technological intelligence. In one form or another it has always been part of human experience, in lightning or electrostatic phenomena, inspiring people to consider ways of harnessing its energy. But on a planet with an extremely salty atmosphere it would not be observable.
The emergence of a scientific culture, Munévar points out, also requires a supportive social history. In our case science only just made it through the vacuum presented by the collapse of religion as a secular force. Galileo and his followers might not have pulled it off. A strong fundamentalist revival might well put an end to science. If the politicians phase out the arms race, there is a very strong likelihood that within twenty years progress in physics will have ground to a halt; and if they dramatically increase the production of weapons capable of global destruction, there is an equal likelihood that science will be terminated along with the rest of humanity.
Even if we grant the inevitable development of a technological civilization with access to Maxwell’s electro-magnetic laws and the ability to manufacture radio transmitters, it is by no means certain that they will mean the same on other worlds as they do here. Munévar cautions ‘against confusing an overlap in performance with an overlap in content’ (ibid.: 6). Two radically different views may be concealed by the apparent ability to do the same thing. Despite a flat contradiction between ancient and modern astronomy regarding the position of the Earth, for practical purposes a sailor or navigator looking at the stars might well prefer either view. Both ancient and modern views allow an overlap in performance despite fundamental incompatibility of content. Likewise, if we receive radio transmissions from another species we should not conclude that these beings have the same understanding of Maxwell’s laws that we do. There is, Munévar concludes, ‘No inevitable, no highly provable connection between
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