Mars Exploration: Surface
& Orbital Reconnaissance

Introduction: Is There Life On Mars? continued

Anthropologist Irven DeVore speaking on Burke's documentary in 1976 made some sobering remarks on this issue of inevitability, and whilst these views are primarily concerned with the probability of finding intelligent life in the Cosmos his fundamental point applies to life generally. He states:

Course we must look, it's a fabulous opportunity, but there are many reasons why I think we just won't find life, and even if we should what are the chances that we will find life sufficiently intelligent that we can communicate with it. When we look back on our own history tracing ourselves through apes and primates back down to amphibians and so on, we tend to see it as a single lineage, as though the whole process were inevitable: there's nothing inevitable about it. We have to think of ourselves as the result of billions of special events, highly unlikely events, such as the development of grasping hands and stereoscopic vision, which evolved millions of years ago in another context, but which gave us our peculiar intelligence, tool using, language using ability, which allows us to build radio telescopes and to look for intelligent life.

In similar vein the biochemist Norman Horowitz in 1967 wrote, "an objective estimate, based on known chemistry and known biology, would lead to a probability for the origin of life of close to zero." For him the Viking results from Mars in 1976 confirmed this view.

Historically, then, optimism and pessimism have existed side by side reminding us of the complexity of the issues, which includes, especially for the non-scientist, the question of how one decides which position to support or accept, if any?

Whether or not we determine life to be capable of evolving on a world other than our own ultimately depends upon how we view the Cosmos: How did it form and what is it made of it? Under what conditions do planetary systems form? The way we have answered these questions at different times in history has led to both favourable and unfavourable evaluations for the probability of life beyond the Earth.

Between the end of the 19th century and the late 1950’s the world of astronomy had seen some major changes in the perceived structure of the Universe, in its size, and in the place of our own Galaxy within it. At the turn of the nineteenth century the prevailing view of the structure of the Cosmos was of a single, vast, aggregate of stars, planets, and nebulae, what Alfred Russel Wallace in his book Man's Place in the Universe (1912 4th edition) called, "...one complete and closely related system..." (p.82). This was a view the truth of which Wallace claimed, "...is now hardly questioned by any competent authority." The historian Agnes M. Clerke used much the same words in 1890 in her book The System of the Stars. In her view, the question of whether nebulae were external galaxies "...hardly any longer needs discussion...No competent thinker, with the whole of the available evidence before him, can now...maintain any single nebular to be a star system of co-ordinate rank with the Milky Way. A practical certainty has been attained that the entire contents,