It’s a question that society has often been asking over the ages: we just really want to know how did we get here? Why do we exist? Are we the only people in the universe? Are we the only signs of life? Professor William Boynton, University of Arizona
In the 1950s American chemist Stanley Miller did a classic experiment. Into a cocktail of these gasses he tried to simulate conditions on the early Earth. Adding electricity to mimic the power of lightning. And what emerged to everyone’s surprise was a flask of slime which turned out to be amino acids. Amino acids are essential to life. Dr Maggie Aderin-Pocock, Do We Really Need the Moon? BBC 2011
We know that there are micro-organisms on Earth that have evolved to have the ability to withstand intense levels of radiation. There are bacteria that grow on the cooling rods of nuclear reactors. Professor Richard Hoover, NASA
Mono Lake is one of the most spectacular and wonderful places on Earth as far as astrobiologists are concerned. It has no fish; it’s about three times the salinity of seawater, and it has a high very PH-like strong soap. And under these conditions only a few forms of life are able to exist. Richard Hoover
We call them extremophiles because they live in what we consider to be extreme conditions. Richard B Hoover
The main reason that astrobiologists are interested in extremophiles is because most of the other bodies of the solar system are either very cold or very dry or very barren atmosphere. Richard B Hoover
The problem then was not only how and why do species change, but how and why do they change into new and well-defined species, distinguished from each other in so many ways; why and how they become so exactly adapted to distinct modes of life; and why do all the intermediate grades die out (as geology shows they have died out) and leave only clearly defined and well-marked species, genera, and higher groups of animals? Alfred Russel Wallace, autobiography
It then occurred to me that these causes or their equivalents are continually acting in the case of animals also; and as animals usually breed much more quickly than does mankind, the destruction every year from these causes must be enormous in order to keep down the numbers of each species, since evidently they do not increase regularly from year to year, as otherwise the world would long ago have been crowded with those that breed most quickly. Vaguely thinking over the enormous and constant destruction which this implied, it occurred to me to ask the question, Why do some die and some live? And the answer was clearly, on the whole the best fitted live ... and considering the amount of individual variation that my experience as a collector had shown me to exist, then it followed that all the changes necessary for the adaptation of the species to the changing conditions would be brought about ... In this way every part of an animal’s organization could be modified exactly as required, and in the very process of this modification the unmodified would die out, and thus the definite characters and the clear isolation of each new species would be explained. ibid.
The manifestations of life, its expressions, its forms, are so diverse that they must contain a large element of the accidental. And yet the nature of life is so uniform that it must be constrained by many necessities. Jacob Bronowski, The Ascent of Man 9/13: Evolution: The Ladder of Creation, BBC 1973
Darwin’s theory of evolution by natural selection is the only workable explanation that has ever been proposed for the remarkable fact of our own existence, indeed the existence of all life wherever it may turn up in the universe. John Maynard Smith, The Theory of Evolution, 1958
We have become, by the power of a glorious evolutionary accident called intelligence, the stewards of life’s continuity on earth. We did not ask for this role, but we cannot abjure it. We may not be suited to it, but here we are. Stephen Jay Gould, The Flamingo’s Smile
Why is this important? It’s probably the most important question there is. What does it mean to be a human being? What is our future? Are there other creatures like us? What have they become? What can evolution produce? How far can it go? Dr Frank Drake, founder SETI, interview Dallas Campbell, The Search for Life: The Drake Equation, BBC 2010
So how do we find the aliens? ... One thing to do is to look for radio waves that might be coming to us from other worlds. So you build big things like this. I think that there’s a good chance that we will find that this planet is not the only one even in this solar system to have spawned some biology. My guess is we will find a signal coming from another world. Dr Seth Shostak, SETI: The Search for Extra-Terrestrial Intelligence
So far the aliens have been coy. Dr Seth Shostak
The Mission of the SETI Institute is to explore, understand and explain the origin, nature and prevalence of life in the universe. SETI welcome sign