SPECIAL ARTICLE THE ORIGIN OF LIFE ON EARTH AND ELSEWHERE * t

T H E particular sequence of thoughts indicated by the title has its origin in my interest in the process of photosynthesis. It began when I asked myself the question: Which came first, the plants or the animals? This question had been answered in a variety of ways, but one can't help but wonder, as one learns more and more about the detailed mechanism by which living organisms store energy and use it, how they got started in the first place. Actually, these thoughts began long before we heard of Sputnik and all of its successors. However, the fact is that it is now becoming possible for us to know, perhaps within five years, whether there are organic chemicals on the Moon and what the genetic nature of the living material on Mars might be. (I am assuming, now, that there is some.) Within the lifetime of most of us we will know these things. It therefore becomes a much more pressing matter for us to surmise how life got here (on Earth) so as to have some clue as to what to look for in outer space. This is another source of the driving force for inquiry in this direction, and a ver