Alfred Russel Wallace, Extraterrestrial Life, Mars, and the Nature of the Universe

Alfred russel Wallace is now generally remembered as one of the great field naturalists of the nineteenth century; the co-discoverer, with Charles Darwin, of the theory of evolution by natural selection; a prolific author on a range of topics to do with natural history; and a vigorous participant in public debates on various scientific, social, and political subjects. The part that Wallace played and the positions he adopted in the often intense and hard-fought debates on extraterrestrial life in the decade of the 1900s, including on the matter of life on Mars, however, have drawn relatively little attention from scholars.¹ Wallace reckoned that the only life in the solar system was found on earth. Further, he dismissed the possibility of intelligent life of the same order as human beings anywhere else in the universe and in this paper I will focus on Wallace’s arguments against this possiblity. Wallace wrote in 1903,

I submit that the whole of the evidence I have here brought together leads to the conclusion that our earth is almost certainly the only inhabited planet in our solar system; and, further, that there is no inconceivability—no improbability even—in the conception that, in order to produce a world that should be precisely adapted in every detail for the orderly development of organic life culminating in man, such a vast and complex universe as that which we know exists around us, may have been absolutely required.

(Man’s Place 1st ed., 306)

Throughout Wallace’s lifetime, it was widely accepted by British astronomers and science popularizers that the universe was populated by extraterrestrial life.² In this paper, then, the main question we will address is, Why did Wallace reject the idea of extraterrestrial life so emphatically and come to regard human beings as, in his words, “the unique and supreme product of this vast universe,” and to believe that “‘the universe was actually brought into existence’ for this very purpose”? (Man’s Place 1st ed., 315).

Wallace was prompted to develop a fully worked-out answer to the question of extraterrestrial life by serious financial concerns and the prospect of securing substantial article and book royalties. But once he had started down this road, he was both energetic and relentless in applying a carefully reasoned mix of scientific and spiritual ideas to address it so that his mature synthesis, what Martin Fichman has termed his “teleological evolutionary cosmology” (Elusive Victorian 1), encompassed nothing less than the nature, structure, and development of the entire universe and the occurrence and evolution of life therein. Key here, we will see, is Wallace’s profound sense of teleology, which was shaped by his conception of human evolution and his deep commitment to spiritualism. I will argue too that Wallace’s acute sense of place—a topic also examined by Andrew Berry in this special issue—was at the heart of the development of his cosmology. In particular, Wallace emphasized the position of earth with respect to the sun, the position of the sun within what was known as the solar cluster of stars, and the position of the solar cluster within the wider stellar universe, which put the sun very close to or at the centre of the universe. If earth had been located elsewhere, intelligent life, in Wallace’s view, could not have developed.

We will see that Wallace’s views on human evolution were fundamental to his views on life beyond earth. A review of these views will therefore form the first section of the paper, before we turn to Wallace and astronomy, the extraterrestrial life debate, and Wallace’s own connected argument on extraterrestrial life.

Wallace on human evolution

Darwin and Wallace were united from the late 1850s onwards about the enormous importance of natural selection for explaining the diversity of nature, but there were nevertheless to be many later disagreements between the two on evolutionary matters. The biggest public split came in 1869. In that year, Wallace reviewed two new editions of geological works by Charles Lyell. In so doing, he broke...