The polymathic Alfred Russel Wallace (1823–1913) is best known for his role in formulating the theory of evolution through natural selection. He had to leave school aged 14 and never attended university, did extensive fieldwork, first in the Amazon River basin (1848–1852) and then in Southeast Asia (1854–1862). Based on this experience, and after reading the corresponding scientific literature, Wallace postulated that species were not created, but are modified descendants of preexisting varieties. Evolution is brought about by a struggle for existence via natural selection, which results in the adaptation of those individuals in variable populations who survive and reproduce. Wallace is not only acknowledged as the “second discoverer of natural selection in the wild”, but also as (co)-founder of biogeography, systematic biodiversity research and astrobiology. Moreover, Wallace was the evolutionary anthropologist who envisioned the Anthropocene, i.e., the “age of Man”.

In numerous of his later publications, Wallace mixed up his spiritualistic philosophy with scientific data and considered the evolutionary development of the intelligence of our species (Homo sapiens) as a “spiritualistic phenomenon”. These speculations were not accepted by his colleagues and damaged the reputation of the gifted naturalist considerably. It is well known that Wallace disagreed with Darwin with respect to the evolutionary development of human intelligence. In his last popular books, Man’s Place in the Universe, The World of Life and Social Environment and Moral Progress, Wallace systematically mixed up (non-religious) spiritualistic ideas with scientific facts and finally became a teleologist. This ‘alternative explanation’ was an unscientific mixture of spiritualistic ideas and natural phenomena. These philosophical speculations were not accepted by his fellows so that the “spiritualistic naturalism” of Wallace is still regarded today as a set of ideas that are outside the world of science.