The late Alfred Russel Wallace who lived from 8 January 1823-7 November 1913 is widely known for independently conceiving the evolution theory through natural selection, was an anthropologist, biologist, geographer and explorer. Alfred did intensive research in the Amazon River Basin and in the Malaya Archipelago where he identified the Wallace line which separates Indonesian archipelago into two. He conducted researches on western portions in which the animals are of Asian origin and the eastern portion where plants reflect Australasia.
He was among the 19th century’s leading expert in the geographical distribution of animal species. He made many more developments including the concept of warning coloration on animals, and the Wallace effect, a hypothesis on how natural selection could contribute to special by encouraging the development of barriers against hybridization.
Alfred Russel Wallace and Evolutionary Thinking
Wallace started his career of evolution with the belief of transformation of species. This concept was earlier adopted by other philosophers like Robert Grant and Jean-Baptiste Lamarck. These early scholars discussed this theory though it had not been accepted by naturalists as many of them considered it a radical theory.
Later on, Wallace started believing in the idea of species transformation partly due to the influence of religion, politics and science.
Wallace then organized field tests so as to conduct hypothesis testing on the relation of species. He worked at the Amazon River basin and among his major findings, geographical barriers was one that differentiated closely-related species of Amazon monkeys. He also highlighted his discovery on distribution of Fossil and living species both geologic and geographic.
These ideas were however not accepted by people like Charles Lyell who believed that species could not mutate.
Wallace and Natural Selection
By 1858, Wallace’s research had convinced him that his findings were correct. He met Charles Darwin and helped him in developing theories to support his views. They worked closely and shared same ideas and finally came up with a Law that controlled the “Introduction of new species”. In February 1998, Wallace wrote an Essay called “On the Tendency of Varieties to Depart Indefinitely From the Original Type” and sent it to Darwin after he trusted Darwin’s theory of distribution of species.
However, it should be noted Wallace did not use the term natural selection that had been adopted by Charles Darwin in his previous work. This term meant the divergence of evolutionary mechanisms adopted by similar species because of environmental pressures.
These ideas gave Wallace greater links to community science and it was up to Darwin’s publication 1859, “the origin of species” that gave his work more credit.
Wallace’s and Darwin’s Differences on Natural Selection
As far as Darwin stated that there were similarities between his work and Wallace’s, there were significant differences between their works.
Unlike Wallace who emphasized on environmental pressures on species varieties differences, Darwin views considered competition for reproduction and survival among species as the key adaptation of species to competition.
Peter J. Bowler, among other scholars noted that Wallace’s discussed on group selection unlike Charles Darwin who emphasized on individual selection.
Wallace also viewed that varieties and species adopted a feedback mechanism for environmental adaptation.
Wallace’s ideas on Sexual Selection and Coloration
This idea was adopted by Charles Darwin after studying differences in caterpillar color schemes. Wallace did not give much emphasis on this after studies showed that odour and taste were the major preferred qualities by predators such as birds.
However, Wallace developed the idea of coloration and it came to make a huge contribution in his work.
Wallace and Darwin however resorted in a lifetime disagreement on the idea of sexual selection. Wallace required different explanations on the Darwin’s idea of sexual selection.
Application of Wallace’s Ideology on Human Evolution
Wallace applied the theory of natural selection to analyze human evolution. He used the example of the differences in cranial sizes between apes and human beings. He argued that the evolution of human beings occurred in two stages
- Adoption of a bipedal body posture.
- Bodily specialization and functionality of the human brain to a more complete factor.
After these theories, Alfred Wallace became a spiritualist and these gave death many of his ideas.
What is more commendable about Wallace is his contribution to Darwin’s work and publication stimulus.
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