Allan Wilson (biologist)

For other people named Allan Wilson (biologist), see Allan Wilson (biologist) (disambiguation).

Allan C Wilson
Born	(1934-10-18)18 October 1934 Ngaruawahia, New Zealand
Died	July 21, 1991(1991-07-21) (aged 56)
Alma mater	University of Otago, University of California, Berkeley
Awards	MacArthur Fellowship
Scientific career
Doctoral advisor	Arthur Pardee
Other academic advisors	Nathan O. Kaplan

Allan Charles Wilson (18 October 1934 – 21 July 1991) was a pioneer in the use of molecular approaches to understand evolutionary change and reconstruct phylogenies, and a contributor to the study of human evolution. He was one of the most controversial figures in post-war biology; his work attracted a great deal of attention both from within and outside the academic world. He is the only New Zealander to win the MacArthur Fellowship.

Early life and education

Allan Wilson was born in Ngaruawahia, New Zealand and raised on his family's rural dairy farm at Helvetia, Pukekohe about twenty miles south of Auckland. At his local Sunday School, the vicar's wife was impressed by young Allan's interest in evolution and encouraged Allan's mother to enroll him at the elite King's College secondary school in Auckland. There he excelled in maths, chemistry, and sports. Wilson already had an interest in evolution and biochemistry, but intended to be the first in his family to attend university by pursuing studies in agriculture and animal science. Wilson met Professor Campbell Percy 'Mac' McMeekan, a New Zealand pioneer in animal science, who suggested that Wilson attend the University of Otago in southern New Zealand to further his study in biochemistry rather than veterinary science. Wilson gained a BSc from the University of Otago in 1955, majoring in both Zoology and Biochemistry. The bird physiologist Donald S Farner met Wilson as an undergraduate at Otago and invited him to Washington State University at Pullman as his graduate student. Wilson obliged and completed a Master's degree at WSU under Farner in 1957, where he worked on the effects of photoperiods on the physiology of birds.

Wilson then moved to the University of California, Berkeley to pursue his doctoral research. At the time the family thought Allan would only be gone two years. Instead, Wilson remained in the United States, gaining his PhD at Berkeley in 1961 under the direction of biochemist Arthur Pardee working on the regulation of flavin biosynthesis in bacteria. From 1961 to 1964, Wilson studied as a post-doc under biochemist Nate Kaplan at Brandeis University in Waltham, Massachusetts. In Kaplan's lab, working with lactate and malate dehydrogenases, Wilson was first introduced to the nascent field of molecular evolution. Nate Kaplan was one of the very earliest pioneers to address phylogenetic problems with evidence from protein molecules, an approach that Wilson later famously applied to human evolution and primate relationships. After Brandeis, Wilson returned to Berkeley where he set up his own lab in the Biochemistry department, remaining there for the rest of his life.

Career and scientific contributions

Wilson's first major scientific contribution was published as Immunological Time-Scale For Hominid Evolution in the journal Science in December 1967. Wilson and his Ph.D. student Vincent Sarich showed evidence that evolutionary relationships of the human species with other Primates, in particular the Great Apes, (Chimpanzees, Gorillas, and Orangutans) could be inferred from molecular evidence taken from living species, rather than solely from fossils of extinct creatures. Their microcomplement fixation method measured the strength of the immunological reaction between an antigen (serum albumin) from one species and an antibody raised against the same antigen in another species. The strength of the antibody-antigen reaction was known to be stronger between more closely related species: their innovation was to measure it quantitatively among many species pairs as an "immunological distance". When calibrated against known divergence times between certain species pairs, they showed that the molecular difference increased linearly with time, in what was termed a "molecular clock". Given the calibration curve, the time of divergence between species pairs with unknown or uncertain fossil histories could be inferred. The data of Wilson and Sarich suggested that divergences between humans, chimpanzees, and gorillas were on the order of 3 ~ 5 million years, far less than the estimates of 9 ~ 30 million years by conventional "paleoanthropologists" from fossil hominids such as Ramapithecus. This 'recent origin' theory of human / ape divergence remained controversial until the discovery of the "Lucy" fossils in 1974.

Wilson and another Ph.D. student Mary-Claire King, subsequently compared several lines of genetic evidence (immunology, amino acid differences, and protein electrophoresis) on the divergence of humans and chimpanzees, and showed that all methods agreed that the two species were more than 99 percent similar. Given the large organismal differences between the two species in the absence of large genetic differences, King and Wilson argued that it was not structural gene differences that were responsible for species differences, but gene regulation of those differences, that is, the timing and manner in which near-identical gene products are assembled during embryology and development.

In the early 1980s, Wilson further refined traditional anthropological thinking with his work with Ph.D. students Rebecca Cann and Mark Stoneking on the so-called "Mitochondrial Eve" hypothesis. In his efforts to identify informative genetic markers for tracking human evolutionary history, he started to focus on mitochondrial DNA (mtDNA) — genes that are found in mitochondria in the cytoplasm of the cell outside the nucleus. Because of its location in the cytoplasm, mtDNA is passed exclusively from mother to child, the father making no contribution. Because it also mutates rapidly, it is possible to measure the small genetic differences between individual within species by restriction endonuclease gene mapping. Wilson, Cann, and Stoneking measured differences among many individuals from different human continental groups, and found that humans from Africa showed the greatest inter-individual differences, consistent with an African origin of the human species (the so-called "Out of Africa" hypothesis). The data further indicated that all living humans shared a common maternal ancestor, who lived in Africa only a few hundreds of thousands of years ago. This common ancestor became widely known in the media and popular culture as the "Mitochondrial Eve". The erroneous implication was that only a single female lived at that time, when in fact the occurrence of a coalescent ancestor is a necessary consequence of population genetic theory, and the "mitochondrial Eve" was only one of many humans (male and female) alive at that time.

This finding was, like his earlier results, not immediately accepted by anthropologists. Accepted thinking had various human groups evolving from different ancestors, over a million years in separate geographic regions, but at basically the same rate around the world. Subsequent investigation by direct DNA sequencing of mitochondrial DNA as well as nuclear DNA

Legacy

Wilson's success can at least partially be attributed to his willingness to adopt new molecular techniques at the earliest stages of their development. For instance, he was one of the first scientists to apply DNA sequencing and PCR to the study of evolution. Throughout the course of his career, Wilson trained more than 200 graduate students and post-docs in molecular evolutionary biology. Indeed, his laboratory was a virtual obligatory passage point for anyone wishing to do empirical work in the field of molecular evolution in the 1970s and 1980s.

His investigations into the origins of humanity through biochemistry were revolutionary, yet at the time of his death in July 1991, while undergoing treatment for leukaemia, he was still a controversial figure. His theories on the evolution and age of modern humans still flew in the face of some anthropological thinking of the time, not to mention inciting anger from American creationists.

After Wilson's death Charles Laird published some thoughts on his lost colleague and friend.

"I have wondered about the parts of his personality that were so unusual even among first-rate scientists—his courage, his openness, his ability to focus on a problem and not let go, his special vision to see the final experiment and not to get distracted by intermediate ones and the details in between…"

External links

• Allan Wilson Centre for Molecular Ecology and Evolution
• Allan Wilson: Evolutionary, Film, 2008 (Documentary), George Andrews Productions
• Background on Allan Wilson
• Work on human evolution
• "Allan Charles Wilson, Biochemistry; Molecular Biology: Berkeley", by Bruce N. Ames, Thomas H. Jukes, Vincent M. Sarich, David B. Wake in University of California: In Memoriam, 1991
• Guide to the Allan Wilson Papers at The Bancroft Library