Ernst Mayr

Ernst Walter Mayr (July 5, 1904, Kempten, Germany – February 3, 2005, Bedford, Massachusetts U.S.) was one of the twentieth century's leading evolutionary biologists. He was also a renowned taxonomist, tropical explorer, ornithologist, historian of science, and naturalist. His work contributed to the conceptual revolution that led to the modern evolutionary synthesis of Mendelian genetics, systematics, and Darwinian evolution, and to the development of the biological species concept.

Mayr's theories on speciation remain the leading view of how new species evolve from common ancestors via Darwinian principles, and he provided the theoretical underpinning for the theory of punctuated equilibrium. Apart from biology, his prolific writings include influential works on the philosophy and history of science, and of biology in particular.

Mayr authored over 20 books and published more than 700 scientific papers.

Mayr was an atheist, stating that "there is nothing that supports the idea of a personal God" (Shermer and Sulloway 2000). At the same time, however, he noted that "famous evolutionists such as Dobzhansky were firm believers in a personal God. He would work as a scientist all week and then on Sunday get down on his knees and pray to God." Sometimes there is an assumption of an either-or dichotomy at work between evolutionary theory and religious faith: Either evolution is true or God exists. In reality, however, these two positions are often successful juxtaposed. Of course, the extreme dogmatic positions on the two sides are exclusionary, with the religious concept of young earth creationism unable to reconcile with the long-time periods evident in descent with modification, and the equally dogmatic adherence of some evolutionists to philosophical materialism (that matter is the ground of all existence and spirit either does not exist or is a product of matter) unable to reconcile with belief in God. Yet, there are a wide variety of religious viewpoints that do allow evolutionary change, including those that accept the pattern of evolution (descent with modification) but not the process of natural selection, and those that accept both the pattern and the process.

Biography

1904 to 1930: Early life and expeditions in New Guinea and Pacific islands

Mayr was born in Kempten, Germany in 1904 and completed his high school education in Dresden. He planned to become a physician and undertook pre-clinical studies. However, he also was attracted to ornithology, the study of birds. Hull (1988) states that "officially he was enrolled as a medical student, but his true love was ornithology." Mayr was introduced to Erwin Stresemann, a well-known ornithologist at Berlin's Zoological Museum, as a result of Mayr's claimed sighting of red-crested pochards in Germany—a species that had not been seen in Europe for 77 years. After a tough interrogation, Stresemann accepted and published the sighting as authentic. Stresemann offered him a position with the Berlin Museum and the prospect of bird-collecting trips to the tropics on the condition that he completed his PhD studies in 16 months. Mayr completed his PhD in ornithology at the University of Berlin in June 1926 at the age of 21, while also completing (in 1925) his pre-clinical studies at medical school (Diamond 2001). Mayr then accepted the position offered to him at the Museum.

At the International Zoological Congress at Budapest in 1927, Mayr was introduced by Stresemann to banker and naturalist Walter Rothschild (Lord Rothschild's Museum), who asked him to undertake an expedition to New Guinea on behalf of himself and the American Museum of Natural History in New York. There was a desire to "clean up" the outstanding ornithological mysteries of New Guinea, by tracking all of the birds of paradise known only from specimens collected by natives and not yet traced to their home ground (Diamond 2001). In New Guinea, Mayr collected several thousands bird skins (he named 26 new bird species during his lifetime) and, in the process also named 38 new orchid species. Mayr did thorough bird surveys of New Guinea's five most important north coastal mountains. In the process, he was officially reported to have been killed by local tribes; survived severe cases of malaria, dengue, dysentery, and other diseases; and had a forced descent down a waterfall and nearly drowned in an overturned canoe (Diamond 2001). Nonetheless, he succeeded in his mission by reaching the summits of all five mountains and amassing large collections (Diamond 2001). None of the findings were the mysterious missing birds of paradise, leading Stresemann to conclude later that they were thus hybrids between known species (Diamond 2001).

During his stay in New Guinea, Mayr was invited to accompany the Whitney South Seas Expedition to the Solomon Islands. With this expedition, Mayr participated in surveys of birds in several islands in the Pacific.

1931 to 1975: Professional career as curator, professor, and author

Mayr received a telegram in 1930 to return to the American Museum of Natural History to identify the tens of thousands of birds specimens collected by the Whitney Expedition (Diamond 2001). In 1931, he accepted a curatorial position at the American Museum of Natural History, where he played the important role of brokering and acquiring the Walter Rothschild collection of bird skins, which was being sold in order to pay off a blackmailer, an unknown woman.

Mayr married Margarete Simon in 1935, and had two daughters with her. (She passed away in 1990.)

During his time at the museum, Mayr produced numerous publications on bird taxonomy, and in 1942, he published his first book, Systematics and the Origin of Species, a text that was renowned for completing the modern evolutionary synthesis.

After Mayr was appointed as curator at the American Museum of Natural History, he influenced American ornithological research by cultivating mentoring relationships with young birdwatchers. Mayr organized a monthly seminar under the auspices of the Linnaean Society of New York. This society, under the influence of J. A. Allen, Frank Chapman, and Jonathan Dwight concentrated on taxonomy and later became a clearing house for bird banding and sight records. There were a group of eight young birdwatchers from the Bronx and later became the Bronx County Bird Club, being led by Ludlow Griscom. Mayr was surprised at the differences between American and German Birding Societies. He noted that the German society was more scientific and concerned with life histories and reports on recent literature. Mayr also encouraged his Linnaean Society seminar participants to take up a specific research project of their own. One of Mayr's seminar participants was Joseph Hickey and under Mayr's influence went on to write A Guide to Birdwatching (1943). Hickey remembered later: "Mayr was our age and invited on all our field trips. The heckling of this German foreigner was tremendous, but he gave tit for tat, and any modern picture of Dr E. Mayr as a very formal person does not square with my memory of the 1930s. He held his own." Mayr's said of his own involvement with the local birdwatchers: "In those early years in New York when I was a stranger in a big city, it was the companionship and later friendship which I was offered in the Linnaean Society that was the most important thing in my life."

Another person that Mayr greatly influenced was Margaret Morse Nice. Mayr encouraged her to correspond with the European ornithologists of the time, and helped her in her landmark study on Song Sparrows.

Mayr joined the faculty of Harvard University in 1953, where he also served as director of the Museum of Comparative Zoology from 1961 to 1970. He retired in 1975 as professor of zoology, showered with honors. He continued, however, for many years on the staff of the museum as professor emeritus.

1975 to 2005: Final 30 years of life, innumerable publications and awards

Following his retirement, Mary went on to publish more than 200 articles, in a variety of journals—more than some reputable scientists publish in their entire careers. Indeed, 14 of his 25 books were published after he was 65. Mayr was 97 years old when he published What Evolution is, and even as a centenarian, he continued to write books. On his 100th birthday, he was interviewed by Scientific American magazine.

Mayr received innumerable awards during his career, including the National Medal of Science, the Balzan Prize, the Sarton Medal of the History of Science Society, and the International Prize for Biology. In 1939, he was elected a Corresponding Member of the Royal Australasian Ornithologists Union. He was never awarded a Nobel Prize, but he noted that there is no Prize for evolutionary biology, and that Darwin would not have received one, either. Mayr did win a 1999 Crafoord Prize. That prize honors basic research in fields that do not qualify for Nobel Prizes and is administered by the same organization as the Nobel Prize.

Mayr was co-author of six global reviews of bird species new to science (listed below).

Mayr's Ideas

As a traditionally trained biologist with little mathematical experience, Mayr was often highly critical of early mathematical approaches to evolution, such as those of J. B. S. Haldane, famously calling in 1959 such approaches "bean bag genetics." He maintained that factors such as reproductive isolation had to be taken into account. In a similar fashion, Mayr was also quite critical of molecular evolutionary studies such as those of Carl Woese. He dismissed Richard Goldschmidt's mechanism for speciation as speciation by means of "hopeful monsters," an epithet that caught on (Hull 1988).

In many of his writings, Mayr rejected reductionism in evolutionary biology, arguing that evolutionary pressures act on the whole organism, not on single genes, and that genes can have different effects depending on the other genes present. He advocated a study of the whole genome rather than of isolated genes only. He also agreed with Dobzhansky that speciation is a populational affair (Hull 1988).

Mayr was an outspoken defender of the scientific method, and one known to sharply critique science on the edge. As a notable recent example, he criticized the search for aliens as conducted by fellow Harvard professor Paul Horowitz as being a waste of university and student resources, for its inability to address and answer a scientific question.

Hull noted in 1988 that "Mayr was—and still is—an outgoing man who is very much at home at professional meetings and conferences, where he vigorously and tirelessly defends his views. He makes no distinctions between august experts and hesitant graduate students. He is as willing to spend time setting one straight as the other."

Modern synthesis

Between 1937 and 1947, neo-Darwinism or the modern evolutionary synthesis integrated Charles Darwin's theory of evolution by natural selection, Gregor Mendel's theory of genetics as the basis for biological inheritance, and mathematical population genetics. This was one of the most significant, overall developments in evolutionary biology since the time of Darwin. Bowler (1988) stated that there is "a sense in which the emergence of the modern synthetic theory can be seen as the first real triumph of Darwinism."

Essentially, neo-Darwinism introduced the connection between two important discoveries: the units of evolution (genes) with the mechanism of evolution (natural selection). By melding classical Darwinism with the rediscovered Mendelian genetics, Darwin's ideas were recast in terms of changes in allele frequencies. Neo-Darwinism thus fused two very different and formerly divided research traditions, the Darwinian naturalists and the experimental geneticists.

Mayr's 1942 work, Systematics and the Origin of Species, was one of the four canonical works of the modern evolutionary synthesis, joining those of G. G. Simpson Tempo and Mode in Evolution, G. Ledyard Stebbins Variation and Evolution in Plants, and Theodosius Dobzhansky Genetics and the Origin of Species. Mayr himself places the key dates for the development of the synthesis between 1937, with Dobzhansky's work, and an international symposium at Princeton, New Jersey, January 2-4, 1947, which marked the formal completion of the synthesis (Hull 1988; Mayr 1982). The modern synthesis remains the prevailing paradigm of evolutionary biology.

Hull (1988) claimed that Mayr wrote his work "in white-hot indignation," in response to Richard Goldschmidt's The Material Basis of Evolution (1940).

"Species problem"

Charles Darwin's famous book "The Origin of Species" presented a theory for how species evolve and change over time. Although Darwin did not provide details on how a new species arises, he viewed speciation as a gradual process. If Darwin was correct, then when new incipient species are forming there must be a period of time when they are not yet distinct enough to be recognized as species. Darwin's theory suggested that there was often not going to be an objective fact of the matter, on whether there were one or two species.

Darwin's book triggered a crisis of uncertainty for some biologists over the objectivity of species, and some came to wonder whether individual species could be objectively real—i.e., have an existence that is independent of the observer (Johnson 1908; Bailey 1896).

While neither Darwin nor anyone else in his time knew a definitive answer to the "species problem"—how multiple species could evolve from a single common ancestor—Ernst Mayr approached the problem with a new definition for the concept "species'." Ernst Mayr's 1942 book, Systematics and the Origin of Species, was a turning point for the species problem. In it he wrote about how different investigators approach species identification, and he characterized these different approaches as different species concepts. He wrote that a species is not just a group of morphologically similar individuals, but a group that can breed only among themselves, excluding all others. When populations of organisms get isolated, the sub-populations will start to differ by genetic drift and natural selection over a period of time, and thereby evolve into new species. He also developed the idea that most significant and rapid genetic reorganization occurs in extremely small populations that have been isolated, the "Founder Principle."

Mayr perspective on what constitutes a species came to be called the Biological Species Concept (BSC), which is that a species consists of populations of organisms that can reproduce with one another and that are reproductively isolated from other such populations. Mayr was not the first to define "species" on the basis of reproductive compatibility. Many others before Mayr had suggested this idea, as Mayr (1982) makes clear in his book on the history of biology. For example, Mayr discusses how Buffon proposed this kind of definition of "species" in 1753. The idea of shared reproduction within species is even contained in the Biblical myth of Noah's ark, in which each species was preserved by saving a reproductive pair.

Theodosius Dobzhansky was a close contemporary of Mayr's and the author of a classic book, that came out a few years before Mayr's, that was about the evolutionary origins of reproductive barriers between species (Dobzhansky 1937). Many biologists credit Dobzhansky and Mayr jointly for emphasizing the need to consider reproductive isolation when studying species and speciation (Mallet 2001; Coyne 1994).

After articulating the biological species concept in 1942, Mayr played a central role in the species problem debate over what was the best species concept. After Mayr's 1942 book, many more species concepts were introduced. Some, such as the Phylogenetic Species Concept (PSC), where designed to be more useful than the BSC for actually deciding when a new species should be described. However, not all of the new species concepts were about identifying species, and some concepts were mostly conceptual or philosophical.

Mary staunchly defended the biological species concept against the many definitions of "species" that others proposed. Mayr was persuasive in many respects and from 1942 until his death in 2005, he and the biological species concept (BSC) played a central role in nearly all debates on the species problem. For many, the Biological Species Concept was a useful theoretical idea because it leads to a focus on the evolutionary origins of barriers to reproduction between species. But the BSC has been criticized for not being very useful, because it is not very much for deciding when to identify new species. It is also true that there are many cases where members of different species will hybridize and produce fertile offspring when they are under confined conditions, such as in zoos. One fairly extreme example is that lions and tigers will hybridize in captivity, and at least some of the offspring have been reported to be fertile. Mayr's response to cases like these is that the reproductive barriers that are important for species are the ones that occur in the wild. But even so it is also the case that there are many cases of different species that are known to hybridize and produce fertile offspring in nature.

His theory of peripatric speciation (a more precise form of allopatric speciation which he advanced) based on his work on birds, is still considered a leading mode of speciation and was the theoretical underpinning for the theory of punctuated equilibrium.

Selected works by Mayr, arranged by year

Books

1942 Systematics and the Origin of Species. New York: Columbia University Press. ISBN 0674862503. One of the founding books of the neo-darwinian synthesis.
1953 with E. G. Linsley and R. L. Usinger. Methods and Principles of Systematica Zoology. New York: McGraw-Hill.
1963 Animal Species and Evolution. Harvard University Press. ISBN 0674037502.
1970 Populations, Species and Evolution. Harvard University Press. ISBN 0674690133.
1976 Evolution and the Diversity of Life: Selected Essays. Harvard University Press. ISBN 067427105X.
1980 with W. B. Provine, eds., The Evolutionary Synthesis: Perspectives on the Unification of Biology. Cambridge, MA: Harvard University Press. ISBN 0674272250.
1982 The Growth of Biological Thought: Diversity, Evolution and Inheritance. Harvard University Press. ISBN 0674364465. A major history of evolutionary thought.
1988 Toward a New Philosophy of Biology: Observations of an Evolutionist. Harvard University Press. ISBN 0674896661.
1991 with P. Ashlock, Principles of Systematic Zoology, revised ed. New York, NY: McGraw-Hill. ISBN 0070411441.
1991 One Long Argument: Charles Darwin and the Genesis of Modern Evolutionary Thought. Cambridge, MA: Harvard University Press. ISBN 0674639065.
1997 This is Biology: The Science of the Living World. Harvard University Press. ISBN 0674884698.
2001 with Jared Diamond, Birds of Northern Melanesia: Speciation, Ecology and Biogeography. New York, NY: Oxford University Press. ISBN 0195141709.
2001 What Evolution Is. New York: Basic Books. ISBN 0465044263.
2004 What Makes Biology Unique? Considerations on the Autonomy of a Scientific Discipline. New York, NY: Cambridge University Press. ISBN 0521841143.

Other notable publications

1923 "Die Kolbenente (Nyroca rufina) auf dem Durchzuge in Sachsen." Ornithologische Monatsberichte 31: 135-136.
1923 "Der Zwergfliegenschapper bei Greifswald." Ornithologische Monatsberichte 31: 136.
1926 "Die Ausbreitung des Girlitz (Serinus canaria serinus L.) Ein Beitrag zur Tiergeographie." J. fur Ornithologie 74: 571-671.
1927 "Die Schneefinken (Gattungen Montifringilla und Leucosticte)." J. für Ornithologie 75: 596-619.
1930 "My Dutch New Guinea expedition, 1928." Ornithologische Monatsberichte 36: 20-26.
1931 "Birds collected during the Whitney South Sea Expedition. XII Notes on Halcyon chloris and some of its subspecies." American Museum Novitates no 469.
1932 "A tenderfoot explorer in New Guinea." Natural History 32: 83-97. Retrieved April 17, 2007.
1935 "Bernard Altum and the territory theory." Proceedings of the Linnaean Society of New York 45, 46: 24-38.
1940 "Speciation phenomena in birds." American Naturalist 74: 249-278.
1941 "Borders and subdivision of the Polynesian region as based on our knowledge of the distribution of birds." Proceedings of the 6th Pacific Scientific Congress 4: 191-195.
1941 "The origin and history of the bird fauna of Polynesia." Proceedings of the 6th Pacific Scientific Congress 4: 197-216.
1943 "A journey to the Solomons." Natural History 52: 30-37, 48.
1944 "Wallace's Line in the light of recent zoogeographics studies." Quarterly Review of Biology 19: 1-14.
1944 "The birds of Timor and Sumba." Bulletin of the American Museum of Natural History 83: 123-194.
1944 "Timor and the colonization of Australia by birds." Emu 44: 113-130.
1946 "History of the North American bird fauna." Wilson Bulletin 58: 3-41. Retrieved April 18, 2007.
1946 "The naturalist in Leidy's time and today." Proceedings of the Academy of Natural Sciences of Philadelphia 98: 271-276.
1947 "Ecological factors in speciation." Evolution 1: 263-288.
1948 "The new Sanford Hall." Natural History 57: 248-254.
1950 "The role of the antennae in the mating behavior of female Drosophila." Evolution 4: 149-154.
1951 "Introduction and conclusion." Pages 85,255-258 in "The problem of land connections across the South Atlantic with special reference to the Mesozoic." Bulletin of the American Museum of Natural History 99: 79-258.
1951 with Dean Amadon, "A classification of recent birds." American Museum Novitates no. 1496.
1954 "Changes in genetic environment and evolution." Pages 157-180 in J. Huxley, A. C. Hardy, and E. B. Ford, eds., Evolution as a Process. London: Allen and Unwin.
1955 "Karl Jordan's contribution to current concepts in systematics and evolution." Transactions of the Royal Entomological Society of London 107: 45-66.
1956 with C. B. Rosen. "Geographic variation and hybridization in populations of Bahama snails (Cerion)." American Museum Novitates no. 1806.
1957 "Species concepts and definitions." 371-388 in E. Mayr. The Species Problem. Washington, D.C. AAAS.
1959 "The emergence of evolutionary novelties." 349-380 in S. Tax, ed., The Evolution of Life: Evolution after Darwin, vol 1. University of Chicago.
1959 "Darwin and the evolutionary theory in Biology." 1-10 in B. J. Meggers, ed., Evolution and Anthropology: A Centennial Appraisal. Washington, D.C.: The Anthropological Society of Washington.
1959 "Agassiz, Darwin, and Evolution." Harvard Library Bulletin 13: 165-194.
1961 "Cause and effect in biology: Kinds of causes, predictability, and teleology are viewed by a practicing biologist." Science 134: 1501-1506.
1962 "Accident or design: The paradox of evolution." 1-14 in G. W. Leeper, ed., The Evolution of Living Organisms. Melbourne University Press.
1965 "Comments. In Proceedings of the Boston Colloguium for the Philosophy of Science, 1962-1964." Boston Studies in the Philosophy of Science 2: 151-156.
1969 "Discussion: Footnotes on the philosophy of biology." Philosophy of Science 36: 197-202.
1972 "Continental drift and the history of the Australian bird fauna." Emu 72: 26-28.
1972 "Geography and ecology as faunal determinants." 549-561 in K. H. Voous, ed., Proceedings XVth International Ornithological Congress. Leiden, The Netherlands: E. J. Brill.
1972 "Lamarck revisited." Journal of the History of Biology 5: 55-94.
1974 "Teleological and teleonomic: A new analysis." Boston studies in the Philosophy of Science 14: 91-117. Retrieved April 17, 2007.
1978 "Tenure: A sacred cow?" Science 199: 1293.
1980 "How I became a Darwinian." Pages 413-423 in E. Mayr and W. Provine, eds., The Evolutionary Synthesis: Perspectives on the Unification of Biology. Cambridge, MA: Harvard University Press. ISBN 0674272250.
1981 "Evolutionary biology." 147-162 in W. Shripshire, ed., The Joys of Research. Smithsonian Institution Press.
1984 "Evolution and ethics." 35-46 in A. L. Caplan and B. Jennings, eds., Darwin, Marx and Freud: Their Influence on Moral Theory. New York: Plenum Press. ISBN 0306415305.
1985 "Darwin's five theories of evolution." 755-772 in D. Kohn and M. J. Kottler, eds., The Darwinian Heritage. Princeton, NJ: Princeton University Press.
1985 "How biology differs from the physical sciences." 43-63 in D. J. Depew and B. H. Weber, eds., Evolution at a Crossroads: The New Biology and the New Philosophy of Science. Cambridge, MA: The MIT Press. ISBN 0262040794.
1988 "The why and how of species." Biology and Philosophy 3: 431-441.
1992 "The idea of teleology." Journal of the History of Ideas 53: 117-135.
1994 with W. J. Bock. "Provisional classifications v. standard avian sequences: Heurisitics and communication in ornithology." Ibis 136: 12-18.
1996 "What is a species, and what is not?" Philosophy of Science 63 (June): 262-277.
1996 "The autonomy of biology: The position of biology among the sciences". Quarterly Review of Biology 71: 97-106.
1997 "The objects of selection." Proc. Natl. Acad. Sci. USA 94 (March): 2091-2094. Retrieved April 18, 2007.
1999 "Darwin's influence on modern thought." Crafoord Prize lecture, September 23, 1999. Retrieved April 18, 2007.
2000 "Biology in the Twenty-First Century." Bioscience 50 (Oct. 2000): 895-897. Retrieved April 18, 2007.
2001 "The philosophical foundations of Darwinism." Proceedings of the American Philosophical Society 145: 488-495. Retrieved April 18, 2007.
2002 with Walter J Bock. "Classifications and other ordering systems." Zeitschrift Zool. Syst. Evolut-Forsch. 40: 1-25.

Global reviews of species new to science

Zimmer, J. T., and E. Mayr. 1943. New species of birds described from 1938 to 1941. The Auk 60: 249-262.
Mayr, E. 1957. New species of birds described from 1941 to 1955. Journal fur Ornithologie (now Journal of Ornithology) 98: 22-35.
Mayr, E. 1971. New species of birds described from 1956 to 1965. Journal fur Ornithologie 112: 302-316.
Mayr, E., F. Vuilleumier. 1983. New species of birds described from 1966 to 1975. Journal fur Ornithologie 124: 217-232.
Vuilleumier, F., and E. Mayr. 1987. New species of birds described from 1976 to 1980. Journal fur Ornithologie 128: 137-150.
Vuilleumier, F., M. LeCroy, and E. Mayr. 1992. New species of birds described from 1981 to 1990. Bulletin of the British Ornithologists' Club 112A: 267-309.

References
ISBN links support NWE through referral fees

Bailey, L. H. 1896. The philosophy of species-making. Botanical Gazette 22: 454-462.
Barrow, M. V. 1998. A Passion for Birds: American Ornithology after Audubon. Princeton University Press. ISBN 0691044023.
Bowler, P. J. 1988. The Non-Darwinian Revolution: Reinterpreting a Historical Myth. Baltimore, MD: The Johns Hopkins University Press. ISBN 0801836786.
Coyne, J. A. 1994. Ernst Mayr and the origin of species. Evolution 48: 19-30.
Coyne, J. 2005. "Ernst Mayr (1904-2005)." Science 307: 1212-1213.
Diamond, J. 2005. Obituary: Ernst Mayr (1904−2005). Nature 433: 700-701. Retrieved April 18, 2007.
Diamond, J. M. 2001. Forward. In E. Mayr, What Evolution Is. New York: Basic Books. ISBN 0465044255.
Dobzhansky, T. 1937. Genetics and the Origin of Species. New York, NY: Columbia University Press.
Hull, D. L. 1988. Science as a Process: An Evolutionary Account of the Social and Conceptual Development of Science. Chicago: University of Chicago Press. ISBN 0226360504.
Johnson, D. S. 1908. Aspects of the species question. American Naturalist 42: 217.
Kutschera, U. 2006. Dogma, not faith, is the barrier to scientific enquiry. Nature 443: 26.
Mallet, J. 2001. The speciation revolution. Journal of Evolutionary Biology 14: 887-888.
Mayr, E. 1982. The Growth of Biological Thought. Cambridge, MA: Harvard University Press.
Milner, R. 1990. The Encyclopedia of Evolution. New York: Facts on File. ISBN 0816014728.
Schilthuizen, M. 2001. Frogs, Flies, and Dandelions: Speciation—The Evolution of New Species. Oxford Univ. Press. ISBN 0198503938.
Shermer, M., and F. J. Sulloway. 2000. The grand old man of evolution. Skeptic 8(1): 76-82. Retrieved April 17, 2007.

External links

All links retrieved March 20, 2024.

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