February 5, 2005

Ernst Mayr, Pioneer in Tracing Geography's Role in the Origin of Species, Dies at 100

By CAROL KAESUK YOON

r. Ernst Mayr, the leading evolutionary biologist of the 20th century, died on Thursday in Bedford, Mass. He was 100.

Dr. Mayr's death, in a retirement community where he had lived since 1997, was announced by his family and Harvard, whose faculty he joined in 1953.

He was known as an architect of the evolutionary or modern synthesis, an intellectual watershed when modern evolutionary biology was born. The synthesis, which was described by Dr. Stephen Jay Gould of Harvard as "one of the half-dozen major scientific achievements in our century," reconciled Darwin's theories of evolution with new findings in laboratory genetics and in fieldwork on animal populations and diversity.

One of Dr. Mayr's most significant contributions was his persuasive argument for the role of geography in the origin of new species, an idea that has won virtually universal acceptance among evolutionary theorists. He also established a philosophy of biology and founded the field of the history of biology.

"He was the Darwin of the 20th century, the defender of the faith," said Dr. Vassiliki Betty Smocovitis, a historian of science at the University of Florida.

In a career spanning nine decades, Dr. Mayr, a professor emeritus of zoology at Harvard, exerted a broad and powerful influence over the field of evolutionary biology. His most recent book, "What Makes Biology Unique?: Considerations on the Autonomy of a Scientific Discipline" (Cambridge University Press), was published in August, one month after his 100th birthday.

Prolific, opinionated, provocative and dynamic, Dr. Mayr had been a major figure and intellectual leader since the 1940's. Setting much of the conceptual agenda for the field, he put the focus just where Charles Darwin first placed it, on the question of how new species originate.

Though Dr. Mayr will be best remembered as a synthesizer and promoter of evolutionary ideas, he was also an accomplished ornithologist. In fact, it was with the sighting of a pair of unusual birds that Dr. Mayr's long career in biology began in 1923 at age 19.

Dr. Mayr was born in Kempten, Germany, in 1904. While still a boy, he was instructed in natural history by his father, Otto, a judge. He quickly became a skilled birdwatcher and naturalist. Intending to become a medical doctor like others in his family, Dr. Mayr was about to leave for medical school when he spotted a pair of red-crested pochards, a species of duck that had not been seen in Europe for 77 years.

Though he took detailed notes, he could not get anyone to believe his sighting. Finally, he met Dr. Erwin Stresemann, then the leading German ornithologist, who was at the Berlin Zoological Museum and who recognized his talents and invited him to work at the museum during school holidays.

After two years of medical studies at the University of Greifswald (chosen because it was in the most interesting German region for birdwatching), Dr. Mayr, like Darwin before him, opted for natural history. He completed his Ph.D. at the University of Berlin in just 16 months.

Dr. Mayr went on to fulfill what he called "the greatest ambition of my youth," heading off to the tropics. In the South Pacific, principally New Guinea and the Solomon Islands, Dr. Mayr collected more than 3,000 birds from 1928 to 1930. (He had to live off the land, and every bird, after being skinned for study, went into the pot. As a result, he is said to have eaten more birds of paradise than any other modern biologist.)

The South Seas experience, he once said, "had an impact on my thinking that cannot be exaggerated." For it was his detailed observations of the differences among geographically isolated populations that contributed to his conviction that geography played a crucial role in the origin of species.

Though Darwin titled his book "The Origin of Species," little in the book, in fact, addresses the question of how new species arise. Dr. Mayr determined that when populations of a single species are separated from one another, they slowly accumulate differences until they can no longer interbreed. Dr. Mayr called this allopatric speciation and detailed his arguments in his seminal book "Systematics and the Origin of Species," published in 1942. Today allopatric speciation ("allo," from the Greek for "other," and "patric," from the Greek for "fatherland") is accepted as the most common way in which new species arise.

"Organic diversity had at last received a convincing explanation," Dr. Jerry A. Coyne, an evolutionary biologist at the University of Chicago, wrote of Dr. Mayr's arguments. Dr. Coyne called the book "one of the greatest achievements of evolutionary biology."

Similarly, the most commonly held view of what constitutes a species remains the one that Dr. Mayr promoted more than 50 years ago, known as the biological species concept. First explicitly defined by Dr. Theodosius Dobzhansky, it states that populations that can successfully interbreed are the same species and those that cannot are different species. While numerous other species concepts have been proposed and debated, this one continues to reign supreme.

Dr. Mayr's focus on species, both their nature and their origins, appears to have derived from his experiences in the South Pacific. When he went to New Guinea, Dr. Mayr once explained in an interview with Omni magazine, there was a popular school of thinking known as the nominalist school of philosophy that held that species did not, in reality, exist. They were merely arbitrary categories, little more than names.

"But I discovered that the very same aggregations or groupings of individuals that the trained zoologist called separate species were called species by the New Guinea natives," Dr. Mayr said. "I collected 137 species of birds. The natives had 136 names for these birds - they confused only two of them. The coincidence of what Western scientists called species and what the natives called species was so total that I realized the species was a very real thing in nature."

Dr. Mayr eventually became a living symbol of the beginnings of the modern field of evolution, one of the last survivors of the handful of biologists, including Dr. Dobzhansky and Dr. George Gaylord Simpson, known as the architects of the evolutionary or modern synthesis.

In the evolutionary synthesis, neo-Darwinism took its place as today's dominant theory of evolution. Taking place between the 1920's and 50's, the synthesis is recognized as a period of conceptual unification, a time of "mutual education," as Dr. Mayr once described it. Laboratory geneticists, studying mutations and population genetics, began merging their views of evolution with those of field scientists like Dr. Mayr who studied the diversity and origins of different species. New findings, in genetics as well as other fields, were reconciled with Darwin's theories of evolution. Competing theories, including Lamarckism (the idea that acquired characteristics can be inherited), were tossed aside, producing a much more unified view of evolution at work.

Over his remarkably productive career, Dr. Mayr wrote or edited 20 books and wrote more than 600 journal articles. After his official retirement in 1975, he published more than 200 of the articles, more than many scientists do in their entire careers. He received awards including the National Medal of Science, the Balzan Prize and the International Prize. He once noted that Nobel Prizes were not given in evolutionary biology, saying, "Darwin wouldn't have won it either."

Dr. Mayr was an ardent promoter of the academic discipline of evolutionary biology, and perhaps its most energetic organizer, playing a critical role in founding the Society for the Study of Evolution in 1946, and serving as the first editor of its journal, Evolution, still the leading journal in the field.

Meanwhile, his birds were never forgotten. As a collector, ornithologist and curator, first at the University of Berlin, then the American Museum of Natural History in the 1930's and 1940's, and finally at the Museum of Comparative Zoology at Harvard, Dr. Mayr made his mark.

By the time he turned 90, in 1994, he had named more than 24 valid bird species, more than any other living ornithologist had at the time. He had named more than 400 subspecies and several new genuses of birds as well.

Dr. Mayr also took a serious interest in organisms other than birds, publishing work on species delineations in plants, hybrids formed by snail species, courtship behavior in fruit flies and the evolution of human blood groups.

Dr. Mayr may have taken the greatest pride in his theory of what he called peripatric speciation and genetic revolutions, an idea he called "perhaps the most original theory I have ever proposed." It was also his least successful.

According to this controversial theory, new species can be produced when very small populations are cut off from the rest of the species. Unlike the more general theory of allopatric speciation, holding that isolated populations slowly accumulate differences until they can no longer interbreed, peripatric speciation posits that extremely small populations, isolated in unusual habitats, undergo what Dr. Mayr termed a "genetic revolution." Undergoing drastic changes in their genome, populations evolve quickly to become new species.

Some scientists have said that this theory is unlikely, unsupported and untestable. Others have defended it as a proposal, saying that while the idea itself may not stand the test of time, it remains significant as one of the first explicit theoretical models of speciation and its genetic consequences.

Dr. Gould also credited Dr. Mayr with sowing the seeds for the "flowering of modern macroevolutionary theory."

While microevolutionary theory seeks to explain how species adapt to particular environments or how evolution among populations can give rise to new species, macroevolution theory encompasses a much bigger picture, examining how some species survive better than others and how likely or unlikely they are to give rise to other species. It was Dr. Mayr's concept of the species and its role in the evolutionary process, Dr. Gould said, that laid the foundations for many of the theories being tested by macroevolutionists today.

In addition to his several lifetimes' worth of work in evolution, Dr. Mayr also fathered an entirely new field of study, creating almost singlehandedly the field of history and philosophy of biology as a distinct discipline, apart from the history of physics and chemistry, Dr. Smocovitis of the University of Florida said.

As with modern evolutionary biology, Dr. Mayr nurtured the new discipline as organizer, mover and shaker. His own contributions include the defining book "The Growth of Biological Thought" (1982), as well as books on the philosophy of biology, Darwin and the evolutionary synthesis.

Dr. Mayr is survived by two daughters, Christa Menzel of Simsbury, Conn., and Susanne Harrison of Bedford; five grandchildren; and 10 great-grandchildren. His wife, Margarete Simon, died in 1990.

Dr. Mayr, a strong believer in the Hegelian dialectic as a way of advancing understanding, was known for his definitive proclamations, which often inspired as many heated rebuttals as nods of vigorous agreement. With so long to consider the great pageant of the history of life, he seemed to have taken on every subject of interest in evolutionary biology, and his views are an unavoidable point at which to begin nearly any argument of substance.

At the time of his 90th birthday, in 1994, when Dr. Mayr was as active and engaged in the field as ever, Dr. Douglas J. Futuyma, an evolutionary biologist at Stony Brook University, wrote, "No one will agree with all his positions, analyses, and opinions." But he added, "Anyone who has failed to read Mayr can hardly claim to be educated in evolutionary biology."