Ernst Mayr, Biologist Extraordinaire
An appreciation of Harvard's visionary of modern evolutionary synthesis
Ernst Mayr, Harvard University professor emeritus and biologist
extraordinaire, died peacefully in Bedford, Massachusetts, on
February 3. He was 100 years old and had been associated with the
biology department at Harvard since he joined its faculty in 1953.
An era in evolutionary thought, called variously the New Synthesis,
neo-Darwinism or the Modern Synthesis, came to an end with his passing.
The death of the last of the great evolutionary biologists of the
20th century concluded an intellectual movement in the study of
evolution—a point of view whose most striking aspect was the
extent to which all of the evolutionary history of life on Earth was
perceived as a subdiscipline of biology. Whereas Thomas Kuhn, author
of The Structure of Scientific Revolutions, might have
called it a paradigm, Ludwik Fleck (author of Genesis and
Development of a Scientific Fact, 1935) would have
recognized the correlated demise of neo-Darwinism and the death of
Professor Mayr as a paradigm lost.
An accomplished naturalist, Ernst Mayr began his work in 1923 at the
age of 19. The last of his 25 books, a collection of essays called
What Makes Biology Unique? Considerations on the
Autonomy of a Scientific Discipline, was published by
Cambridge University Press in the summer of 2004, one month after
his 100th birthday! This fact attests to Mayr's intellectual talents
and unwavering interest in science, its history and philosophy.
And last May, shortly before Mayr's centenary birthday in July, an
open celebration of his work and life was held in the auditorium of
the Mineralogical and Geological Museum at Harvard. The place was
crowded with admirers, spectators, students from universities and
colleges from all over the Boston area and beyond. Several famous
evolutionary biologists, colleagues, many of whom were among his
former students and are now professional leaders, came to pay
tribute. What struck me at this well-attended, enthusiastic
gathering was that, among the marvelous lecturers in an all-day
session about the evolutionary panorama of life on Earth, the most
moving and informative of the talks, in my opinion, was the final
statement by Ernst Mayr himself!
Mayr was born in Kempten, Germany (Bavaria), to an educated family,
many of whom were physicians. His father, Otto Mayr, was a judge and
a bird-watching enthusiast. During his school holidays Ernst worked
at the Berlin Zoological Museum at the invitation of Erwin
Stresemann, the best ornithologist in the country at that time.
Following his two years of study at the University of Greifswald,
oriented toward medicine as urged by his family, he completed his
doctoral program in 16 months at the University of Berlin. Why did
he opt to study at Greifswald? Why did he go north to a relatively
unknown academic institution? Because his real interests were in the
study of natural history, especially watching birds.
Nature Not Books
Like Darwin, Mayr was always fascinated by live animals in nature.
He was particularly compelled by the question: How do species
originate? Some three years before he died, he told me about his
delight when the University of Berlin called him back to celebrate
the 75th anniversary of receipt of his doctorate degree. I asked him
if I might accompany him to attend the scientific program. "Oh,
you don't want to do that," he remarked. "There will be no
science, just endless and boring talks by administrators."
We had been discussing modes of speciation, and I had shown him our
10-minute film on Mixotricha paradoxa, an Australian
termite protist, in his daughter Susanne Harrison's kitchen in
Bedford. I had explained "symbiogenesis" as a mode of
speciation. "I get it, I get it," he said, first
pensively, then excitedly as he watched the five or more integrated
microbial symbionts that comprise a single Mixotricha
protist swim away as a single individual.
I tried to distinguish "symbiosis" from
"symbiogenesis" for him. "Oh, you don't have to tell
me what 'symbiosis' is!" he exclaimed, a little impatiently.
"I studied symbiosis with Paul Buchner in Greifswald, who was a
young instructor there" for a very short time before he moved
on, eventually to Italy. Buchner, author of the seminal work
Endosymbiose der Tiere mit pflanzlichen Mikroorganismen
(1953), was the founder of modern symbiosis research.
Mayr took seriously Louis Agassiz's admonition. He studied
"Nature not Books" between 1928 and 1930 when he collected
more than 3,000 birds in the South Pacific, mainly the Solomon
Islands and New Guinea. He learned to live off the land. After
removal of the skin and feathers in the preparation of "study
skins" and taxidermic samples for species identification,
morphological analysis and shipment to museum collections, nothing
would be wasted: The innards went to pot for dinner. That Ernst Mayr
ate more birds of paradise than any other modern ornithologist is a
Mayr's work in the field, especially with avian diversity, led him
to his most familiar contribution to science, documented in his two
dozen single-authored or edited books and more than 600 scientific
publications. He framed the animal species concept. Members of the
same species can mate and breed to produce fertile offspring. Even
plants and animals that greatly resemble each other are not to be
assigned to the same species if they are not interfertile. On the
other hand, animals that look very different from each other (such
as Great Danes and Yorkshire terriers) if they produce fertile
offspring do belong to the same species.
He told me about the wood duck and the green-headed mallards
illustrated on his conservation-society shower curtain—that
they were perfectly fertile, and a mating between these birds
resulted in normal numbers of healthy chicks. He said that
nevertheless he agreed that the two very different-looking ducks
must be assigned, as they are, to two different species. Why?
Because, he insisted, even when they live on the same pond, such as
the duck pond here in Amherst, they only mate with their own kind.
His definition of species, he insisted, is "organisms are
members of the same species that, in nature, mate to
produce fertile offspring."
He always emphasized the importance of the environment. Speciation
could almost always be associated with geographical isolation. When
members of the same species are separated for long times by
environmental barriers (such as newly formed volcanic mountains,
islands, rivers or climatic change), the barriers lead to impeded
mating. It is these isolated populations that tend to form new
species. The importance of geographical details in the origin and
evolution of species was always emphasized. "I don't need to
measure the pH and see that it is lower than six in that
soil," he would say. "When sphagnum and cranberries grow
in the bog there, we know what the pH must be." A
proud naturalist, Mayr was a superb writer who communicated
primarily by handwritten notes. He was the last of the
neo-Darwinians to revere nature, work inside her and with her. His
life always extended beyond the computer and mathematical models.
What Evolution Is
We celebrated the publication of our books, both brought out by
Basic Books, in the summer of 2002. At his lovely retirement
village, with the help of many friends as well as family (including
Mayr's daughters Susanne and biologist Christa Menzel of Simsbury,
Connecticut), we had a wonderful bibliophilic party. For our book
(Lynn Margulis and Dorion Sagan, Acquiring Genomes: A Theory of
the Origins of Species), Mayr had written the fascinating,
not uncritical, foreword. But Mayr's book was what we all came to
celebrate. For readers unfamiliar with his comprehensive opus
spanning more than 75 years of scientific productivity on a panoply
of evolutionary themes, I recommend that you begin with this one,
his 24th: What Evolution Is. Designed for the curious,
nonspecialist reader, it is a fine read for those interested in the
achievements of importance in 20th-century evolutionary biology.
Not immodestly, Mayr considered his 2002 trade book to be the single
best summary of uncontested, documented evolutionary thought.
"Evolution" refers to the results of experimental,
observational and theoretical science that support the common
ancestry of all life on Earth. Yes, of course, people are primates
directly related to other great apes such as gorillas, chimps and
bonobos. Yes, of course, humans were not made by an all-seeing,
all-knowing white-man deity. Indeed, evidence points to the
possibility that several species of nonhumans became extinct because
of our aggressive, even murderous, greedy ancestors. These early
Homo sapiens, related to us, displayed traits that
The questions and answers, at the end of the book especially, help
any reader, even one naive with respect to science, to understand
the basic concepts of this most important area of study. Mayr's
reasonableness is especially pertinent today in the face of
ignorance, prejudice and religious fundamentalism. For those who try
to deny the validity of science that uses carefully collected
evidence from investigators worldwide, this book is a responsible antidote.
Some three weeks before his death, I called him at home in Bedford
and asked, "Ernst, how are you? How do you feel?" He
responded cheerily, "I feel fine. That is, I feel exceptionally
well given the diagnosis." "What diagnosis?" I asked.
"Didn't I tell you? The doctors tell me I have cancer. It has
already metastasized, but I don't feel sick at all." "Oh,
Ernst, I'm so sorry," I responded. "Well, Lynn," he
said cheerfully, "I will have to die of something."
© Lynn Margulis