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Ernst Mayr

Interview: Ernst Mayr
The Darwin of the 20th Century

April 5, 2001
Cambridge, Massachusetts

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To begin at the beginning, Dr. Mayr, what was your childhood like?

Ernst Mayr: I had on the whole a very happy childhood. To begin with, I would say, it looked as wonderful as it could be. After all, I was born in Germany in 1904. At that time, Germany was very prosperous. The world, as a whole, was peaceful and very prosperous. My father had a brilliant career. He was promoted to a justice of the Supreme Court of Bavaria at the very young age of 47. My mother came from a banking family and was very affluent. I had two brothers with whom I got along very well, and everybody in the family was healthy so nothing could have been more wonderful. And then, of course, in 1914 the great catastrophe began, the first World War, in which several of my cousins were killed and other friends, and eventually things got from bad to worse. Then came the post-1918 famine where we really starved. We didn't have enough to eat. And then came the 1923 inflation in which the whole family fortune was wiped out. But in spite of all these misfortunes -- and they were really, really tragic misfortunes we had. And then in 1917 my father died at the young age of 49 from cancer and my mother had to raise us three boys all by herself.

In spite of all these misfortunes and difficulties, the childhood was still a rather happy one because my mother was an absolutely marvelous person who coped with all these difficulties, and I had hobbies and things that I was interested in.

As Darwin put it about himself, I was born a naturalist. At the age of six, already I was a passionate bird watcher. My older brother had an aquarium, which we jointly took care of, and we caught little fish and little sticklebacks in the streams and ponds of the neighborhood, and snails and things, and watched all the water life, the larvae of insects living in the water. And my mother was a great collector of mushrooms. She knew not only the poisonous and the edible ones but she knew everything about the in between kinds of mushrooms, which is the majority. She really knew mushrooms well. And both of my parents took us three boys every weekend on a little excursion, on a hike, on a walk, and we studied the spring flowers or my father took us to a limestone quarry where we found ammonites and other fossils, or we went to a heron colony and watched that. Anyhow I was almost trained to be a naturalist.

And the most important thing is...

My father had a wonderful library, and we always bought books galore, and I devoured all the books of explorers that went to various places in the world. I admired what Humboldt had done and Bates and Darwin and the Swedish explorers, Sven Hedin and others. I was dreaming all the time about someday being an explorer, going to the tropics, going to the jungles, seeing new things, discovering strange animals and so forth, but of course it was a dream world.

In the meantime I went dutifully to the gymnasium, the German equivalent of the high school. I prepared myself for a medical career because my family was definitely a medical family. My father's brother was a medical man. There were three generations of doctors prior to my father's generation, and I was to be the doctor of my generation. I didn't mind that at all. I liked the idea. When my father died of cancer it confirmed my desire to be a doctor because I said, "Surely something could have been done to save his life," As a young person, one is full of such ideas. I finished my high school and I started medical school and right at that period something very unexpected happened.

On one of my bird watching excursions, and I went out to the field almost every day after I finished the gymnasium, I saw -- on a pond -- I saw a duck with a red bill, and I said, "I've never heard of a duck with a red bill. What can this possibly be?" And I dashed back on my bicycle to the town of Dresden, where we were living at the time, and tried to find somebody to confirm it because I said, "Well, if somebody else doesn't see it, nobody will ever believe that I saw such a thing." And, of course, I couldn't find anybody and eventually at the meeting of the Dresden Ornithological Society, I met a pediatrician who said to me, "Well, I don't know whether you saw this or not, but why don't you tell it to Germany's leading ornithologist, Professor Stresemann in Berlin?" And I said, "Well, how should I ever get in touch with him?" And he said, "Well, that's easy. He and I are very good friends. We studied together. I'll write you a letter of introduction and when you go to your university town you have to go through Berlin anyhow to change trains. Why don't you stop for a while and see him," and so forth. And so I did.


I went to the museum and I met Professor Stresemann, who greatly impressed me, even though I now have reconstructed, he was only 34 years old at the time. He demanded that he could see my daily notebooks of my bird observations, which I kept very carefully and made all sorts of sketches and everything else. Then he asked me questions about birds, one after the other, then he showed me specimens, and that was the hardest part because the specimens in the trays in the museum didn't look at all like the birds in the field. But anyhow when it was all finished, he said, "Well yes, I believe you, and I'm going to publish your observation." And he said, "What you saw was a Red-crested Pochard. That's a Mediterranean duck. Every once in a long while one of them strays across the Alps to Central Europe. The last one that did so before your observation..." this was 1923 "...the last one before that was in 1846." So it really was a strange thing. So he published it and a little friendship developed between myself and Stresemann, who was much taken by my incredible enthusiasm.

Was that your publication, or did he author the paper?

Ernst Mayr: Oh, it was my publication. In fact, it was my first publication. 1923.

Did Dr. Stresemann continue to take an interest in your career after your first publication?

Ernst Mayr: Stresemann took to me and he saw my enthusiasm and he said, "Would you be interested, in your college vacations, to come here to the museum as a volunteer?" I thought somebody had given me a key to paradise. I said, "Of course, I would," and I did. And he put me to work unpacking new collections that came from expeditions in various places of the world and I was permitted to identify specimens that hadn't been yet identified and so forth. I had a wonderful time, and I had opportunity to talk with Stresemann about all sorts of things. And one day he said to me, after I talked about my dreams about the tropics of expeditions and the jungles and all that, he said to me very seriously, "Now look here, young man. If you become a medical doctor you will never have a chance to go to the tropics, you will be far too busy." When he saw how my face fell, he said, "Well, but there is an alternative. Let me make a proposal. Suppose, after you finish your first half of the medical study... " -- in Germany the preclinical period and the clinical are sharply separated -- "...after you've finished your preclinical period, why don't you stop studying medicine, take a degree in zoology, a Ph.D., and when you have that then I can find a place for you in an expedition somewhere, I'm quite sure."

Was he trying to convert you away from medicine by doing this?

Ernst Mayr: I'm not so sure, but he really was trying to do me a favor. I was such an enthusiast at that time. Anyhow, I talked it over with my mother and she said, "Well, if that's what you want, go right ahead." She was a wonderful woman. And so I did.

As soon as I had my candidate of medicine degree, I stopped medicine and I went into zoology, and I did something that is almost unbelievable. In 16 months I fulfilled all the requirements of a Ph.D. candidate in zoology, including a semester of philosophy and a great deal of botany and so forth, and I had written my thesis in that time. I was ready for the examination, and on the 24th of June my oral examinations were all completed and I was awarded a Ph.D. in zoology.

What was your dissertation about?

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Ernst Mayr: My dissertation was a biogeographical one. In a way, it was connected with that duck that appeared in Central Europe after 80 years but this dealt with a small finch-like bird, a relative of the canary, also a Mediterranean species, which in the years between about 1770 and the present time, had spread from the Mediterranean on both sides of the Alps into Central Europe. The argument among the ornithologists was that maybe it had been there all along and had just been overlooked before. So my thesis was to trace the movement through all the natural history literature of all the little local societies and whatnot, and then try to explain it in ecological terms.

Did you have to go through museum collections to document the presence of specimens from an earlier period?

Ernst Mayr: No. The observers are the really important thing. There are bird watchers everywhere, and always have been, right back to the year 1800 and earlier. They would record what they saw, just like the Vicar of Selborne, who recorded every day what he saw. But I had to get the most obscure natural history journals, provincial societies in France for instance, and I had to do a great deal of library work and also constantly interpret what I read, because sometimes people would record that bird and it really wasn't true. You have to know who was reliable and who wasn't. Anyhow, I got together a very convincing story, and mapped the spread of the bird in 25-year periods and developed a number of ecological theories about spreading. I just read, within the last year or so, somebody giving me credit of having been the first to have developed this biogeographic ecological theory. Anyhow, it was printed the next year in the big German ornithological journal.

You also worked on bird migration early on, didn't you?

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Ernst Mayr: Yes. I was quite interested in bird migration, in connection with the spreading of the Serin Finch, which was the bird that I worked on. When a bird spreads northward into new territory, what happens in the winter? Does it stay there now, or does it go back to its home territory? These connections between the breeding place in an unsuitable climatic region and the winter quarters, how this developed and whether the winter quarters are always the same, whether there is any competition between the wintering temperate zone birds in the tropics, and all that. I was very much interested in all those questions. Just two weeks ago I was sent a manuscript by a young man who had taken up exactly these same questions, not knowing that I had worked on this sort of thing and had developed theories about it.

Perhaps what was most important was that I showed in how many places wintering birds occur in the same places where other populations of that very same species nest and breed and raise young. And there is no interbreeding ever between the wintering birds and the local residents, because their hormonal state is totally different so they just don't even recognize each other as being the same species. I developed a theory that spreading birds, for instance, always pick a few optimal spots to settle down first. Then these became centers of spreading, and they expanded out from these optimal places into less suitable places until finally the whole region was filled with breeding pairs.

In many ways, your theoretical work grew out of biogeography and a real interest in biogeographic patterns, didn't it?

Ernst Mayr: I was very much interested in biogeography. Cleaning out some of my drawers in the museum the other day, I found a lot of notes that I had written in the 1920s. It was material for a book on biogeography, which I was planning to write and which I never wrote. Yes, biogeography was perhaps my foremost interest at that time, as a result of my Ph.D. thesis. I was quite annoyed about a book that was published at that time by Hesse, which was very popular. It was translated into English and called itself Ecological Biogeography. When I studied it, I said, "No, this is not a book on ecological geography. This is a book on geographical ecology." They are two very different things. But we still do not have yet a good book on ecological geography.

There's a book that I now have in press, together with a co-author, Jared Diamond, dealing with the birds of the islands northeast of New Guinea: the Solomon Islands and the Bismarck Archipelago, which usually are combined as Northern Melanesia. We have this book in press right now, and that deals a great deal with the ecology of biogeography. Why are certain species spreading and others not? Which ones disperse most easily? Which can endure competition? Which others cannot endure competition? It is a great deal of ecology related to biogeography. I've sort of come full circle from my early Ph.D. interests to one of the very last things that I will be writing in my life.

Your current work on biogeography of birds in Northern Melanesia actually brings us to the topic of your expeditions to New Guinea and the Solomon Islands. How did that come about?

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Ernst Mayr: Stresemann said that maybe if I switched to zoology and got my Ph.D. he might be able to get me on to an expedition. He was quite serious about that and he tried very hard. There was an expedition going to Cameroon in Africa and that didn't work out. Another one was to Peru in connection with some American oil explorations, and that didn't work out. Finally Stresemann persuaded Lord Rothschild of England -- the famous owner of the largest private bird collection -- that he should have a collector in New Guinea. Actually Rothschild had had a collector there but he had a stroke and had to give up working, so there was a vacancy.

Again, one of these chance things in my life. Rothschild didn't know anything about this fellow, Ernst Mayr, but was persuaded by Stresemann, in whom he greatly believed. He said, "All right. I'll send him out and I have a very definite task for him. There are some so-called rare birds of paradise..." This was in the days when ladies put birds of paradise and other feathers on their hats. Every year the natives all over New Guinea skinned out birds of paradise and sold them to dealers and the two major dealers were in Rotterdam and Paris, and then the people who adorn hats bought from these dealers.

Once in a while, a unique specimen turns up among all the well-known birds of paradise, something that nobody had seen before. Where these species occurred was a great puzzle and expeditions went out to all sorts of places and never found these rare ones. There were three mountain ranges in Dutch New Guinea that hadn't been properly explored, so my task given to me by Lord Rothschild was to go to those three mountain ranges and collect them thoroughly and see whether I could find one or the other of those rare birds of paradise.

I had no experience, of course. I had never shot a bird. I had never skinned a bird. Stresemann was very -- how shall I say -- optimistic about the whole thing, but I got a rush job training in some of these things and I went over to England and I talked it over with Rothschild and his curator about further matters of collecting. And then, the most fortunate thing was that I stopped in Java at the Dutch Colonial Museum, and they had some very experienced native Javanese assistants who had been on expeditions and were even good at bird skinning, and they agreed to lend me three of those to accompany me to New Guinea. In due time, I got to New Guinea and I established camps in various altitudes and in various villages, and collected, and collected, and collected. In due time I learned from these three Javanese whatever there is to be known about life in the jungle and in the mountains and how to make a camp and how to deal with the natives. And I built up rather beautiful collections.

I don't know whether you are interested in some of my adventures that I had during that period.


Ernst Mayr: Well, the first thing that happened was in the very first camp...

After I had been up in the mountains about three or four weeks, suddenly a troop of -- I think it was five -- of the native police of Indonesia appeared in my camp, and they had a letter which said that the Governor of New Guinea and the Moluccas -- that was one person -- couldn't allow that a person of such distinction as I, because I had letters from the German government, to be unprotected and these five police soldiers should protect me against these dreadful natives. Of course, I had gotten on fine with the natives. I couldn't see any danger at all, but these soldiers, every evening they just became guardians of the entrances to my little camp so that nobody could enter it and do something to me. Pretty soon they saw all sorts of things happening there. They were terribly scared of the natives and pretty soon shooting started. "Oh, but we saw something and we had to shoot at it." I was really annoyed and I was also a little bit concerned because I felt maybe there is something to all of this, and one night they woke me up after another shooting spell and said, "We just shot somebody." And I said, "Oh, my God, that's the end of my expedition here." I said, "Where is he?" So they took me across a little brook that was alongside my camp and I looked around with a kerosene lamp and I couldn't see anything. There wasn't anybody there.

So I sent these fellows to the coast to explain the whole thing and I went inland to a higher village and started a new collecting period. And after about two weeks...

Suddenly somebody rushed into my little hut and said, "Oh, there are a lot of people coming. A lot of soldiers coming." And I said, "Now what?" And I went outside and I could see the ridge that came up from the coast, and the pass was right at the very top of the ridge. There was a column of about -- I think it was 105 people or something like that. There were two white men in uniforms of officers of the Colonial Police Force, and about 20 soldiers, and the rest were porters carrying all their stuff and food and so forth. I still didn't know what it was all about, but I decided to go down in the valley separating my ridge from this coastal ridge. There was a river flowing there, and I went down there, and the leading officer of the other group waded into the river towards me, and he said, "Oh, I'm so glad you're still alive." I said, "I didn't know I wasn't supposed..." "Oh," he said, "The soldiers that you sent back to the coast reported that the natives had attacked your camp and had massacred you and all your people there, and 'we,' -- the police soldiers -- 'by shooting all of our ammunition have been able to escape and get down to the coast." They made up that story because they were embarrassed, appearing on the coast when they were supposed to protect me. And, as it appeared, having abandoned me. They had a court-martial later on and so on and so forth. A long story, but anyhow I was also told I had to now immediately return back to the coast. It was just too dangerous. But I knew that there was a lake even further in and even higher up that I'm sure was very interesting. So I totally disobeyed the order from the Dutch Government and I went up to that lake and sure enough discovered a new finch up there and several rare birds that I had never encountered anywhere else in New Guinea. So I had a really marvelous time.

That's just one little story . There were two other mountain ranges where I had similar experiences. At the end of that period, in about seven months, I had collected over 3,000 birds. The main reason for my great success was that I knew how to make use of the natives.

After I'd been a little while in this first collecting place, I realized that every bird the natives saw and that they had shot, they knew the name. So I recorded the Latin name that I knew and the name the natives gave me. Since they knew birds so well -- I had three little bird guns -- I gave them to the natives and I told them always when they came with a particularly rare bird, let's say a nieda, I said, "Well, I want more nieda, and then they went out and they brought back nieda and not the common stuff, you know. And at the end, when I finally summarized everything, I found that I had in this locality collected 137 species of birds, and the natives had given me the names of 136 of these. There were only two little nondescript looking little warblers, green warblers, which they had given the same name to the two different species. And I'm sure if I had gotten the right kind of an old man he would have been able to have the name of that 137th species.

So they had a pretty good species concept themselves, would you say?

Exactly. The biological species is an absolutely obvious entity to any good naturalist, and they were very clever. In the pidgin English language of Eastern New Guinea, they would name a male bird of paradise for a particular thing, and if we saw a female and I said, "What's that?" they said, "Oh, that's mama belong..." and then the name of the male. They knew perfectly well that they were not two different species, which by the purely typological species concept might have been the case. They knew exactly which bird had only one egg in the nest, which species have two eggs in the next, and they were superb woodsmen. Very often in certain localities in New Guinea and in the Solomon Islands I would distribute all the guns to the natives and I would go out and collect orchids and other things that the natives weren't interested in collecting.

The road to success is rarely a straightforward one in science and other fields. What sort of setbacks did you experience along the way? If you had major setbacks, what did you learn from them?

Ernst Mayr: In my case, setbacks is probably not quite the right word.

I am at the present time -- and even more so, let's say, 20 years ago -- rather aggressively assertive, and that is due to the fact that, in many ways, all through my early life I was sort of a neglected entity. Now to begin with, I was the middle one of three brothers and in my family, unknowingly, the family always had some preferential things for the oldest one and some preferential treatment for the youngest one, but there was no special preferential treatment in any respect for the middle one, and I resented it. And then I moved around in school a good deal. I first was in Bavaria, in Munich, and then moved to Dresden where they speak a totally different dialect, and I was placed in the seating order as the last one and gradually integrated into the class, and I always had to fight for my existence so to speak. Then in the university I realized that biologists -- zoologists in my case -- really were not considered as highly as the physicists and mathematicians, and again I had to assert myself. And then of course, when I came to America in 1931, I was a German, and Germany at that time was not in very high regard, and in 1933 Hitler came to power and it got even worse, and again I was sort of silently -- unknowingly perhaps -- discriminated against. And then of course, I was a museum person, and at the minute I was branching out into fields like evolutionary biology, history of biology, philosophy of biology. At the beginning, I was a museum man and they didn't have a very high reputation. I wasn't a professor. I wasn't teaching anywhere. And again and again when it came to awarding honors in those days -- now I get more honors than I need -- but I didn't get the honors because I was only a museum person, you see. The result was that I tended to very aggressively defend my views and all that, because if I didn't I would have been ignored.

It sounds like you turned various forms of marginal status into an asset by allowing that to spur you on and prove that you really deserved to be paid attention to.

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Ernst Mayr: Yes, exactly. I had to do that in order to be paid any attention to at all. I have said things that later on other people picked up and made better known, and I have to point it out. I say, "I said this years before, but nobody paid attention to it." Now, for instance, group selection or selection of social groups has become very popular. Well, I pointed out the presence of group selection years ago and nobody ever paid any attention to it. Then the question, "What is the target of selection?" Well, the geneticists of evolutionary synthesis, from Fisher's work in 1930 on, always said it was the gene that was the target of selection, and I fought that in publication after publication. In 1963, in my book, I specifically said the phenotype is the target. Not even the genotype, the phenotype was the target of selection. Well, this was 1963, but that has become generally accepted among the geneticists only since about 1975 or 1980. Very often I had to fight for the recognition of my ideas, particularly since, in those earlier days, I wasn't in any prominent position where people would listen to me.

Natural history used to be denigrated as a kind of stamp collecting by many physical scientists. But in the last 50 years it's really emerged as a sophisticated domain of formal hypothesis testing. You played an absolutely key role in that transformation. What are your thoughts on that?

Ernst Mayr: I have always felt that natural history and anything related to natural history was very much neglected in the thinking of most people. For instance, when they write the history of the evolutionary synthesis, they only mention the mathematical people. The real synthesis, which took place between 1937 and '47, was the synthesis between the "gene pool adaptation," "genetic reconstruction" type of evolutionary biology and the natural history type of biology which is concerned with speciation. There are these two fields. The geneticists don't like to admit it. Recently, some of them finally admitted that the study of biodiversity is as important as the study of adaptation and the turnover in the gene pool. Of course, in connection with conservation, the field of naturalists has also received new impetus and new encouragement, but for a long time natural history was simply considered stamp collecting.

Was there any particular scientific discovery in your career that for you, at least, resembles the kind of epiphany or sudden insight that Newton is supposed to have had with universal gravitation and the famous apple, or that Darwin had in the Galápagos Islands?

Ernst Mayr: Very definitely.

I remember that I was in Naples at the time, and incidentally I went to Pompeii with Jim Watson on the day before, and I had arguments on evolution with a Belgian evolutionist by the name of Heutz, H-e-u-t-z, and we argued and argued, and we couldn't get together at all. And I went back to the hotel and I suddenly had an insight. "Well," I said, "If we have a very small population, a founder population, with a very much impoverished gene content, then a genetic reconstruction -- genetic reordering -- is so much faster and easier than in a large widespread population, and that rapid turnover in a marginal peripheral little population is the secret of why suddenly evolutionary changes occur that will not be reflected in the fossil record, because the chance that one of these little founder populations that rapidly changes will be discovered by geologists is nil." And so I got this idea of the evolutionary importance of the small population for a great speed-up in revolutionary rate. I then came back to lecture on it in Oxford the same year and finally published a paper in 1954 in which I developed the thing. And this paper was later used by Eldredge and Gould. They named this process that I had discovered and described. They named it.

Your paper was the famous Genetic Revolutions in Small Populations, and they called the process "Punctuated Equilibrium," didn't they?

Ernst Mayr: Yes. "Punctuated Equilibrium." I even said in my 1954 paper, and I repeated it again in my 1963 book, that this is what explains, in part, why there are so many gaps in the fossil record. Those kinds of populations would never be discovered by geological work. They said just that, but I had said that in my original paper already.

Keeping in mind that no one can be creative without making some mistake or other, what would you consider to be those areas where you have been wrong theoretically, and what have you learned from those experiences?

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Ernst Mayr: Everybody, looking back, finds that certain things one believed turned out to be wrong. For instance, there was a time when E. B. Ford recognized different kinds of polymorphism, one of them neutral polymorphism, and he said that was one of the chronic errors. In my 1942 book you will find quite a few pages which are devoted to neutral polymorphism, polymorphisms that couldn't be due to any selective forces. Well, I've completely reneged on that one and within a very short time, I think within three or four years.

The next thing is sympatric speciation. When I published my 1942 book, the majority of taxonomists still believed, as had Darwin, that sympatric speciation was the major, if not the almost universal form of speciation. I said, "No, it's geographic speciation," following the lead of some continental European authors. If you read my work carefully, which most of my opponents don't do, I don't say a sympatric species is impossible. I say, "No case of sympatric speciation has been proven, has been well documented." I thought it would be very rare because it would mean simultaneous preference for a given set of characters of the mate, and for the location where the mate is found. Two different things. I said simultaneous preference for two such very different things is impossible. Well, it has now been shown that it occurs very commonly in fishes, particularly cichlid fishes. So here's another thing where my intuition was wrong.

There are other things where I've been accused of having been wrong but I wasn't really wrong. For instance, in 1950, and in preliminary publications before that, I showed that the 115 or so species names for fossil hominids -- and the 32 generic names for fossil hominids -- were ridiculous, and that one should make a null position and adopt the smallest possible number of species in general that are needed to explain the variation among fossil hominids. I furthermore said we have to make the assumption that at any one time only one hominid existed and eliminate about 95 synonyms. Well, pretty soon it was shown that the so-called robust Australopithecus existed side by side with the gracile Australopithecus, therefore the idea that there was at any one time only one fossil hominid is wrong. There are two.

That's about the only really major mistake I made in that line. On the other hand, from the very beginning, I always pointed out that all mammals have geographic races. The primates, for instance, whenever a genus of primates has several species, they are allopatric, with only two exceptions. You have sympatric species of lemurs and cercopithecus. But the South American monkeys, for instance, the different species are all allopatric. And I said, "I'm sure that when you had Australopithecus africanus and Australopithecus afarensis, there must have been a lot of allospecies in other parts of Africa where they haven't found any fossils yet. But in some very recent publications it was stated that I had always fought for a linear sequence of fossil species, which I never had.

So people haven't read you carefully enough?

Ernst Mayr: Their own thinking is strictly linear, so they think that way. I don't know a single specialist in fossil man who really understands geographic variation.

What do you see as the greatest challenges that face a natural history approach today?

Ernst Mayr: There are so many things. Behavior is sort of the pace maker of anything that happens in evolution. All these connections between how behavior varies without genetic changes into behavior that is different because of genetic changes, there is still an awful lot to be done in that whole area. Molecular biology has sort of entered all of biology. We don't have a museum anymore that doesn't have its DNA sequencing machinery. With the molecular methods being used in all branches of biology, I'm beginning to ask, "Is there any molecular biology left? Is there something that isn't really part of some other field?"

Molecular biologists have developed an enormous interest in evolution and that was surely a complete surprise to them. But if you go now to an issue of the Proceedings of the National Academy of Sciences and look at the articles on molecular biology you will find that a quarter if not a third of them deal with evolutionary problems. When molecular biologists take a certain molecule, they are interested in its evolution. "How did it come to be like this in such and such an animal while it is like that in some other animal, and yet this is basically the same gene or the same molecule?" So now the lines drawn between different points of biology have become very vague in many respects. Let me go back now to the question of natural history.

About two years ago, three years ago, for maybe the 20th time I went over the whole business of the species concept. What is a species? I looked at the major figures in the evolutionary synthesis, and I looked at Robzhansky and myself, and Huxley and Stebbins, all of us had reasonable species concepts, and the only person that had a species concept that I thought was quite absurd was the paleontologist G.G. Simpson. And then I said to myself, "Well, he can't have been a naturalist in his youth if he had such a peculiar, unworkable species concept." So I went to Simpson's biography and what did I find? I found that in college he was an English major. He had never been a naturalist as a youngster. He never collected anything, and he discovered geology in his senior year in college, and from there he went to stratigraphy and finally to paleontology. Not surprisingly, not having been a naturalist, he has no idea what a species is and he never had. I argued with him about the species concept year after year, but lacking that background, he was unable to see it, and that is the thing. Being a naturalist -- having had that background of being a naturalist -- gives you a view of nature that cannot be acquired just learning from books.

It's something that you live with. That was where Darwin had his great advantage, and where people like me have a great advantage.

If Charles Darwin were here today and you could ask him one or two questions, what would you want to ask him?

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Ernst Mayr: It would be a lot of personal questions. I would ask him why, after he had developed such an interesting and modern species concept, under the guidance of various zoological consultants, as represented in his notebooks, he suddenly, under the influence of botanists, switched back to a strictly topological species concept, which got him in all sorts of troubles and prevented him from solving what had been the object of The Origin of Species, namely the problem of speciation, which is not solved in that book. "Why did you believe the botanists in all these things, when all the information they gave you was wrong? Didn't you see that what they said was in conflict with what you knew from the zoological observations? Why did you follow the botanists instead of the zoologists?" That's a question, of course, he wouldn't like to hear.

Do you think his friendship with Joseph Hooker led him astray in that regard?

Ernst Mayr: It wasn't so much Hooker. It was a number of others, a man by the name of Watson and two or three other botanists who completely gave him wrong information on species and varieties. Darwin confused the two kinds of varieties: populations that are different and individuals that are different. It wasn't Hooker actually, but he certainly was surrounded by botanists. One reason perhaps was that his principal zoological consultant, Strickland, got killed in an accident. He lost his major zoological consultant and that undoubtedly played a role in this.

When you were doing your field work in New Guinea, did it ever occur to you that you would become the world famous biologist you are today?

Ernst Mayr: I had no idea. In fact, I'm still a little bit puzzled when people say I am a world famous person. I just do my work and publish it and have a wonderful time, and I have never tried to catch public attention by going to the media and doing the things some of my colleagues do. I will not mention any names. So no, it never occurred to me and I don't think my family realizes it. I was interviewed about three or four years ago by Ms. Yoon of The Washington Post, and I mentioned that I had two daughters. She interrupted me and said, "Did they realize how famous you are?" And I said to her, "I hope not." And I really mean that. You see, I basically deal with relatively unspectacular kinds of things. The people that deal with the spectacular issues, of course, are much more famous. I am famous among my peers but I'm not famous among the general public.

Lots of people have great minds and great potential but they don't succeed. Why do you think you've succeeded where others have not? What abilities of yours made it work so well?

Ernst Mayr: I have been thinking about this question myself. One of the answers is that...

Very often I see a statement made by somebody which clearly to me is wrong, and then I work out what is the real right answer, and this happens to me very often. Of course, some of these answers that I find are already in the literature, but sometimes I am the first one who makes that discovery and I think this attention to wrong statements and endeavor to correct them is part of the answer. I always think about things, and if something puzzles me... Well, that of course was one of Darwin's secrets. Whenever something puzzled him, he tried find a theory. He made a conjecture, as (Karl) Popper would call it, and see if it worked out and that's true even today. I go walking with a friend every day and constantly he's amazed at me. I see something and I begin to ask questions. Why are these big rocks here? There shouldn't be any big rocks here, you know. Things like that. I like to ask questions and I think that is part of the secret of my success, that I'll ask questions and occasionally I'll find a very good answer.

What would you most like to be remembered for a century from now?

Ernst Mayr: Well, this has changed in the course of my life. In my early career, my development of the so-called new systematics was the thing I was very proud of, and at the species level everybody followed my idea. The latest thing I'm most proud of that has not yet been fully appreciated by the philosophers is my development of the philosophy of biology.

I am the first one who clearly has said that there are aspects of biology that have nothing to do with vitalism that are so different from anything in the physical sciences that biology simply requires a separate philosophy. For instance, biopopulation, the whole concept of biopopulation, is something that is alien to anybody in the physical sciences and yet it is one of the basic philosophical concepts of biology. The idea that in the physical sciences anything that happens has only one causation and that's the natural laws. In biology everything and anything that happens has two sets of causations, the natural laws and the genetic programs. That's just two of these really fundamental differences between biology and the physical sciences and I'm the first person that has really made this clear and has pointed this out.

Is this the famous distinction between ultimate causes and proximate causes?

Ernst Mayr: That is another aspect of the same distinction, exactly. Another thing is that theories in the physical sciences are always based on natural laws. Natural laws like they have in the physical sciences, we don't have in biology. No specific ones. We have regularities that are sometimes referred to as laws, but they're not the same as the natural laws of the physical sciences. Theories in biology are invariably based on concepts, whether it is the concept of natural selection or "resources" or whatever you name selection. It's a concept that is the basis of any biological field.

What scientific problems have you tried to solve in your career that have eluded you?

Ernst Mayr: I don't think I ever have tackled any scientific problems that ultimately I wasn't able to solve. I think I've always been realistic enough to tackle things that I could solve. There may be exceptions. I don't recall at this moment. I've been very much interested in animal behavior at certain times of my life, but I realized that this would require total attention, and I wasn't willing to give it, so I didn't follow up on it.

What advice would you give to younger scientists today who are just starting out about how to succeed in the profession?

James Watson Interview Photo
Ernst Mayr: The interests of a person plays a considerable role. For instance, people who are born naturalists should choose different professions than people who have a spectacular mathematical talent. I think it depends on a person's talent, what he should choose and what he should love. If you don't love what you're doing, you're not going to do a good job.

We understand you played some kind of a role in James Watson's career and his thinking about DNA. Can you tell us a little bit about that?

Ernst Mayr: Well, this is almost like a joke, but when I was at the American Museum in New York, a lot of young people came and saw me. I was well-known as someone young people, particularly bird watchers, could talk to. It was well-known that I had a great deal of experience in anything having to do with birds.

One day Jim Watson's parents appeared in my office. They had some other thing to do in New York, no doubt, because they lived in Chicago. They knew I was an ornithologist and I think Jim knew about me and had already acquired a certain admiration for my work. So Ms. Watson asked me, "Jim wants to become an ornithologist. Where should he go for his studies of ornithology?" At that time, of course, everybody went to Cornell. And I said -- probably to their surprise -- I said, "He shouldn't study ornithology at all. He should, in his undergraduate career, get a very good basic training in biology. And when, after four years, he was still keen on ornithology, then I would be willing to suggest where you should go for graduate school in ornithology. Maybe other people said the same thing. I don't credit myself as being the only one who guided his future. Anyhow he did follow just that. He went to a good school -- I think it was the University of Chicago -- got an excellent training in biology, and of course in the course of that he encountered all sorts of interests, all sorts of problems that are far more interesting than bird watching, and so he never followed up his intention to become an ornithologist, but he became the discoverer of the double helix, all through my giving him good advice!

What kind of talents do you believe that you lack, that you might liked to have had?

Ernst Mayr: I never was very good at mathematics, and I take a book that is even considered not very difficult, let's say, like Fisher's Genetic Theory of Evolution, and I'm very soon stumped by the mathematical formulae he introduces. Another thing is, it turns out I'm not very good with my hands, so if I had gone into medicine I wouldn't have been a good surgeon. I would have been a very good diagnostician. I can sort of have an intuition for just hints of observational things like that. It depends a little bit on a subset, on what field you're in. I have assessed that I'm no good with my hands, no good mathematically, I have a superb memory. I'm very discriminating and I have one thing, I mentioned earlier, I share with Darwin, and that is an incredible curiosity and the ability to ask questions. And very broad interests. There's hardly any field that I'm not interested in. People in the faculty luncheons and things like that, I get next to a fellow from the business school and I can have a very good conversation with him on his field, because I'm interested in that, too. Or you name it, I'm interested in that field. So, broad interests. Of course, most of the great scientists have very broad interests, and those are feeding in from other fields into the special thing he's working on and helps to broaden his approach to his special field.

You were talking a little bit about your diagnostic skills, which really are dependent on the kind of mind that's good at synthesis of information. There's a story I heard you tell about how you diagnosed your own kidney problems to the amazement of the physician. Can you tell us that story?

Ernst Mayr: When I was about 30, I had suddenly developed bleeding from my... I had blood in my urine -- let's put it that way -- and no special pains or anything, but every three or four months I'd have another spell of bleeding. Finally, being very unsuccessful with ordinary doctors, I went up to the urogenital clinic at P and S: Physician and Surgeon Medical School of Columbia University in New York, up on Broadway and 168th Street. I went up to the floor "I", which said "Urogenital." I didn't know anybody. And the receptionist said, "Whom do you want to see?" And I said, "I want to see some specialist of urinary problems." And so she got an intern, a fellow by the name of Rathbone, who got me into his office, and he said, "Now, young man, what's your problem?" And I said, "I think I have a tumor in my left kidney." And he immediately laughed. He said, "Now young man, a tumor in a kidney is a thing very difficult to diagnose. Whatever got you to have that diagnosis?" And I said, "Well," I said, "The blood in my urine is rather black, and so I decided it wasn't something in the bladder but up in the kidney. And the second thing is I don't have any special pains, any really acute pains. So it isn't a kidney stone." And then I said "In my left kidney, I sometimes have a heavy feeling in my left side, so I decided it is in my left kidney. And then my father died of sarcoma of the kidney and so to guess that it might be a tumor was the obvious one for me, and that's how I came to my diagnosis." And he said, "Well," he said, "We have to make all the tests." And they cytoscoped me and they x-rayed me and they finally found something. By God, it looked like a little papilloma in the pelvis of the left kidney. And they said, "Well, we have to watch this. Come back in half a year and we'll take another x-ray, and if it has grown in the meantime then we'll have to operate on it." Well, it had grown and my left kidney was taken out. And when I was lying there about three or four days after the operation, the physician in charge of the floor came by with his students every day for the clinical analysis and when he came to my bed, he said, "Now, here we have a very unusual case. Here is a patient who came to us with a ready-made diagnosis, and for once he was right!"

In your own opinion, what are the most important contributions you've made to science?

Ernst Mayr: That is a difficult question to answer because I've worked in so many fields. I've worked in five different fields. Now which are the most important? In some ways, the development of the biological species concept, which I did not invent, but I certainly was the person that brought it to general knowledge. And the whole field of new systematics -- I really am the one who developed it -- was one of my major contributions. There's another one, which is still not yet realized by almost anybody.

I have done more, I believe, for the development of a philosophy of biology than any other person. Others have written books on the philosophy of biology but always in the framework of the standard philosophy of science, which is based on physics, logic and mathematics, while I have been trying to show that there are a certain number of basic concepts in biology -- like the genetic program or biopopulation and a few others -- that make biology just simply totally different from the physical sciences, and therefore also requiring an entirely different philosophy.

Why do you think it took so long for people to appreciate the differences between a biological approach to scientific explanation and a physical sciences approach?

Ernst Mayr: I think it was a professional thing. All the people that went into philosophy of science came from logic, from mathematics, and from the physical sciences. In earlier periods, all the people that did philosophy of biology in the whole 19th Century and the early part of the 20th Century were affected by the bug of vitalism. In other words, they believed that physics was a pure science but that biology required that extra thing which nobody understood: the vis viva, or lebenskraft or elan vital. That had to be refuted first, and the complete refutation of vitalism didn't happen until about the 1920s or '30s. Only then could you develop a complete philosophy of biology that was based on biology, that was based on living organisms but explained everything at the cellular, molecular level, all in terms of physics and chemistry, not invoking any "vital forces" or something like that.

Are there other theoretical disagreements or controversies you'd like to weigh in on, or mistakes you see other theoreticians making today?

Ernst Mayr: Well, I have spent several years now in corresponding with numerous people on the subject of cladistics and I've come to the following conclusion. Darwin, in the 13th chapter of the Origin said, "You cannot recognize any taxon, or any species, or even higher than taxon, without making sure first that all the members are descendants of the nearest common ancestor." He said the classification must be genealogical. However, Darwin continued and said this repeatedly, "Genealogy alone never gives you a good classification." We first have to make groups of similar things, and then make sure that they're pure by subjecting them to this cladistic analysis.

On the other hand, the cladists suggest that Darwin said, "I do not pay any attention to the amount of difference or similarity. I go just by the branching points." Which means in order to have a so-called classification, you take the different branches of a tree and make these into a sort of a classification. That is a disastrous thing that leads to nothing but complete nonsense. So when a cladist talks about avian dinosaurs, that's just total nonsense. No bird is a dinosaur. No dinosaur is a bird, just because they happen to be on the same phyletic lineage. If you do the Darwinian thing and recognize degrees of difference then, of course, you have to cut that lineage in various places and make the kind of taxons that are useful and meaningful. That's what makes a classification. Cladification by just putting the clades together is total nonsense. I think in another 10 or 15 years, the cladistic wave that we are having at the present time will have completely died down and be forgotten. I won't be there when it happens.

Tell us a little bit about your most current scientific projects. You have a number of them going and they're all making good speed.

Ernst Mayr: Unfortunately I have too many projects going. Two of them, fortunately, are already in the editors' hands. One is this book on the birds of Northern Melanesia I'm doing with Jared Diamond, and that deals with speciation and particular ecology, biogeographic dispersal and all the other questions. We have material for each one of the 194 species and I think it will be considered a classic when it is published.

The second book is an evolution book. We already have some extremely good books, three of them, great big books -- 700 pages -- on evolution by Futuyma, by Ridley and by Strickberger. And if a beginner wants to have a book on evolution we can give him those kinds of books. We have otherwise a whole series of good books refuting the claims of the Creationists, but we don't have a mid-level book that is a good introduction into evolutional biology without going into the utmost detail. That's the kind of book I've written. It is, as I said, already in the editor's hands, and will come out some time this year.

Now I'm working also on a book that I'm surprised nobody else has written before.

If you asked anybody which book has, at the present time, the greatest impact, and had the greatest impact on the thinking of Western man, of course, the Bible is in first place. And then the next thing is "What's next?" Well, for a while, of course, it was Karl Marx with Das Kapital, but ever since the bankruptcy of Marxism was declared in '89, I think you would never place that right after the Bible. And then the only other book that is really in the running there is Darwin's Origin of Species.

So what I'm doing is an extremely detailed analysis of the first edition of Darwin's Origin of Species in 1859. I really look at every sentence, and compare it with what he said before and afterwards, and why he said that and so on and so forth. That book consists of two parts. I have a first draft of the first part. I still have to do the second part. Otherwise the whole thing will take me another two years before it's finished. Finally, I have a manuscript of about 70 pages on the basic principles, the theory of ordering material, usually referred to as classification. But I discovered that classification is only one of many systems of ordering. For instance, a telephone directory is a system of ordering, but it is not a classification. This is very important, because right now in the field of taxonomy we have a great controversy going between people who order in the traditional manner, by recognizing classes of similar entities and lodging them in a hierarchical system, or one which divides up the phylogenetic tree into branches and sorts in these branches. These are two very different systems, although the partisans of the branching approach do not realize how different they are. I have a manuscript that is in the next to the last draft and might not be published this year but certainly will be finished this year. That's the work I've been doing lately.

Dr. Mayr, at age 96, your productivity continues to leave all of us in awe, and on behalf of the Academy of Achievement I'd like to thank you for a fascinating interview.

Ernst Mayr: Well, you're welcome.

This page last revised on Apr 14, 2014 12:06 EDT