Biology in the Twenty-First Century
This address was delivered at the 51st Annual Meeting of the American
Institute of Biological Sciences, in Washington, DC, on 22 March 2000, where
Professor Ernst Mayr Received the AIBS Distinguished Servive Award.
by Ernst Mayr
he award
given to me by the American Institute of Biological Sciences fills me with
pride and gratitude, particularly since it was also awarded to my friend,
Ledyard Stebbins, perhaps the greatest botanist of the twentieth century. It
greatly saddened me to learn of his death in January. How gratifying that he
was still able to receive this honor in person last year at the meeting of
the Botanical Society of America. On that occasion, Ledyard expertly
described the trials and tribulations of evolutionism and its ultimately
overwhelming victory in the twentieth century.
It was not only evolutionary biology that had to fight
for recognition, but indeed biology as a whole. It would, therefore, be
appropriate at this anniversary of AIBS to say a few words about biology as
a whole and its meaning for mankind. There is a great danger that a
specialist becomes so deeply involved in his detailed researches that he
forgets to consider the ultimate meaning of his findings.
We are celebrating this jubilee of AIBS because it
signifies the unification of biology. Biology has given rise to an almost
endless number of special societies ranging from molecular biology to
several branches of ecology, systematics, physiology, developmental biology,
evolutionary biology, paleontology, behavioral biology, and many more, all
with their own journals, their own societies, their own jargon, and their
own literature. The members of many of these societies have virtually no
contact with those of other societies. It was AIBS, more than anything else,
which, by forming an umbrella organization, as had existed for many other
branches of science, established a cohesion among the specialized
disciplines of biology.
Most living biologists, particularly the younger ones,
may not realize how young a science biology is. To discover this, let us
take a glance at the history of biology. The field had a most promising
beginning with Aristotle in the third century before Christ. Aristotle was
quite extraordinary because he was not only an excellent naturalist,
particularly a very knowledgeable student of marine animals, but also
interested in physiology and embryology. Alas, this promising beginning was
not further followed up for almost 2000 years. In the sixteenth,
seventeenth, and eighteenth centuries the famous Scientific Revolution took
place, characterized by such names as Galileo, Kepler, Newton, and
Descartes. When they made their great discoveries in the physical sciences,
where was biology?
To be sure, there was a considerable interest in living
nature but no cohesive science. There were two camps: one was
the naturalists, who studied nature in the spirit of
Natural Theology, who discovered evermore
pieces of evidence for God's near perfect design of the living world. The
writings of these naturalists reveal a remarkable understanding of the life
histories and adaptations of living organisms but were not seen, at that
time, as being science. Medicine was the other stronghold of biology. It
produced marvelous achievements in such fields as anatomy (Vesalius),
embryology (Harvey), and physiology. Botany was vigorously advanced at that
period because all medications used by medicine were derived from herbs and
an exact identification of plants was of crucial practical value. All great
botanists from the sixteenth to the end of the eighteenth century, with the
single exception of John Ray, were medical doctors. This includes the great
Linnaeus, often called the founder of systematics.
Around the year 1800, three different authors, the
French zoologist Lamarck and two Germans, introduced the word biology,
referring to the study of the world of life. These authors called for the
development of such a science, but it did not yet exist. There could not be
a science of biology until one had first learned a great deal more about the
living world; the major biological disciplines had first to be founded. This
took place in the 38 years from 1828 to 1866: embryology (Von Baer, 1828),
cytology (Schwann-Schleiden, 1830s), physiology (Claude Bernard, Helmholtz,
1840s), evolution (Wallace-Darwin, 1858-1859), and genetics (Mendel, 1866).
Yet a real synthesis did not take place until 75 years
later. Until then the workers in functional biology (physiology, embryology)
ignored the achievements of evolutionary biology (and genetics) and vice
versa. Indeed, major controversies within each of these fields had to be
settled first. As far as evolutionary biology is concerned, in the early
1930s there were two factions, on one side the experimental geneticists,
mostly interested in the mechanism of evolution and studying variation
within a population as well as the achievement and maintenance of
adaptation, and another faction consisting of the naturalists, systematists,
and paleontologists, primarily interested in the study of biodiversity, that
is, species, speciation, and macroevolution. In the years 1937 to 1947, a
synthesis of the two fields was achieved owing to a mutual understanding of
each others' views. The result was the so-called evolutionary synthesis,
actually very much of a return to classical Darwinism, evolution as
variation and selection.
The next major event was the founding of
molecular biology through
the discoveries of Avery and of
Watson and
Crick, between 1944 and 1953. One might have expected that this would result
in a major revolution in evolutionary biology, but this did not take place.
What molecular biology made possible was a fine-grained analysis but it did
not result in a refutation of the underlying Darwinian theory. Molecular
biology indeed made some magnificent contributions to our understanding of
evolution—such as that the material of inheritance is nucleic acid
rather than proteins and that the genetic code is the same for all organisms
from the bacteria up, indicating a single origin of life—but it did not
touch the basic Darwinian framework. Perhaps the greatest contribution made
by molecular biology was that it gave a new lease on life to developmental
biology, which for several decades had been virtually dormant. One could
refer to the last 50 years as the era of nucleic acids. But DNA only gives
information and instructions; the real work in development is done by
proteins. I foresee that the next 50 years will be more and more an era of
the proteins. Others will report on these findings in various lectures at
these meetings and bring us up to date on the developments in the other most
active fields of biology, such as neurobiology. I will not try to preempt
these presentations.
Instead, I will try to take a look at the future. With
all these achievements, will I be willing to say that the task of biology is
finished? Not by any means! To be sure, the major theoretical framework of
modern biology is remarkably robust. Even in a field as tumultuous as
evolutionary biology, our currently accepted theories are remarkably similar
to Darwin's original proposals. However, the basic philosophy of biology, as
it developed in the last 50 years, has become quite different from the
classical philosophy of science as it prevailed from the Vienna school of
Carnap and Neurath to Popper and Kuhn. In the rejection on one hand of all
vitalistic theories and of such concepts as cosmic teleology, and on the
other hand of all physicalist concepts such as essentialism, determinism,
and reductionism, and their replacement by an acceptance of the frequency of
random events, plural solutions, the importance of historical narratives,
multiple causations, population thinking, and the greater importance of
concepts than of laws in theory formations, the new biology has undergone a
complete revolution.
But what about our understanding of the basic biological
phenomena? I have the feeling that we are remarkably far advanced in the
understanding of the basic phenomena—let us say how a neuron works or
the nature of genes. Where our knowledge lags behind is in the understanding
of complex systems. The first of these is the developmental system, the
development of a zygote from the fertilized egg to the finished adult. There
is still an enormous amount to be learned, not only about the interaction of
various kinds of genes, particularly regulatory genes, but also about the
inducing interaction between different tissues.
The second complex system of which we still have a very
insufficient understanding is, as we all know, the central nervous system.
I wonder whether we will ever know all the interactions of the three billion
neurons of our central nervous system, each of which has up to a thousand
connections (synapses) with other neurons? I find it totally miraculous that
at the age of ninety-five I can suddenly remember a name of which I had not
thought of for eighty years! There is no doubt that we still have a long way
to go in our understanding of the mind.
The third complex system is the ecosystem, the
interaction of the thousands of organisms from the largest trees to the
smallest bacteria in the biota of a locality and what controls their
presence, frequency, and interactions. There is a great future ahead in the
study of these three systems.
What is the probability that the new advances in gene
technology and other modern biological techniques affect our own personal
life? What is the chance that as a result of ongoing biological researches
we may one day have to face something entirely new and undesirable?
Unfortunately, too many people take science fiction seriously and believe
the most absurd accounts of possible future developments. They are afraid
that the new gene techniques might produce monsters and other misfits. I am
convinced that there is no chance for this whatsoever. To be sure, there are
now techniques for the replacement of defective genes, perhaps even in the
germ line. I specifically said defective genes. However, at the present time
we have neither the knowledge nor the methods to make people more
intelligent or more altruistic or, for that matter, more stupid or more
malicious.
There is no subject on which in recent years more
nonsense has been written than on cloning. To talk about whole populations
of Einstein clones is simply absurd. A single clone in a family might be
justified occasionally but this clone would not differ significantly from a
monozygotic twin in that family.
When thinking about the future of biology, let us think
of the vast benefits which biology has brought to mankind in the past.
Indeed, biology is likely to continue to bring us in the future equally
unexpected benefits, particularly in medicine and agriculture. The great
reduction of premature mortality in mankind and correspondingly the virtual
doubling of human life expectancy in the last 100 years is an achievement of
biology.
Let me sum it up. Biology is healthy and well and is
looking with confidence to great further achievements in the future.
Furthermore, and this is perhaps my most important conclusion, being a
biologist is so much fun!
Ernst Mayr is Alexander Agassiz Professor of Zoology,
Emeritus, at Harvard University.
[ Ernst Mayr, "Biology in the Twenty-First Century,"
Bioscience 50 (Oct. 2000): 895-897. ]
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