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Ernst
Mayr: This is Biology:
the
science of the living world
(Belknap/Harvard:1997)
“More and more
clearly, Ibegan to see that biology was a quite different
science from the physical sciences; it differed fundamentally
in its subject matter, its history, its methods, and its
philosophy. While all biological processes are compatible
with the laws of physics and chemistry, living organisms
could not be reduced to these physiochemical laws, and
the physical sciences could not address many aspects of
nature that were unique to the living world. The classical
physical sciences, on which the classical philosophy of
science was based, were dominated by a set of ideas inappropriate
to the study of organisms: these included essentialism,
determinism, universalism, and reductionism. Biology,
properly understood, comprises population thinking, probability,
chance, pluralism, emergence, and historical narratives.
What was needed was a new philosophy of science.”
(Mayr, p.xiii)
And thus, perhaps the greatest of living biologists introduces
the conceptual bases of his discipline...which he, perhaps
more than any other, has done so much to clarify and promote.
We would do well to pay him heed, particularly given that
the contemporary general understanding of this area is
so heavily skewed toward genetics and the modeling of
population biologists, who also (and invariably) happen
to use drastically simplified - and clearly falsified
- assumptions re gene activity, a fact little known to
most of their lay audience. By clearly insisting upon
the intractable pluralism of biology as a whole, and through
tracing the intellectual history of some of its key strands,
Mayr delivers us a crucially whole
perspective upon this most varied of disciplines, and
one with profound implications for its (unnecessarily
fraught) relation to the humanities.
For those of you who don’t know, Ernst Mayr is the
last surviving key player in the creation of the modern
synthesis - or neodarwinism, as it is better known. His
contribution was that of reformulating taxonomy and related
disciplines (the rootstock of scientific biology) into
systematics...reconciling its techniques and assumptions
with the emerging synthesis of Darwinism and genetics
and, as in all of the other key stages of the synthesis,
then prompting shifts in these areas as well. For this
intellectual movement was hardly the surrender to population
genetics that some of the latter’s more extreme
proponents appear to have assumed. Rather, the accommodation
was mutual, as Mayr has repeatedly insisted, and - although
key areas such as development were not included, largely
due to the paucity and intractable complexity of the evidence
then to hand - the result was a stunning success, on both
practical and intellectual grounds.
Much later in his career, Mayr gradually began to concentrate
upon the philosophy and history of biology, culminating
in the magisterial Growth
of Biological Thought in 1982, to be followed by
a series of shorter - and, in the main, more accessible
- works, following up on different aspects of this, in
which the book under review here is the third and, perhaps,
the most important. It is this unequaled background which
makes his such an authoritative voice, despite being little
known to the general public...and, therefore, if you want
to know what biology actually
is - as opposed to the partisan claims of certain celebrated
specialists - this is definitely the book to turn to.
And, as we shall see, the reality is that the humanities
has much more in common with its scientific neighbor than
most suspect...
“The incorporation
of biology has modified many of the tenets of the philosophy
of science.... The rejection of strict determinism and
of reliance upon universal laws, the acceptance of merely
probabilistic prediction and of historical narratives,
the acknowledgment of the important role of concepts in
theory formation, the recognition of the population concept
and of the role of unique individuals, and many other
aspects of biological thought have affected the philosophy
of science fundamentally. With probabilism now dominant,
all aspects of logical thought that are based on typological
assumptions have become highly vulnerable. The complete
certainty which, following Descartes, had been the ideal
of the philosophers of science seems less and less important
as a goal.”
(Mayr, pp.36-7)
“Those who have
a high regard for natural laws are mostly thinking about
the regularities of nature.... [However,] regularities
are abundant in the living world, too, but most of these
regularities are not universal and without exception;
they are probabilistic and very much restricted in space
and time.... In biology, concepts play a far greater role
in theory formation than do laws.... In evolutionary biology,
for example, they include selection, female choice, territory,
competition, altruism, biopopulation, and many others.
Concepts, of course, are not restricted to biology....
I have the impression, however, that the number of basic
concepts is rather limited in the physical sciences, and
in such fields of functional biology such as physiology,
where the discovery of new facts is very important....
The classical philosophy of science has made curiously
little reference to the important role of concepts in
theory formation. The longer I study theory formation,
however, the more I am impressed by the fact that theories
in the physical sciences are usually based on laws, those
in biology on concepts.”
(Mayr, pp.62-3)
“As far as the
demarcation between science and the humanities is concerned,
the tendency of writers in the past to ignore the heterogeneity
of both fields has led to many misconceptions. There is
more difference between physics and evolutionary biology
- both of which are branches of science - than between
evolutionary biology (one of the sciences) and history
(one of the humanities).... In other words, the sharp
break between the ‘sciences’ and the ‘nonsciences’
does not exist, once biology is admitted into the realm
of science.”
(Mayr, pp.37-8)
That this is, still, a controversial view - rather than
a simple truism - is due, I feel, to incomprehension on
both sides, to
a large extent driven by ill-informed polemics rather
than real understanding. It’s also worth noting
that the much better informed approach has been largely
driven by historians - from Marc Bloch to John Lewis Gaddis
- on the humanities side, and by natural historians -
rather than laboratory biologists - on the other. For
it is they who, invariably, have to deal w/the whole,
messy depth of their subjects...and, at that level, the
similarities are most obvious...
This is not to say, however, that they are identical,
by any means. The differences, driven by interacting
psychological, social and cultural factors, remain crucial
to the humanities, and the human sciences. What it does
strongly suggest, however, is that the work of doing so
should rather naturally build upon a proper understanding
of the organismic basics - the territory, of course, of
biology. Meanwhile, it’s also remarkable how clearly
(and easily) Mayr disposes of those philosophical myths
which have traditionally seen historical approaches as
basically “unscientific”...yet another reason
why this book is such a valuable one for humanists:
“The reason why
historical narratives have explanatory value is that earlier
events in a historical sequence usually make a causal
contribution to later events.... [So] the most important
[scientific] objective of a historical narrative is to
discover causal factors that contributed to the occurrence
of later events in a historical sequence. The establishment
of historical narrative does not in the least mean the
abandonment of causality, but it is a particularistic
causality arrived at strictly empirically. It does not
relate to any law but, rather, explains a simple, unique
case.”
(Mayr, pp.65-6)
“Causality in
simple interactions is often highly predictive.... However,
such a simple solution is rarely available in biology,
except at the cellular-molecular level. The problem is
particularly perplexing whenever the effect is the end
of a whole chain of events. It is perhaps a residue of
teleological thinking that makes us search at the beginning
of the process for the cause producing the predictable
end effect. But in biology, this approach is usually not
successful; in fact, it is often misleading.... An interaction
between two individuals, prior to its conclusion, goes
through a whole series of stages, during most of which
each of the acting individuals has several options available.
Which of these he will choose is not strictly determined
at the beginning of the stage, but depends upon a number
of factors and contingencies. Strict causality can usually
be construed only when the chosen option at each step
of the chain of actions is looked at retrospectively.
In fact, the whole process (even its random components)
can be considered to have been causal when retrospectively
considered. One could therefore say, somewhat paradoxically,
that causation in complex situations is an a posteriori
reconstruction, or, to put it differently, causation consists
of a series of steps which, taken together, can be called
the cause.”
(Mayr, pp.66-7)
“There is a further
complication as far as causation in biology is concerned.
Every phenomenon or process in living organisms is the
result of two separate causations, usually referred to
as proximate (functional) causations and ultimate (evolutionary)
causations. All the activities or processes involving
instructions from a program are proximate causations.
This means particularly the causation of physiological,
developmental, and behavioral processes that are controlled
by genetic and somatic programs. They are answers to ‘How’
questions. Ultimate or evolutionary causations are those
that lead to the origin of new genetic programs, or to
the modification of existing ones...They cannot be investigated
by the methods of chemistry or physics, but must be reconstructed
by historical inferences - by the testing of historical
narratives. They are usually the answer to ‘Why’
questions.... Many famous controversies in the history
of biology came about because one party considered only
proximate causations and the other party considered only
evolutionary ones.... [But] when one looks carefully at
a biological problem, one can usually discover more than
one causal explanation.... Such pluralism of beliefs presents
a problem for both verification and falsification....
Curiously, pluralism in biological explanation was much
better appreciated by the old-time naturalists than by
modern specialists.... [Moreover,] almost every protracted
controversy in biology was terminated by the rejection
of both previous
explanations, and the adoption of a new one.”
(Mayr, pp.67-9)
As the great proponent of what he terms “population
thinking” - the accordance of crucial importance
to individual variation that modern biology has inherited
from Charles Darwin - Mayr is probably the best qualified
to correct the anti-biological foolishness of proudly
“anti-essentialist” thinkers in the humanities.
For, what they clearly don’t realize is that systematic
thinking along these lines, although anticipated by Adam
Smith, was most thoroughly advanced by Darwin, in biology...making
their accusations of “determinism” re biological
thinking about 150 years behind the times! Similarly,
Darwin also dealt the crucial blow against teleology,
thus also undermining the kind of “metanarratives”
they oppose. Any good historian of biology could easily
tell them this...definitely furthering my already well-founded
suspicion that much of this so-called “scholarship”
is simply bogus...
One key feature of this book, in fact - a usefully atypical
one, today - is Mayr’s robust defense of the descriptive
and classificatory base of science...all too commonly
sneered at as mere “stamp collecting”. This
is perhaps to be expected, with Mayr’s background
in systematics, but it is, nonetheless, an extremely important
case to make. As he argues, “what” questions
have a clear logical priority over “how” and
“why” questions - which cannot even be seriously
proposed until the proper range of facts are clearly laid
out. Moreover, exactly how those facts are to be classified
is, itself, a crucial intellectual task:
“Every classification
system has two major functions: to facilitate information
retrieval and to serve as the basis for comparative research.
Classification is the key to the system of information
storage in any field.... Classifications are heuristic
systems.”
(Mayr, pp.125-6)
Another of the (many) pleasures of this book - albeit
one which is necessarily under-represented in this review
- is Mayr’s encyclopedic knowledge of the history
of biology, most evident in those chapters outlining the
growth of understanding in various key subdisciplines.
This allows him to get to the core...not only of key historical
disputes, but also of their modern counterparts, and to
advance some highly insightful conclusions which could
provide much-needed lessons for us all:
“The reasons why
some theories have to struggle for the better part of
a century before they are accepted, while a few new ideas
succeed almost instantaneously, are manifold; I will list
six of them. One reason that consensus takes a long time
to achieve is that different sets of evidence lead to
different conclusions.... A second reason...is that disagreeing
scientists adhere to different underlying ideologies,
making certain theories acceptable to one group which
are impossible for another group.... The replacement of
ideologies (‘deep paradigms’) meets far more
resistance than the replacement of erroneous theories.
Such viewpoints such as vitalism, essentialism, creationism,
teleology, and natural theology were an essential part
of the worldview of those who held them, and were not
easily given up. Opposing concepts therefore spread only
slowly, by recruiting adherents who did not yet have a
firm worldview. A third reason is that at a given time,
several explanations may seem to account for the same
phenomena equally well...[or,] in some cases, there is
actually a pluralism of possible answers.... Sometimes
a consensus cannot be reached because one biologist is
concerned with proximate, the other with evolutionary
causations.... [And finally,] some factors that work against
the acceptance of new ideas are not strictly scientific....
Presumably in these cases one of the other five reasons
above was primary, but once a tradition was established
it was tenaciously maintained even in the face of all
opposing evidence.”
(Mayr, pp.102-4)
To these, however, I feel we should add two that have
clearly played an important part, particularly in disciplines
where, respectively, mechanism and mathematical modeling
have served as the gold standard. The first is where,
although factual evidence appears to converge upon some
outcome, no plausible mechanism which could account for
it has yet been proposed, as in the case of continental
drift in geology. The second, and much more serious problem
- as it so evidently leads to theoretical ossification
- is where mathematical tractibility, rather than the
evidence per se, serves as the justification for the dismissal
of more factually-based theories, usually pluralistic,
which are not so easily (or at all) modelled. Population
biology - with its extremely unrealistic “beanbag
genetics” assumptions - is clearly the main offender
here in the life sciences. Admittedly, one could - at
a stretch - incorporate these within Mayr’s typology
(under classifications one & two, perhaps), however
I feel that, due to both their prominence and persistent
recurrence, they amply deserve separate status.
The first book by Ernst Mayr that I encountered, well
over a decade ago, was One
Long Argument: Charles Darwin and the Genesis of Modern
Evolutionary Thought which, to my mind, is an exemplary
work in the history of ideas - demonstrating the strongly
differential reception of Darwin’s theories, and
making clear just how this can be tied to the long-established
ideologies which they challenged. For, contra Spencer’s
- not Darwin’s
- misnamed “Social Darwinism”, his theories
seriously (and effectively) undermined some of the crucial
shared assumptions of the day - essentialism, teleology,
the passive nature of the female - and, aside from the
basic fact of evolution as such - had little support until
well into this century, with sexual selection only fully
established as late as the 1970s. Here, he restates some
of the core arguments of that earlier work, and provides
a useful corrective to some of the misunderstandings which
still bedevil Darwin’s legacy, especially in popular
understandings...
“Darwin’s
Origin of Species
established five major theories relating to different
aspects of variational evolution: (1) that organisms steadily
evolve over time (this we might designate as the theory
of evolution as such), (2) that different kinds of organisms
descended from a common ancestor (the theory of common
descent), (3) that species multiply over time (the theory
of the multiplication of species, or speciation), (4)
that evolution takes place through the gradual change
of populations (the theory of gradualism), (5) and that
the mechanism of evolution is the competition among vast
numbers of unique individuals for limited resources, which
leads to differences in survival and reproduction (the
theory of natural selection).”
(Mayr, pp.177-8)
“Only in recent
years have evolutionists fully understood how drastically
different Darwin’s theory of evolution through natural
selection was from earlier essentialistic or teleological
theories. When Darwin published the Origin ,
he had no proof for the existence of natural selection;
he postulated it only from inference. Darwin’s theory
was based on five facts and three inferences.... The first
three facts are the potentially exponential increase of
populations, the observed steady-state stability of populations,
and the limitation of resources. From this follows the
inference that their must be competition (a struggle for
existence) among individuals. Two further facts, the genetic
uniqueness of every individual and the heritability of
much of individual variation, lead to the second inference,
differential survival (that is, natural selection), and
to the third inference that a continuation of this process
through many generations would result in evolution....
The principle of natural selection is so logical and so
obvious that today it can hardly be questioned at all.
What can be, and indeed must be, tested in each individual
case is to what extent natural selection has contributed
to the characteristics of a particular component of the
phenotype. For each characteristic, the questions that
must be asked are: Was the evolutionary emergence of this
characteristic favored by natural selection, and what
was its survival value that has led to its being favored
by natural selection? This is the so-called adaptional
program.”
(Mayr, pp.189-91)
“If natural selection
does not necessarily produce evolutionary progress, neither
does it produce perfection, as Darwin pointed out...[as]
there are numerous limits or constraints on its power
to bring about change. First of all, the genetic variation
needed to perfect a characteristic may not be forthcoming.
Second, during evolution, the adoption of one among several
possible solutions to a new environmental opportunity
may greatly restrict the possibilities for subsequent
evolution...Another constraint on natural selection is
developmental interaction. The different components of
the phenotype are not independent of one another, and
none of them responds to selection without interacting
with one another. The whole developmental machinery is
a single interacting system...[and so,] organisms are
compromises among competing demands.... The structure
of the genotype itself imposes limits on the power of
natural selection. The classical metaphor of the genotype
was of a beaded string...[and] each gene was more or less
independent of the others. Not much is left of this previously
accepted image. It is now known that there are different
functional classes of genes...[and] deciding how they
all interact with one another, and particularly, what
controls the epistatic interactions between particular
gene loci, is still a rather poorly understood area of
genetics. A further constraint on natural selection is
the capacity for non-genetic modification. The more plastic
the phenotype is (owing to developmental flexibility),
the more this reduces the force of adverse selection pressures....
Finally, much of the differential survival and reproduction
in a population is the result of chance, and this also
limits the power of natural selection. Chance operates
at every level of the process of reproduction.... Yet
over time...relative fitness always plays a major role.”
(Mayr, pp.198-200)
At the heart of Mayr’s account of the history of
biology lies the long-running dispute between mechanistic/physicalistic
approaches, and those who postulated vitalistic forces...a
dispute only resolved after centuries of wrangling. Often
understood today as a qualified victory for the former,
Mayr clearly explains that this was not at all the case
- since physicalist accounts - very like those of the
vitalists, actually - relied upon very vaguely specified
forces to cover awkward facts, whilst the (scientific,
as opposed to mystical) vitalists built up an important
body of empirical work in exactly those areas in which
narrow physicalist accounts were most deficient. And when,
finally, the dispute was resolved, the modern account
proved markedly different to both
its predecessors:
“When biologists
and philosophers speak of ‘life’...they usually
are not referring to life (that is, living) as contrasted
with death but rather to life as contrasted with the lifelessness
of an inanimate object.... The problem here is that ‘life’
suggests some ‘thing’ - a substance or force
- and for centuries philosophers and biologists have tried
to identify this life substance or vital force, to no
avail. In reality, the noun ‘life’ is merely
a reification of the process of living. It does not exist
as an independent entity.... [And] there was always a
camp claiming that living organisms were not really different
at all from inanimate matter; sometimes these people were
called mechanists, later physicalists. And there was always
an opposing camp - called vitalists - claiming instead
that living organisms had properties that could not be
found in inert matter.... In this century, it has become
clear that both camps were partly right and partly wrong.
The physicalists had been right in insisting that there
is no metaphysical life component, and that at the molecular
level life can be explained according to the principles
of physics and chemistry. At the same time, the vitalists
had been right in asserting that, nevertheless, living
organisms are not the same as inert matter but have numerous
autonomous characteristics, particularly their historically
acquired genetic programs, that are unknown in inanimate
matter. Organisms are many-level ordered systems, quite
unlike anything found in the inanimate world. The philosophy
that eventually incorporated the best principles from
both physicalism and vitalism (after discarding the excesses)
became known as organicism, and this is the paradigm that
is dominant today.”
(Mayr, pp.2-3)
“This new paradigm
accepted that processes at the molecular level could be
explained exhaustively by physiochemical mechanisms, but
that such mechanisms played an increasingly smaller, if
not negligible, role at higher levels of integration.
There they are supplemented or replaced by emerging characteristics
of the organized systems.... According to W.E. Ritter,
who coined the term ‘organicism’ in 1919,
‘Wholes are so related to their parts that not only
does the existence of the whole depend on the orderly
cooperation and interdependence of its parts, but the
whole exercises a measure of determinative control over
its parts.”...[Hence,] explanatary reductionism
is quite unable to explain characteristics of organisms
that emerge at higher levels of organization.... To sum
up, organicism is best characterized by the dual belief
in considering the organism as a whole, and at the same
time the firm conviction that this wholeness is not to
be considered something mysteriously closed to analysis,
but that it should be studied and analyzed by choosing
the right level of analysis. The organicist does not reject
analysis, but insists that analysis should be continued
downward only to the lowest level at which this approach
yields relevant new information and new insights. Every
system...loses some of its characteristics when taken
apart, and many of the most important interactions of
components of an organism do not occur at the physiochemical
level, but at a higher level of integration. And finally,
it is the genetic program which controls the development
and activities of the organic integrons that emerge at
each successively higher level of integration.”
(Mayr, pp.16-20)
Ernst Mayr’s This
is Biology is the work of an aging scholar, profoundly
knowledgable about his subject matter, and well able to
take that broad view which is so useful to those of us
coming to the discipline from the outside. In this, it
is almost diametrically opposed to our usual diet of popular
science and, although somewhat more difficult to digest,
is markedly more nourishing to our understanding. By (rightly)
insisting upon the importance of all
the key questions - the “what”, the “how”,
and the “why” - and by tracing the histories
of foundational subdisciplines that concentrate upon these,
Mayr is able to show us the very real (and necessary)
pluralism of biology as a whole, in a way that is not
only relevatory re the task at hand, but which also has
many lessons for those of us who labour in other disciplines.
Let us just hope that his voice does not go unheard...
“Typological thinking
is never enlightening in the study of life, but it has
been most vicious and deleterious in the consideration
of human races. Modern molecular research has revealed
that all so-called human races are very closely related
to one another, and are simply variable populations...[with
a] wide overlap in of their curves of variation.... Most
of the truly crucial characteristics usually attributed
to human race have nothing to do with their genotypes
but are ethnic, cultural properties. Races have been said
to be friendly, cruel, intelligent, stupid, reliable,
devious, industrious, lazy, suspicious, prejudiced, emotional,
inscrutable, and what not. Indeed, almost any attribute
a person may have has been claimed to characterize one
or another human race. I am unaware of any scientific
confirmation of any of these claims.... That no two individuals
are alike is as true of the human population as of all
other sexually reproducing organisms. Each individual
is a different combination of morphological, physiological,
and psychological characteristics, and of the genetic
factors that contribute to the shaping of these characteristics.
There is no doubt as to the great plasticity of the human
phenotype, particularly as far as behavioral characteristics
are concerned, but genes also make a contribution....
Indeed, few human characteristics can be found in which
there is not a great deal deal of variation (polymorphism)
in every human population. It is precisely this diversity
that forms the basis for a healthy society. It permits
a division of labor, but it also requires a social system
that makes it possible for each person to find the particular
niche in society for which he or she is best suited....
Neglect of human biological diversity in the name of equality
can only do harm; it has been an impediment in education,
in medicine, and in many other human endeavours. Great
sensitivity and a high sense of justice are required to
apply the principle of equality in the face of human biological
diversity. As Haldane (1949) said so rightly, ‘It
is generally admitted that liberty demands equality of
opportunity. It is not equally realized that it also demands
a variety of opportunities, and a tolerance of those who
fail to conform to standards which may be culturally desirable,
but are not essential for the functioning of society.”
(Mayr, pp.244-7)
John
Henry Calvinist
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