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Toward a New Philosophy of Biology: Observations of an Evolutionist
A collection of twenty-eight essays, five previously unpublished, grouped into nine Philosophy, Natural Selection, Adaptation, Darwin, Diversity, Species, Speciation, Macroevolution, and Historical Perspective. The book, Ernst Mayr notes in the Foreword, is an attempt “to strengthen the bridge between biology and philosophy, and point to the new direction in which a new philosophy of biology will move.”
576 pages, Paperback
First published January 1, 1988
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About the author
Ernst W. Mayr
102 books165 followersFor the computer scientist, see Ernst Wilhelm Meyr
Ernst Walter Mayr (July 5, 1904 – February 3, 2005) was one of the 20th century's leading evolutionary biologists. He was also a renowned taxonomist, tropical explorer, ornithologist, and historian of science. His work contributed to the conceptual revolution that led to the modern evolutionary synthesis of Mendelian genetics, systematics, and Darwinian evolution, and to the development of the biological species concept.
Although Charles Darwin and others posited that multiple species could evolve from a single common ancestor, the mechanism by which this occurred was not understood, creating the species problem. Ernst Mayr approached the problem with a new definition for the concept of species. In his book Systematics and the Origin of Species (1942) he wrote that a species is not just a group of morphologically similar individuals, but a group that can breed only among themselves, excluding all others. When populations within a species become isolated by geography, feeding strategy, mate selection, or other means, they may start to differ from other populations through genetic drift and natural selection, and over time may evolve into new species. The most significant and rapid genetic reorganization occurs in extremely small populations that have been isolated (as on islands).
His theory of peripatric speciation (a more precise form of allopatric speciation which he advanced), based on his work on birds, is still considered a leading mode of speciation, and was the theoretical underpinning for the theory of punctuated equilibrium, proposed by Niles Eldredge and Stephen Jay Gould. Mayr is sometimes credited with inventing modern philosophy of biology, particularly the part related to evolutionary biology, which he distinguished from physics due to its introduction of (natural) history into science.
Ernst Walter Mayr (July 5, 1904 – February 3, 2005) was one of the 20th century's leading evolutionary biologists. He was also a renowned taxonomist, tropical explorer, ornithologist, and historian of science. His work contributed to the conceptual revolution that led to the modern evolutionary synthesis of Mendelian genetics, systematics, and Darwinian evolution, and to the development of the biological species concept.
Although Charles Darwin and others posited that multiple species could evolve from a single common ancestor, the mechanism by which this occurred was not understood, creating the species problem. Ernst Mayr approached the problem with a new definition for the concept of species. In his book Systematics and the Origin of Species (1942) he wrote that a species is not just a group of morphologically similar individuals, but a group that can breed only among themselves, excluding all others. When populations within a species become isolated by geography, feeding strategy, mate selection, or other means, they may start to differ from other populations through genetic drift and natural selection, and over time may evolve into new species. The most significant and rapid genetic reorganization occurs in extremely small populations that have been isolated (as on islands).
His theory of peripatric speciation (a more precise form of allopatric speciation which he advanced), based on his work on birds, is still considered a leading mode of speciation, and was the theoretical underpinning for the theory of punctuated equilibrium, proposed by Niles Eldredge and Stephen Jay Gould. Mayr is sometimes credited with inventing modern philosophy of biology, particularly the part related to evolutionary biology, which he distinguished from physics due to its introduction of (natural) history into science.
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January 9, 2023
The leading evolutionist Ernst Mayr contributed to strides in the understanding of speciation during the 1940’s, when the neo-Darwinist revolution was getting underway, and thereafter became a fixture at Harvard University’s Agassiz Museum of Comparative Zoology alongside another great figure in evolutionary biology as well as in the intellectual world at large, Stephen Jay Gould. As befits an intellectual of stature, Mayr does not confine himself to technical writings in his trade but contemplates the significance of the field of his specialty to a wide audience of the educated public. We have already reviewed his monumental The Growth of Biological Thought: Diversity, Evolution and Inheritance (Harvard University Press, 1982, see our review here) – intellectual history in a high register. We wish now to take up a collection of more occasional writings entitled Toward a New Philosophy of Biology: Observations of an Evolutionist (Harvard University Press, 1988).
What to expect from Mayr? In view of his earlier work, one can anticipate magisterial dicta from the pen of a scholar more learned, perhaps, than any other biologist of his generation. The format consisting of short pieces spanning the better part of his career, lends itself to an oracular tendency. The first section [pp. 8-23] is devoted to the autonomy of biology, or staking out its claim to be a scientific discipline in its own right – which means not just to have a separate and characteristic subject matter but also a distinctive methodology, as against the imperial claim of physics to embrace all of the natural world. For, as Aristotle underscores, the appropriate method ought to be adapted to the domain of phenomena under investigation. In short, Mayr sees as unique to biology the following factors: hierarchical complexity at all levels, organization into populations, possession of a genetic program and, in a more abstract vein, the precedence of a comparative over an experimental method, irreducible concepts (embracing processes such as meiosis, gastrulation, predation), presence of theories having broad explanatory power not expressible in the form of laws and lastly, prediction that, at best, is probabilistic and not deterministic in nature [pp. 14-21]. Teleology, in particular, is susceptible to multiple meanings, some but not all legitimate according to current understanding [pp. 38-66].
Among the manifold topics Mayr goes on to touch on, let us pick out two on which to concentrate for the sake of review:
1) In this reviewer’s judgment, Mayr’s point about essentialism is deep. What he means by this is the tendency, going back to Plato’s Philebus, to categorize everything according to an essence that is supposed to characterize the thing (including biological species). Thus, man is the rational animal. The problem with such a logical approach is that it turns out to be poorly suited to thinking about biological evolution where, as Darwin teaches us, variation of phenotypic characters across members of a given species emerges as a crucial concept. Thus, Mayr:
We call the concept which emphasizes the uniqueness of every individual population thinking. [p. 224]
Therefore, Darwin poses not just another scientific theory but a revolution, necessitating the replacement of essentialism by population thinking, and this is why his views became so contested before winning general acceptance. For us, the shift implicates the time-honored philosophical problem of the one and the many. From a modern physicist’s point of view, too, it points to the richness inherent in a system with mind-bogglingly many degrees of freedom and unimaginable stretches of time in which they can play out. And lastly, to the dialectician, it suggests a possible deficiency of Greek thought itself, interesting because here the rationalistic striving finds the resources with which to criticize itself. As for the purely biological issue at stake, Mayr aptly characterizes it thus:
Since an essence is constant and sharply delineated against other essences, it cannot possibly evolve. [p. 176]
2) Common descent makes sense only in the context of evolution [p. 200]. Why so? ‘The entire Linnaean hierarchy suddenly became quite logical, because it was now apparent that each higher taxon consisted of the descendants of a still more remote ancestor’ [p. 201]. Also: the enormous organic diversity was only beginning to be appreciated during 19th century [p. 205]. The demise of essentialism necessitated the biological species concept based upon the observed fact of reproductive isolation (what is not an immediately evident notion, somewhat like the formal definition of continuity in analysis).
The firming up of the concept of species leads ineluctably to the problem of speciation:
If one defines species simply as morphologically different types, one evades the real issue. A more realistic formulation of the problem of speciation did not occur until the development of the biological species concept (K. Jordan, Poulton, Stresemann, Mayr). Only then was it seen that the real problem is not the acquisition of difference but of ‘distinctness’. The problem is thus the acquisition of reproductive isolation in relation to other contemporary species. Transformation of a phyletic line in the time dimension (gradual phyletic evolution, as it was later designated) sheds, of course, no light on the origin of diversity. [p. 206]
If it were true, as some sociologists have claimed, that the theory was the inevitable consequence of the Zeitgeist of early nineteenth-century Britain...one would think that the theory of natural selection would have been embraced at once by almost everybody. Exactly the opposite is true: the theory was almost universally rejected. [p. 210]
We omit here to trace the intellectual controversy that ensued, leading to the decline of finalism (a very good account of the reasons why on p. 248-252, ‘but also developed literally thousands of distinct phyletic lines within each of these kingdoms, most of them not in the slightest tending toward the characteristics of man’) and the eventual triumph of Darwinism in the mid-twentieth century. Some high points along the way: a critique of Jacques Monod [pp. 243-244]; ‘The shift from the concept of species-as-class to species-as-individuals was an inevitable byproduct of the shift from essentialistic to population thinking’ [p. 346]; ‘A class, having a constant essence, cannot evolve’ (not quite as simple as this, an essence could incorporate time-dependence of its defining properties as long as it is somehow regular), [p. 347]; does microevolution explain macroevolution? [pp. 402-422]; recognizes a role for constraints alongside natural selection as a determinant of the pace of evolutionary change [p. 407]; holism versus the beanbag view of the gene [p. 449]; paleontology and the question of punctuationism, or criticism of Stephen Jay Gould and Niles Eldredge [pp. 452, 457-458]; a good illustration of the difference between mere speculation and empirical science: see Mayr’s solid observational basis for his theory of peripatric speciation [p. 461]; proximate versus ultimate causation [p. 512]; and why the evolutionary synthesis happened when it did [p. 526].
The connection between speciation and macroevolution comes in here for some penetrating analysis. Let us content ourselves with the following pertinent passage to quote:
The great importance of the speciation event is that it links macroevolution with microevolution. The fact that the individual is the target of selection and that the population and the species are the locale of evolutionary change automatically reduce all macroevolutionary processes to the microevolutionary level. The actors in this process, however, are not genes but genotypes and gene pools, entire cohesive systems of genes. The important insight is that whatever happens either in microevolution or in macroevolution, and whatever genetic phenomena are involved, proceeds through the selection of individuals. Admittedly, genetics has so far been unable to analyze that part of the genotype that does not ordinarily vary in a local population but is so tightly integrated that it gives the genus, the family, the order, the phylum, its particular character. But even this part of the genotype, when it varies, varies in individuals and is subject to the recombination-selection cycles of ordinary allelic variation. For the extreme reductionists among the geneticists, who look at evolution, even macroevolution, in terms of changing frequencies of genes, there is a complete continuity among all phenomena of evolution. But for those who think of evolution also as a change of species and higher taxa, and this includes Darwin, evolution has always been considered as hierarchical in structure. [p. 479]
All around, a good measure of the enjoyment one can derive from reading this fine work comes from the chance to see Mayr’s undisputed expertise speaking, as when he discusses fish in the great African lakes [pp. 386-395]. The biological species concept adumbrated above has the consequence that one has to recognize a number of species of what to outward appearances are very similar looking fish, since their populations are in fact reproductively isolated. How this could come to pass and the timescale over which it happened makes for a fascinating investigation. The point few among Mayr’s peers sufficiently appreciate is that
Rates of evolution, speciation and extinction may differ by several orders of magnitude in different organisms and under different circumstances [p. 544].
In sum, an excellent treatment of philosophical themes in biology for someone non-expert in the field who wants to go more deeply into the matter. Let us confine ourselves, in closing, with a remark on the question as to whether this essay collection lives up to its ambitious title? Mayr himself is no professional philosopher and one will look in vain for a completely orderly, systematic account of its theme, such as one has come to expect from philosophers. Perhaps, then, the just way to state the matter would be that one can find in the present work abundant materials for a new philosophy of biology, but that the work of assembling them into an articulated and refined theory awaits the attention of someone with the requisite intellectual bent.
What to expect from Mayr? In view of his earlier work, one can anticipate magisterial dicta from the pen of a scholar more learned, perhaps, than any other biologist of his generation. The format consisting of short pieces spanning the better part of his career, lends itself to an oracular tendency. The first section [pp. 8-23] is devoted to the autonomy of biology, or staking out its claim to be a scientific discipline in its own right – which means not just to have a separate and characteristic subject matter but also a distinctive methodology, as against the imperial claim of physics to embrace all of the natural world. For, as Aristotle underscores, the appropriate method ought to be adapted to the domain of phenomena under investigation. In short, Mayr sees as unique to biology the following factors: hierarchical complexity at all levels, organization into populations, possession of a genetic program and, in a more abstract vein, the precedence of a comparative over an experimental method, irreducible concepts (embracing processes such as meiosis, gastrulation, predation), presence of theories having broad explanatory power not expressible in the form of laws and lastly, prediction that, at best, is probabilistic and not deterministic in nature [pp. 14-21]. Teleology, in particular, is susceptible to multiple meanings, some but not all legitimate according to current understanding [pp. 38-66].
Among the manifold topics Mayr goes on to touch on, let us pick out two on which to concentrate for the sake of review:
1) In this reviewer’s judgment, Mayr’s point about essentialism is deep. What he means by this is the tendency, going back to Plato’s Philebus, to categorize everything according to an essence that is supposed to characterize the thing (including biological species). Thus, man is the rational animal. The problem with such a logical approach is that it turns out to be poorly suited to thinking about biological evolution where, as Darwin teaches us, variation of phenotypic characters across members of a given species emerges as a crucial concept. Thus, Mayr:
We call the concept which emphasizes the uniqueness of every individual population thinking. [p. 224]
Therefore, Darwin poses not just another scientific theory but a revolution, necessitating the replacement of essentialism by population thinking, and this is why his views became so contested before winning general acceptance. For us, the shift implicates the time-honored philosophical problem of the one and the many. From a modern physicist’s point of view, too, it points to the richness inherent in a system with mind-bogglingly many degrees of freedom and unimaginable stretches of time in which they can play out. And lastly, to the dialectician, it suggests a possible deficiency of Greek thought itself, interesting because here the rationalistic striving finds the resources with which to criticize itself. As for the purely biological issue at stake, Mayr aptly characterizes it thus:
Since an essence is constant and sharply delineated against other essences, it cannot possibly evolve. [p. 176]
2) Common descent makes sense only in the context of evolution [p. 200]. Why so? ‘The entire Linnaean hierarchy suddenly became quite logical, because it was now apparent that each higher taxon consisted of the descendants of a still more remote ancestor’ [p. 201]. Also: the enormous organic diversity was only beginning to be appreciated during 19th century [p. 205]. The demise of essentialism necessitated the biological species concept based upon the observed fact of reproductive isolation (what is not an immediately evident notion, somewhat like the formal definition of continuity in analysis).
The firming up of the concept of species leads ineluctably to the problem of speciation:
If one defines species simply as morphologically different types, one evades the real issue. A more realistic formulation of the problem of speciation did not occur until the development of the biological species concept (K. Jordan, Poulton, Stresemann, Mayr). Only then was it seen that the real problem is not the acquisition of difference but of ‘distinctness’. The problem is thus the acquisition of reproductive isolation in relation to other contemporary species. Transformation of a phyletic line in the time dimension (gradual phyletic evolution, as it was later designated) sheds, of course, no light on the origin of diversity. [p. 206]
If it were true, as some sociologists have claimed, that the theory was the inevitable consequence of the Zeitgeist of early nineteenth-century Britain...one would think that the theory of natural selection would have been embraced at once by almost everybody. Exactly the opposite is true: the theory was almost universally rejected. [p. 210]
We omit here to trace the intellectual controversy that ensued, leading to the decline of finalism (a very good account of the reasons why on p. 248-252, ‘but also developed literally thousands of distinct phyletic lines within each of these kingdoms, most of them not in the slightest tending toward the characteristics of man’) and the eventual triumph of Darwinism in the mid-twentieth century. Some high points along the way: a critique of Jacques Monod [pp. 243-244]; ‘The shift from the concept of species-as-class to species-as-individuals was an inevitable byproduct of the shift from essentialistic to population thinking’ [p. 346]; ‘A class, having a constant essence, cannot evolve’ (not quite as simple as this, an essence could incorporate time-dependence of its defining properties as long as it is somehow regular), [p. 347]; does microevolution explain macroevolution? [pp. 402-422]; recognizes a role for constraints alongside natural selection as a determinant of the pace of evolutionary change [p. 407]; holism versus the beanbag view of the gene [p. 449]; paleontology and the question of punctuationism, or criticism of Stephen Jay Gould and Niles Eldredge [pp. 452, 457-458]; a good illustration of the difference between mere speculation and empirical science: see Mayr’s solid observational basis for his theory of peripatric speciation [p. 461]; proximate versus ultimate causation [p. 512]; and why the evolutionary synthesis happened when it did [p. 526].
The connection between speciation and macroevolution comes in here for some penetrating analysis. Let us content ourselves with the following pertinent passage to quote:
The great importance of the speciation event is that it links macroevolution with microevolution. The fact that the individual is the target of selection and that the population and the species are the locale of evolutionary change automatically reduce all macroevolutionary processes to the microevolutionary level. The actors in this process, however, are not genes but genotypes and gene pools, entire cohesive systems of genes. The important insight is that whatever happens either in microevolution or in macroevolution, and whatever genetic phenomena are involved, proceeds through the selection of individuals. Admittedly, genetics has so far been unable to analyze that part of the genotype that does not ordinarily vary in a local population but is so tightly integrated that it gives the genus, the family, the order, the phylum, its particular character. But even this part of the genotype, when it varies, varies in individuals and is subject to the recombination-selection cycles of ordinary allelic variation. For the extreme reductionists among the geneticists, who look at evolution, even macroevolution, in terms of changing frequencies of genes, there is a complete continuity among all phenomena of evolution. But for those who think of evolution also as a change of species and higher taxa, and this includes Darwin, evolution has always been considered as hierarchical in structure. [p. 479]
All around, a good measure of the enjoyment one can derive from reading this fine work comes from the chance to see Mayr’s undisputed expertise speaking, as when he discusses fish in the great African lakes [pp. 386-395]. The biological species concept adumbrated above has the consequence that one has to recognize a number of species of what to outward appearances are very similar looking fish, since their populations are in fact reproductively isolated. How this could come to pass and the timescale over which it happened makes for a fascinating investigation. The point few among Mayr’s peers sufficiently appreciate is that
Rates of evolution, speciation and extinction may differ by several orders of magnitude in different organisms and under different circumstances [p. 544].
In sum, an excellent treatment of philosophical themes in biology for someone non-expert in the field who wants to go more deeply into the matter. Let us confine ourselves, in closing, with a remark on the question as to whether this essay collection lives up to its ambitious title? Mayr himself is no professional philosopher and one will look in vain for a completely orderly, systematic account of its theme, such as one has come to expect from philosophers. Perhaps, then, the just way to state the matter would be that one can find in the present work abundant materials for a new philosophy of biology, but that the work of assembling them into an articulated and refined theory awaits the attention of someone with the requisite intellectual bent.
Displaying 1 of 1 review