on September 24, 2002
This is a very good introductory overview of evolutionary theory, suitable for the enthusiastic novice, the educated skeptic, the qualified biologist, or for those who simply wish to know what has been going on in this fascinating field for the last 150 years and more of scientific enquiry.
The writer, Ernst Mayr, only recently passed away aged over 100, and had been through a good deal of this scientific development, and is therefore in a unique position to approach the subject. Jared Diamond (author of 'The Third Chimpanzee', 'Guns, Germs and Steel') describes the result: "there is no better book on evolution". Whilst a little skeptical of this hyperbole, I decided to check it out, and wasn't disappointed.
Discussions range from the philosphical (everything in this Earth seems to be in a state of flux" p7), to the palaeontological ("the older the strata in which a fossil is found...the more different the fossil will be from living relatives" p13-although see also the occassional stasis of the genotype on p278-79), to the embryonic (eg 'recapitulation'-an important point), to the modern discovery of 'transposable elements' (gene jumping and copying-p100). Important developments in the theory include the 'branching theory' of Darwin (p19), to the theory of common descent (p21), to discussions of biogeography (species distribution), molecular biology (including the molecular clock), to the formation of new genes by doubling and insertion, leading to diversification (p108-9). The reader will find all the scientific development and current investigations exhaustive, but (hopefully!) rarely exhausting.
The causes of speciation have come along way since Darwins 1859 Origin: allopatric,dichopatric, peripactic, sympatric (not found in mammals p180), instantaneous (chromosome doubling), parapatric, and hybridisation. Concepts to ponder over-in case of being caught out at parties.
The historical background of 19th century philosophy is introduced (for which modern day philosophy is a little embarrassed) including 'essentialism' (constant essence of species ie "a natural kind"-with variants either irrelevant or accidental), and 'finalism' (the belief that everything moves toward greater perfection -eg Kant, and others), as compared to Malthus', Wallace's and Darwin's 'population thinking' (the study of variation in populations-a crucial concept).
3 theories of evolution are based on essentialism -transmutationism (origin of new types by mutation or saltation), transformationism-gradual change to a new natural 'type' by the influence of the environment, including use and disuse or inheritance of acquired characters (ie Lamarckism), and orthogenesis-the propensity of the living world to move towards perfection (typified by Kant, amongst others). (There are querks possible in these examples-for example some transmutational theories may be non-essentialist- however these 'higher arguments' are sometimes over semantics as much as over concepts). 'Essentialism' was certainly one of the most significant ideological barriers to evolutionary thought, and still is today. (Some present day philosophers still seem obsessed by it-see 'Darwins Dangerous Idea' by Daniel Dennett for a good discussion of philosophical issues and debate).
Having little time for 'labels' I have never bothered with such labels as 'Darwinism', 'Neo-Darwinism' etc etc, but after reading this book, I found that my position is mostly that of 'Darwinism' anyway. (Some relief, I think, whatever 'Darwinism' may mean).
A good summary of 'Darwinism' is provided (p86):
1) non-constancy of species
2) descent from common ancestor
3) gradualness (but see also below for semantical distinction with punctuationism)
4) diversity (by species multiplication)
5) natural selection (but see also Baldwin Effect below).
These basic tenants have been thrown around and debated for over a century, but it is becoming increasingly obvious that most variants of these ideas amongst evolutionary debates, do not, in fact contradict these basic principles (eg punctuated equilibrium-page 270-"punctuated equilibria, which at first sight, seem to support saltationism and discontinuity, are in fact strictly populational phenomenon, and therefore gradual"). I'm not sure I agree with this point, although I can see the contention is at least partly semantical.
To get some flavour from the book, rather than from me, some veritable gems include:
"sweeping generalisations are rarely correct in evolutionary biology" p271.
"there is no justification in the widespread assumption that consciousness is a unique human property"
"Selection seems able to to recruit genes in new developmental processes that previously had seemed to have other functions" p113.
"Species are groups of interbredding natural populations that are reproductively isolated from other such groups" p166.
"An organism has to be well adapted as a whole, but it also must be able at all times to cope with its ancestral genome" p154.
"There is alot of structure in the genotype that cannot be discovered and explained by a purely reductionist approach" p145.
"Surely when a population suddenly encounters an extremely adverse situation, the more genetically diverse it is, the greater the chance that it contains genotypes that can better cope with the environmental demands" p105.
"some groups speciate profusely, whereas in others speciation seems to be a rare event" p271.
"most of the variation of genotypes available for natural selection in a population is a result of recombination, not of mutations" p280.
"biological causes and natural selection are dominant in background extinction, whereas physical factors and chance are dominant in mass extinction" p203.
"most new evolutionary lineages arise by budding rather than by splitting" p191.
"rate of speciation is apparently primarily determined by ecological factors" p186.
"Any behaviour that turns out to be of evolutionary significance is likely to be reinforced by the selection of genetic determinants for such behaviour" (eg the Baldwin Effect p137-a very important concept).
And my favourite-"the phenotype of the individual as a whole ..is the actual unit of selection" p126.
One final point -the final discussion of human evolution, and in particular, evolutionary aspects of human behaviour is understandably brief-that is for the present century to unravel!
A wellspring of clean, clear, refreshing information, for the thirsty soul.
on April 3, 2006
In the introduction, Mayer states that this book is written for 3 groups of people. One of which is just anyone that is interested in evolution, biologist or not. "Great!" I thought. I have read some stuff on evolution such as the Blind Watchmaker, so I figured I could handle this. I thought wrong. I suppose I just dont know enough basic biology to understand a lot of the stuff Mayer discusses. But the reason that I wanted to read this book... so that I would understand evolutionary biology!
Indeed, there is a wealth of information in this book, but it seems like all of this stuff is just second nature to Mayer, and he doesnt realize that most people will have no idea about what he is talking about.
For instance, when disussing Biased Variation (pg 99), Mayer states "Some genes affect the segregation of alleles during meiosis in a heterozygote such that the allele of one parental chromosome goes to the gametes in more than half of the instances. If this allele controls the unfit phenotype, it will be selected."
The book is packed with stuff like this. I suppose if I had some background in biology I might have some idea of what that means.
Anyway, the books is probably a gold mine for anyone educated in biology, but I am gonna have to say that if you just want a basic intro to biological evolution, this is not the book for you. Or at the very least, it wasnt the book for me.
on November 16, 2001
This book is simply a MUST for anyone interested in the theory of evolution, including, and especially for, those human beings who are curious about the origins of their present constitutions, both biological and psychological, and who want to be informed of the most up-to-date natural and scientific explanations about them, rather than to continue to lie ignorantly, though comfortably, in the consolation of religious or supernatural dogmas.
I cannot think of anyone else who is able to present all levels of the complexity and subtely of the process of evolution and the theory of natural selection with such precision and clarity than Ernst Mayr, a venerable scientist, "the world's greatest living evolutionary biologist" (Steven Jay Gould), "the Darwin of the 20th century" (New York Times).
This book is not only consisted of rigorous arguments, but also full of compelling illrustrative examples picked up from the diversity of living beings on our earth of various geological ages (from the fossil record to modern human beings) and places in support of those arguments.
Mayr's knowledge in biology is so comprehensive and his narrative so straighforward and lucid that he recounts those examples of evolution history just like a grandfather telling some everyday stories to his grandsons.
And I especially recommend those who once found or still find the so-called "GENE EYES' VIEW" (as popularized by Richard Dawkins) attractive shall seriously study this great work. And then he or she, I think, will soon discover that how imprecise and misguiding is the metaphorical language of those sociobiologists in their description of almost every parts of the process of evolution. This book shall at least provoke our cautions towards the trend of reductionism and atomism in various branch of scientific endeavor.
Besides, Jared Diamond's preface is also well written. It let us have a look into the extraordinary life of this great scientist. I am especially moved to read that Mayr "at the age of 97, still writing a new book every year or two."
Finally, I have also to point out what seems to me to be hardly a harmless drawback of this otherwise excellent work. This is the author's explicit belief, as expressed in the section on HUMAN ETHICS, in the "moral education" of the "world's great religion", especially for the "cultures of the Christian world". I feel quite puzzled how Mayr could think that some "perfectly sound" ethical principles could ever be deduced from a utterly absurd world-view, as that which is presented by the creationists, which, in so far as I understand it, seems to Mayr to have already been completed refuted by the Darwinian evolutionists.
(But not for dummies.)
Perhaps the most remarkable thing about this book is that the author was born in 1905. What legendary biologist Ernst Mayr might next want to share with us is his secret for remaining so mentally acute for so many years! Reading this exposition on evolution by "The world's greatest living biologist and a writer of extraordinary insight and clarity" (Stephen Jay Gould, on the jacket cover) is somewhat like taking Evolution 101 as it might be taught by Professor Mayr. As he writes in the Preface, his purpose is didactic. He would like us to know more about evolution and how it works.
First he presents the evidence for evolution, explaining (I hope) once and for all how evolution can be established as a fact even though we cannot perform experiments as we might in physics or chemistry: "Evolution...must be inferred from observations. Such inferences subsequently must be tested again and again against new observations, and the original inference is either falsified or considerably strengthened..." (p. 13) He adds on page 276, "I cannot see why...an overwhelming number of well-substantiated inferences is not scientifically as convincing as direct observations. Many theories in other historical sciences, such as geology and cosmology, are also based on inferences. The endeavor of certain philosophers to construct a fundamental difference between the two kinds of evidence strikes me as misleading."
To this I might add that all the evidence we have of the external world is from inference. Even so-called direct observations (whatever they may be) are inferences from the evidence of our senses and must be checked against the same inferences that others make.
Next Mayr explains how change and adaptation take place. He then explains why there is biodiversity. These are the first three parts of the book. Part Four is on human evolution and Chapter 11 in particular is a splendid, concise interpretation of the evidence for human evolution.
One of the thorny issues Mayr addresses is selection. He explains that it is the individual (the phenotype) that is selected, and not the gene and not the population. "[A] gene as such can never be the object of selection" because it "is only part of a genotype, whereas the phenotype of the individual as a whole (based on the genotype) is the actual object of selection." (p. 126) The gene cannot be the object of selection for another reason, namely that a single gene seldom, if ever, acts independently of other genes. They work together to bring about some feature of the phenotype and are subject to the action of regulatory genes (hox and pax genes). (p. 127) Furthermore, "Many genes do not have standard selective value. A gene may be beneficial when placed in one particular genotype, but it may be deleterious when placed in a genotype with different genes." (p. 128)
One of the things I learned here (p. 129) is that the phenotype includes "all the products of the behavioral genes. This includes the nest a bird builds, or the web of a spider, or the path of migration of a migratory bird." It also includes the gametes. Thus the ability of a spermatozoon to "swim" is part of the phenotype and is subject to natural selection.
Another interesting issue is group selection. Mayr defines two group types, "casual groups" and "cohesive social groups." Members of the former "are associated in a group [that] makes no contribution to their fitness." The latter, however, "owing to social cooperation among its members" "can indeed be a target of selection." This cleared up the group selection fuzziness for me.
It is interesting to note, however, that Mayr's argument seems to imply that if the cooperating group is the same as the species, then a species can be selected. However he writes on page 280, "The species as a whole is never the target of selection." He explains that "the differential success of [an] entire species is superimposed on...individual selection." Or, if I may phrase it another way, the differential success of a species is the result of the differential success of its individual members. What this really means, however one wishes to phrase it, is that selection can apply to an entire species (through its members).
A very fine example of Mayr's intelligence and sensitivity can be gleaned from reading his answer to the question on page 262, "Are there human races?" There are indeed races, Mayr explains, but the "race problem" is a result of "a faulty understanding of race. These people," he continues, "are typologists, and for them every member of a race has all the actual and imaginary characteristics of that race. To translate this bias into an absurd example, they would assume that every African-American can run the 100-meter dash faster than any European-American." What a race is, is a population and its members are individuals, not types. This is true of species as well.
There are a number of other technical and crucial issues in evolution that Mayr addresses including saltation and punctuated equilibria, altruism, kin selection, speciation, the origin of birds, etc. He even goes into a little exobiology on page 263. The book includes two appendices designed to help the reader cope with criticisms and questions about evolution. Appendix B sets forth 24 questions about evolution, such as "Is evolution a fact?" (yes) and "Is the Gaia hypothesis incompatible with Darwinism?" (no), etc. There is a glossary and an excellent index. There is some repetition, but I think we can take that as emphasis since this is an exercise in public education.
Although Mayr uses a minimum of jargon and writes in a straightforward manner, the issues are not simple. They need to be studied to be understood and appreciated. This is why I call this book Evolution 101 by Professor Mayr.
on August 26, 2003
Ernst Mayr is a commanding figure in the field of evolutionary biology. Having published an awesome average of nine scientific papers a year since 1925, he has produced (at age 97) a comprehensive book on evolution for the general public. I think "What Evolution Is" will best suit readers who already have some familiarity with biology as well as with science in general.
The author does not take the reader's acceptance of evolution for granted. On the contrary, he pays considerable attention to opposing views and carefully builds a case using the mass of evidence which has accumulated in the 140 years since Darwin's speculative missile burst on a comfortably religious 19th-century world. That world was almost universally assumed to be inhabited by specially-created humans presiding over a vast array of plants and animals provided solely to sustain, entertain and amuse them.
Mayr ably describes and explains the chain of factual evidence and logical inference which has established (with extremely high probability) that in actuality all living things evolved over billions of years through a partly random, partly directed, wholly automatic process which tended to suppress harmful changes and reinforce beneficial ones. The inevitable conclusion is that humans were not supernaturally created as finished products, but rather were simply fortunate enough to emerge from a very lengthy parallel development contest as hands-down winners in the intellectual capacity category. Implicit in Mayr's section on human ethics is the idea that along with markedly superior intelligence should come a self-imposed sense of moral responsibility.
As an active participant in the development of evolutionary science, Mayr doesn't hesitate to state clearly and defend vigorously his positions on controversial issues. He freely acknowledges (as did Darwin) that evolutionary rates can and do vary considerably, but he views the Eldredge-Gould punctuated equilibrium concept as no more than a minor modification of the classical picture. On another contentious question, Mayr holds firmly that natural selection should be viewed as acting on the whole animal (the phenotype) rather than on individual genes or subsets of genes.
The last chapter contains Mayr's views on the current frontiers of evolutionary biology. As major unsolved problems he cites a) finding the true extent of biodiversity; b) solving the mystery of static species ("living fossils") which hardly change over hundreds of millions of years; and c) explaining the relatively rapid (200-300 million years) proliferation of new structural types in the early Cambrian. The second of two appendices is a sort of rap session in which the author gives pithy responses to twenty-four FAQs about evolution. These serve as a quick-reference guide to many of the points Mayr has tried to drive home in the main text.
"What Evolution Is" includes a generous complement of good quality illustrations and charts. Mayr makes liberal use of technical terms, but is careful to compensate by providing a fairly comprehensive glossary. I recommend this book to anyone ready to step up a notch from the normal run of popular books on evolution.
on April 10, 2003
The term "Evolution" refers to organisms changing as they reproduce and generate. Over millions of generations, the accumulated changes are substantial and diverse enough that descendants and progenitors can no longer be included in the same species.
This is fact, not theory.
But by what path did the ecosystems of yesterday change into the current biosphere? What "forces" operate on specie to push them one way or another? What is selected, and what process does the selection? Tentative answers to these questions are what we call theory. A theory is an explanation of accepted facts. Evolution is not "just a theory". The word refers to both a fact and to a theory to explain the fact.
Let's compare with physics 400 years ago. For instance, let's look at the theory of things-falling-down. Everybody agrees that things fall down when deprived of support. "Things-falling-down" is thus fact. Aristotle stated that heavy objects fall faster. That was a >>theory<< of things-falling-down; it tried to describe precisely how things fall down. It so happens that Aristotle's theory was wrong, as Galileo found when he began measuring how fast balls rolled down a inclined plane.
That a theory of gravity was found incorrect did not nullify the fact of gravity. Same with evolution.
Evolution is documented. Examples of speciation (one species coming from another) abound in the fossil record. These are the facts. Men like Mayer, Gould, Dawkins study the "how" of these facts. They are the great theorists seeking to explain how evolution works. That it does is obvious, how it does less so.
on November 30, 2003
In the foreword, Jared Diamond says the book excels in filling a mid-level gap for educated lay people between biology texts and introductory material. He is right on the money. I was introduced to evolution in high school and college biology courses but further confused by television shows that are all over the map and all claiming to support evolution. I am a Christian Creationist but I do not hesitate to recommend this book for those interested in seeing a coherent account of evolution told by a true expert in the field. Mayr did not change my mind about macroevolution, but he did help me clear up a lot of my thinking about the current state of both evolutionary and creation science. I view the book as a very informative explanation, even a defense, of contemporary evolutionary thought. Mayr's gradualism is presented as the contemporary extension of Darwin's first revolution 150 years ago and of the evolutionary synthesis of the 1940's that brought molecular biology into the evolutionary fold. Other views of evolution and creation through the past 200 years are contrasted to Mayr's well-developed vision of how life gradually evolves. He generally builds a positive case for his position rather than directly attacking others.
Since Amazon has the technology to show the table of contents I will only summarize the contents of the book in an alternative way that Mayr himself hints at throughout the book. Chapters 1-4 are largely observations from the living world that suggest some sort of evolutionary process is at work. Chapter 5 devotes a lot of pages to modern theories of genetics and inheritance. Chapters 5-7 describe processes occurring within populations of living organisms. Throughout the book, Mayr stresses that diversity among populations, rather than unity of types, is the prevailing lesson of evolutionary biology. Chapters 5-9 form a major unit that describes the various mechanisms of microevolution including speciation. Chapters 10-12 get into higher-level macroevolution and use humans as a case study of mosaic evolution in a social species. I found these final chapters the least convincing and poorly backed by evidence (though it is well written and interesting to read). Mayr often admits the fossil record, especially for humans, is sketchy proof for evolution. To his credit he builds much of his case around observable biology rather than sketchy paleontology. Marvin Lubenow's "Bones of Contention" is an interesting and detailed analysis of the hominid fossils for those open to a very different (creationist) perspective.
Though I find much to disagree with in the philosophical assumptions and in some leaps of naturalistic faith used in the book, I think it serves its intended audience very well. The book could be better if it had more footnotes for further reading, especially to fossil statements and other phenomena such as rafting reptiles, teeth in baleen whale embryos etc. The bibliography is very extensive and Mayr does provide a list of anti-creationist books so the info can probably be located in those. If you are not well versed in biology and genetics you will probably want a dictionary handy, but this is exactly the sort of book I wanted as a deep introduction. Mayr is an honest, balanced and gifted writer for his position.
on June 23, 2004
If you are a Biologist or are a curious naturalist this is a book for you. Mayr makes an outstanding abstract of evolution, he clearly defines it with mastery. I would just like to add that this is my favorite subject and have read a good amount of books on evolution and this is clearly one of the best (don't be mislead by the size nor the price). Of course there are huge treatises on evolution (like The Structure of Evolution, of Stephen Jay Gould), but such a Bible is, for most of the cases, unpractical and unnecessary. Mayr clears evolutions' place in Biology putting it at its' very center. Great book, great style.
on June 12, 2002
My impression matches that of reviewer Dennis Littrell: an excellent introduction, but definitely not a "Dummies" series book. Mayr's book is extremely well-organized and actually gets better as it progresses. One of the finest chapters is near the end, "How Did Mankind Evolve?" where he spells out what we know and where the holes are in the human evolutionary record.
Diagrams are usually very clear and a reader can see the work of a strong editor. "What Evolutions Is" includes an FAQ (frequently-asked questions list); glossary; and appendix covering key evolutionary issues.
The reasons that it's not "Evolution for Dummies" is that it is replete with biological jargon and has occasional annoying lapses.
The hardest chapters for the non-biologist are about the simplest of animals. Ironically it's because these simple creatures have the longest names and a narrow significance to biologists, e.g., "The protostomes and deuterstomes derived from ancestral bilateralian." What that last sentence means is "Multicellular animals split into two types of basic embryo formation."
An example of one of the lapses, Mayr uses "mya" as an abbreviation in dating of specieis throughout the book but it's Chapter 11 before "mya" is defined as "million years ago."
Mayr covers an interesting range of 12 topics in the book and he avoids the typical trap of taking the history of evolutionary biology in chronological order, as many issues finish as dead ends. Rather, he treats the main threads of evolutionary biology and succinctly describes how the scientific evidence has been gathered via paleontology, anthropology, genetics and biology.
It would be hard for a non-biologist to read this book and not find several surprises.
on July 17, 2006
"What Evolution Is" by Ernst Mayr is a great introduction to evolutionary biology for the educated layperson. It begins by flatly denying Creationism and gives readers a bibliography in order for him or her to do more research on that front. The book then discusses Darwin and some other evolutionary theories that preceded him. Mayr then goes on to explain topics such as genetics, speciation, natural selection, and finally, human evolution. The book does get technical in parts but this is a technical book; this is science. One weakness is that Mayr occaisonally talks about a concept or a term and then defines it in the next chapter, as if expecting the reader to know what it is (although the glossary is good and there is always the dictionary.) I think another reviewer mentioned this as well. Overall, though, I would definitely recommend this book to the educated layperson who wants to learn more about evolutionary biology. I would look elsewhere, though, if one is looking for information about human evolution, for this is not the author's purview, but he does outline the subject for the sake of continuity; the reader should look elsewhere for information about paleoanthropology. The author does rely a lot on his own research, but that's to be expected because the author was on the forefront of the "Darwinian synthesis" in the 1940s. He has a lot to win or lose on the whole thing. There is an excellent bibliography in the back, as well, and I look forward to researching more on the subject and also reading more of Dr. Mayr's work in the future.