on October 23, 2000
Richard Lewontin's "The Triple Helix" is a delightful literary composition in four movements consisting of three lectures and an essay on contemporary trends in biology and genetics. While the three in the triple helix metaphor refers to the interactive nature of a gene, an organism and an environment, it is also a reference to the notion that the human DNA (double helix) nucleotide-sequencing project is less than the be all and end all of genetics research.
In the first movement (Gene and Organism), Lewontin reviews major discoveries in biology from Darwin to the Genome Project. In his critique the author carps the metaphors of biology, especially the once useful words and phrases like Decarte's metaphor of the world as a "machine", general use of the word "development" (unrolling or unfolding of something that is already there) to mean ontogeny and embryo genesis and the "Holy Grail", i.e., the Genome Project (the project that determined the nucleotide sequence of the entire human genome). Using elegant examples from contemporary biology, Lewontin dispenses with the ideas (1) that a cell is anything much like a machine and (2) that as a blueprint, DNA sequencing would be sufficient to define anatomy, development and function.
In the second movement (Organism and Environment), the author clears up the meaning of "ecological niche". Accordingly, environment and organism are so closely related that, except in the laboratory, neither exists in the absence of the other.
"Organisms not only determine what aspects of the outside world are relevant to them by peculiarities of their shape and metabolism, but they actively construct, in the literal sense of the word, a world around themselves."
In movement three "Parts and Wholes, Causes and Effects"; the reader is treated to a glimpse into Lewontin's home life:
"As I write this chapter I think at one moment of the sentence I am writing, but then I wonder which sonata my wife will practice next, and then I recall the work done by the plumber today and then I return my attention to the manuscript."
Also included in movement three are (1) highly instructive lessons on values of fitness of nine genotypes in the Australian grasshopper (2) a discussion of variety among ceratopsian dinosaur horns and collars (3) a story about a Vermont man with a 150 year-old axe, and (4) the history of infectious disease in nineteenth century Europe.
In the finale, Lewinton dispenses with holism, Gaia, catastrophe, chaos and complexity theories and adds:
"Rather than searching for radically different ways of studying organisms or for new laws of nature that will be manifest in living beings, what biology needs to do to fulfill its program of understanding and manipulation is to take seriously what we already know to be true . . . the fact that biological systems occupy a different region of the space of physical relations than do simpler physico-chemical systems . . ."
"New experimental techniques are in part induced by the problems that are under investigation by a community of scientists with common interests, but once those technologies exist they have great power in determining the questions that are asked."
The same is said of great men.
This little book contains three lectures given by Lewontin at the Lezioni Italiani in Milan a few years ago. It is technical and aimed at an educated readership. Since there is not enough space here to discuss the entire book, I will concentrate on a brief discussion of the first, "Gene and Organism."
In this lecture Professor Lewontin outlines the role that genes, environment and chance ("random noise") play in the development of an organism. As he phrases it on page 20: "the organism is not specified by its genes, but is a unique outcome of an ontogenetic process that is contingent on the sequence of environments in which it occurs." This means that you could take the same genetic code and have it unfurl in Hyde Park and get an organism different from one you would get having it unfurl on, say, the Boston commons. Lewontin shows how cuttings from the same plant cultured at different altitudes developed differentially, and in a manner that could not be predicted. The reason they could not be predicted is that there is a significant amount of random variation ("developmental noise") that occurs as the plant grows. Lewontin gives the further example of a multiplying bacterium on page 37. The bacterium divides in 63 minutes. In another 63 minutes the daughter cells should divide again, giving four bacteria, but actually there is some random variation in how long it takes them to divide, so that one daughter divides in say 55 minutes, the other in an hour and five minutes. And this continues so that the bacteria culture does not increase in pulses, but continuously in random increments. This difference in timing in multi-cellar organisms may result in morphological differences since a catalytic enzyme may arrive too late to, say, grow a side bristle on a fruit fly (an example that Lewontin gives). Lewontin applies this understanding to the development of our brains on page 38. First there are random connections set. "Those connections that are reinforced from external inputs during neural development are stabilized, while the others decay and disappear." This process, Lewontin advises us, can lead to differences in cognitive function that are neither strictly genetic nor strictly environmental. They are influenced by random (unpredictable) factors.
This understanding is the reason that Lewontin is less than thrilled with the Human Genome Project. He believes, as he makes clear in another book, It Ain't Necessary So: The Dream of the Human Genome and Other Illusions (2000), that we will be disappointed by what can be accomplished simply from sequencing the genetic code, his point being that even though we know the code, the environmental and random factors cannot be known in any precise or predictive sense. It is true that the genome for a chimp will always code for a chimp and never for a rabbit, but whether that chimp is good at math or has unusually aggressive tendencies is something we cannot know from an understanding of the genetic code alone. Chance and environmental factors in development can result in a passive chimp even though its parents are aggressive.
Applying this idea to evolution in general, we can see that individual variation is not strictly a result of environmental differences but also of chance differences. Consequently, what we are is not shaped strictly by adaptive pressure (natural selection) but is to some extent the result of purely random processes. At one time in my life I studied chance and random events, and one of the most important things I learned is that the term "random" is not clearly defined, except in the sense that something that is random is unpredictable, which is a "you can't prove a negative" sort of definition. I also learned that there is considerable doubt as to whether a truly randomizing device actually exists. All real world devices, such as roulette wheels and computer random number algorithms can be shown to have some tiny bias, or to break down at the extremes. (Don't trust the random number generator on your computer when you are generating a very large number of trials: it will begin to repeat, and your Monte Carlo simulation will be flawed.) So what Lewontin calls "random events" are actually events that we simply do not know enough about to describe accurately. It may be that with greater ability we will eventually be able to describe or control these events. However, it may also be that at some level such events are the direct result of the probabilistic nature of a quantum event, and therefore in principle unpredictable. I suspect that Lewontin believes something like this.
In the second lecture Lewontin makes the point that to a significant degree organisms create their environment, and it is wrong to think of a place (such as the surface of the moon) without organisms as an environment. His dictum is "...[T]here are no environments without organisms" (p. 67). In the third lecture Lewontin discusses some of the problems associated with genetic causation and its analysis. There is a fourth chapter in which Lewontin attempts to provide some direction for future studies in biology.
I did not understand his assertion on page 81 that "Only a quasi-religious commitment to the belief that everything in the world has a purpose would lead us to provide a functional explanation for fingerprint ridges or eyebrows or the patches of hair on men's chests." The hair, I imagine is the result of sexual selection, but surely the fingerprint ridges allow us a better grip, and our eyebrows shade the sunlight as well as providing some small cushioning for our eye sockets.
on May 3, 2000
Lewontin is a challenging and original thinker and this book reflects his grappling with the current trends of evolutionary biology. It is also a call to return to the "first principles" of science: experiment and observation without preordained judgments, some of which he seems to challenge as even ideologically based. The unspoken question, it seems to me, in much current biological/genetic research is the nature/nuture debate. Lewontin stakes a claim that, while this is an interesting question, the question itself my be wrong, because it incorrectly shapes a number of other questions scientists ask. The dialectic between the organism and its enviroment, captured by Lewontin using the term "coevolutionary process," is far too complex to be rendered in the reductionist terms of nature/nurture. With a spate of "evolutionary" explanations for everything, he provides a fair, well-stated and welcome warning.
on July 15, 2001
Like everything else in life why should the reading of the Human Genome remain free discussion and debate on its merits and its false promises? THE TRIPLE HELIX like another recent book in the same vein - THE CENTURY OF THE GENE, - take it as their duty to throw cold water on all the happy gene talk in recent popular science books.
The Human Genome Project is not the primary target for criticism here; what Mr Lewontin objects to is the simplified approach of popular biology that insists on treating genes, organisms, and environments as distinctly seperate. Instead "taken together, the relations of genes, organisms, and environment are reciprocal relations in which all three elements are both cause and effects. Genes and environment are both causes of organisms, which are, in turn, causes of environments, so that genes become causes of environments as mediated by the organism." Quite plainly he says that organisms alter, modify, or in some cases create, their environments. Therefore in the great either/or debate on nature versus nurture, Mr Lewontin would argue it's neither/nor.
Taking neither side of the debate may lead one to believe that Mr Lewontin is then a supporter of a new theory, or an advocate of a new approach to determining biological truths. Not so. "It is not new principles that we need but a willingness to accept the consequences of the fact that biological systems occupy a different region of the space of physical relations than do simpler physico-chemical systems...that is, organisms are internally heterogeneous open systems."
General readers can manage the book because Mr Lewontin writes well, and in being critical, he takes time to explain his views. He's a leftist so he hits out at the usual targets, but he's also an independent thinker so sacred subjects of the left such as conservationism and protecting the environment also get a bit of stick. He believes that environments exist only with reference to the animals and plants that inhabit them, and furthermore, an environment can not be held in an unchanging state.
I enjoy reading some of the popular biology books that Mr Lewontin criticizes and his views on some of my pet subjects made me sit up. You need thick skin when reading Mr Lewontin but there are few better to learn from.
on January 7, 2001
This little book is a nearly perfect antidote to books like Matt Ridley's Genome which tend to overstate the importance of decoding the human genome. In this wide-ranging discussion, Lewontin argues, among other things, that genes do not 'compute' organisms, and that organisms actively 'construct' their own environments. Lewontin's writing is elegant and concise. He succeeds in communicating (sometimes difficult) concepts in ways that a layman can understand.
P.S. The book information given above, as to page count, is inaccurate: I count 136 pages, not 192. Indeed, my only minor complaint is that the book is rather expensive, considering its length.
on May 10, 2002
Ok, so my review will be short. I believe this book is excelent since it accomplish to set clear why genetic determinism is wrong. Genes do not act by their own, they do so inside a cell which (at least in multicelular organisms) is just one more in millions (being that a prudent estimate to a small organism) whith whom it comunicates. Now, this is just part of the story, you still have to consider this organism lives in a specific habitat in which it develops (crucial step) and in which it feeds, moves (if it can), etc. So utimately genes are a full orchestra directed by surroundings.
I highly recomend this book to anyone interested in Molecular Biology, Genetics or Developmental Biology, it is basic but esential.
on November 2, 2015
Lewontin does a good job of supporting the argument that species mutation occur based on genetic as well as environmental factors. Environmental factors, viz. food, air, water, etc, may contain oxidants that influence the genetic processes of an organism over the course of its life. An interesting read.
on June 9, 2013
This thin volume, adapted from a lecture series by the author, offers a concise explanation of the relationships between genes, organism, and environment. Lewontin's thesis is radical in the literal sense of "getting to the root" of biological relationships. The reader should approach the book with a basic understanding of biology, but one does not need to be a biologist to understand Lewontin's clear analysis and instructive examples.
According to Lewontin, the popular narrative of genetic determinism ignores the equally important factors of environment and developmental noise in ontogeny. Furthermore, the metaphor of "adaptation" views the organism as an object to be fitted to a pre-existing niche, whereas a more appropriate model is "construction," as the actions of organisms actively affect their own environments. Additionally, Lewontin shows that explanations by single-factor causation do not hold up in biology because the conditions of an organism involve multiple causal pathways. And, "Taken together, the relations of genes, organisms, and environments are reciprocal relations in which all three elements are both causes and effects." (100)
I have read this book twice in the last few years, and it has been a tremendous help for me in understanding biology both for academic purposes as well as for my own personal understanding of the world around me.
on December 8, 2008
The effect of genes on an organism is complex. If one plots a phenotypic variable (e.g. height of an organism) as a function of an environmental variable (e.g. temperature) for a number of different genotypes, the result is in general a mishmash of nonlinear curves (pp. 20-25). Thus the respective influences of genes and environment on phenotype are hard to separate. Furthermore, randomness is a considerable factor in the development of an organism. E.g., insects often have very different number of sensory bristles on their right and left sides, which is clearly not attributable to genes or environment (p. 33). The development of the human brain also seems to depend crucially on randomness (p. 38).
One should not think of organisms as trying to "fit" the "given" environment. Instead, organisms create their own environment. The environment of a bird, for example, is best described in terms of the activities of the bird: it eats insects in the summer and switches seeds in the fall, it flies south in the winter, etc. (p. 52). Flies in a dry area are "actually living in small crevices and between leaves where the local humidity is high" (p. 53). Ants build nests, snails have shells, and humans and trees alike are surrounded by an atmosphere of their own creation (a strong wind cancels this out and reveals what the "given" environment is like) (p. 54). "Weeds are precisely those species which can grow only in disturbed conditions, roadsides, gardens, burned areas, harvested forests, and which, having grown, change the conditions of the area so that they cannot produce a second generation. ... [This] is a manifestation of a general principle...: that the conditions which make possible the coming into being of a state of the system are abolished by that state." (pp. 59-60).
on June 12, 2003
This an interesting book by an author who, pretty much, stopped writing when he completed his message.
His main message is that DNA is not the be-all and end-all when it comes to the structure of life. Other important factors are the conditions within the organism's cell (including what chemicals are present, and how the DNA folds), what the organism's environment is, and how the organism changes that environment.
Lewontin worries that because scientists can now easily analyze and manipulate genetic structure, scientists will overemphasize research on the DNA structure itself, leaving other important and significant biology unstudied.
The author also points out that while dramatic mutations are chosen to study mutations, many mutations aren't so dramatic, and that some of the "dramatic mutations" are in fact the combination of several lesser mutations.
The writing is unnecessarily complex in places, including one passage where the author claims "Causal claims are usually ceteris paribus, but in biology all other things are almost never equal." How many readers recognize the Latin phrase "ceteris paribus" ? The author also buys into the duality so common in discourse: _either_ DNA is the only important thing, _or_ DNA is a minor side-issue. What happened to the middle road?