Tag Archives: evolution

Making sense of genotype-phenotype distinctions, version 4

The predominant current-day meaning of genotype is the DNA passed to the organism by its parents at the organism’s conception. The phenotype is the physical and behavioral characteristics of the organism, for example, size and shape, metabolic activities, and patterns of movement. To examine the relationship between the genotype and the phenotype is to be drawn into investigations that include: Continue reading

50 whys to look for genes: 21. Abnormal conditions provides insight about origin of normal conditions

Five offspring of a couple in a remote area of Turkey grew up walking quadrupedally on their hands and feet, as portrayed in the popular science documentary ‘Family That Walks on All Fours.’ Among the various angles of research on the siblings was genetic analysis identifying a mutation in a gene on chromosome 17 influencing cerebellum development and the work of certain evolutionary biologists try to link this gene to the evolution of human bipedalism 3 million years ago.  Indeed, other deleterious effects of the gene are depicted as reversing the progress in fine motor coordination and intelligence that accompanied human evolution. Continue reading

50 whys to look for genes: 18. Organisms are the survival machines of genes

“They are in you and in me; they created us, body and mind; and their preservation is the ultimate rationale for our existence… Now they go by the name of genes, and we are their survival machines.” Dawkins, The Selfish Gene (1976)

In other words, the genes we have are those that gave our ancestors advantage over competitors in survival and reproduction.  Any gene that does not give an advantage will die out—will not survive.


As the previous post noted, “parameters, such as the ‘fitness’ of [i.e., the advantage conferred by] genes or genotypes… are difficult or impossible to estimate,” even in well-controlled laboratory populations. Continue reading

50 whys to look for genes: 17. Evolution = change of gene frequencies in populations

Biology textbooks usually define evolution as a change of gene frequencies in populations over time.  A change in the frequency of some observed trait over time might be related to changes in environmental conditions and reversed if those conditions revert to earlier levels.


Evolution could be defined as a change of trait frequencies in populations over time, leaving for investigation whether the change is reversible, accompanied by a change of gene frequencies, and so on. Continue reading

Teaching Evolution = changes in the diversity of forms (of something) over time

Notes from presentation, 10/11/2006.

Studying biological evolution requires us to note six features:

— There is a diversity of forms and patterns in that diversity

— There is a geological record and patterns in this record

— Organisms tend to be adapted to their environment

— Characters or features of organisms are part of an organized form which is developed anew each generation

— There is change over time and sometimes improvement over observable time.

— All life and change occurs at some place/ in some circumstances  Continue reading

A constructionist perspective on the structure of ecological complexity, follow-up questions

It would be interesting to investigate why the constructionist perspective on ecological complexity (see below) is overlooked. One answer is that people haven’t come across what has been written on that perspective by me and others. But I’m more interested in why hasn’t it been discovered and enunciated by others for themselves and why they don’t discuss its implications once they know about it. This post presents the idea again (quoting from a 2010 post, which draws from Taylor 2005, 3-17) then reviews Robert May’s response to it over the last 30 years. Continue reading

Biology as Politics: The direct and indirect effects of Lewontin and Levins

Introduction to my essay review of

Biology Under the Influence: Dialectical Essays on Ecology, Agriculture, and Health, by Richard Lewontin and Richard Levins, Monthly Review Press, 2007

In “A Program for Biology,” one of this collection’s thirty-one essays, the Marxist biologists Richard Lewontin and Richard Levins (hereon: L&L) list recent “big mistakes” in scientific approaches to complex phenomena: “the green revolution, the epidemiological transition [from infectious to chronic diseases], sociobiology, the reification of intelligence testing, and the current fetishism of the genome.”  They attribute such mistakes to the “posing [of] problems too narrowly, treating what is variable as if it were constant and even universal, and offering answers on a single level only” (p.81).  What they point to is not simply the “philosophical tradition of reductionism,” but also “the institutional fragmentation of research, and the political economy of knowledge as a commodity” (p.9).  Indeed, their critical position extends beyond science to rejection of “the greed and brutality and smugness of late capitalism” (p.373).

Their anti-capitalist stance notwithstanding, the foci or starting points of L&L’s essays, like their 1986 collection, The Dialectical Biologist, lies in research in the life sciences.  Regarding the green revolution, for example, L&L see:

 …that a view based on unidirectional causation leads to the expectation that since grasses need nitrogen, a genotype that takes up more nitrogen would be more productive; since pesticides kill pests, their widespread use would protect crops; and since people eat food, increased yields would alleviate hunger (p.84).

The actual outcomes did not end up matching such simple causation because:

 …the increase in wheat yield was partly achieved by breeding for dwarf plants that are more vulnerable to weeds and to flooding; the killing of pests was accompanied by the killing of their natural enemies, their replacement by other pests, and the evolution of pesticide resistance.  The successful yield increases encouraged the diversion of land from legumes.  The technical packages of fertilizers, pesticides, irrigation, and mechanization promoted class differentiation in the countryside and displacement of peasants (p.84).

“A Program for Biology” ends with three fundamental questions for the study of complexity:

Why are things the way they are instead of a little bit different (the question of homeostasis, self-regulation, and stability)?  Why are things the way they are instead of very different (the question of evolution, history, and development)?  And what is the relevance to the rest of the world? (p.86)

The third question, rephrased in a later essay as “how [do we] intervene in these complex processes to make things better for us”? (p.115), invites… readers to ask what L&L’s essays tell us about having an effect—direct or indirect—on the complex processes of the production and application of scientific knowledge.  The essay review approaches this third question as it relates to social studies of science and technology and L&L’s contributions from four angles:

  • a more vigorous culture of science criticism;
  • a visible college of Marxist scientists in the USA;
  • inquiries into the diverse social influences shaping science; and
  • motivating readers who want to pursue their science as a political project.

Indirect contributions—influences on and appropriations by other actors in the wider realm of biology as politics—are discussed as well as the more direct effects.

Gender, Race, and the Complexities of Science and Technology: A bibliography

In a 2011 graduate course on “Gender, Race, and the Complexities of Science and Technology,” students were asked to add an annotated reference or resource (=person, organization…) to the evolving googledocs bibliography each week.  (Annotations were to convey the article’s key points as well as its connection to the student’s own inquiries and interests.)  The result is as follows: Continue reading

The challenge of integrating ecological dynamics into evolutionary theory VIII: Darwin, the preempter of criticisms

When Darwin, in the third chapter of On the Origin of Species, explored evolution’s ecological context he was not simply laying out a program of research for a future science now called ecology (see previous post).  He was responding to anticipated criticisms of his theory of natural selection as the mechanism for evolutionary change that produces the “that perfection of structure and co-adaptation which most justly excites our admiration.” Continue reading

The challenge of integrating ecological dynamics into evolutionary theory VI: Five approaches

Integrating the structure and dynamics of evolution’s ecological context (see previous posts) remains a neglected project within evolutionary theory.  Nevertheless, the different approaches to theorizing ecological organization can still be read in terms of the ways that evolutionary theory fits into them, whether or not this is made explicit.  Table 1 provides a classification of five basic orientations.

Central to the first three orientations is the notion of system, which I use in the strong sense of an entity that has clearly defined boundaries and has coherent internal dynamics, dynamics that govern the system’s responses to external influences and determine its structure, stability and development over time (Taylor 1992). System in this sense can refer not only to the basic units of systems ecology, but also to the guilds and communities of community ecology.  These three orientations differ according to the relative time scales of ecological and evolutionary processes.  In contrast to viewing ecological organization as system-like, various ecologists have emphasized what I call its “unruly complexity” (Taylor 2005).  That is, organisms and processes transgress the boundaries of any unit of ecological structure, spanning levels and scales; natural categories for and reduction of the complexity are elusive; ecological structures are subject to restructuring; control and generalization are difficult.  The two non-system orientations differ according to whether this unruly complexity can be disciplined theoretically.   Table 1’s distinctions are illustrated in Taylor (2000) through a review of twentieth century theories of ecological organization.

In the next post in the series, I note Darwin’s keen awareness of the structure and dynamics of evolution’s ecological context and mention some research that follows in that tradition.

Table 1. Five orientations to theorizing ecological organization and evolution.

Focus Orientation Time scales
system (or community) system evolves as a Coherent whole Fast return to equilibrium; slow change or evolution of system
individuals in context of system Stable system Fast return to equilibrium

intermediate speed evolution of population of individuals

slow change of system

system transient, yet Regularly reoccurring Fast passing of transient context (e.g.,succession)

intermediate speed evolution of population of individuals

slow change in nature of transient context

ecological organization as not system-like Anti-Theory Relevant processes not separable into “ecological” and “evolutionary” time scales
unruly complexity can be Disciplined

Taylor, P. J. “Community” pp. 52-60 in E.F. Keller & E. Lloyd (eds.) Keywords in Evolutionary Biology, Harvard University Press, 1992
—- “From natural selection to natural construction to disciplining unruly complexity: The challenge of integrating ecology into evolutionary theory,” in R. Singh, K. Krimbas, D. Paul & J. Beatty (eds.), Thinking About Evolution: Historical, Philosophical and Political Perspectives, Cambridge: Cambridge University Press, 377-393, 2000.
—- Unruly Complexity: Ecology, Interpretation, Engagement Chicago: University of Chicago Press, 2005.