sexual reproduction

Genetic Experimentation

Genetic Experimentation: The Adaptive Function of Sex & ConjugationExcerpt from the Introduction:

Sex has long been a difficult problem for Darwinian theory. “The existence of sexual reproduction poses a big theoretical puzzle to Darwinians.” (Dawkins 1986, p. 268). Although in some species, such as our own, sex is necessary for reproduction, that is not its adaptive function. Many lower organisms reproduce asexually (cloning). In many of these species, organisms switch to sexual reproduction at some stage in their life cycle. There are species, such as dandelions, that have even reverted from sexual reproduction to asexual. If reproduction was the function of sex, cloning would be far simpler, more efficient and wouldn’t require males. Moreover, even in species in which reproduction is tied to sex, reproduction itself doesn’t explain the genetic manipulations that accompany sex, including the intricate molecular processes involved in meiosis and crossing-over. Furthermore, conjugation, which like sex involves genetic manipulations in the transfer of DNA, occurs separate from reproduction.

That sex is a puzzle should be embarrassing for evolutionary biology. Sex must be extremely important. Most organisms reproduce sexually at some point in their life cycle. Sexual reproduction is present in all taxa and most species. No known “higher” organisms have evolved through cloning. All either reproduce sexually (at least periodically) or evolved from ancestors that did. (Bell 1982, p. 437; Maynard Smith and Szathmary 1995, pp. 164-66). As research of microorganisms has progressed, it is no longer even clear that any lower organisms have evolved by cloning since they engage in conjugation.

Not only should it be embarrassing, that sex remains a puzzle should be a clue that something fundamental is wrong with the whole neo-Darwinian framework. A leading theorist on the subject, John Maynard Smith, once remarked that “[o]ne is left with feeling that some essential feature of the situation is being overlooked.” (Ridley 1993, pp. 40-41, quoting Smith). The essential feature that has been overlooked, which Maynard Smith did not consider, is that population genetics and the concept of chance mutation are wrong. After describing sex as inconsistent with evolutionary theory, Williams stated that his “purpose is to propose minimal modifications of the theory to account for the persistence of so seemingly a maladaptive character.” (Williams 1975, Preface, v). The argument that follows is that sex can’t be solved with minimal modifications to neo-Darwinism; neo-Darwinian theory needs radical surgery, including removal of the concepts at its core.

The hypothesis set forth in this book is that genetic rearrangements are not due to “mutations” in the sense of random errors. Rather, they are produced by experimental genetic tinkering. This is the adaptive function of sex in higher organisms. It is the adaptive function of conjugation in lower organisms.

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Genetic Experimentation ~ Table of Contents

Genetic Experimentation: The Adaptive Function of Sex & ConjugationINTRODUCTION 1
Mendel, Neo-Darwinism, and the Problem of Sex 4
Mendel, Neo-Darwinism, and Point Mutations 8
The Doctrine of Blind Variation 10
Proof that Organisms Engage in Genetic Experimentation—Even within the Framework of
      Population Genetics 12
Opening the Black Box: The Immune System and Genetic Engineering 19
Opening the Black Box: Conjugation as Genetic Engineering 21
Opening the Black Box: Shifts in the Meanings of “Gene” and “Mutation” 24
Opening the Black Box: The Evolution of Proteins through Genetic Rearrangement 25
Opening the Black Box: Transposons, Introns, and Exons 26
Opening the Black Box: Noncoding DNA 28
Opening the Black Box: Homeotic Genes 30
Evolution through Changes in Developmental Sequences 31
Speciation through Polyploidization 35
The Connection between Sex and Genetic Rearrangements 36
Genetic Experimentation: The Continuum from Conjugation and Sex 40
Point Mutations and the Rival Allele Model of Evolution: Why Have They Stuck? 43
Directed Variation and Rearrangements 52
Organisms as Epigenetic Systems: Perceptive and Flexible 54
Organisms as Epigenetic Systems: The Genetic Library 56
The Genetic Library: Atavism and Homoplasy 56
The Genetic Library: Genomic Imprinting 60
The Genetic Library: The Contextual Shift Hypothesis 62
The Genetic Library: Its Significance for Genetic Experimentation 63
Communicating Environmental Information to Reproductive Cells 66
Criteria for Evaluating Theories of Sex 69
Theories of Sex that Do Not Acknowledge Genetic Experimentation 71
Theories that Do Acknowledge Sex as Experimentation 73
Sex, Recombination, and Rearrangements 78
A Higher Level of Genetic Experimentation? 80
Epilogue: Philosophical Implications of Directed Experimentation 84

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About the Author & Project

Britt W. Hanson
Britt W. Hanson

Each of these three books aims to solve a significant scientific puzzle: the evolution of group altruism; the evolution of culture and its relationship to natural selection; and the function of sex. Along the way, these books present theories of human nature, creativity, free will, and goal-directed causation, while also unloosening biology and the social sciences from the shackles of mechanical determinism.

I did not set out to do any of this. In the mid-1990s, I had asked a simple question: why, over the millennia, has the human species put its ingenuity towards extracting more and more resources and generating more and more people? And this follow-up question: do we have any control over this trajectory, or is it somehow ingrained in us?

When I couldn’t find an answer to these in the social sciences, I turned to evolution, expecting that what modern humans do should have some connection with what our ancestors evolved to do. Eventually I stumbled onto sociobiology. I became persuaded that a fundamental thesis of sociobiology must be correct: human culture must derive from human biology, as evolved through natural selection. The alternative is a blank slate hypothesis. But the more I examined sociobiology, the more I also became persuaded that most of the rest of its propositions were wrong.

My skepticism began with kin selection. In On Human Nature, E.O. Wilson stated that kin selection accounted for cooperation among close relatives, implying that kin selection could explain tribalism in our ancestors. This led me to wonder how modern human societies could have expanded so far beyond tribes of close kin. I searched for sources that would provide a rationale for how kin selection works. In The Selfish Gene, Richard Dawkins emphasized again and again that kin selection does not predict tribalism at all. It is not a group theory. It is a theory of selfish individualism. Dawkins argued that group altruism is impossible, even theoretically. Although Dawkins is a persuasive writer, this did not seem right. Human groups, including tribes, are real. And the more I examined Dawkins’ selfish gene rationale for kin selection, the more I questioned its plausibility.

My interest was in humans, but it occurred to me that animal societies could not function if each individual member calculated altruism by degrees of relatedness, as predicted by kin selection. Poring over studies of animal societies, I quickly came to see that animals bestow altruism according to group membership, not degree of relatedness. In Ants and The Social Insects, E.O. Wilson made clear that this is true of ants and other social insects. So why then were evolutionary biologists, including Wilson, so enthusiastically proclaiming that kin selection was correct? Where were the skeptics?

In 1998, I came across two articles by Mary Jane West-Eberhard, which cast doubt upon kin selection. These articles contained what to me was a surprising, extraordinary fact: the division between queens and worker castes is epigenetic. This was directly at odds with the way that kin selection modeled the existence of “selfish” queens and “altruistic” workers as due to rival alleles for selfishness and altruism. Epigenesis didn’t solve the problem of altruism—some genetic selection must occur for worker altruism to evolve—but it did lead me from simple skepticism to a conviction that kin selection was just plain wrong. Evolutionary biology needed a theory that explained altruism at the level of the group. The theories of group selection, however, used the same gene-centered approach as did kin selection, and they were thus not persuasive, either. So I set out to devise a theory of group altruism. The outline of what I eventually called “dynastic theory” came about in short order.

Dynastic theory explains why animal societies are structured around lines of descent—what I call “dynastic structure”—and, hence, are groups of kin. I could project this structure to bands and tribes of human pre-cultural ancestors. But this still didn’t account for the fact that modern human societies have bonds that extend far beyond kinship.

I set myself to the task of figuring this out. I guessed that the solution had something to do with the distinctive way in which humans evolve, through culture. This was something else that sociobiology did not seem to get right. In places, sociobiologists were suggesting that human culture evolves just like natural selection, or maybe even through natural selection. At other times, sociobiologists pointed out that human biology has hardly changed over the past tens of thousands of years and that biological differences do not account for cultural differences. If so, natural selection of genetic variation could have nothing to do with the evolution of culture. Moreover, when I thought through specific examples of the evolution of cultural traits, it became clear that culture evolves independently of natural selection. The trick was to explain how this could happen. What emerged, in the year 2000, was a theory of cultural evolution: the theory of directed creativity.

This theory—and in particular, the very concept of creativity—conflicted with determinism, which is a premise of science. I was reluctant to open this can of worms, but it seemed too important not to do so. What emerged was a theory of guided free will and a theory of teleological causation—which is not to be confused with cosmic purpose or theology.

Meanwhile, during my reviews of kin selection, I became aware that biologists regard the function of sex as an unsolved evolutionary puzzle. This was striking. Biologists were heralding the neo-Darwinian synthesis as completing Darwin’s theory, yet the synthesis couldn’t account for a trait as apparently fundamental and as (nearly) ubiquitous as sex? Adding to the puzzle, to be consistent with kin selection, sociobiologists were asserting that sex must hurdle two-for-one leaps of benefits in order to evolve from asexual reproduction.

By this time, I had become thoroughly skeptical of almost every aspect of the neo-Darwinian framework. And since dynastic theory solved the problem of altruism without the need for leaps, I thought I might also easily solve the puzzle of sex. This quest, however, turned out to be far more difficult and time-consuming than solving altruism and cultural evolution. A sketch of the theory of sex and conjugation was completed by the end of 2002, but by then I was exhausted and needed to make a living. I took up these projects again several years later, attempting to put the several theories into comprehensible, readable forms. Given the scope and magnitude of the subject matter, this has taken several years. I hope that I have succeeded.

I realize that what these three books purport to accomplish appears to be all quite grand. I also realize that it is possible that they are simply grandiose.

The reader will rightly be skeptical, all the more so since I am not a trained evolutionary biologist, an anthropologist, or a philosopher. I am a lawyer. One of the questions that I asked myself early on in developing dynastic theory, and kept asking throughout the project, was how someone like me could possibly perceive flaws in evolutionary theory and put together improved theories. I think that my outside perspective proved to be essential. When a puzzle remains unsolved, it is usually because errors are embedded in orthodox assumptions that are so ingrained that no one questions them. In this case, the ingrained assumptions are embodied in the neo-Darwinian synthesis—a synthesis that became orthodoxy, became identified with Darwin, and then hardened into a phalanx of concepts and doctrines that is extremely difficult to breach. That is why outstanding scientists keep mulling over the same ideas and falling short of solutions. As science historian Thomas Kuhn observed, “normal science” occurs inside a scientific discipline; significant change arrives from the outside, from those who challenge ingrained assumptions. I didn’t begin with a priori assumptions. I began with the empirical patterns, then worked backwards until the puzzles were solved. The reader will judge whether I have solved them successfully.

Most of all, though, the end hope is that these books might contribute to the understanding of the questions that prompted them: why has our species evolved in the direction of more, more, and more? And do we have a choice?

–Britt Hanson