Acquiring genomes Book

Margulis and Sagan put forward an alternative to a neo-darwinian theory that states that evolution results from random mutations that are acted upon by the environment (natural selection). Random mutations are mostly detrimental to species demise. The real engine of evolution occurs through "symbiogenesis," which means that two or more separate organisms unite and eventually fuse their genetic structures so that formerly independent entities now have an integrated genome that is passed on through the generations. The integration begins at the bacterial level (no cells, but genetic structure). Life rests on the 1800 million years when bacteria lived before there were nucleated organisms. Rather than a line of common descent, the evolutionary tree is, the authors argue, a fusion of once-independent organisms. We are, they emphasize, "composite beings." Organisms they write, "must have a reason to come together," and organisms engage in several different levels of association ("complementary living") prior to the integration of genomes. This in the authors' view supports the punctuated theory of evolution advocated by Gould and others, which argues that major evolutionary change comes in discontinuous jumps, as opposed to gradual, mutation by mutation changes as the neo-darwinians believe.

In a difficult to follow discussion, the authors argue that the evolution of life is ultimately a product of the 2nd law of thermodynamics where complex life forms and systems arise to bring their surroundings into thermo equilibrium. This view stands in contrast to an argument that, at least in the short term, life is an exception to the 2nd law as it concentrates energy for use rather than dissipating it as the 2nd law requires. They write that nature abhors a temperature gradient and builds complex systems (life, ecosystems) to, thereby, reduce "the gradient between the sun and space." In this way, the authors also make it clear that life is not only tied to the 'lowest' microbe level, but to non-life and the physical world.

Margulis and Sagan are critical of the neo-darwinians, the "self-proclaimed evolutionary biologists" who have "dogmatically overemphasized" random mutation, and ignored "the much larger part of the story of evolutionary innovation, the symbiotic joining of organisms." This comes, they believe, from the neo-darwinian "zoocentric" training in only one of the five kingdoms of life, a background that distinctly ignores the tie of animals and ourselves to microbes. The neo-darwinians over use the "old, tired" social darwinist metaphors of "intraspecific competitive struggles." The authors go on to say that their book avoids use of terms such as cooperation, competition, mutual benefit, competitive advantage, which is a terminology "not only fallacious but dangerously so" and is a "philosophical error." Taking on Richard Dawkins directly, the authors say there's no selfish gene. "There's no life in a gene. There is no self." The authors write that the minimal definition of self is a cell, a living system, and they argue that "words like competition, cooperation, and selfish genes" be replaced by meaningful terms such as "metabolic modes (chemoautotrophy, photosynthesis), ecological relations (epibiont, pollinator)...."

While that language is unlikely to enlighten the reading public much, the authors want to move us away from overly simplistic notions about the evolutionary processes and particularly from the paradigm that emphasizes competition and winners and losers. The counter term, cooperation, is also overly simplistic as it suggests that some sort of 'good will' is involved and does not capture adequately the integration of genetic structures over time after several levels of association have occurred. What interests the authors in this book is the "modulated coexistence between former predators, pathogens and their hosts, their shelter and food sources....[where] exploitive relationships may eventually become convivial to the point where neither organism exists without the other."

This is all fair criticism given the authors' perspective. Nevertheless, the authors themselves do not shy away from using common-day language that is rich in implication. They speak of the living cell as the first sign of the "true self". That cell is a composite of formerly independent genetic structures that now give the cell its "character," which is turn gets passed on through the generations. The integration requires "a reason," which introduces the idea of motivation based on 'self-interest' that, in turn, involves "something like free choice." In their description of energy gradients, the authors go even further, suggesting that the "purpose" of life is to facilitate if not expedite the movement to thermo equilibrium. They write, "without invoking any vitalism or mysticism or spiritualism, we can recognize in ourselves a 'purpose.' This purposefulness is an offshoot of the thermodynamic tendency to come to equilibrium. Complex systems, life included, tend to arise in order to bring their gradient-rich surroundings to equilibrium."

It is not so clear that this view of purpose conflicts with Dawkins' selfish-gene theory where the 'purpose' of life is to move genes into the next generation. The authors do not like the selfish gene notion. Again, they say, the gene is not a self, yet Dawkins was perhaps writing more metaphorically, finding a way to describe life's impulse, whether in pre-nucleated cell structures (prokaryotes) or nucleated structures (eukaryotes) to 'self-replicate.' In their book, Margulis and Sagan do not really counter that view and it's possible from their perspective that life's deeper purpose is to self-replicate in order to move cosmic thermodynamics toward equilibrium.

While the book's writing is uneven, moving back and forth from good story telling to more technical-laden information, the authors 'attack'-style language against the neo-darwinians detracts from an otherwise very interesting and thought provoking argument.