Lynn Margulis (1938–2011)

I'm a sucker for popular science books. As a minor member of one of C P Snow's Two Cultures, I am respectful of but in no way conversant with the scientific mind (and even less so of technology), so popular science writings are my way of consuming regurgitated scientific principles without too much indigestion.

Lynn Margulis is a celebrated microbiologist who has, by all accounts, done sterling work on the relationships between bacteria, fungi, plants and animals. Her main contribution to show more science is her endosymbiotic theory, which postulates that over millions of years organisms have often absorbed or been absorbed by others, developing and evolving into new organisms (I think I have that right). For example, human cells have long been known to include bacterial relics such as mitochondria, which among other attributes process oxygen and provide the energy that keeps us going, and without which we would certainly not have evolved to be here.

The Symbiotic Planet goes further than that, however, and suggests links with James Lovelock's Gaia hypothesis. Gaia, so beloved by some mystics, feminists and romantics, is actually the name currently given to the processes that help to regulate the planetary eco-systems that sustain life in its myriad forms, not some anthropomorphised goddess that needs worshipping (as would have happened in the classical period).

There are lots of exciting ideas here, the distillation of many years of work, collaboration and stamina, and I certainly am in no position to criticise the science behind them. Her writing at times exhibits passion and poetry, and you can see that this is a real powerhouse of a woman who converses and argues with other scientists (inter alia, she was married to Carl Sagan for nearly a decade) to expand horizons and perpectives.

What I am less happy about in this book, though, is its poor editing and occasional lack of clarity and direction. Many of her other books are co-authored (often with one of her sons) and I feel that this publication could have done with more imput from other minds. We have a whole chapter on her early career which, while interesting, diverts from the main thrust of her arguments. There are fine diagrams, but they are often placed arbitrarily amongst the pages and labelled inconsistently when compared one with another. There is an index, but we non-scientists, at whom the book must largely be aimed, would have welcomed a glossary when new terms are introduced (though to be fair these are sometimes partly explained a few pages on, but sometimes not at all). And there are occasional misspellings (an obvious one is 'archaebacteria', appearing twice on one page as 'archeabacteria', which raises concerns about those I must have missed).

Most of these faults must be laid at the door of an editor (was there one?), because there is no doubting the enthusiasm, expertise and creativity of the author, still evident many years on from the book's original publication date. In fact, one of the plus-points of this book for me, as a non-scientist, was the analogy I can see with the creative arts (not to mention technology). I've often suspected that it's hard to create new art-forms de novo, and that most artistic innovation is the symbiosis of two or more distinctly different genres; The Symbiotic Planet's arguments provide the perfect parallel when discussing the evolution of life-forms.

http://calmgrove.wordpress.com/2012/07/08/symbiosis/ show less

This is an immensely fascinating, and immensely frustrating book.

It expands substantially on the standard Margulis/Sagan spiel, that eukaryote organelles (mitochondria and chloroplasts) derive from bacteria that were ingested, but not digested, by other bacteria, to make the much bolder claim that speciation is driven by this process of one genome acquiring another genome whole.

The fascinating part of the book is the many examples of absolutely bizarre symbioses and so on that I'd never show more have dreamed of, including things like
* worms that incorporate algae into their skin and live via photosynthesis,
* tubeworms that incorporate archae and live off their byproducts, * echinoderms can fertilize sea squirt (chordate!) eggs to give rise to viable offspring, some of which develop along the male parent pathways, some along the female parent pathways.

So what's frustrating?

Firstly the book is an angry polemic, repeatedly striking out at a parody of neodarwinism that looks grossly simplified, even to me. Half its agenda seems to be to tell us about some very interesting biology, while the other half is to tell us that all other biologists are fools. For example it repeatedly states the (obvious) point that SNPs are probably not powerful enough to generate the diversity we see around us, but never discusses the facts that most diversity is actually believed by most biologists to be generated through crossing over of chromosomes along with diploidy, ie through sex; neither does it deal with the fact that while end-protein SNPs are limited in what they can do, SNPs in regulatory proteins can have profound effects on development.

Secondly the book leaves too much unsaid. Just as we get to really fascinating details, like how exactly the nucleus of eukaryotes could have evolved from the fusion of a eubacterium with an archae, the discussion kinda peters out. The really interesting and unexplained stuff (at least to my mind) like quite how the absorbed archae lost all its cytoplasm (but became the nucleus), and what happened to the DNA of the host eubacterium.

Thirdly, I have to wonder the extent to which the authors overstate their case. The examples they give are quite fascinating; the idea, that the eukaryotic nucleus, mitochondria and choloroplasts are ingested genomes is full of promise. Even some of the other ideas they give, that larval forms of marine life derive from a different genome from the adult form seem promising. But to leap from this to the uneqivocal statement that genome acquisition is the ONLY driver of speciation seems an awful leap, and a more satisfactory book would list and discuss the qualms of those who disagree with them, rather than simply describing them all as unscientific know-nothings, (a description that seems a bit rich coming from authors who have discussed the existence of free-will in bacteria). show less

Margulis strives in this short book to connect the idea of Gaia with her symbiotic theory of evolution and does so quite convincingly to my mind. I appreciate her scientific explication of the Gaia Hypothesis, as opposed to the widespread, pop-spirituality one of a personified uber-organism. In Margulis's words, "Gaia itself is not an organism directly selected among many. It is an emergent property of interaction among organisms, the spherical planet on which they reside, and an energy show more source, the sun." show less

Lynn Margulis was one of those scientists who's theory was mocked and derided for a long time until it was proven. It's a fascinating look at a theory of convergent evolution as opposed to traditional Darwinian divergent evolution. Vindication aside, the bitterness of the author is very, very, apparent in this intruiging book. (did i mention bitter?) However, this is one of the few popular evolution books that deals with microbiology,(also one of my favourites) and I agree with the author's show more critique that, like in physics, starting at the bottom with the microbes & viruses & DNA is the best place to look for the mechanisms of evolution. show less