Pharyngula

gen•e•sis

Some fields of science are so wide open, such virgin swamps of unexplored territory, that it takes some radically divergent approaches to make any headway. There will always be opinionated, strong-minded investigators who charge in deeply and narrowly, committed to their pet theories, and there will also be others who consolidate information and try to synthesize the variety of approaches taken. There are dead ends and areas of solid progress, and there is much flailing about until the promising leads are discovered.

Origins of life research is such an unsettled frontier. I wouldn’t want to work there, but the uncertainty and the confusion and the various small victories and the romance of the work do make for a very good story. And now you can read that story in Robert Hazen’s Gen•e•sis: The Scientific Quest for Life’s Origins (amzn/b&n/abe/pwll).

Now I am not a geologist, a chemist, or a geochemist, and most of this book is written from the perspectives of those disciplines. I’ve been interested in abiogenesis for a long time, but I’ve always approached it as a biologist, assuming that the best way to attack the problem was to start with life and extrapolate backwards, moving from the complex to the simpler. Gen•e•sis turns that around, though, and most of the focus is on prebiotic chemistry—how the earth acquired a collection of organic precursors that would form the building blocks of life. I can assure you, at least, that since my prior understanding of this stuff was just about nil, even the most technical parts of this book are approachable by the lay reader.

One thing, though, that you will not find in the book is The Answer. Hazen is forthright in summarizing the difficulties in the various theories and explaining that our knowledge is very sketchy. He also exhibits the virtues of a real scientists faced with an intractable problem: at the same time that he’s explaining that some crucial piece of the puzzle is missing, he’ll outline a positive research program to find and test that part of the story (strangely, though, that program never involves emphasizing the existence of a controversy or legislating a program of instruction in the high schools…). For example, one model for the origin of life is that metabolism, in particular some analog of the citric acid cycle, arose first. This model has a major flaw, though, in that no one has found a pathway that generates one crucial molecule, oxaloacetate, under plausible prebiotic conditions. Does that mean the model is to be discarded? No, it means there is a specific line of research that needs to be pursued first, and he proposes experiments using an environment rich in hydrogen sulfide that might bridge the gap.

That’s another strength of the book: it is written by a practicing scientist, and describes how researchers in this field are doing their work. If you’ve been curious about how people can do experiments that address conditions 4 billion years ago, you’ll find examples here.

He also covers some of the major personalities—Stanley Miller, Sydney Fox, Bill Schopf, Günter Wächtershäuser (man, how can you argue with a three-umlaut scientist?), and Jack Szostak, for instance—and their ideas and how they relate to one another. Hazen’s got his own biases in how things happened and he isn’t reticent about sharing them, but still, he manages to be extraordinarily even-handed and complimentary to his competitors and colleagues.

If there is a weakness to the book, it is that it is focused so strongly on the pre-biotic world. While it does have a short discussion of the RNA world hypothesis, how early biology would have worked is not an emphasis—once cell-like precursors start maintaining a self-sustaining metabolism and replicating, well, we’re going to find another book to discuss that. Gen•e•sis is very specifically about the subject in the title: how did a dead world, warm and wet and rich in minerals and gasses, spawn a chemistry that led to the complex early replicators?

It’s a book that describes research into early origins, so while I’ve already said that Hazen won’t try to give The Answer, he does propose Some Answers, so I’ll at least mention the three models he proposes. These aren’t complete, of course, but it’ll give you an idea of the directions the results are taking.

  • Life began with metabolism, and genetic molecules were incorporated later. Wächtershäuser is a key figure here, and I’d also mention Stu Kauffman. The idea is that you could have sloppy replication (actually, simple growth) of a chemical environment, and informational macromolecules would be a later refinement that made the process more robust and reliable.
  • Life began with self-replicating genetic molecules, and metabolism was incorporated later. This idea hypothesizes that the first molecules of life were complex polymers that were launched into cycles of Darwinian competition, and the elaborations of metabolism were later features that accumulated, conferring greater fitness on the possessors.
  • Life began as a cooperative chemical phenomenon arising between metabolism and genetics. This is a kind of best of both worlds compromise, but hey, why not? It’s a big planet, and one of the things that you learn in this book is that there are many ways that complex molecules are generated spontaneously. I have no problem with the idea that lots of chemical reactions were taking many different directions, and that the origin of life was a “you got chocolate in my peanut butter/you got peanut butter in my chocolate” moment.

Gen•e•sis is readable, entertaining, and informative, and it doesn’t stint on the satisfyingly pragmatic details of the process by which this wide-open field of research is done. If you’ve ever wondered what was going on in the first 10-100 million years of the Earth’s history after the planet had cooled down, this book will give you some ideas.

Comments

  1. #1 Torris
    April 1, 2006

    Thanks for the review PZ! Robert Hazen’s book sounds very interesting. Now I’ll have to buy a copy and read it for myself.

  2. #2 zed
    April 1, 2006

    Hmm, isn’t there a sort of biological precedent for this chocolate/peanutbutter concurrence in the evolution of the first eukaryotic orgaisms? If I remember correctly, there was a sort of pre-aerobic microbe that formed a symbiotic relationship with an aerobic bacterium to cope with the rising levels of oxygen in their environment.

  3. #3 george cauldron
    April 1, 2006

    I trust they give serious consideration to my preferred theory, the Alien-Septic-Tank-Dump hypothesis.

  4. #4 with a Y
    April 1, 2006

    Speaking of unfinished reading lists. I accidentally left my half read copy of Sam Harris’ ‘The End of Faith’ on a Delta puddle jumper in Salt Lake City while switching planes today on my way to Omaha. I hope some nice Mormon enjoys the free book.

    Not all was lost. I finally got to crack open Dawkins ‘Climbing Mount Improbable’ on the rest of the trip. A good read so far.

  5. #5 FrankieFurly
    April 1, 2006

    Sorry, I should have said 3.465 billion year old chert. I couldn’t be bothered to run downstairs and check the book earlier with the result that my error encompassed a timespan roughly comparable to that stretching between the heydey of the trilobites and the heydey of this blog. For all I know I’ve now spelled “heydey” incorrectly.

  6. #6 Jonathan Badger
    April 2, 2006

    Cool. Günter’s stuff is still relevant, apparently (I met him ten years ago when he came to visit Carl Woese in Illinois). I think it’s cool that a patent lawyer like Wächtershäuser (he does have a doctorate in chemistry besides his law degree, true), can do research on the side.

  7. #7 wamba
    April 2, 2006

    If there is a weakness to the book

    What, you’re not going to take points off for the religious title?

  8. #8 DeafScribe
    March 19, 2007

    I come to this discussion a year late.

    A few weeks ago, I picked up Christian de Duve’s Vital Dust and 22 pages in, he’s detailed some of the things we don’t know, circa 1995, when the book was written. Knowing biology research is in continual ferment, I wondered how much more has been learned in the 12 years since.

    After skulking around a bit I found Hazen’s book. It seems to be the most balanced and comprehensive overview of origins study available to date, and it also notes that we have much more to learn. But as PZ points out, Hazen also reports on the directions further research is taking.

    I’m encouraged – thanks, Kristine – by the mention that Wchtershuser is largely self-taught. That’s the only way I’m ever going to get a deeper understanding of the subject. And thanks, PZ, for giving us your informed perspective. I’m delighted to find my impression – that this is a solid book and a fine introduction to the field – is valid. I’m nearly halfway through now and enjoying every minute of it.

  9. #9 sailor
    March 25, 2007

    Dr Dave:
    “That one is on my reading list, but I’ll have to admit that the last reccommendation I acted on (the evo-devo book whose name escapes me now… you know the one) I found interesting but somewhat impenetrable to a non-biologist. I faded out well before the midway point.”

    Me too. Robert Hazen also does an origens of life course on DVD (teach-12.com). It is really excellent and needs no prior knowledge. I highly recommend it and his book is probably equally understandable

  10. #10 Tim Fuller
    June 17, 2008

    It is totally ‘gay’ to title the book Genesis even though the word isn’t ‘owned’ by the Church. It just leads to confusion and possible cross dressing.

    Enjoy.

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