by Christoph
I had a short exchange with Philip Ball recently days when he announced his next book How Life Works on Twitter. If you don't recognize the author's name: Philip is a chemist by training, holds a PhD in physics, was a long-time editor of Nature, and is a prolific book author and science writer. In short someone who always looks deeply into- and out-of the box, many boxes. With the How Life Works theme and this author, it's no wonder Janie and I can't wait to get our hands on the book. Our recent exchange was about the book cover (see here)
Me any reason why plants & fungi were left out from this lovely circus? I ask only out of curiosity...
Philip Good question (and you'll notice that there are no prokaryotes either) - and the reason is that the book is mostly about metazoans like us. It touches on the other kingdoms, but they have their own stories!
Me sure enough I noticed the missing proks but I sympathise with the artist who probably thought it too challenging to cover all size scales of living beings in one image. ok then, this is «how life works vol. I, metazoans»
Philip It's more: we should be more careful in assuming that what is true for E. coli is true for the elephant (as the recent work on ribosome decoding shows).
From the online archive of the Institut Pasteur.
Philip, you mildly mock biologists that still cling to the quote attributed to Jacques Monod: "Anything found to be true of E. coli must also be true of elephants." Quotes have their own history, and according to H. Friedmann, Monod may have adapted it from an earlier remark by the Dutch biochemist and microbiologist Albert Jan Kluyver (1888–1956):"From the elephant to butyric acid bacterium – it is all the same!"
The smart phonetic alliteration "of E. coli ... of elephants" always reminds me of one of these very French, Voltaire-type flashes of esprít. Yet, the quote sounds less flashy in the original, almost dogmatically dry (Diderot-type?):"Tout ce qui est vrai pour le Colibacille est vrai pour l'éléphant." Monod was fluent in French and English, and in 1954, when he first uttered the phrase during a lecture, it was and certainly meant to be provocative. What was so provocative about it, back then?
In the early fifties of last century, it was by no means settled among biologists that anything smaller than algae (Botany Department) and amoebae (Zoology Department) belonged to the category of "life form" at all. It was clear to biologists since Pasteur, Koch, Lister, etc. that these micro‑bes were not simply "miasmata," bad air. They were indeed life forms not to be ignored by physicians and pathologists, to say the least (microbiology departments were successively established at many universities at the beginning of the twentieth century, for example at Georg-August-Universität Göttingen, Germany in 1900). But to posit that microbes were genuine cellular life forms, with their own genetic material, genetics, and physiology, was scandalous (see Elio's recent Interlude in Microbiology).
The results of Avery and colleagues (transformation), of both Lederbergs (conjugation), and of Monod, Jacob and colleagues (physiology, gene regulation) were initially not received with particular enthusiasm, mixed feelings prevailed (scientists!). Cricks "central dogma" (1957) generously ignored any concerns.
A reverberation of these early struggles can be heard in the term "prokaryotes", which is still widely used, and in which the prefix "pro-" implies a "not yet" or "not quite" (see a more in-depth reasoning by Nanne Nanninge here in STC). And don't assume that such prefixes would not influence the thinking of scientists, unconsciously! There still are (admittedly few) botanists in the 21th century who claim blue-green algae – cyanobacteria, that is – belong in "their department." Only 10 years ago, I seriously argued with an expert yeast geneticist about whether bacteria have chromosomes: "I know the Cairns image, and you bacteria nerds call them that, but they are actually not chromosomes. period." Go figure.
Philip, when you said on Twitter that "the book is mostly about metazoans like us. It touches on the other kingdoms, but they have their own stories!" I replied without thinking much: "...ok then, this is «how life works vol. I, metazoans»" (I avoid capitals when tweeting). This wasn't something that was just said lightly, and this is where my slight discomfort comes into play at your mention of Monod's quote. It's a question of balance. To tackle the question of How Life Works we can – or should – no longer pitch metazoans against E. coli as representative of the prokaryotes (bacteria and archaea). (I didn't miss your half sentence:"...other kingdoms, but they have their own stories ".) Metazoans are far too similar among each other compared to the differences between prokaryotes. This is true for almost all their cellular structures and functions, as well as their regulatory networks. We must learn to deal with the admittedly utterly confusing fact that all cellular life forms are phylogenetically related and use essentially the same biochemical building blocks (amino acids, sugars, fats, nucleotides), but assemble, combine, and put them to work in vastly different ways. Emanuele Severi shared a quip on Twitter he had heard at a conference: "What is true for E. coli might be true for an elephant, but certainly not for Bacillus!" (Emanuele meant Bacillus subtilis). I bet that biologists of any faction will be in for some surprises about How Life Works when more becomes known about the caprices with which the descendants of bacteria and archaea and ancestors of metazoans will delight us, the protists.
I agree with you, Philip, that Monod's quote is (readily mis)used to spread an oversized, very soft and prettily embroidered blanket over differences between life forms that are not yet fully understood. For example, the significant structural and kinetic differences between human ribosomes and those from E. coli. (I wouldn't dare to put E. coli ribosomes under the same blanket with those from chloroplasts or mitochondria, both descendants of bacteria). But peeking out from under the blanket at one corner is something that I, as a scientist and personally, would not want to miss: there is only one life on this planet, and we are all related to each other in incredible ways. With this in mind, I would like to continue using Monod's quote... and work as scientist to unravel the equally incredible differences between life forms. And no, I don't intend to snatch away your work on the next volume(s) of How Life Works. (imagine a smiley here).
I wouldn't claim that what I have written down here is particularly original. Rather, I've picked up snippets of thoughts from other, more competent minds and put them together. A citation list would be awfully long, and this is a blog after all.
Finally, I note that I really like the illustration that intimately joins two E. coli cells by conjugation and two elephants by their trunks, even though I see that the flagellar ends of the bacteria are incorrectly drawn tapered, which I was lamenting just recently.
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