Aaargh! Physicists! Again!

A while back, two physicists, Paul Davies and Charles Lineweaver, announced their explanation for cancer with a novel theory, which is theirs, that cancers are atavisms recapitulating in a Haeckelian reverse double backflip their premetazoan ancestry. They seemed very proud of their idea.

I was aghast, as you might guess. They even claimed that human embryos go through a fish/amphibian stage with gills, webbed feet, and tails in a pattern of Haeckelian development. They do not understand evolution, development, or cancer, facts that were apparent even in the absence of their admission that they had no prior knowledge, and it was freaking embarrassing to see two smart guys with a measure of legitimate prestige in their own specialties charging off into another discipline with such crackpot notions.

Now they’ve done it again, repeating the same claims all over again. And worse, they’ve now published it in the journal Physical Biology, under the title “Cancer tumors as Metazoa 1.0: tapping genes of ancient ancestors”.

The genes of cellular cooperation that evolved with multicellularity about a billion years ago are the same genes that malfunction to cause cancer. We hypothesize that cancer is an atavistic condition that occurs when genetic or epigenetic malfunction unlocks an ancient ‘toolkit’ of pre-existing adaptations, re-establishing the dominance of an earlier layer of genes that controlled loose-knit colonies of only partially differentiated cells, similar to tumors. The existence of such a toolkit implies that the progress of the neoplasm in the host organism differs distinctively from normal Darwinian evolution. Comparative genomics and the phylogeny of basal metazoans, opisthokonta and basal multicellular eukaryotes should help identify the relevant genes and yield the order in which they evolved. This order will be a rough guide to the reverse order in which cancer develops, as mutations disrupt the genes of cellular cooperation. Our proposal is consistent with current understanding of cancer and explains the paradoxical rapidity with which cancer acquires a suite of mutually-supportive complex abilities. Finally we make several predictions and suggest ways to test this model.

Oh. My. Gob. So…much…wrongness.

I read the paper. I cringed. This blogger read the summaries. He cringed. I think anyone who is the least bit informed about biology will feel the same way…but this crap will continue to get published in legitimate journals because…because…hey, physicist! They must know something we don’t! (Well, they do know things we don’t, but we know things they don’t, and knowledge of cosmology doesn’t translate into knowledge of molecular biology. Or vice versa.)

The conceits of the paper are 1) a lack of knowledge about cellular evolution that allows them to posit evidence-free scenarios; 2) peculiar notions about molecular biology that allow them to imagine whole invisible networks of primeval genes lurking as atavisms beneath the polished exteriors of urbane and civilized modern cells; and 3) bizarre misconceptions about cancer causing mutations that they can’t back up with a single specific example.

So let’s start with the first objection, the weird evolutionary history enshrined in the title. They postulate a step in evolution just above the colonial stage, with groups of cells having marginal specializations — which is reasonable, up to a point.

The transition from unicellular to complex multicellular organisms took place over an extended period starting at least 1 billion years ago (Hedges and Kumar 2009). Importantly, ‘advanced’ metazoan life of the form we now know, i.e. organisms with cell specialization and organ differentiation, was preceded by colonies of eukaryotic cells in which cellular cooperation was fairly rudimentary, consisting of networks of adhering cells exchanging information chemically, and forming self-organized assemblages with only a moderate division of labor. These proto-metazoans were effectively small, loosely-knit ecosystems that fell short of the complex organization and regulation we associate with most modern metazoans. In short, proto-metazoans, which we dub Metazoans 1.0, were tumor-like neoplasms.

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