The Haeckelization of Paul Davies

Davies is up to his same old nonsense again: he's in Australia, lecturing people about his theory of the causes of cancer.

Seven years ago, the National Cancer Institute in the US asked Professor Davies to use his insight as a physicist to look at cancer. His conclusion is that most cancer biologists are thinking about the problem the wrong way.

Rather than treat cancer as a disease of cell mutation, he and his colleague Dr Charley Lineweaver at the Australian National University have developed what they say is a new theory of cancer that traces its origins to the dawn of multicellular life more than a billion years ago.

Professor Davies believes cancer cells are a "reversion to an ancestral phenotype", the physical expression of deep genetic information that springs from the very nature of multicellular life.

Goddamn.

First thing you need to know is that Davies is a cosmologist: he's had no medical or biological training. His colleague, Lineweaver, is an astronomer who likewise has no relevant expertise in medicine or biology. This is an example of a peculiar phenomenon that occasional grips some physicists with a kind of arrogant hubris that allows them to decide that they know all things in all fields, and that all those biologists need is the kind of ignorant arrogance that allows physicists to think all problems are reducible to math with the smallest number of parameters possible.

The second thing you need to know is that that physicist has reduced cancer to the simplest possible explanation he can think of, and it's based entirely on a bad concept from 19th century biology, a model for how organisms evolve that was promoted by Ernst Haeckel in a time before we knew anything about genetics, genes, or molecular biology. That concept has proven enduringly popular, I suspect because it appeals to simplistic notions about how evolution works. Ernst Haeckel had the excuse that he was living in a time before even Mendel's work was known; Davies has no such excuse.

It's like that list of children's misconceptions about physics that I posted the other day. It's appropriate that there are a lot of naive ideas about astronomy on that list, like these:

• Stars and constellations appear in the same place in the sky every night.
• The sun rises exactly in the east and sets exactly in the west every day.
• The sun is always directly south at 12:00 noon.
• The tip of a shadow always moves along an east-west line.
• We experience seasons because of the earth's changing distance from the sun (closer in the summer, farther in the winter).
• The earth is the center of the solar system. (The planets, sun and moon revolve around the earth.)
• The moon can only be seen during the night.
• The moon does not rotate on its axis as it revolves around the earth.
• The phases of the moon are caused by shadows cast on its surface by other objects in the solar system.
• The phases of the moon are caused by the shadow of the earth on the moon.

Imagine if a biologist were asked to deliver an outsider's perspective on problems in cosmology, and they said stuff like that. That's not just an outsider's perspective, that's an ignoramus's perspective, and it is not helpful. It's just plain embarrassing. Now imagine that said biologist was invited to major universities around the world to deliver popular addresses on the solution to cosmology. This has become absurd and damaging.

I've tried before to explain why Davies is wrong. I tried a second time. Orac has shown how Davies and Lineweaver are tied to outright quackery. Apparently no one is paying attention, or cares what real biologists say about cancer, preferring to listen to a Real Scientist, one with degrees in physics, the one Real Science. I'm going to try and explain it all a third time. If any of you physicists out there understand what I say, could you go hammer it into Davies' skull, since he's too arrogant to listen to real experts?

Ernst Haeckel was an influential German embryologist, and he made an early attempt to wed developmental biology to evolutionary biology, but unfortunately he made the effort before we knew anything about genes or genetics, so he had to guess how morphology was inherited. He spun out a theory based on a few valid observations -- embryos of different vertebrate embryos all resemble each other at an early stage -- that revolved around the hypothesis that evolution proceeded by taking an existing form and tacking on additions to the developmental process. So, for instance, we humans evolved from fish, so our embryos go through a fish stage, which is then modified by adding limbs to resemble an early tetrapod. This is called recapitulation theory, because it proposes that embryos develop by replaying, or recapitulating, their evolutionary history.

The big problem with it is that it is wrong. Even at the time Haeckel was pushing this idea, another 19th century embryologist who was rightfully famous for the accuracy of his observations, Karl Ernst von Baer, was shouting from his manor in Estonia that Haeckel was full of shit (maybe not those precise words…or maybe their equivalent, since he was never shy about stating his views forcefully) because embryos do not recapitulate their ancestry, that human embryos do not go through a stage that resembles that of their adult ancestors, but rather simply first express the general basic traits of their phylum and gradually add specializations unique to their species.

Haeckel's ideas were dead before they were born, although he didn't know it, and despite their potency in the popular culture. But everyone who knows any developmental biology knows they were shown to be wrong 150 years ago, and that modern genetics has made them even deader. It's a zombie theory that we keep blasting holes in and yet it just keeps walking, thanks to its grasp on the popular imagination. And Davies keeps that corpse shuffling along.

He even acknowledges Haeckel's role in his theory of cancer!

A century ago the German biologist Ernst Haekel pointed out that the stages of embryo development recapitulate the evolutionary history of the animal. Human embryos, for instance, develop, then lose, gills, webbed feet and rudimentary tails, reflecting their ancient aquatic life styles. The genes responsible for these features normally get silenced at a later stage of development, but sometimes the genetic control system malfunctions and babies get born with tails and other ancestral traits. Such anomalous features are called atavisms.

Yes, he got one thing right: Ernst Haeckel said that. He doesn't seem to recognize that we now know Haeckel was wrong.

It's like saying that Aristotle thought that objects fell down because they had a natural tendency to move towards the center of the universe, which happened to be at the center of the earth. Yes, that's true. He said that, and it's a part of the history of science. It doesn't mean that it's a useful theory for developing rocket propulsion systems, or describing the motion of the planets. But there goes Davies, blithely citing Haeckel to support his theory of cancer.

And that theory is fact-free bonkers. Worse, it's counter-factual.

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.

Only someone who has never examined a colonial organism would make that ludicrous comparison. Cancers are not turning into sponges or Volvox. Colonial organisms are stable, functional, self-regulating populations of cells. Cancers are sick and unstable (one of the things that occurs is a disabling of repair mechanisms -- they spawn new variants rapidly, most of which are going to die); cancers are starving and hypoxic, which is on reason they're falling back on the inefficient mechanism of glycolysis; and they've often knocked out the regulatory controls on the cell cycle. Even single-celled organisms monitor the cell cycle. Cancers are not atavistic.

Here's a comparison for you: take my Honda Fit, cut the brake lines, flatten a tire, and set the back seat on fire -- then try to explain to me that you were recreating a classic Ford Model T in my driveway. Not that you know anything about a Model T. You just think old cars weren't as good as new cars, so damaging a new car is sending it on a journey back in time.

He's also wrong on the genetics. He seems to think that there is a mysterious vault of ancient gene networks from 2 billion years ago locked deep in the genome, and cancer is like Geraldo Riviera, cracking open a sealed wall and allowing old modes of existence to rise again. It's not true!

All genes are evolving. The genes that were working together in ancient eukaryotes have all changed over time; they are adapted to work in modern eukaryotes. They might have descended from ancestral alleles that existed billions of years ago, but drift and selection have done their work and the modern genes and gene networks have changed, or they drive fundamental biochemical processes that you can't change in significant ways without breaking the organism wholesale. Cancer disrupts ancient mechanisms that regulate cell growth, it does not replace them with older versions.

There is no github or version control system for cells. Ask Max Delbruck: "Any living cell carries with it the experience of a billion years of experimentation by its ancestors." Experimentation. Not static preservation of ancient states.

Really, you cannot imagine how painful it is for me to read Davies' "theories". They're no better than the kooky claims of ignorant quacks, but they're coming from a fellow with a rather distinguished career in science.

I'm not alone. The article cited up top also has comments from competent Australian researchers who are not happy with Davies (although they're far more polite than I am, which is surprising coming from Australians.)

Darren Saunders is a senior lecturer at the University of NSW school of medical science. "It's so frustrating," says Dr Saunders, who is also a Visiting Fellow at the Garvan Institute of Medical Research. "It's like watching someone go through a biology text book from first principles."

"He is critical of mainstream cancer research for having a lot of money, but Davies has also been well-resourced and really only come up with some uncertain theoretical insights."

Yeah, I teach undergraduates, and right now they seem much cleverer than a certain senior physicist who can't be troubled to learn the basics.

"The multidisciplinary approach is worthwhile. It's a great idea to come in unencumbered by dogma but you can't also be unencumbered by evidence," he says. "Part of the frustration is that if [Davies and his colleagues] spent a bit of time digging into the literature, they'd find evidence that blows a lot of holes in these ideas."

"Unencumbered by evidence" ought to be Paul Davies' motto.

Here's a bit of an overview of the evidence, from Hanahan and Weinberg's Hallmarks of Cancer paper. It diagrams 10 key changes in cancer, together with boxes and arrows pointing to each with current strategies for dealing with them. Just take a moment and think about how these fit into the "atavism" model.

One feature, at about 8:00 on the diagram, is "genomic instability & mutation". Cancers are not genetically stable, which is one of the things that makes them difficult to treat -- they keep changing as you find ways of killing them. Do you think ancient organisms were genetically unstable?

Apparently, another thing ancient multicellular colonial organisms did as a routine part of their existence was to coax blood vessels to infiltrate them: "inducing angiogenesis" at 7:00.

I guess they were also swimming about in an ocean full of growth suppressors (1:00) and antibodies (2:00), and oxidative phosphorylation was an invention of multicellular animals (10:00).

I suspect you're willing to think about it. Maybe you're even willing to download the paper and read about it in more detail. Pat yourself on the back; you're a wiser person than Paul Davies.