How Aliens Are Going to Cure Cancer

One of my friends recently asked me what an astrobiology publication is like.  As a member of the NASA-funded Advent of Complex Life astrobiology team, I feel like I should be able to answer that. 

Given that there is no actual alien biology to study (yet), I have often considered the field as more of a think-tank, where scientists from all disciplines get together and discuss what it takes for life to evolve, what that life would be like, and how to detect it.  I would say that most of the researchers I know in astrobiology wouldn’t call themselves astrobiologists first and foremost; instead they are “geochemists” or “geneticists” whose work has consequence for astrobiological questions.

However, a paper just came out in the journal Physical Biology from two thinkers that I would definitely consider astrobiologists, Paul Davies and Charles Lineweaver.  Paul Davies is one of those big-thinkers who, at least in his popular writings, likes to play with philosophy as much as science.  When I was a high-school student I read one of his books, “The Last Three Minutes”, which was an enjoyable review of the different ways astronomers think the universe will end, and how humanity could survive these scenarios.  I have met Charles Lineweaver at several astrobiology conventions, and he has always been a unique thinker and a highly engaging guy to talk to.

In this paper, Davies and Lineweaver discuss the implications of thinking about cancer in an ancient evolutionary context.  In the current paradigm, cancerous cells are often considered “rouge agents” that, through mutations, loose their ability to communicate with other cells. Without the proper means to talk to the rest of the body, these cells reproduce uncontrolled.  In Davies’ and Lineweaver’s paradigm, these mutations actually cause the cell to revert back to an ancient cell-state, before animals became highly specialized, multicellular organisms. This is a type of atavism, where a mutation causes an ancestral state to be “turned on” again in a living organism. For example, humans are sometimes born with tails, horses with extra toes, and whales with hind legs (check out Gould 1980 for an popular-science account of atavisms).  In this paradigm, cancer cells are a reversion to a primitive ancestor of metazoans (scientific jargon for animals), so Davies and Lineweaver call cancer “Metazoa 1.0”.  Usually, the gene pathways that lead to cancerous “Metazoa 1.0” are controlled by more evolutionarily advanced gene pathways.  But if a mutation causes the normal gene networks to fail, the cell defaults to an robust, ancient gene network, creating a dangerous cancer cell.

What I really like about this work is that Davies and Lineweaver cover all of the proper bases when suggesting a scientific paradigm shift: (1) they show how their theory explains more of the data than the previous theory (2) they offer testable hypotheses their paradigm predicts, and (3) they show how their paradigm has novel consequences for the field.  I’ll quickly mention some of the main points they cover from each of these topics.

(1) Cancer as Metazoa 1.0 – Better Explanation of Data

Cancer cells are surprisingly well-coordinated and well-defended for cells that are the results of mutation.  Davies and Lineweaver note that cancerous tumors sometimes work together for the good of the group, such as when tumors build their own blood supplies (a process called angiogenesis). Cancer cells also have a whole battery of defenses that they commonly use to defend themselves against the body, including the ability to silence cancer-suppression genes, avoid detection by removing their own surface-receptor proteins, and secreting corrosive enzymes to move freely between tissues (Davies and Lineweaver offer a much more comprehensive list).  In the “rouge cell” paradigm, cancer cells gain these advantages through cellular Darwinism, where only the most sophisticated cancer cells are able to avoid the body’s defenses and reproduce through the body.  But Davies and Lineweaver argue that these complex behaviors seem too universal and too common to be the result of selection at the cellular level.  The vast majority of mutations that make cells go cancerous should lead to failure, but instead most cancers utilize all of these complex defenses.  This makes more sense if you think of cancers as a reversion to an ancestral, semi-multicellular cell-type that coordinates with similar cells and has a host of natural defenses that evolved long-ago. 

(2) Cancer as Metazoa 1.0 – Novel Hypotheses

If your new theory cannot be distinguished a priori from the previous theory, then your new hypothesis is not scientific (a point I plan to pursue in future posts).  Davies and Lineweaver offer several hypotheses that they predict from their theory.  For example, they suggest that if we study the order in which a cancerous cell develops traits, there should be broad patterns in the development of different cancer types.  If cancer cells are reverting to the same ancient genetic toolkit, we might expect cancer cells to first exhibit one trait (such as switching on membrane-dissolving proteins) followed by a second trait (such as activating genes that allow for cancer proliferation).  If cancers are simply randomly generated rouge cells, they are just as likely to display any, all, or none of these traits at any given stage in their development. 

(3) Cancer as Metazoa 1.0 – New Promises

In the “rouge cell” theory of cancer, there are as many ways for cancer to develop as there are ways for genetic mutations to mess up a cell (which is more or less infinite).   This would make President Obama’s pledge to find for a “cure for cancer” during our lifetime, or any lifetime, an impossible dream.  But if most serious types of cancer are the result of a reversion to an ancestral toolkit of genes, then there would be a unifying principle to cancer.  This would allow scientists to focus on pathways critical to “Metazoa 1.0”, which could lead to broad, gene-based cancer therapies. 

I highly recommend checking the paper out yourself; it is an easy and interesting read for scientists and non-scientists alike*. If you read Davies’ and Lineweaver’s press release, they consider this work a direct application of astrobiology research.

And now you know how the search for alien life will cure cancer.

*If you are not affiliated with a University, you might have a hard time accessing the paper, if you want a PDF copy let me know and I’ll send it to you.

Works Cited

Davies PC, & Lineweaver CH (2011). Cancer tumors as Metazoa 1.0: tapping genes of ancient ancestors. Physical biology, 8 (1) PMID: 21301065


Gould, S. J. (1983). Hen's teeth and horse's toes: Further reflections in natural history. New York: Norton.