“They went looking for our beginning. What they found could be our end”

Normally I don’t do reviews of new movies.  And, strictly speaking, this isn’t going to be a review.  The first part will be, but the second part will be me rambling about science stuff brought to mind by said movie.  Prometheus was billed as a psuedo-sequel to Alien.  Being a fan of Alien, I knew that when Prometheus came into theaters I would go to see it.  I wasn’t particularly optimistic as to how good it would be, and so I was pleasantly surprised when the movie sucked me in and didn’t let me go until the end of its run time.  Prometheus is a hauntingly beautiful and deeply engrossing film, showing off stark awe-inspiring visuals of a dead world.  The characters are fully realized and come to life on screen…

I could go on, but I won’t belabor the point.  My friend Amanda Rudd did an in depth review of the movie over on her blog, and she did a better job of it than I could.  No, instead I want to focus on the one quibble I had with the film.  Prometheus raises a lot of profound questions about life, religion, and the origins of humanity.  When the movie begins, we see a freakishly muscled humanoid alone on a barren, rocky world.  He watches a ship take off in the distance before taking a sip of some nasty tar-looking substance that starts to break him apart on a molecular level.  The nameless alien tumbles into the river where even his DNA breaks into pieces.  It’s never said with any certainty, but presumably this is the moment Earth is seeded with life.

You read that right.  Prometheus rewrites human history by introducing the concept that life was seeded by a species of alien beings called The Engineers.  The action of the movie centers around the crew of the ship Prometheus, who have been dispatched to an alien moon whose coordinates were found in ancient cave paintings and carvings the world over in order to ascertain whether The Engineers in fact exist and to see if any still live.  Those among other things–you’ll have to see the movie to find out the rest.

There is a scene near the beginning when the crew of Prometheus are brought out of hibernation and briefed on their mission.  And here comes the point when I got annoyed.  You see, there was a biologist among the crew.  It’s a smart thing to bring a biologist along to an alien world where you suspect there to be life since, after all, life is their forte.  However, this biologist was not a particularly good one.  When Dr. Elizabeth Shaw, played by the lovely Noomi Rapace, mentions the idea that The Engineers seeded the Earth with life, the biologist exclaims that such an idea would “overturn 300 years of Darwinism”.

In retrospect, that statement surprises me because of the intelligent manner in which Prometheus handles the many questions it raises (but never answers).  The biologist’s exclamation shows a very fundamental misunderstanding of both evolutionary theory and how scientific theories in general work, things any decent biologist should understand (but maybe not a script writer, although they should have done better research).

Charles Darwin, author of “On the Origin of Species”. His theory of evolution by natural selection revolutionized the science of biology and changed how people saw themselves in relation to the natural world.

The theory of evolution explains the diversity of life on Earth.  It’s a fairly complex theory, but on a basic level it’s pretty simple.  One of my favorite ways to define it is as follows: “the change in the frequency of alleles [expressed genes] over time”.  Basically, in a given population certain members of the species carry an array of genes that enhance their chances of survival.  Those more likely to survive can pass their favorable genes on to the next generation, and so on and so forth.  That’s a gross oversimplification, but for our purposes it will suffice because it points out the point I want to make.  Namely, evolutionary theory doesn’t comment at all on the origins of life!  It explains how the diversity we see in the biological world came to be, but it doesn’t explain how it started.

On the surface that may seem odd, but a quick look at the scientific use of the word theory should clear any confusion.  I did an entire post on this topic before, so I’ll be brief.  A scientific theory, in a basic sense, explains how something in nature works.  This is different from a fact, which is something that is consistently observed and held to be true.  Evolution has been observed in nature, established from fossil, morphological, and genetic evidence among other things.  It is a fact.  The theory of evolution explains how evolution works.  That is the nature of a scientific theory.

Now, one facet of a theory is that it has a range of validity.  As I said above, the theory of evolution explains the diversity of life, not its origins.  Evolutionary theory’s range of validity begins only after life begins, when there is something there for natural selection and other selective pressures to act upon.  In order to explain the origins of life, another theory is needed.  Currently, the big contender for the theory to explain the origins of life on Earth is called abiogenesis, which is a big fancy word that means that life came from non-life.  For the moment though, nobody is quite sure specifically how this process occurred, but the evidence is gaining and I imagine in our lifetime we will see DNA created from raw molecular materials.

But Prometheus doesn’t touch on abiogenesis.  Instead, it touches on an alternate hypothetical scenario by which life came to be on Earth called panspermia, specifically directed panspermia.  Panspermia means essentially that life came to Earth from somewhere else, probably by hitching  a ride on a comet or meteorite.  Directed panspermia is the idea that an alien species seeded Earth with the rudiments of life and then let evolution take its course, which is the premise behind Prometheus.  However, such an idea does not overturn Darwinism (I don’t like that word but we’ll go with it), although it is a fascinating thing to think about.  Who knows?  Maybe Prometheus is prescient and we will come to discover that all of us are really the descendents of beings from the sky.

Did you get a chance to see Prometheus?  What did yo think of it if you did?  How would it impact you if it turned out that life on our planet was seeded by an alien species?