Science Warning! Is a series about the science behind some of our favorite SciFi stories. Today we take a look at Annihilation starring Natalie Portman.
As a biologist, I find watching Annihilation a thrilling experience. The movie so expertly blends science-fiction and horror into a narrative where the rules of life are twisted to create a world that feels truly unique. Natalie Portman stars as Lena, a biologist with a rough military past out to avenge her husband by leading a group of ultra badass women scientists on a suicide mission into the Shimmer, an alien veil emanating from a lighthouse that changes the DNA of whatever steps inside. Annihilation is about our biology, at least vaguely, and although the scientific aspects of this movie are a bit of a stretch, some of the concepts discussed are great stepping stones from which we can learn about some real biology.
The Biological Species Concept
Early on in our journey through the Shimmer, Lena and her team are attacked by a vicious alligator like creature with teeth like a shark. One member of the team hypothesizes that maybe this creature is some sort of crossbreed. Lena quickly shuts down this argument by claiming, “No, different species can’t crossbreed.”
This isn’t entirely accurate. Actually, different species crossbreed all of the time. In fact, there are some pretty amazing hybrid species that are relatively common in agriculture and in the wild. Ligers are crosses between male lions and female tigers and are, surprisingly, the largest type of felines in the world! Mules are hybrids produced by female donkeys and male horses. Mules make great work animals because they are stronger than a horse of comparable size with the tame disposition of a donkey. Different plant species readily hybridize all of the time! Sweet Corn, Tangelos, Pluots, and Plumcots are just a few of the hybrid foods we can find at the grocery store. The world of plants is crazy and there are so many hybrid species out there that it would be impossible to list them all. Heck, even ancient humans and neanderthals would hybridize and produce viable offspring, and the evidence for this is present in all of our DNA!
But what defines a species? This is actually a really controversial question in biology. There are many competing definitions of what makes a species, but the predominant method of defining a species comes from the biological species concept. The biological species concept defines a species solely as a population of interbreeding individuals that are reproductively isolated from other groups of organisms, meaning that there is some barrier that prevents breeding between different populations. Under this species definition, organisms that look almost nothing alike but readily interbreed with each other are considered to be the same species.
Hold up though, we were just discussing that there are tons of different species that can crossbreed, are they not really species then? Well under the biological species concept, no. However, not all species have been classified according to the biological species concept. In my opinion, Charles Darwin had the best take when he said, “I look at the term species as one arbitrarily given for the sake of convenience to a set of individuals closely resembling each other.”
Essentially, a species is whatever somebody decides a species is, and because taxonomists were classifying species for hundreds of years before the development of the biological species concept, we have tons of species that would not be classified as such by now. Imagine, if a shark and alligator really could interbreed to create the monster in Annihilation, would you really consider sharks and alligators to be the same species? This is a wildly unrealistic example, but it does appropriately address some of the debate surrounding the biological species concept.
Now the next time you watch Annihilation with your friends, you can pause the movie, correct Lena, and annoy everybody else with educated rambling about the biological species concept and interbreeding. Just make sure to suspend your disbelief for the rest of the movie. Discussing the science behind science fiction is fun, but just because a movie might not be spot on scientifically, that doesn’t mean it should ruin our enjoyment of the film. So until next time, happy viewing!