How ‘Annihilation’ Can Be Explained With Hox Genes

The science almost makes sense here, and that's the point.

Annihilation follows a team of female scientists as they venture into a mysterious, alien zone expanding across the Florida panhandle. As they venture into Area X (nicknamed “the Shimmer”), the group encounters increasingly bizarre mutations, from a crocodile with shark teeth to plants in the shape of human bodies to a balding bear that can scream in the voice of one of their dead co-workers.

At one point in the movie (release February 2018), Tessa Thompson (playing astrophysicist Josie Radek) looks down at her arm, which is slowly mutating into some sort of plant, and speculates that “the shimmer is a prism, but it refracts everything” — meaning not just light, but DNA.

Annihilation
Jennifer Jason Leigh in "Annihilation."

That sounds pretty scientific, but is it actually accurate? The short answer is: kinda? The long answer requires a deeper discussion of the specific genes that control the way animal bodies are formed.

We’re talking specifically about Hox genes, a real family of genes that appear in all animal life and actually get a shout out in Annihilation. As biologist PZ Myers explains in a paper for Nature Education, Hox genes tell our bodies where to grow limbs and segments and determine they way our bodies are organized.

Hox genes were originally discovered by scientists studying mutations in fruit flies (like extra limbs), which they learned were caused by mutations to those genes. We now know that humans have 39 Hox genes, while chickens only have 23. Plants, however, have zero, which throws a wrench in Thompson’s hypothesis for why she’s turning into a tree in Annihilation.

Tessa Thompson's plant arm in 'Annihilation'
Tessa Thompson's plant arm in 'Annihilation'

Then again, it’s worth noting that Hox genes are part of a larger family of homebox genes, which appear in all cell-based life and also influence the shape that organisms take. So it’s possible Thompson could be right, even if she’s using the wrong term.

More broadly, that seems to be the approach Annihilation towards its science: Make sure it sounds good (even to other scientists) without worrying about whether anything that happens is actually factual.

As geneticist Adam Rutherford, who consulted on the film explained to The Daily Beast, the goal was to “constantly make sure it reflected how scientists talk, to make sure we wouldn’t cringe.”

In that case, mission sort of accomplished. And as for the actual science of Annihilation, it seems to mostly make sense. Now if someone could just explain that final dance scene to me we’ll be all set.

This December, Inverse is counting down the 20 best science moments in science fiction this year. This has been #1.

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Media via IMDB (1, 2), Paramount Pictures