Full spoilers for Annihilation follow.
Studies have found male DNA in the brains of women who bore male children. Cells from the fetus made their way into the mother’s body and then became a part of the mother; it’s called microchimerism. It’s not clear if that sharing of cells does anything to the mother, but this fact lays bare the intense mutability of our existence as solid beings.
Annihilation finds terror in that concept. Loosely based on the first book in a scifi trilogy, Annihilation is Alex Garland’s unique and personal vision of a world unmoored from certainty and stability, both emotionally and physically. It’s a world where love, trust and flesh itself can be molded and changed… often without our permission, or without our conscious understanding of the causes that led to these effects.