Within all life is self-destruction and with that alteration comes change. We can't always control it, but sometimes we make decisions that cause our own self-destruction. A moment or moments that alter us on a deep level. In Annihilation, a science fiction movie based on a novel of the same name by Jeff Vandermeer, there's much exploration of self-destruction on a biological and also on a mental level.
Annihilation tells the story of Lena (Natalie Portman), a grieving woman whose military husband, Kane (Oscar Isaac), returns home after being missing for twelve months. Lena's situation becomes increasingly confusing once Kane falls very ill on the day of his return and they're forcefully taken to a US government facility. At the government facility, Lena meets Dr. Ventress (Jennifer Jason Leigh), who informs her that Kane's condition is worsening. Dr. Ventress later tells Lena about the "Shimmer," an expanding, translucent bubble that the government knows very little about. Aside from Kane, everyone else who has entered the Shimmer has never returned home.
Dr. Ventress and Lena have a conversation about Lena's husband and why he would have volunteered for such a mission:
Lena: Why did my husband volunteer for a suicide mission?
Dr. Ventress: Is that what you think we’re doing? Committing suicide?
Lena: You must have profiled him. You must have assessed him. He must have said something.
Dr. Ventress: So you’re asking me as a psychologist
Dr Ventress: Then, as a psychologist, I think you’re confusing suicide with self-destruction. Almost none of us commit suicide, and almost all of us self-destruct. In some way, in some part of our lives. We drink, or we smoke, we destabilize the good job…and a happy marriage. But these aren’t decisions, they’re…they’re impulses. In fact, you’re probably better equipped to explain this than I am.
Lena: What does that mean?
Dr. Ventress: You’re a biologist. Isn’t the self-destruction coded into us? Programmed into each cell?
Lena joins three other female scientists in an expedition to enter and research the Shimmer. The other women in the crew are a paramedic Anya (Gina Rodriguez), a geomorphologist Cassie (Tuva Novotny), and a physicist Josie (Tessa Thompson). The women discover mutated beings and nature (all of which are nature's displays of self-destruction due to the effects of the Shimmer). Their fascination with the region becomes less so the more they venture in to find the lighthouse, a landmark for the meteor that caused the Shimmer crashed three years ago. They find an alligator with shark teeth and later on a bear that cries out in a human voice. The Shimmer changes everything it touches by mutating the DNA of all creatures, including the women on the expedition.
Not only does the Shimmer cause mutations in nature, but each woman who entered had already experienced or was experiencing self-destruction. Cassie had lost who she was because of the death of her child: "In a way, it's two bereavements. My...beautiful girl...and the person I once was." Anya was a recovering drug addict and lost her mind, tied the others up, and was killed by a mutated bear. Josie had issues with self-harm and eventually gave into the process of "refacting" (the process of genetic altering and distorting caused by the Shimmer) to avoid a brutal death. Dr. Ventress was already dying of cancer and she disintegrates into a nebulous structure once she reaches the lighthouse. Lena was self-destructive (she was cheating with her co-worker) before her husband left on his information retrieval mission into the Shimmer. The major difference between Lena and the others is that she's the only one who survived and found out the truth, from footage that Kane left behind, that her Kane had committed suicide in the Shimmer. Which meant the Kane that returned to her was a doppelganger of him.
Lena is eventually faced with a copy of herself and has to use her own self-destructive tendencies to destroy her copy and the lighthouse that is the core of the Shimmer by giving the copy an active phosphorus grenade. The copy doesn't flee from the grenade, but instead it gives into its own destruction. Lena is physically altered by the Shimmer and entered the region one person and returned another person. That's precisely what self-destruction does: it changes us in some way.
The choices that the main characters made throughout the film weren't accidental. They were decisions that could likely lead to the character's own destruction, but nobody chose self-preservation. What the movie examines is not only the concepts of life, death, and evolving, but also how a person and how the natural world can self-destruct. In real life, people destroy their relationships knowingly, abuse substances, self-harm, etc., as forms of self-destruction. There doesn't need to be an alien or a region with mutated life to bring about that actuality. For example: those of us who are mentally ill can be aware of our self-destructive behaviors/patterns. And if those behaviors/patterns persist, then that's self-destruction in itself—the knowing that you're destroying yourself but not caring or trying to do anything about it.