We tend to view parasites as destructive, even repulsive, unwanted nuisances. However, scientists are finding that parasites often perform beneficial roles in the ecosystem. Some scientists think we should be protecting parasites from extinction.
Scientists are concerned that we have not studied the roles of parasites in maintaining a balanced ecosystem. For example, a parasite known as Toxoplasma gondii infects mice, causing them to lose their fear of cats. Cats have an acid in their gut that Toxoplasma gondii needs to reproduce, so the mouse is an intermediate host for the parasite to get into the cat. This appears to be a highly designed system in which a parasite controls the mouse population through cats.
Kayce Bell of the Los Angeles County Natural History Museum said, “If you remove something from an ecosystem, we cannot foresee what the consequences will be.” That is true of familiar plants and animals but may also be true of parasites. Moreover, it seems that some parasites keep other parasites under control. In 2020, scientists who study parasites published a paper in the journal Biological Conservation calling for protecting parasites from extinction, beginning with a study of what parasites exist.
Scientists estimate that 40% of all known animal species on Earth are parasites. The bottom line is that we don’t understand the role parasites play in the natural world. The fact that we don’t know what beneficial things parasites do is a challenge as we struggle to conserve ecosystems worldwide. Everywhere we look, we see a system design that testifies to a Designer.
— John N. Clayton © 2024
Reference: “The Problem with Parasites” in Discover magazine for September/October 2024, pages 21-28