Carrie Arnold, for Quanta Magazine:
By removing Wolbachia from these wasps, the researchers showed that the Wolbachia infections were the wasps’ major barrier to interbreeding. “It was as if they were no longer two separate species,” Bordenstein said. “This was some of the first evidence that a symbiotic microbe could wedge two species apart.”
Far from being a rare, one-off event, Bordenstein’s findings suggested that the microbiome has played a larger than expected role in the evolution of new species. Thousands of insect species are infected with Wolbachia, making symbiosis a potentially major player in the development of these species.
Wolbachia, a bacteria that lives on most insects, apparently greatly affects mate choice.
The idea that microbes and fungus drive behavior in more complicated forms of life is not a new one. In real life, there are documented cases of mind controlling fungi that infect various insects, and Toxoplasma gondii might even affect human behavior. In fiction, David Brin wrote The Giving Plague about a virus that caused altruism in humans, and Greg Bear earlier wrote Blood Music, though his biological nanites went quite a bit farther than just altering behavior in humans.
We have a great deal to learn about our microbiome, and what as-yet unknown effects they might have on us. Seemingly unrelated things like bathing habits and intestinal bacteria are increasingly being shown to have profound implications for health.