Jonathan Lambert writes:

Twilight falls on the Tanzanian plain. As the sky turns a deeper purple, a solitary spotted hyena awakens. She trots along the border of her clan’s territory, marking the boundary with a sour paste from under her tail. She sniffs a passing breeze for hints of itinerant males interested in mating, giving little attention to her stomach’s rumbling over the remnants of the previous night’s hunt or the itch on her flank. The lone hyena chooses what she will do next to make her living.

Except she is not alone. That paste she secretes is produced not by her own cells but by billions of bacteria housed within her scent glands. The scents on the breeze from potential mates also come from unique microbial concoctions. A diverse array of bacteria that line her gut are helping to break down her meal. Others assist her immune system in fending off the hordes of parasites and pathogens trying to invade her skin and other tissues.

Who precisely is it, then, trying to survive on the Tanzanian plain? Can we consider the fates of the hyena and the microbes within her independently? Or does their interaction form something new, greater than each part alone?

“We’ve underestimated the potential contribution of microbes to traits we’ve been studying for decades or centuries,” said Kevin Theis, a microbiologist at Wayne State University who studies the paste-making microbes of the hyena. “If the genes for these important traits are actually in the microbiome and not the animal itself, then we need to take a systems-level approach and look at the host-microbe system as a whole.” [Continue reading…]