Slime mold can learn—and more breakthroughs

Strawberries have genes that ‘jump.’ Plus: the world’s most diverse collection of mammal milk.Monday, April 8, 2019

This story appears in the February 2019 issue of National Geographic magazine.

Not-so-simple slime mold

Though slime molds lack brains and neurons, the single-celled organisms still may be capable of basic forms of learning and adaptation. In studies led by biologist Audrey Dussutour, one slime mold species, Physarum polycephalum, exhibited the ability to overcome its aversion to certain things—a behavior known as habituation. In a later study, the slime mold then seemed to remember what it had learned. —Catherine Zuckerman

Taking stock of animal milk

After her baby was born last year, Calaya (below), a western lowland gorilla, allowed researchers to collect a small sample of her milk. Though sensitivity prevented her from providing further samples, contributions from other primates like her are part of a conservation effort at the Smithsonian’s National Zoo, which maintains the world’s most diverse repository of mammal milk. The bank, which contains milk from more than 200 species, has two purposes, says biologist Mike Power. The samples help the zoo develop nutritious formulas for animals that must be hand-reared. They also shed light on the origins of Homo sapiens. “The data we get from gorilla milk,” he says, “help me understand how human milk has evolved.” —Catherine Zuckerman

Strawberry sex ed

Unlike most plants, strawberries are either male or female. It’s a botanical trick that new research suggests is made possible by sex-determining genes that “jump,” or switch locations, over generations. Next up: trying to understand why. —Catherine Zuckerman

The best tool for the job

The mating moves of male stag beetles (genus Odontolabis) may be influenced by their equipment, researchers suggest. Some have hefty mandibles, as seen here, and can muscle out rivals for mates. Smaller ones with lesser mandibles may resort to sneak attacks on females. —Patricia Edmonds

Correction: After her baby, Moke, was born, Calaya allowed a small amount of her milk to be sampled, but then became sensitive to the process and stopped donating. Her milk is not part of the samples at the zoo's repository.