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Readers ask about shrinking frogs, whether distance is defined in an expanding universe, and more

I know how to talk

The guttural frogs of the Indian Ocean islands have shrunken limbs and bodies that may be evidence that the "dwarfism of the islands" can evolve rapidly, Jake Buehler reported in “Frogs on Two Islands Are Declining Rapidly” (SN: 19/12/20 and 1/2/21, p. 13).

"I thought that island dwarfism usually occurs with fairly large animals … and that small animals … tend to evolve to larger sizes on the islands," he read. Tim Cliffe he wrote. "If small animals tend to grow, do the authors talk about why these little frogs would be on the path to dwarfism?"

In general, yes, large animals become smaller when they colonize the islands and small animals become larger, Buehler of. “This‘ island rule ’is not absolute and whether or not an animal moves towards dwarfism or gigantism may depend on the benefits that their body size and dietary restrictions on the island normally provide them,” he says. The researchers noted that a relatively large body size can protect guttural frogs from predators. On the islands, frogs can become smaller as there are fewer hungry predators to deter, Buehler of.

Or maybe the island’s toads have a distributed mating program, which could explain why amphibians are reduced. "On the mainland, guttural frogs mate once a year and females that grow to large sizes quickly produce many eggs." Buehler of. But the island’s frogs can mate all year round, which would deflate the importance of growing large and producing a ton of eggs. “Finding out why life on the island is making these frogs smaller is the next step in this project,” he says.

Defining the distance

A collision of two black holes 17 billion light-years from Earth has caught records for the farthest, most energetic, massive fusion of black holes. Erika Engelhaupt he wrote in "Superlative Science" (SN: 19/12/20 and 1/2/21, p. 34).

Some readers have wondered how the fusion of the black hole could have occurred 17 billion light-years from Earth if the Big Bang had occurred 13.8 billion years ago.

"Distance is really very difficult to define for an expanding universe and in which space-time is not static," says the physics writer for Science News Emily Conover. "The gravitational waves produced by the fusion took 7 billion years to reach us. That's what's called 'time-lapse,'" she says. "But that's not the same as the distance from the source of us. Because the universe expanded in the time it took those waves to reach us, the source is 17 billion light-years away, according to a standard method of defining distance. That's why that distance also doesn't conflict with the age of the universe, "she says.

Space to improve

A compound in hallucinogenic mushrooms eased the symptoms of depression in 13 people in a small study, but larger studies are needed, Laura Sanders reported in “Psilocybin Can Help Treat Depression” (SN: 19/12/20 and 1/2/21, p. 6).

“The article spoke of the concern that most participants were white and that a wider diversity would be more useful” in determining the effectiveness of the compound, reader Robert Walty he wrote. “This is quite true, and as a 75-year-old man, I am also concerned about depression in the elderly,” he wrote, noting that depression is common among older adults. "I'm looking forward to broader studies with a real diversity of participants."

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