Unless the writer is deliberately implying an archaic theory of evolution in this article, the statement “Ultrasonic perception may have developed as the frogs (Amolops tormotus) struggled to hear each other . . .” cannot be true. That’s not how natural selection works.

John Wymore
Albuquerque, N.M.

Frogs that could hear frequencies higher than the water’s roar might have had an advantage. “Struggled to hear each other” shouldn’t be interpreted as “struggled to evolve.” Indeed, evolution doesn’t work that way .—S. Milius