Scientists have found a striking similarity in the DNA that enables some bats and dolphins to echolocate.
A key gene that gives their ears the ability to detect high-frequency sound has produced the exact same amino acid changes over time in both creatures.
The researchers report their findings in the journal Current Biology.
It may be the first time that identical genetics has been shown to underpin the evolution of similar characteristics in very different organisms.
Nature is full of cases where the path taken by evolution has resulted in the same traits, or phenotypes, developing independently in diverse animal groups.
Examples would include the tusks displayed by elephants and walruses, or the bioluminescence seen in fireflies and jellyfish.
“It’s common on a morphological scale but it’s assumed not to occur at a DNA level because there are so many different ways to arrive at the same solution,” explained Dr Stephen Rossiter of Queen Mary’s School of Biological and Chemical Sciences.
“The fact that we’re able to link convergence of the DNA with a phenotype I think is unique, and in such a complex phenotype as hearing as well,” he told BBC News.