He knows she's listening. And now we know that she knows he knows.
Using the word "know" loosely, that's a simplified version of a new analysis of zebra finches by neuroscientists at the University of California, San Francisco.
Sarah Woolley explains that males sing a song differently when they're in front of females than when they're just twittering to themselves. Now she and Allison Doupe have found that females prefer the ladies-are-listening version. An area of the female brain associated with processing social context gets especially active during the males' formal serenades, Woolley and Doupe report in the March PLoS Biology.