In studying autism, British researches have come to the conclusion that a significant number of boys learn how to read facial expression more slowly than their female counterparts.[1] This disparity apparently gradually disappears as the children age, and then briefly reappears in both sexes during the teenage years. Once again we see that any attempt to treat the sexes as interchangeable must necessarily fail.
[1] Mr. Jonathan Amos. "How boys miss teacher's reprimand" BBC News World Edition (online) 2005-09-08. http://news.bbc.co.uk/2/hi/science/nature/4227296.stm