Letters to the Editors; February 1993; Scientific American Magazine; by Staff Editor; 1 Page(s)

Robert M. May makes excellent points in "How Many Species Inhabit the Earth?" [SCIENTIFIC AMERICAN, October 1992]. I was especially taken by his suggestion that butterflies have attained the "honorary status of birds." Giving the currently known species of butterflies as 17,500, he estimates the true number as no more than 20,000. Later in the same issue ("Singing Caterpillars, Ants and Symbiosis"), Philip J. DeVries cites the number of known butterfly species as "more than 13,500." It presents a nearly perfect example of May's central thesis concerning the uncertainty of the number of taxa.

I am concerned that some of the opinions in "Sex Differences in the Brain," by Doreen Kimura [SCIENTIFIC AMERICAN, September 1992], are misleading and potentially damaging. Your readers deserve to know that Kimura's opinion regarding a biological foundation for occupational sex segregation is not shared by all scientists.