 Evelyn Fox Keller offers the following example. The understanding of ovum/sperm reproduction was shaped (wrongly) by thinking of the sperm as masculine and the ovum as feminine. The projection of human gender expectations onto the gametes resulted in an assumption that the ovum was passive (as women stereotypically are) and the sperm active (as men stereotypically are). Writing in 2001, Keller recounts a shift to the recognition of an active role for both gametes: 