OPINION LETTERS

摘要

Thierry Lode (5 November, p 30) claims that the cost of having redundant males shows that sex is not a good solution for reproduction. However, division into males and females came well after the origin of sexual reproduction. Many invertebrates are hermaphrodites - where they have the advantages of sex and both parties can reproduce. Some reptiles can reproduce asexually and some fish can switch sex when it suits them. The division into males and females is only complete for birds and mammals.