There are a number of species of fish that are able to change their gender. Male fish often take care of the young but in the gender-adapting fish the leading male will change into a female when a larger male moves into the group. The gender change takes between 4 and 10 days. If the larger male moves on again the other one will change gender again.
It is thought that the male great white shark also changes gender when it gets older, possibly as a way to ensure the life of the species.
Not much such luck if you’re an ugly bloke without a job and think you might do better as a woman. Gender-changing operations are expensive. Rather keep looking for a job. After all, even though they’re not oil paintings there are some guys who managed to make a lot of money basically out of thin air.
First attempts at human sex change
It was not the first such operation: in 1930, German doctor Magnus Hirschfeld removed the testicles of Einar Mogens Wegener, who would become Lili Elbe. Further operations were performed by Dr. Kurt Warnekros in attempt to transplant ovaries and a uterus but Lili’s body rejected the transplants and she died in 1931.
It is important to note that Lili was intersexual, meaning she had both male and female biological characteristics.
First successful human sex change
The first successful human sex change took place in 1950 when Danish doctor Christian Hamburger changed GI New Yorker George William Jorgensen into Christine Jorgensen.
Christine Jorgensen 1954. Img Wikipedia
Also see List of transgender people.