Now, 10 offspring later, Herschel's genes are still sought after."You need a healthy captive population as a safety net for the wild," said Diane Wilson, a zoological manager at the Zoo.
"If you ever want to put the population back into the wild, you want them as healthy as possible. Inbreeding is dangerous because it can propagate defective genes.
For Lisa Wathne, a spokeswoman for People for the Ethical Treatment of Animals, zoos and the efforts they go to arrange mating are cruel and inhuman.
Given the choice between the terrors of captivity and extinction, Wathne said, "I think animals would choose to be extinct."But while Herschel is gone - zookeepers were forced to euthanize him in 1997 because of arthritis - his genes live on.
If a population is dwindling, for example, a zookeeper might have to mate a bear with her uncle.
Der er nok at vælge i mellem; det er bare at få købt en billet til et af de mange arrangementer., hvis du vil se, hvornår Zoos dygtige guider og formidlere næste gang tager ud og ser på Traner eller besøger andre zoologiske haver.
They figure which zoos are best for penguins, which chimps get to mate and which bears should stay on birth control.
They consult directories of captive species populations - called "studbooks" in the business - to see who is related to whom. The results are family trees whose arms twist and bend and weave.
"He had the best sperm of any banteng bull I have ever seen," she said.
Now Herschel's genes sit in liquid nitrogen tanks - roughly the size of beer kegs - in the Endangered Species Research Center and Veterinary Hospital at the Zoo.