In 2006, staff members at two zoos in the United Kingdom identified two female Komodo dragons that each laid an unusual clutch of eggs. The eggs developed into healthy offspring, even though neither female had been in recent contact with a male of that species. Genetic testing confirmed parthenogenesis. Although most Komodo dragons in the wild continue to reproduce sexually, this giant lizard is one of a growing number of vertebrates that reproduce parthenogenetically in captivity. Scientists still aren’t sure what triggers the switch.