Zoologists said they were delighted and perplexed at the birth of four rare Komodo dragons, whose paternity remains a mystery.
The four reptiles were born last month from a clutch laid at London Zoo by a female called Sungai. Sungai normally lives at the Thoiry wildlife park, west of Paris, but was lent to London as part of a European breeding programme to help this badly-endangered species. But Sungai laid the fertilised eggs before even meeting her British lover -- and the last time she is known to have had intercourse was two years ago, with another Thoiry Komodo dragon called Kinaam.
Thoiry founder Paul de la Panouse told AFP that there were two possible answers to the riddle.
"Either female komodo dragons are spermthecal, meaning that they have the ability to store sperm or fertilised eggs for long periods, in this case for two years, or they are parthogenetic, meaning that they are self-reproductive -- they produce clones of themselves," de la Panouse said. Genetic tests will be carried out to try to explain the mystery.
The Komodo dragon (Varanus komodoensis) is the world's biggest lizard, reaching up to three metres (10 feet) long. The creature is carnivorous, killing goats, deer and other mammals through deadly bacteria in its saliva.
The dragon is found on the Indonesian islands of Komodo, Rinca, Gili Motang and Flores, but its numbers have dwindled to around 6,000 as a result of poaching and invasive species.