In what could bring back memories of "Jurassic Park," researchers have revealed virgin births among wild snakes in the North American area.
Science website io9.com said the phenomenon, also known as facultative parthogenesis, had been especially rare among vertebrates.
Citing the latest issue of Biology Letters, the researchers led by geneticist Warren Booth showed evidence North American pit vipers can reproduce without males fertilizing them.
One female from each species studied - 22 copperheads and 37 cottonmouths - were found in the study to have had a likely virgin birth, io9.com said.
"I think the frequency is what really shocked us. That's between 2.5 and 5 percent of litters produced in these populations may be resulting from parthenogenesis. That's quite remarkable for something that has been considered an evolutionary novelty," it quoted Booth as saying.
Last year, pit vipers became the fourth species of captive parthenogenic snake capable of such virgin births, io9.com said.
In their study, the researchers looked into virgin births in wild populations of copperhead and cottonmouth female pit-vipers, two geographically separated and long-studied species of snake.
When the snakes gave birth, the scientists studied the physical and genetic characteristics of the offspring.
A separate report on the BBC said this was the first time a form of virgin birth has been found in wild vertebrates.
It said scientists believe the findings "could change our understanding of animal reproduction and vertebrate evolution."
The BBC report said a virgin birth, or parthenogenesis, is when an egg grows and develops without being fertilized by sperm.
It results in offspring that only have their mother's genetic material. "No fatherly contribution is required," it said.
But the BBC noted such a birth is not uncommon in invertebrates such as aphids, bees and ants.
It also happens in a few all-female species of lizard such as geckos and whiptails.
Virgin births began to be documented in captive snakes in the mid-1990s, followed by a captive giant lizard in 2006 and a captive shark in 2007.
BBC said it "remains unclear whether the female snakes actively select to reproduce this way, or whether the virgin births are triggered by some other factor, such as a virus or bacterial infection."
"Any answer is pure speculation at this point," it quoted Booth as saying. — TJD, GMA News