Washington:
In a finding which could have many practical uses for human health including male contraception, US scientists claim to have discovered that the human sperm gene is 600 million years old.
A team at Northwestern University has found that the sex-specific gene, called Boule, which is responsible for sperm production, has remained unaltered throughout evolution and is found in almost all animals.
The research has also revealed that Boule is the only gene known to be exclusively required for sperm production -- from an insect to a mammal.
"This is the first clear evidence that suggests our ability to produce sperm is very ancient, probably originating at the dawn of animal evolution 600 million years ago. This finding suggests that all animal sperm production likely comes from a common prototype," lead scientist Prof Eugene Xu said.
According to him, the discovery of Boule's key role in perpetuating animal species offers a better understanding of male infertility, a potential target for a male contraceptive drug and a new direction for future development of pesticides or medicine against infectious parasites or carriers of germs.
Our findings also show that humans, despite how complex we are, across the evolutionary lines all the way to flies, which are very simple, still have one fundamental element that's shared.
"It's really surprising because sperm production gets pounded by natural selection. It tends to change due to strong selective pressures for sperm-specific genes to evolve. There is pressure to be super male to improve reproductive success.
"This is the one sex-specific element that didn't change across species. This must be so important that it can't change. Boule is likely the oldest human sperm-specific gene ever discovered," Xu said.
For the study, the scientists searched for and discovered the presence of the Boule gene in sperm across different evolutionary lines -- human, mammal, fish, insect, worm and marine invertebrate.
"A sperm-specific gene like Boule is an ideal target for a male contraceptive drug," Xu wrote in the latest edition of the 'PLoS Genetics' journal.