Now a birth control pill for men?

A plant extract traditionally used by African warriors as a heart stopping poison on their arrows may help develop a birth control pill for men, a study conducted on mice suggests. 

Mammals also produce ouabain and it is thought to help control blood pressure. With some alterations, researchers created a derivative that zeros in on alpha 4 in sperm cells, and interferes with their ability to swim, which is essential to its role in fertilisation, the team said.