Thai veterinarian Juthamas Sumanam (L) performs a vasectomy on a macaque monkey in the town of Lopburi, 155 km (96 miles) north of Bangkok, August 19, 2009. Thailand started a birth control programme to sterilise male monkeys with the aim of controlling their population in the famous monkey town of Lopburi. The programme took place after many villagers complained about the increasing numbers of monkeys and their aggressive attacks on people. Picture taken August 19, 2009. (REUTERS/Chaiwat Subprasom)

A Thai veterinarian prepares male macaque monkeys before their vasectomy procedures in the town of Lopburi, 155 km (96 miles) north of Bangkok, August 19, 2009.