Big monkey voice 'means less sperm'

The deep, growling roar of the howler monkey may hide reproductive shortcomings, according to biologists. A study by an international team of scientists has revealed that the primates either develop big voices, or big testes - but not both. Scientists made the discovery while trying to understand the "evolution of the animals' incredible roars". The findings suggest such evolutionary trade-offs may be more common that previously thought. They are published in the journal Current Biology.READ MORE AND WATCH VIDEO-BBC LINK-http://www.bbc.co.uk/news/science-environment-34607031