Average testosterone levels in men have halved in the last 50 years, scientists say, suggesting society is facing a male fertility crisis. Rising levels of obesity and diabetes are expected to play a role, but the team behind the work suggests that environmental factors such as endocrine-disrupting chemicals – which can be found in a variety of household items – and global warming may also be factors in the apparent decline. Ian Sample spoke to science correspondent Hannah Devlin to find out how the work has been received and what researchers want to see in response to their discovery
