BOULDER, Colorado, May 23 (TNSjou) -- The University of Colorado Boulder campus issued the following news: * * * Overpopulation can impair fertility. New study explains why By Lisa Marshall Scientists have reported it for decades: Overpopulation can impair reproduction. Crowded chickens lay fewer eggs. Crowded mice have smaller broods. In humans, several studies have associated increased population density with reduced fertility. External factors, such as resource scarcity and social influences, undoubtedly play a role. But researchers h more PR