Listen closely to those baboon calls - they may tell you a thing or two about human speech. Scientists who studied baboons’ wahoos, yaks, barks and other vocalizations have found evidence of five vowel-like sounds - a sign that the physical capacity for speech may have evolved over much longer timescales than previously thought. The findings, described in the journal PLOS One, could have significant implications for our understanding of human speech’s development and the emergence of language. Scientists studying the evolution of speech are left in a tricky bind because, unlike bones or shells, spoken words leave no fossil imprints in the geological record. How do you study the development