Published in Current Biology · View the paper (DOI)
Researchers found that howler monkey species with larger hyoid bones produce sounds with lower frequencies, suggesting a larger body size. This is associated with smaller testes and vice versa, indicating a trade-off between vocal investment and sperm production.
Coverage from 3 institutions
- For howler monkeys, deeper roars mean less sperm Cell Press · Oct 22, 2015 · first to report
- Deeper calls, smaller balls University of Utah · Oct 22, 2015
- Calls vs. balls: Monkeys with more impressive roars produce less sperm University of Cambridge · Oct 22, 2015