Chimps (IMAGE) Max-Planck-Gesellschaft Caption In contrast to bonobos chimpanzees show a decline in thyroid hormone levels during puberty. Credit MPI f. Evolutionary Anthropology/ S. Metzger Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.