title: Age-related changes in thyroid hormone levels of bonobos and chimpanzees indicate heterochrony in development.
abstract: We present information on age related changes of thyroid hormone levels in bonobos (N = 96) and chimpanzees (N = 100) ranging between one and 56 years of age. Fresh urine samples were used for hormone measurements with a commercial competitive total triiodothyronine (T3) ELISA. In both species, immature individuals had higher TT3 levels than adults and there was a marked decrease in TT3 levels between age classes. The two species differed in terms of the timing of TT3 level changes, with chimpanzees experiencing a significant decline in TT3 levels after 10 years of age and bonobos after 20 years of age. The decline of TT3 in chimpanzees appears to coincide with the time when somatic growth terminates while TT3 values in bonobos decrease much later. This temporal asymmetry in urinary thyroid hormone levels indicates heterochrony in the ontogenetic changes of the two sister species and developmental delay in bonobos. The prolongation of high TT3 levels in bonobos, which is characteristic of immatures of both Pan species may affect the behavior of bonobos; namely, the low intensity of aggression they display. Given that developmental studies are often based on post-mortem analyses of skeletons, measures of urinary thyroid hormones offer a non-invasive tool for exploring ontogenetic changes in living wild and captive hominoids.
authors.affiliation: Max Planck Institute for Evolutionary Anthropology, Department of Primatology, Deutscher Platz 6, D-04103 Leipzig, Germany; Centre for Research and Conservation, Royal Zoological Society of Antwerp, K. Astridplein 26, B 2018 Antwerp, Belgium. Electronic address: verena_behringer@eva.mpg.de.
authors.forename: Verena
authors.initials: V
authors.lastname: Behringer
authors.affiliation: Max Planck Institute for Evolutionary Anthropology, Department of Primatology, Deutscher Platz 6, D-04103 Leipzig, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Deschner
authors.affiliation: Max Planck Institute for Evolutionary Anthropology, Department of Primatology, Deutscher Platz 6, D-04103 Leipzig, Germany.
authors.forename: Róisín
authors.initials: R
authors.lastname: Murtagh
authors.affiliation: Centre for Research and Conservation, Royal Zoological Society of Antwerp, K. Astridplein 26, B 2018 Antwerp, Belgium.
authors.forename: Jeroen M G
authors.initials: JM
authors.lastname: Stevens
authors.affiliation: Max Planck Institute for Evolutionary Anthropology, Department of Primatology, Deutscher Platz 6, D-04103 Leipzig, Germany.
authors.forename: Gottfried
authors.initials: G
authors.lastname: Hohmann
mesh_terms: D000375:Aging; D000818:Animals; D003430:Cross-Sectional Studies; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D008297:Male; D019974:Pan paniscus / Q000254:growth & development* / Q000378:metabolism*; D002679:Pan troglodytes / Q000254:growth & development* / Q000378:metabolism*; D013045:Species Specificity; D013963:Thyroid Hormones; D014284:Triiodothyronine / Q000652:urine*
chemical_list: D013963:Thyroid Hormones; D014284:Triiodothyronine
keywords: Endocrinology; Ontogeny; Pan; Somatic growth; T3