Reproductive hormone profiles in captive male orangutans

Implications for understanding developmental arrest

Bibliographic Data

ID8319906
AuthorsAnne Nacey Maggioncalda (Stanford University, corresponding author), Robert M Sapolsky (0000-0002-7435-5838, Stanford University), Robert M Sapolsky Robert M Sapolsky, Nancy M Czekala (Zoological Society of San Diego)
Year1999
Volume109
Issue1
Pages19-32
Publication date1999-05-01
Peer ReviewedYes
Open AccessYes
TypeARTICLE
VenueAmerican Journal of Physical Anthropology (JOURNAL)
Journal identifiersISSN: 0002-9483 • E-ISSN: 1096-8644
PublisherWiley (PUBLISHER • GB)
DOI10.1002/(sici)1096-8644(199905)109:1<19::aid-ajpa3>3.0.co;2-3
PMID10342462
OpenAlexW2019784039
LanguageEN
Citations received38
References cited34

For many years researchers have described some male orangutans as "subadult." These males are of adolescent to adult age and are reproductive, but have little to no secondary sexual trait development. Until now the only endocrine study of this arrest of secondary sexual trait development was performed by Kingsley (1982, 1988). She found that "subadult" or arrested males have lower testosterone levels than similar age developing adolescents or adult males. In this study, urine samples were collected over a two-year period from 23 captive male orangutans in order to more fully define male endocrine profiles. Three study males were juveniles, seven were arrested adolescents, six were developing adolescents, and seven were mature adults. Morning samples were analyzed by radioimmunoassay for levels of testicular steroids and gonadotropins and group hormone profiles were compared by analysis of variance. Results illustrate that arrested adolescent orangutans have significantly lower testosterone and dihydrotestosterone (DHT) levels than developing adolescents, but significantly higher levels than juveniles. Luteinizing hormone (LH) levels also differed between arrested and developing adolescents, with arrested males having lower levels. However, follicle stimulating hormone (FSH) levels were similar in both morphs of adolescent male. The overall hormone profiles for arrested and developing adolescent male orangutans suggest that arrested males lack levels of LH, testosterone, and DHT necessary for development of secondary sexual traits. However, they have sufficient testicular steroids, LH, and FSH to fully develop primary sexual function and fertility. These endocrine data help define alternative developmental pathways in male orangutans. The authors discuss the relationship between these developmental pathways and male orangutan reproductive strategies, and hypothesize about their prepubertal socioendocrine determination.

Biology · Endocrine system · Hormone · Luteinizing hormone · Secondary sex characteristic · Sexual maturity · Testosterone (patch) · Animal Behavior and Welfare Studies · Endocrinology · Hypothalamic control of reproductive hormones · Internal Medicine · Medicine · Physiology · Sperm and Testicular Function

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