Hair Steroid Signatures of Cooperative Breeding in Male and Female Common Marmosets (Callithrix jacchus).

Authors

Benjamin N Laubi, Gaëtan Glauser, Erik P Willems, Carel P van Schaik, Judith M Burkart

Published in

International journal of primatology. Volume 47. Issue 4. Pages 988-1014. Epub May 23, 2026.

Abstract

Cooperative breeding presents social and reproductive challenges that differ from those associated with independent breeding, but its endocrine correlates are not well understood. We investigated cumulative steroid hormone profiles in common marmosets (Callithrix jacchus), a primate species characterized by shared caregiving and clearly defined reproductive roles between primary breeders and non-breeding helper group members. Using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) on hair samples, we simultaneously quantified six steroid hormones across 71 individuals varying in breeding role, sex, age, and group reproductive context. Glucocorticoids were highest in breeder females, declined with age, and were higher in breeders when dependent offspring were present. Testosterone showed a comparatively modest male-female difference and was positively associated with the presence of dependent offspring in breeders, whereas androstenedione closely paralleled testosterone across age, consistent with shared regulation. Ovarian steroids showed clear sex differentiation in progesterone, with markedly elevated levels in breeder females, whereas estradiol differences were smaller, emerging as a modest sex effect within breeders and an age effect in helpers. Together, these findings highlight weaker sexual dimorphism in sex hormone profiles than often reported for independently breeding primates. They also reveal hormonal signatures of stress and vigilance related to caregiving, consistent with cooperative breeding in marmosets. Our study demonstrates the value of hair for long-term hormonal assessment and underscores the utility of HPLC-MS/MS for quantifying multiple hormones with high specificity in socially complex primates.
The online version contains supplementary material available at https://doi.org/10.1007/s10764-026-00568-9.

PMID:
42876644
Bibliographic data and abstract were imported from PubMed on 15 Oct 2026.

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