Transition to siblinghood causes a substantial and long-lasting increase in urinary cortisol levels in wild bonobos
- Leibniz Institute for Primate Research, Germany
- University of Veterinary Medicine Vienna, Germany
- University of Osnabrück, Germany
- George Washington University, United States
- Max Planck Institute of Animal Behavior, Germany
- Max Planck Institute for Evolutionary Anthropology, Germany
Abstract
In animals with slow ontogeny and long-term maternal investment, immatures are likely to experience the birth of a younger sibling before reaching maturity. In these species, the birth of a sibling marks a major event in an offspring's early life, as the older siblings experience a decrease in maternal support. The transition to siblinghood (TTS) is often considered to be stressful for the older offspring, but physiological evidence is lacking. To explore the TTS in wild bonobos, we investigated physiological changes in urinary cortisol (stress response), neopterin (cell-mediated immunity), and total triiodothyronine (T3, metabolic rate), as well as changes in behaviors that reflect the mother-offspring relationship. Following a sibling's birth, urinary cortisol levels of the older offspring increased fivefold, independent of their age, and remained elevated for seven months. The cortisol level increase was associated with declining neopterin levels, however T3 levels and behavioral measures did not change. Our results indicate that the TTS is accompanied by elevated cortisol levels and that this change does not coincide with nutritional weaning and attainment of physical independence. Our results suggest that bonobos and humans experience TTS in similar ways and that this developmental event may have emerged in the last common ancestor.
Data availability
Source data for statistics and figures in the paper is permanently stored at GRO Behringer, 2021, "Replication Data for: Transition to siblinghood", https://doi.org/10.25625/O1OD2I.
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Author details
Funding
Deutsche Forschungsgemeinschaft (BE 5511/4-1)
- Verena Behringer
Max Planck Institite for Evolutionary Anthropology (open access funding)
- Gottfried Hohmann
Max Planck institute of animal behaviour (open access funding)
- Barbara Fruth
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Ethics
Animal experimentation: All samples were collected non-invasively and with permission of the Institut Congolais pour la Conservation de la Nature (ICCN).
Copyright
© 2022, Behringer et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Transition to siblinghood causes a substantial and long-lasting increase in urinary cortisol levels in wild bonobos
eLife 11:e77227.
https://doi.org/10.7554/eLife.77227
