Journal of Population Research - Health and Demographic Surveillance Systems (HDSS) are geographic open cohorts operating in countries with absent/incomplete vital registration. Data on demographic...

Kin recognition, the ability to identify genetic relatives, relies on familiarisation for the creation of recognition templates. During development, parent and embryo(s) are exposed to chemical, audit...

by Heungjin Ryu, Chie Hashimoto, David A. Hill, Keiko Mouri, Keiko Shimizu, Takeshi Furuichi In most mammals, female sexual receptivity (estrus) closely coincides with ovulation, providing males with precise fertility signals. However, in some anthropoid primates living in multi-male societies, females display extended receptivity along with exaggerated sexual swellings that probabilistically indicate ovulation. This raises the question about how males successfully time mating, particularly when ovulation is difficult to predict from such signals. To address this question in bonobos, we combined daily variation in swelling size, hormonal profiles, and male mating behaviors. By estimating day-specific ovulation probabilities relative to the onset and subsidence (detumescence) of maximal swelling, we also examined how male efforts correlate with female fertility. Our results revealed that while ovulation probability was widely distributed and difficult to predict when aligned with the onset of the swelling phase, male behavior was closely aligned with the conception probability. Males concentrated mating efforts late in the phase and stopped after detumescence. High-ranking males intervened in copulations involving females with higher conception probabilities, specifically those with maximal swelling and older infants. When multiple females exhibited maximal swelling, males preferentially followed females whose maximal swelling started earlier and who had older infants. Male–male aggression increased when there were more females with maximal swelling. However, this tendency was reversed when male party size exceeded the average. Importantly, our results revealed that the low predictability of ovulation is best explained by inter- and intra-individual variation in the length of maximal swelling phase, rather than ovulation occurring randomly within that phase in bonobos. Males effectively manage such a noisy signal by prioritizing late-phase ovulatory cues and integrating reproductive history, thereby extracting usable timing information. This behavioral mechanism helps explain the persistence of conspicuous yet noisy ovulatory signals in bonobos. Since males are capable of inferring ovulation timing even under noisy conditions, selection may not favor highly precise female signals. Instead, it shifts more of the time and energy costs onto males, allowing conspicuous female traits to be maintained.

A critical consequence of joining social groups is the possibility of social transmission of information related to novel behaviours or resources. Network-based diffusion analysis (NBDA) has emerg...

Birkbeck

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Developmental Psychobiology is a multidisciplinary journal at the interface of developmental biology & psychology – advancing the field of behavioral development.

Abstract. The idea that organisms benefit by acquiring information through social connections is a cornerstone of our understanding of social evolution and

The upcoming conference of the European Human Behaviour & Evolution Association will take place in Leiden, The Netherlands, 14th-17th of April 2026. EHBEA conferences bring together researchers applyi...

Women often score higher on average than men on self-report measures of empathy. However, self-report estimates of empathic tendencies and other attributes could be susceptible to a range of biases. F...

By Thomas V Pollet, Jeanne Bovet & 2 more. This study found that only a quarter of indexed entries and 40% of contributors in evolutionary psychology textbooks are women. We propose solutions to impro...

Devenir père est une aventure dans la vie d’un homme, mais aussi une métamorphose physiologique que la science commence tout juste à révéler. Enquête sur les racines biologiques de la paternité à part...