Ovulatory shift, hormonal changes, and no effects on incentivized decision-making

Employing an incentivized controlled lab experiment, we investigate the effects of ovulatory shift on salient behavioral outcomes related to (i) risk preferences, (ii) rule violation, and (iii) exploratory attitude. As evolutionary psychology suggests, these outcomes may play an important role in economic decision-making and represent behavioral aspects that may systematically vary over the menstrual cycle to increase the reproductive success. Exploiting a within-subjects design, 124 naturally cycling females participated in experimental sessions during their ovulation and menstruation, the phases between which the difference in the investigated behavior should be the largest. In each session, hormonal samples for cortisol, estradiol, and testosterone were collected. The group of women was also contrasted against an auxiliary reference group composed of 47 males, who are not subject to hormonal variations of this nature. Our results reveal no systematic behavioral differences between the ovulation and menstruation phases

Why Did Memetics Fail? Comparative Case Study

Although the theory of memetics appeared highly promising at the beginning, it is no longer considered a scientific theory among contemporary evolutionary scholars. This study aims to compare the genealogy of memetics with the historically more successful gene-culture coevolution theory. This comparison is made in order to determine the constraints that emerged during the internal development of the memetics theory that could bias memeticists to work on the ontology of meme units as opposed to hypotheses testing, which was adopted by the gene-culture scholars. I trace this problem back to the diachronic development of memetics to its origin in the gene-centered anti-group-selectionist argument of George C. Williams and Richard Dawkins. The strict adoption of this argument predisposed memeticists with the a priori idea that there is no evolution without discrete units of selection, which in turn, made them dependent on the principal separation of biological and memetic fitness. This separation thus prevented memeticists from accepting an adaptationist view of culture which, on the contrary, allowed gene-culture theorists to attract more scientists to test the hypotheses, creating the historical success of the gene-culture coevolution theory

Ritualized commitment displays in humans and non-human primates

Collective ritual is virtually omnipresent across past and present human cultures, and analogous behaviors were documented in non-human primates. However, surprisingly little is known about the evolution of ritual in the hominin lineage as well as their underlying neurocognitive mechanisms. Here, we identify similarity, coalitional, and commitment signals as the essential features of collective ritual and argue that these signals evolved to facilitate mutualistic cooperation. We compare evidence for the communicative function of ritual between contemporary hunter-gatherers and non-human primates and discuss the underlying cognitive mechanisms facilitating these signals. Importantly, we will provide experimental evidence from our lab supporting the role of ritual as a platform for cooperative communication. Synthesizing this evidence, we will suggest that between 500 and 300 ka, collective ritual as a repetitively performed communicative act evolved from rudimentary signaling systems to help facilitate mutualistic cooperation and collective action