Jan Havlicek

Charles University in Prague | CUNI · Department of Zoology (PF)

Perception studies describe numerous discrete morphological facial features as important to judgments of various characteristics. Interestingly, little is known about whether people actually direct their visual attention to these features and how specific contexts or sex affect this attention. We, therefore, examined visual attention to faces in th...

There is robust evidence to the effect that homosexual individuals have systematically less offspring. The sexually antagonistic genes hypothesis claims that this fitness-related disadvantage of homosexual individuals is compensated by their other-sex relatives exhibiting greater fertility than the relatives of straight individuals. It would allow...

While there is substantial research on what people want in their romantic and sexual partners, much of this work focuses on WEIRD, youthful samples, fails to consider the role of undesirable characteristics (i.e., things people do not want in partners) at all, or in conjunction with desirable characteristics (i.e., things people do want in partners...

This poster presents findings from a large-scale Czech study comparing well-being and self-esteem between gender-diverse populations and cisgender individuals within the cultural context of Eastern Europe. The study reveals that binary transgender and non-binary/genderqueer individuals report significantly lower life satisfaction and self-worth com...

Research shows that male body odor plays an important role in women’s mate choice and that olfactory abilities are associated with women’s sexual functioning. What remains unclear is what types of partner’s odor actually shape women’s experience during intimate activities. This study therefore explored women’s experience associated with the partner...

Olfactory and cognitive performance share neural correlates profoundly affected by physiological aging. However, whether odor identification and discrimination scores predict global cognitive status and executive function in healthy older people with intact cognition is unclear. Therefore, in the present study, we set out to elucidate these links i...

Puberty tends to be viewed as a “turning point” in hedonic perception of body odor-related smells. The pubertal stage, a potential proxy for the underlying physiological changes, may contribute to variation in odor hedonic perception. Other potential modulators of odor hedonics are general semantic knowledge about odors (which also tends to be subs...

Studies investigating facial attractiveness in humans have frequently been limited to studying the effect of individual morphological factors in isolation from other facial shape components in the same population. In this study, we go beyond this approach by focusing on multiple components and populations while combining geometric morphometrics of...

Several previous studies have shown that in mammals, the health status of conspecifics can be assessed based on perceptual cues. Olfactory, visual, or acoustic cues may lead to avoidant behavior, thus reducing the risk of contagion by close contact with infected individuals. We tested whether immune system activation after immunization leads to per...

Although chemical signaling is an essential mode of communication in most vertebrates, it has long been viewed as having negligible effects in humans. However, a growing body of evidence shows that the sense of smell affects human behavior in social contexts ranging from affiliation and parenting to disease avoidance and social threat. This article...

#bodyimage #bears #twinks #geeks #jocks

The behavioral immune system, with disgust as its motivational part, serves as the first line of defense in organisms’ protection against pathogens. Laboratory studies indicate that disgust sensitivity adaptively adjusts to simulated environmental threat, but whether disgust levels similarly change in response to real-life threats, such as a pandem...

Elevated levels of nausea and vomiting in pregnancy (NVP) and disgust sensitivity have been observed in the first trimester and both are thought to have a protective function for the mother and her fetus. Their aetiology is not clear, however, with previous studies attributing elevated NVP and disgust to various factors including endocrine changes,...

Background A recent study focusing on dietary predictors of nausea and vomiting in pregnancy (NVP) found that women with higher levels of partner support, and those who had used oral contraception (OC) when they met the father, both tended to report less severe NVP compared with previous non-users or those with less supportive partners. We provide...

Introduction Considered a part of the behavioral immune system (BIS), disgust sensitivity is expected to be adjusting as a response to the actual level of the environmental health risks. Methods In this preregistered study, we tested the hypothesis that disgust sensitivity would be higher during the COVID-19 pandemic compared to the pre-pandemic p...

Mate choice in humans is specific by the involvement of kin both in partner choice and in the functioning of the relationship. The influence of relatives ranges from providing advice all the way to arranged marriages. Existing research so far tended to map neither the actual parental interventions and further reactions (counteractions) nor the inde...

Women tend to choose partners who resemble their father in certain characteristics. In non-human mammals, similar parental imprinting-like effects are often odour-mediated1,2, which requires not only learning of parental odour but also similarity between parents and prospective mates in the microbial communities responsible for production of the cr...

Assessing the attractiveness of potential mating partners typically involves multiple sensory modalities, including the integration of olfactory, visual, and auditory cues. However, predictions diverge on how the individual modalities should relate to each other. According to the backup signals hypothesis, multimodal cues provide redundant informat...

Previous research has indicated that facial attractiveness may provide cues to the functioning of the immune system. Mating with individuals who have a more effective immune system could lead to a higher reproductive success. Our main aim was to test a possible association between immunoreactivity (stimulated by vaccination) and perceived facial at...

Recent work has demonstrated that human body odour alters with changing emotional state and that emotionally laden odours can affect the physiology and behaviour of people exposed to them. Here we review these discoveries, which we believe add to a growing recognition that the human sense of smell, and its potential role in social interactions, hav...

Mate choice appears to be driven by a set of mate preferences. It is, however, unclear how preferences for individual characteristics are integrated into actual mate choice decisions. According to the Additive model, the most desirable partner is the one with the highest overall sum of relevant characteristics. In contrast, the Threshold model pred...

This paper comments on Caton et al's (2022) direct replication of Třebický et al (2013) . In this commentary, we provide our reflections on several points raised by this direct replication. Specifically, we focus on three main areas: i) a critique of the stimuli used, ii) analytic decisions taken in the original study, and iii) shape analysis of th...

The occurrence of depression is influenced by social relationships, however, most studies focus on individuals, not couples. We aimed to study how depressive symptoms of couples evolve over time and determine, which characteristics are associated with their distinct trajectories. A multi-centric cohort sample of 11,136 heterosexual couples (mean ag...

Background: A recent study focusing on dietary predictors of nausea and vomiting in pregnancy (NVP) found that women with higher levels of partner support, and those who had use oral contraception (OC) when they met the father, both tended to report less severe NVP compared with previous non-users or those with less supportive partners. We provide...

The aim of this report is to present the research project „Effect of parental characteristics on mate choice“ supported by the Czech Science Foundation (GA18–15168S). It is a multidisciplinary project involving not only psychological but also biological and chemical methods, contributing to a more comprehensive understanding of the studied phenomen...

Studies show that specific vocal modulations, akin to those of infant-directed speech (IDS) and perhaps music, play a role in communicating intentions and mental states during human social interaction. Based on this, we propose a model for the evolution of musicality—the capacity to process musical information—in relation to human vocal communicati...

According to the congruency hypothesis, relationship satisfaction is predicted by the congruency (or non-congruency) between current use of oral contraceptives (OC) and their use during relationship formation. This is based on reports that OC may alter women’s mate preferences, so that attraction to their partner may have changed in non-congruent w...

Human childrearing is characterized by cooperative care and grandmothers are usually the most prominent alloparents. Nevertheless, it has been argued that limited resources may intensify competition among kin. The effect of grandmothers’ presence on child survival may thus crucially depend on the family’s socioeconomic status. We evaluate the impac...

Studies show that specific vocal modulations, akin to those of infant-directed speech and perhaps music, play a role in communicating intentions and mental states during human social interaction. Based on this, we propose a model for the evolution of musicality –the capacity to process musical information– in relation to human vocal communication....

CZECH ABSTRACT | Zahájení kojení je komplexní proces ovlivňovaný nejen fyziologickými procesy a chováním matky, ale i reakcemi novorozence. Při vyhledávání prsu novorozencem hrají, mimo taktilních, vizuálních a chuťových vodítek, klíčovou roli čichové podněty z mateřského mléka a sekrece žláz nacházejících se na areole. Hlavním cílem tohoto přehled...

Previous studies have shown that women perceive male faces with a more reactive immune system as more attractive, but whether body odor might likewise provide cues to immune function has not been investigated yet. These two studies tested a possible relationship between body odor quality and immunoreactivity (Study 1) and immune system function (St...

Vyhýbání se sexu s příbuznými neboli incestu je považováno za univerzální jev. Jednotlivé obory se však liší vysvětlením vzniku zábrany incestu. Cílem této přehledové studie je představit teorie vyhýbání se incestu z perspektivy kulturní a evoluční antropologie, a přispět tak k pochopení komplexity celé problematiky. Důvodem nízkého výskytu incestu...

Nausea and vomiting during pregnancy (NVP) is a condition that affects women around the world. Previous studies show that NVP is associated with dietary changes and aversions towards certain kinds of food. It has been suggested that these changes could have adaptive functions, such as protecting the embryo from harmful teratogenic substances in cer...

Men look different than women, well that is not a big surprise, but we wanted to study the phenomena of sexual dimorphism of human faces more thoroughly. Every human face can be represented as a position in a 144-dimensional space. That is a start. We collected face shapes in 8 different cultures, In Cameroon, Namibia, Brazil, Colombia, Czech Repub...

Sexual selection, including mate choice and intrasexual competition, is responsible for the evolution of some of the most elaborated and sexually dimorphic traits in animals. Although there is sexual dimorphism in the shape of human faces, it is not clear whether this is similarly due to mate choice, or whether mate choice affects only part of the...

Odhady výskytu incestu se značně rozcházejí. Výsledky mohou být ovlivněny zdrojem, ze kterého jsou data čerpána (např. soudní záznamy), ale také rozdílným chápáním pojmu incest. Zároveň není zřejmé, které faktory jsou pro výskyt incestu specifické. Cílem této přehledové studie je představit výskyt incestního chování a okolnosti, které ho obvykle do...

We assessed the relative contribution of economic, personal, and affective power bases to perceived relationship power. Based on evolutionary studies, we predicted that personality dominance and mate value should represent alternative personal power bases. Our sample was comprised of 84 Czech heterosexual couples. We measured the economic power bas...

Evidence suggests that personality may influence romantic relationship quality in several ways. Quality of relationship can be affected by an individual's personality (actor effect), partner's personality (partner effect), by discrepancy between ideal and actual partners' personalities (discrepancy effect), or by similarity between partners' person...

Behaviorální imunitní systém představuje vedle tělesného imunitního systému další obranný nástroj organismu. Jeho hlavní funkcí je detekce a vyhnutí se potenciálně ohrožujícím podnětům, jež mohou vést k přenosu patogenů. Včasná vyhýbavá reakce organismu významně snižuje energii, jež by jinak byla vydána na metabolicky náročné reakce tělesného imuni...

Now published in Chemical Senses doi: 10.1093/chemse/bjaa041. Recent anecdotal and scientific reports have provided evidence of a link between COVID-19 and chemosensory impairments such as anosmia. However, these reports have downplayed or failed to distinguish potential effects on taste, ignored chemesthesis, generally lacked quantitative measure...

The major histocompatibility complex (MHC) is a core part of the adaptive immune system. As in other vertebrate taxa, it may also affect human chemical communication via odour-based mate preferences, with greater attraction towards MHC-dissimilar partners. However, despite some well-known findings, the available evidence is equivocal and made compl...

Although anthropologists frequently report the centrality of odours in the daily lives and cultural beliefs of many small-scale communities, Western scholars have historically considered the sense of smell as minimally involved in human communication. Here, we suggest that the origin and persistence of this latter view might be a consequence of the...

Dominance hierarchy is often established via repeated agonistic encounters where consistent winners are considered dominant. Human body odour contains cues to psychological dominance and competition, but it is not known whether competition outcome (a marker of a change in dominance hierarchy) affects the hedonic quality of human axillary odour. The...

Changes in olfactory perception observed in cross-sectional studies may not reflect actual ongoing change within individuals. The aim of the present study was to assess intra-individual as well as inter-individual variation in olfactory scores in preschoolers across five waves over a two-year period. The participants were 157 children (79 boys) ag...

Sexual selection, including mate choice and intrasexual competition, is responsible for the evolution of some of the most elaborated and sexually dimorphic traits in animals. Although there is clear sexual dimorphism in the shape of human faces, it is not clear whether this is similarly due to mate choice, or whether mate choice affects only part o...

Mixed Martial Arts (MMA) is a multielement combat sport where fighters need to quickly react to an opponent’s movements under fatigued conditions. Research indicates that fast reaction time is important in many sports, but the effect of fatigue has shown negative, null, or even positive influences on reaction time. However, few studies have been co...

Mate poaching is a behavior intended to lure someone away from their current romantic relationship to form either temporary or permanent relationships with them.Mate poaching appears to be a ubiquitous behavior found in various regions of the world. Schmitt et al. (2004) conducted a survey with 53 nations on 5 continents and found that more than ha...

Perceived vocal attractiveness and measured sex-dimorphic vocal parameters are both associated with underlying individual qualities. Research tends to focus on speech but singing is another highly evolved communication system that has distinct and universal features with analogs in other species, and it is relevant in mating. Both speaking and sing...

The function of mate retention strategies is to preserve the bond between romantic partners and to prevent desertion, which is also why such behaviours are often elicited by the presence of a potential rival. Most existing studies on mate retention are based on self‐reports, which are prone to various biases. In this study, we observed non‐verbal b...

Mate choice is assumed to either follow the Additive Model, which predicts that a potential partner with the highest sum of preferred characteristics will be chosen over a candidate with a lower overall score. Alternatively, the Threshold Model predicts that individuals have a certain threshold for each characteristic and potential partners who do...

Femininity-masculinity affects perceived attractiveness and indicates biosocial qualities. Physiological and morphological femininity-masculinity is primarily influenced by reproductive hormones; however, its perception is mediated biopsychosocially, and it is not clear if self- and other-rated femininity-masculinity is associated. We examined poss...

Recent research suggested that individuals weigh obnoxious traits in a potential partner (i.e., dealbreakers) more severely than the preferred characteristics (i.e., dealmakers). In our previous studies we identified the most important 7-7 relationship dealbreakers and dealmakers. Following the established “budget allocation” paradigm our aim was t...

Postpartum depression (PPD) affects up to 19% of all mothers, with detrimental effects on both mother and child. The antidepressant and anxiolytic effects of plasma oxytocin are well-documented, but it is still disputable whether synthetic oxytocin (synOT) may protect women against postpartum mood alterations. The current study examined the associa...

In non-genetic systems, such as culture, inheritance is often non-particulate. Owing to blending and consequent loss of variability, however, selection in such systems has been considered ineffective. The issue of loss of variability was solved by the Galton–Pearson model, which assumes a constant offspring variability and predicts gradual adaptati...

There is substantial evidence for assortative partner preferences in humans based on physical characteristics. In contrast, evidence suggests that olfactory preferences tend to be disassortative, with people preferring body odour of potential partners who are dissimilar at key genetic loci, perhaps to gain fitness advantage through offspring hetero...

Previous studies on various vertebrates have shown that quantity and quality of food intake affect odour attractiveness as perceived by potential mates. In humans, the quality of body odour is similarly affected by ingested foods, such as by variation in meat and garlic intake. Nevertheless, it is not known whether quantity of food has an impact on...

Sample of highly formidable roar.

Sample of successful roar FFT spectral peak frequency.

Sample of low formidable roar.

Sample of low formidable utterance.

Sample of highly formidable utterance.

Sample of failed roar F0 measurement spectrogram.

Exploratory correlation table.

Objective. Sexual Strategies Theory (SST) suggests that men and women have different benefits when engaging in long- and short-term relationships with multiple distinguished objectives (e.g., acquiring good genes or resources). Several previous studies tested variation in mating strategies using preferred characteristics with inconclusive results....

In non-genetic systems, such as culture, inheritance is often non-particulate. Owing to blending and consequent loss of variability, however, selection in such systems has been considered ineffective. The issue of loss of variability was solved by the Galton-Pearson model, which assumes a constant offspring variability and predicts gradual adaptati...

There is evidence across a range of bi-parental species that physiological changes may occur in partnered males prior to the birth of an infant. It has been hypothesised that these hormonal changes might facilitate care-giving behaviours, which could augment infant survival. The mechanism that induces these changes has not been identified, but evid...