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Sperm competition in humans
Vydarená, Eliška ; Havlíček, Jan (advisor) ; Tomášek, Oldřich (referee)
Sperm competition has been observed and studied many times in a lots of animal species. It is currently also being considered in humans. Despite the number of studies, most of them were mainly focused on insects and birds. So far, only a small number of studies have dealt with sperm competition research in humans. For this reason, the question if sperm competition appeared and had selection pressure for the creation of various adaptations even in human evolution remains a controversial topic. In this bachelor thesis, I summarize the current knowledge of sperm competition in humans, the frequency of extra-pair copulation and paternity, and in individual chapters to indicate what adaptations to sperm competition may have developed in humans during their development. Key words Sperm competition, human sexuality, sperm, reproductive strategies
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The breeding and foraging ecology of the House Sparrow in rural and urban environments
HAVLÍČEK, Jan
This study describes the effect of farming practices, farmland utilization, and habitat composition in farmland settlements on the distribution and population density of the House Sparrow. Another goal of this study was to describe food availability for offspring and habitat use in rural and urban settlements. The results imply the importance of farms, their surroundings, small-scale farming, and the presence of natural habitats (shrubs, trees, ruderal vegetation) for the local House Sparrow populations. Increased home range size and flight distance were found in urban breeding pairs, implying the absence or lower availability of critical food sources in the urban environment. Future perspectives, threats, and management recommendations to prevent negative factors affecting House Sparrows and the entire bird community inhabiting similar habitats are discussed in this study.
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Vocal expressions in preverbal children
Štěpánková, Marie ; Havlíček, Jan (advisor) ; Houzar, Alžběta (referee)
The main acoustic communication channel in humans is speech. However, people also exhibit a number of non-speech vocal manifestations. Vocal manifestations contain several parameters that can be measured and parameters that can be perceived. Vocalization can be divided into positive and negative, so it can be assumed according to the contexts in which they occur. Based on this, their possible communication function can be assumed. Vocal expressions are important for communication with the environment especially in preverbal children, i.e. from birth to about 1 year of life. Vocal manifestations include, for example, crying, laughing, grumbling or babbling. Some vocalizations can contribute to speech development. Key words: vocal display, preverbal children, acoustic communication, speech, humans
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Morphological and behavioural changes during menstrual cycle in catarrhine primates
Molnárová, Kristýna ; Havlíček, Jan (advisor) ; Másílková, Michaela (referee)
Females of Old World monkeys and apes (Catarrhini) exhibit a menstrual cycle, during which changes in skin colouration and/or sexual swellings can be observed in some species, located mainly in the anogenital region and around the ischial callosities, but also on the chest, abdomen or face. These morphological changes can be compared with changing hormone levels and also the way males respond to them, which is reflected in the degree of visual attractiveness. The odour of females may also be attractive to males, and with changes in the odour over the cycle, males could assess the reproductive status of females based on olfactory inspection. Males may also assess female readiness to mate through behavioural changes, which include various proceptive displays such as different gestures, facial expressions, vocalizations and the presentation of morphological changes, among others. The aim of this thesis is to summarize and critically review the available literature dealing with morphological and behavioural changes during the menstrual cycle in females of Old World monkeys and apes. Several hypotheses have been proposed to explain the possible function of these cyclical changes, such as those related to male competition, increased paternal care and reduced risk of infanticide. Furthermore, hypotheses...
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Effect of prenatal hormonal levels on human sexual orientation
Freudenfeld, Petr ; Havlíček, Jan (advisor) ; Kubička, Lukáš (referee)
Sexual orientation is extensively studied topic nevertheless its etiology remains unclear. Several theories have been proposed to explain it. One of them is Neurohormonal theory of homosexuality. According to this theory, sexual orientation is affected by prenatal levels of androgen hormones. This thesis includes selected studies of experimental manipulations with prenatal levels of hormones in model mammalian species to explain effects of these hormones. Main part of the thesis focuses on the effect of prenatal androgens in humans using somatic biomarkers, for example 2D:4D digit ratio. Studies concerning sex, age and ethnic differences are described in detail. Great attention is dedicated to studies of sexual orientation. In women it seems that sexual orientation could be influenced by prenatal hormones, in men this theory isn't supported. This thesis summarizes and critically evaluates available literature concerning the effects of prenatal hormones on human sexual orientation.
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Relationship between male facial morphology and assessments of fighting ability
Třebický, Vít ; Havlíček, Jan (advisor) ; Stirratt, Michael (referee) ; Blažek, Vladimír (referee)
Social interactions may sometimes collide and result in conflicts which can be solved among others by means of physical violence. However, physical confrontations entail a risk of injuries and other fitness-affecting consequences. Thus, it seems likely that cognitive and behavioural processes to assess the fighting ability may have evolved by means of natural selection. This would facilitate adaptive decisions and responses to decrease costs and increase benefits from potential confrontations. Behavioural characteristics are often assessed according to physical traits such as facial appearance. People are relatively accurate in attributions of certain characteristics from facial traits, like physical strength or propensity for aggression. However, previous research was not based on data about actual fighting ability. Therefore, we conducted a series of empirical studies testing perception of formidability, accuracy of the perception and attempted to identify facial morphological traits related to the assessments and actual fighting performance. To test these issues, we employed Mixed Martial Arts contestants and used their record of victories and defeats. The results of our first study revealed that people are indeed able to relatively accurately assess the fighting ability of others. The fighting...
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Perception of individual variation in body odour in human adults
Fialová, Jitka ; Havlíček, Jan (advisor) ; Schaal, Benoist (referee) ; Stopka, Pavel (referee)
The thesis consists of two parts. The first part introduces the topic of human chemical communication and reviews current evidence on individual variation in human body odour and its perception. This part is framed by sexual selection theory. In the first chapter, the concept of the theory of communication is introduced followed by a discussion on the specifics of chemical communication. Next, the formation of individually specific body odour signatures with reference to skin glands, their volatile products and the subsequent metabolization by skin microflora is described. The next chapters are dedicated to selected interindividual body odour cues such as sex and kin recognition, genetic compatibility in genes of Major Histocompatibility Complex, and health and reproductive status in a mate choice context. Furthermore, interactions between perfumes and body odours are discussed. Finally, methods of body odour sampling are introduced and a rationale behind presenting individual samples or body odour blends is discussed. The second part is comprised of six scientific papers, specifically three reviews and three empirical studies. Review papers summarize factors affecting human body odour quality with emphasis on diet and affective states. The first text shows that human body odours contain cues to...
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The Cultural Attraction Theory and its Empirical Evidence
Hillerová, Pavlína ; Havlíček, Jan (advisor) ; Horský, Jan (referee)
One of the approaches to study cultural evolution is the cultural attraction theory. This thesis aims to introduce this theory via literature analysis and subject it's empirical backing to a critique. The opening chapter briefly presents the theory and describes the circumstances of it's formation. Next, I outline the specific theoretical concepts (culture as a chain of representations, attractors, transformations). Mainly, the latter are complemented with empirical studies, both supporting and conflicting the respective theory. The last part of the thesis compares cultural attraction theory against dual inheritance theory, which has been contrasted by the aforementioned from the very beginning. Both of these perspectives have it's specifics and can provide an explanation for distinct cultural phenomena. These two theories can complement one another and together constitute an integral theory for cultural evolution study.
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Evolutionary rationale of manifestation of personality traits to vocal expression
Kozák, Jan ; Pivoňková, Věra (advisor) ; Havlíček, Jan (referee)
Previous research in the field of vocal expression in relation to personality variables slightly uncovered some acoustic parameters that correlate with personality characteristics in different models of personality. However, just few studies have examined antisocial personality characteristics including also Dark triad traits. The Dark triad itself is a relatively new concept that has not been studied in relation to the acoustic parameters. This explorative study examines the correlation between acoustic parameters of the voice spectrum and personality traits of Dark Triad, NEO-FFI and Self-deception. For this research were selected voice samples in the form of prolonged phonation vocals / a /, / e /, / i /, / o /, / u /, reading of text, and neutral spontaneous description. Research was attended by 66 participants who completed personality questionnaires SD3, NEO-FFI and SDQ. From an acoustic perspective were measured 21 parameters describing voice quality in software PRAAT. Data analysis revealed significant correlations between personality traits and some acoustic parameters. As an important parameters have showed HNR, jitter and shimmer. The results confirm that certain personality traits are manifested through the human voice. The actual mechanism of influences on voice in this work was only...
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