Markus J Rantala

University of Turku | UTU · Department of Biology

Current paradigm in psychiatry sees bipolar disorder as highly heritable disorder with environmental factors playing only a little role in it. Since bipolar disorder has been found to be rare among people with traditional lifestyles (e.g., hunter-gatherers, Old Order Amish and Hutterites) and more common in people who have adopted Western lifestyle...

Predation can have both lethal and non-lethal effects on prey. The non-lethal effects of predation can instil changes in prey life history, behaviour, morphology and physiology, causing adaptive evolution. The chronic stress caused by sustained predation on prey is comparable to chronic stress conditions in humans. Conditions like anxiety, depressi...

The evolutionary advantages behind the leading mating strategy in humans—serial monogamy, often paired with infidelity—have been discussed at length in evolutionary psychological literature. Alternative mating strategies have received less attention from evolutionary psychological and relationship science researchers alike. That is until the recent...

The development of high-throughput behavioral assays, where numerous individual animals can be analyzed in various experimental conditions, has facilitated the study of animal personality. Previous research showed that isogenic Drosophila melanogaster flies exhibit striking individual non-heritable locomotor handedness. The variability of this trai...

The optimal body mass hypothesis posits that the body reserves of wintering birds are balanced between the risk of starvation and predation. In this study, we tested whether the body mass of wintering Great Tits (Parus major) was higher under conditions of less predictable food resources. We compared body mass, body mass index, the speed at take-of...

Host immune activation is common under a pathogen invasion. This physiological response can promote changes in the body surface compounds, thus providing chemical cues related to health that might be useful to conspecifics. By recognizing the current immu-nological status of social partners, individuals can modulate their behavior to minimize the r...

Evolutionary approaches to human mating strategies have associated facial and physical attractiveness with cues of health, fertility, and personality traits both in men and women. In this study, we tested the hypothesis that these associations may be mediated by psychological flexibility (an indicator of mental health) and/or sociosexual orientatio...

Hormones are key factors in determining the response of organisms to their environment. For example, the juvenile hormone (JH) coordinates the insects' development, reproduction, and survival. However, it is still unclear how the impact of juvenile hormone on insect immunity varies depending on the sex and reproductive state of the individual, as w...

We propose that major depressive disorder is not a unitary disease. Instead, different triggering factors causing periods of low mood can give rise to different and sometimes even opposite symptom patterns. Some of the symptoms of depression are maladaptive; others may be psychobehavioural adaptions to solve the adaptive problem that triggered the...

Schizophrenia has been an evolutionary paradox: it has high heritability, but it is associated with decreased reproductive success. The causal genetic variants underlying schizophrenia are thought to be under weak negative selection. To unravel this paradox, many evolutionary explanations have been suggested for schizophrenia. We critically discuss...

Objective Findings on the associations between sex hormones and immune function are scarce and mixed, especially in women. To contribute to the understanding on how sex hormones and immune function interact, we analyzed relationships between testosterone, estradiol, and immune responses in women.Methods Two doses of hepatitis B vaccine were adminis...

Previous work has reported a relation between pathogen-avoidance motivations and prejudice toward various social groups, including gay men and lesbian women. It is currently unknown whether this association is present across cultures, or specific to North America. Analyses of survey data from adult heterosexuals ( N = 11,200) from 31 countries show...

Background Parasites are among the main factors that negatively impact the health and reproductive success of organisms. However, if parasites diminish a host’s health and attractiveness to such an extent that finding a mate becomes almost impossible, the parasite would decrease its odds of reproducing and passing to the next generation. There is e...

Free-living organisms face multiple stressors in their habitats, and habitat quality often affects development and life history traits. Increasing pressures of agricultural intensification have been shown to influence diversity and abundance of insect pollinators, and it may affect their elemental composition as well. We compared reproductive succe...

Metacommunity models describe species occupancy frequency distribution (hereinafter ‘SOFD’). Our goal is to present how the differences in eight macroinvertebrate orders dispersal ability affect SOFD patterns. A total of 293 species from eight macroinvertebrate orders were observed in 14 eutrophic lakes in southern Finland. Species occupancy ranged...

Significance In many monogamous species, a substantial proportion of offspring is sired by other males than the one providing care at the nest. Although females often solicit extra-pair mating, the benefits of extra-pair copulations to females are not fully understood. In this study on pied flycatchers, we tested whether extra-pair paternity in nei...

Objective Phenotypic markers associated with developmental stability such as fluctuating asymmetry, facial attractiveness, and reports of minor ailments can also act as indicators of overall physical health. However, few studies have assessed whether these markers might also be cues of mental health. We tested whether self- and other-perceived faci...

BACKGROUND Past work has shown massive variation in depressive symptoms between patients, challenging the perception of major depressive disorder (MDD) as being uniform. This appears quite relevant also for digital mental health (DMH) interventions. While individualization is one of the key potentials of these approaches, this is regularly not util...

When organisms’ environmental conditions vary unpredictably in time, it can be advantageous for individuals to hedge their phenotypic bets. It has been shown that a bet-hedging strategy possibly underlies the high inter-individual diversity of phototactic choice in Drosophila melanogaster . This study shows that fruit flies from a population living...

Objective The ability of parasites to hijack the nervous system, manipulating the host’s physiology and behavior in ways that enhance the parasite’s fitness while damaging host fitness, is a topic of ongoing research interest in evolutionary biology, but is largely overlooked in mental health research. Nevertheless, recent evidence has shown that T...

The genes of the Major Histocompatibility Complex (MHC), which plays a fundamental role in the immune system, are some of the most diverse genes in vertebrates and have been connected to mate choice in several species, including humans. While studies suggest a positive relationship between MHC diversity and male facial attractiveness, the connectio...

The development of costly traits such as immune function and secondary sexual traits is constrained by resource availability. The quality of developmental conditions and the availability of resources in ontogeny may therefore influence immune system functions and other biological traits. We analyzed causal pathways between family socioeconomic posi...

A scientific approach to human health and behaviour cannot afford to ignore the insights provided by evolutionary biology. Pure socialisation accounts overlook key evidence on the relations between biological sex and health, leading to biased understanding and potentially counterproductive interventions. Many observed sex disparities in health refl...

While COVID-19 infection and mortality rates are soaring in Western countries, Southeast Asian countries have successfully avoided the second wave of the SARS-CoV-2 pandemic despite high population density. We provide a biochemical hypothesis for the connection between low COVID-19 incidence, mortality rates, and high visceral adiposity in Southeas...

Bipolar disorder is a mental health disorder characterized by extreme shifts in mood, high suicide rate, sleep problems, and dysfunction of psychological traits like self-esteem (feeling inferior when depressed and superior when manic). Bipolar disorder is rare among populations that have not adopted contemporary Western lifestyles, which supports...

Previous literature has shown associations between the Dark Triad (i.e., narcissism, Machiavellianism, psychopathy), other-perceived attractiveness, and personality. Nevertheless, the study of the Dark Triad as predictor of traits related to sociosexual dynamics (i.e., self-perceived attractiveness, mate value, and number of sexual partners) still...

Bisexual behavior is an order of magnitude more common than exclusive homosexuality in women. Many evolutionary hypotheses on sexual orientation have focused on homosexuality, particularly in men, yet there has recently been a growing recognition that male and female homosexuality may have different evolutionary origins, and that the various forms...

Juvenile hormone has been suggested to be a potential mediator in the trade-off between mating and insects' immunity. Studies on various insect taxons have found that juvenile hormone interferes with humoral and cellular immunity. Although this was shown experimentally, studies using highly virulent parasites or pathogens are lacking so far. In thi...

Although obesity is known to be a risk factor for COVID-19 severity, there is an urgent need to distinguish between different kinds of fat – visceral and subcutaneous fat – and their inflammation status in COVID-19. These different fat types have partially diverging biochemical roles in the human body, and they are differentially associated with SA...

Anthropogenic pollution has a disadvantageous influence on various life-history traits. Although direct effects are well known, potential fitness-related trans-generational costs are less studied. Previously, empirical findings have demonstrated that environmental conditions faced by the parental generation have an effect on the traits expressed by...

The elemental composition of organisms belongs to a suite of functional traits that change during development in response to environmental conditions. However, associations between adaptive variations in developmental speed and elemental body composition are not well understood. We compared body mass, elemental body composition, food uptake and fat...

Immune function, height and resource accumulation comprise important life history traits in humans. Resource availability models arising from life history theory suggest that socioeconomic conditions influence immune function, growth and health status. In this study, we tested whether there are associations between family income during ontogeny, ad...

We investigated the intra- and trans-generational effects of larval diet on immune function, body size and development time of the greater wax moth, Galleria mellonella (Lepidoptera : Pyralidae). We found that moths reared on a diet diluted with cellulose (a low-nutrition diet) were about one-third smaller, had about one-fifth longer development ti...

Only dominant individuals have unrestricted access to contested resources in group-living animals. in birds, subordinates with restricted access to resources may respond to intragroup contests by acquiring extra body reserves to avoid periods of food shortage. In turn, higher body mass reduces agility and increases predation and mortality risk to s...

We present data from 122 nations showing that Baumard’s argument on the ecological predictors of life history strategies and innovation is incomplete. Our analyses indicate that wealth, parasite stress, and cold climate impose orthogonal effects on life histories, innovation, and industrialization. Baumard also overlooks the historical exploitation...

We present data from 122 nations showing that Baumard's argument on the ecological predictors of life history strategies and innovation is incomplete. Our analyses indicate that wealth, parasite stress, and cold climate impose orthogonal effects on life histories, innovation, and industrialization. Baumard also overlooks the historical exploitation...

The development of indirect mechanisms of intrasexual competition (e.g., visual identification of possible rivals) could be related to personality traits such as aggressiveness and self-esteem. However, the study of endocrine changes associated to indirect mechanisms of intrasexual competition is scarce. The aim of this study was to investigate the...

The elemental composition of organisms relates to a suite of functional traits that change during development in response to environmental conditions. It may be a part of a phenomenon known as ‘developmental programming’, which hypothetically creates phenotypes that are better adapted to their environments. However, associations between development...

Eating disorders are evolutionarily novel conditions. They lead to some of the highest mortality rates of all psychiatric disorders. Several evolutionary hypotheses have been proposed for eating disorders, but only the intrasexual competition hypothesis is extensively supported by evidence. We present the mismatch hypothesis as a necessary extensio...

[Target Article.] Women’s capacity for sexual fluidity is at least as interesting a phenomenon from the point of view of evolutionary biology and behavioral endocrinology as exclusively homosexual orientation. Evolutionary hypotheses for female nonheterosexuality have failed to fully account for the existence of these different categories of nonhet...

Female sexual orientation and its various species-wide and species-specific manifestations comprise a topic to which one scientific article can hardly do justice. We have nevertheless attempted to analyze the topic more broadly than any one scientific article of which we are aware. To this end, we applied Tinbergen’s four questions and life history...

Objectives According to the ectoparasite avoidance hypothesis, natural selection has shaped human hairlessness to reduce the potential for the body to host disease carrying ectoparasites. However, men retain sexually dimorphic and conspicuous patches of facial and body hair. The ectoparasite avoidance hypothesis also proposes that sexual selection...

The elemental composition of organisms belongs to a suite of functional traits that may adaptively respond to fluctuating selection pressures. Life history theory predicts that predation risk and resource limitations impose selection pressures on organisms' developmental time and are further associated with variability in energetic and behavioral t...

The strength of sexual selection on secondary sexual traits varies depending on prevailing economic and ecological conditions. In humans, cross-cultural evidence suggests women’s preferences for men’s testosterone dependent masculine facial traits are stronger under conditions where health is compromised, male mortality rates are higher and economi...

Digit ratio (2D:4D)-a reliable marker of prenatal sex hormone exposure-and low facial fluctuating asymmetry a marker of developmental stability-are associated with specific personality traits in both sexes. Recently, the interest in the dark triad of personality (Machiavellianism, narcissism, and psychopathy) has increased. However, whether 2D:4D a...

[In press for Behavioral and Brain Sciences]. We present data from 122 nations showing that Baumard’s argument about the ecological predictors of life history strategies and innovation is incomplete. Our analyses indicate that wealth, parasite stress, and cold climate impose orthogonal effects on life histories, innovation, and industrialization....

Objectives: Male height and health affect a diverse range of social and economic outcomes such as competition for resources and mates. Life history theory predicts that limited availability of bioenergetic resources curbs the development of central life history functions such as somatic growth, immunity, and investment in offspring. Although genet...

Organisms in the wild are likely to face multiple immune challenges as well as additional ecological stressors, yet their interactive effects on immune function are poorly understood. Insects are found to respond to cues of increased infection risk by enhancing their immune capacity. However, such adaptive plasticity in immune function may be limit...

Evidence suggests that brain serotonin (5-HT) is one of the central mediators of different types of animal personality. We tested this assumption in field crickets Gryllus integer using a selective serotonin reuptake inhibitor (SSRI). Crickets were selected for slow and rapid development and tested for their coping styles under non-stressful condit...

It has been recently suggested that female mate choice, based on sexually selected ornaments, is an important component of social wasps' reproductive biology. The correlates of male ornaments that could be of a female's interest, however, remain to be investigated. Males of the Neotropical paper wasp Polistes simillimus have sexually dimorphic mela...

The ovulatory shift hypothesis proposes that women's preferences for masculine physical and behavioral traits are greater at the peri-ovulatory period than at other points of the menstrual cycle. However, many previous studies used self-reported menstrual cycle data to estimate fecundability rather than confirming the peri-ovulatory phase hormonall...

Higher testosterone levels have been positively related to a variety of social behaviors and personality traits associated with intrasexual competition. The aim of this study was to evaluate the role of testosterone levels and personality traits such as aggressiveness, competitiveness, and self-esteem on the task of choosing a fighting competitor (...

Motta-Mena and Puts (2017) have recently reviewed the endocrinological substrates of human female sexuality. We point out a shortcoming in their review, since their claim that estrogen “has a limited role, if any, in masculinizing the human brain and behavior” does not stand up to close scrutiny, especially when applied to females.

Predator-prey interactions are an important evolutionary force affecting the immunity of the prey. Parasitoids and mites pierce the cuticle of their prey, which respond by activating their immune system against predatory attacks. Immunity is a costly function for the organism, as it often competes with other life-history traits for limited nutrient...

Animals normally respond to stressful environmental stimuli by releasing glucocorticoid hormones. We investigated whether baseline corticosterone (CORT), handling-induced corticosterone concentration(s), and body condition indices of members of willow tit (Poecile montanus) groups differed while wintering in old growth forests and managed young for...

Research in pharmacopsychology has much to benefit from an evolutionary approach to psychopathology. This is because the possible benefits of medication can be properly understood only by analyzing why the symptoms of mental disorders exist in the first place. This rationale applies not only to major depressive disorder, but also to medicine more g...

Major depressive disorder constitutes one of the leading causes of disability worldwide. However, it is not a unitary disease — it is a heterogeneous syndrome, with patients differing remarkably in symptom profile, pathophysiology and treatment responsiveness. Previous attempts to subtype major depressive disorder have showed limited clinical appli...

Communities of symbiotic microorganisms that colonize the gastrointestinal tract play an important role in food digestion and protection against opportunistic microbes. Diet diversity increases the number of symbionts in the intestines, a benefit that is considered to impose no cost for the host organism. However, less is known about the possible i...

Deficiency of food resources in ontogeny is known to prolong an organism's developmental time and affect body size in adulthood. Yet life history traits are plastic: an organism can increase its growth rate to compensate for a period of slow growth, a phenomenon known as ‘compensatory growth’. We tested whether larvae of the greater wax moth Galler...

Vertebrates differ in their ability to mount an adaptive immune response to novel antigens. Bioenergetic resources available to an organism are finite; investment in reproduction compromises immune function and may therefore affect critical life history trade-offs. We tested whether reproduction impairs the ability to produce an antibody response a...

The causes and consequences of among-individual variation and covariation in behaviours are of substantial interest to behavioural ecology, but the proximate mechanisms underpinning this (co) variation are still unclear. Previous research suggests metabolic rate as a potential proximate mechanism to explain behavioural covariation. We measured the...

Insect cuticle hardens and darkens during the processes of cuticular melanization and sclerotization, and it provides an effective physicochemical barrier against parasites and pathogens. If an invader manages to breach this barrier defense, it is attacked by immune mechanisms in the hemocoel. In this study, we set out to investigate the associatio...

People who are more avoidant of pathogens are more politically conservative, as are nations with greater parasite stress. In the current research, we test two prominent hypotheses that have been proposed as explanations for these relationships. The first, which is an intragroup account, holds that these relationships between pathogens and politics...

This poster presents our work on the evolution of female nonheterosexuality. It differs from our previous poster titled ”Female homosexuality: a testosterone-mediated fast life history strategy?” in that it is pitched to a more general audience.

Facial hair is a prominent secondary sexual trait, particularly given the importance of the face in interpersonal communication. Bizarrely by animal standards, men expend considerable effort every day trimming, waxing or shaving this androgen-dependent trait. Why some men shave this cue of masculinity off, and why women's preferences for facial hai...