The Comparative Effect of Occupational and Musical Enrichment on Fecal Glucocorticoid Metabolite Levels in a Captive Colony of Stumptail Macaques (Macaca arctoides).

Environmental enrichment improves captive animal welfare by reducing stress-related behaviors. Previous studies in a captive colony of stumptail macaques (Macaca arctoides) reported a reduction of aggression, coprophilia, and stereotypic behaviors after an occupational enrichment program; however, the effect on stress hormones such as glucocorticoids has not been investigated yet. The goal of this study was to compare the effect of sex, age, and social rank on changes in fecal glucocorticoid metabolites (fGCM) after applying two kinds of enrichments (occupational vs. musical) in a captive colony of stumptail macaques. We collected 234 fecal samples from 25 stumptail macaques under the following conditions: (1) basal (no enrichment), (2) three weeks of occupational enrichment, and (3) three weeks of relaxing/classical music. The Generalized Estimated Equation Model showed an increase in fGCM levels after the occupational enrichment only in adult subjects (p = 0.003 compared to basal). The fGCM levels reached by the adults after the occupational enrichment was higher than that of juveniles (p = 0.002) and subadults (p = 0.02). Occupational and musical enrichment decreased fGCM levels only in middle-ranking individuals (p < 0.001 and p = 0.013, respectively). No sex differences were found. In conclusion, there were age and rank differences in individuals' physiological reactivity to the effects of environmental enrichment which need to be considered when planning enrichment programs.

Psychopathology, cortisol and testosterone responses to traumatic images: differences between urban and suburban citizens in a middle-income country.

Background: Living in urban places has been associated with a higher risk of psychopathology as well as with altered hypothalamus-pituitary-adrenal (HPA) axis and consequently altered cortisol response, but studies have concentrated mainly in high-income countries population. The role of other hormones such as testosterone, implicated in stress response and with human social behaviors, have not yet been investigated. The aim of this study was to compare symptoms of psychopathology as well as cortisol and testosterone in response to traumatic images between urban and suburban people in a middle-income country. Methods: A sample of 67 women and 55 men (N = 122, 18-45 years) from urban and suburban places of Mexico participated in the study. We quantified salivary cortisol and testosterone in response to images with traumatic and violent content (basal, 15, 30, and 45 min after images). Participants answered a general information questionnaire and the Symptom Checklist-90-R to assess their psychopathological traits. We performed Generalized Estimating Equation Models to analyze hormonal levels and MANOVAs to compare differences in participants' psychopathology symptoms. Area under the curve respect to ground (AUCG) of hormonal levels and sex differences were also compared. Results: Suburban citizens showed no cortisol response, whereas urban people showed a cortisol peak 15 min after the image's exposure; however, suburban people had higher AUCG and basal levels compared to urban ones. Contrastingly, testosterone levels declined in all participants excepting the urban women, who showed no testosterone response. Although similar testosterone profile, AUCG levels were higher in urban than suburban men. Participants living in suburban areas had higher scores of somatizations, obsessive-compulsive, and interpersonal sensitivity, as well as more sleep disorders than participants living in urban areas. Conclusion: This study offers novel evidence about differences in cortisol and testosterone responses to a social stressor and in mental health indicators between a population of urban and suburban citizens, highlighting the impact of urbanization process on physiological and psychological outcomes in a middle-income country.

Testing the Challenge Hypothesis in Stumptail Macaque Males: The Role of Testosterone and Glucocorticoid Metabolites in Aggressive and Mating Behavior.

The "challenge hypothesis" predicts higher male-male aggressive behavior along with increases in testosterone levels during times of reproductive challenges and social instability. In addition, in some primate species, higher glucocorticoid levels can be observed as well, but this is usually modulated by dominance rank. We studied rank-related aggressive behavior, mating activity, and fecal testosterone and glucocorticoid metabolites (fTm and fGCm) in male stumptail macaques (Macaca arctoides) in order to test some predictions of the "challenge hypothesis". Over a 20-month period, we collected data on aggressive behavior and copulation, as well as fecal samples (n = 700) to quantify fTm and fGCm in seven adult stumptail males living in captivity. During periods of mating activity, male-to-male aggression increased in higher- and middle-ranking males. Neither fTm nor fGCm levels predicted male-to-male aggression. fGCm levels (but not fTm) were positively associated with male-to-female aggression; however, this association was pronounced during periods of mating activity. fGCm levels differed according to social rank, with middle-ranking males having the highest levels. Both hormones were higher during periods of mating activity, but only in higher- and middle-ranking males. Taken together, our findings partially support the challenge hypothesis in a non-seasonal primate and shed some light on the unique social and mating system of the stumptail macaque.

Comparison of two psychotherapies in cortisol response and their efficacy in reducing symptoms of anxiety and depression in women victims of intimate partner violence / Comparación de dos psicoterapias en la respuesta del cortisol y en su eficacia para reducir los síntomas de ansiedad y depresión en mujeres víctimas de violencia de pareja

Abstract Introduction There is a growing need to implement evidence-based psychological treatments for women victims of intimate partner violence (IPV) who commonly experience stress-related disorders such as anxiety, depression, or suicide risk, as well as altered cortisol reactivity. Objective 1. To compare the changes in depressive and anxious symptomatology, quality of life, and cortisol reactivity after two different interventions, Acceptance and Commitment Therapy (ACT, based on psychological flexibility) or Interpersonal Therapy (IPT, based on empowerment) in women exposed to IPV. 2. To compare the changes in relation to the presence of suicide thoughts. Method A clinical sample of 50 women (ages 21-74) randomly assigned to attend ACT or IPT, completed pre- and post-intervention questionnaires about intimate partner violence, quality of life, depression, anxiety, and measurements of salivary cortisol reactivity (basal, 15, 30, and 45 minutes after a cognitive challenge). We used Generalized Estimating Equation Models for data analysis. Results There was a significant improvement post-intervention in all variables, regardless of the type of psychotherapy or the presence of suicide thoughts. Before interventions, women that reported suicide thoughts had severe symptoms of depression, anxiety, worse quality of life, and a cortisol hyper-response profile, in contrast to women without suicide thoughts who had moderate symptoms and no cortisol response. Cortisol response to the cognitive test decreased in all women after both therapies. Discussion and conclusion Although different psychological approach, ACT, and IPT effectively improved mental health, quality of life, and changed cortisol reactivity of women exposed to IPV, including women at suicide risk.

Resumen Introducción Son necesarios tratamientos basados en evidencia para mujeres víctimas de violencia de pareja (IPV), con trastornos relacionados con estrés como ansiedad, depresión y riesgo suicida y alteraciones en la reactividad del cortisol. Objetivo Comparar los cambios en la sintomatología depresiva, ansiosa, calidad de vida y reactividad del cortisol después de aplicar Terapia de Aceptación y Compromiso (ACT, basada en la flexibilidad psicológica) o Terapia Interpersonal (IPT, basada en el empoderamiento) en mujeres expuestas a IPV y compararlos en función al pensamiento suicida. Método Una muestra clínica de 50 mujeres (entre 21 y 74 años) fueron asignadas aleatoriamente a recibir ACT o IPT, completaron antes y después, cuestionarios sobre IPV, calidad de vida, depresión y ansiedad, y mediciones de cortisol (basal, 15, 30 y 45 minutos después de un reto cognitivo) en saliva en respuesta a un reto cognitivo. Utilizamos modelos de Ecuaciones de Estimación generalizada para analizar los datos. Resultados Mejoraron significativamente todas las variables, independientemente del tipo de psicoterapia y del pensamiento suicida. Antes de la intervención, las mujeres con ideación suicida presentaron depresión y ansiedad severas, peor calidad de vida e hiper-respuesta de cortisol, en contraste con las mujeres sin ideación, quienes presentaron síntomas moderados y una respuesta de cortisol plana. El cortisol disminuyó en todas las mujeres después de ambas terapias. Discusión y conclusión Ambas terapias IPT y ACT mejoraron la salud mental y calidad de vida de las mujeres con IPV y modificaron la reactividad del cortisol, incluyendo a las pacientes que reportaron ideación suicida.

Increased Cortisol Response and Low Quality of Life in Women Exposed to Intimate Partner Violence With Severe Anxiety and Depression.

Background: Intimate partner violence (IPV) is one of the most prevalent forms of violence against women globally and it is considered a public health problem. Because the experience of IPV is stressful and traumatic for victims, they are at high risk of developing alteration of the Hypothalamus-Pituitary-Adrenal (HPA) axis functioning as well as anxiety and depression symptoms. The aim of this study was to compare the quality of life and changes in cortisol response to an acute stressor between women exposed to IPV and non-exposed women. Differences according to symptoms of anxiety and depression including the risk of suicide thoughts, were also analyzed. Method: Our sample size consisted of 130 women (ages 18-68) grouped as follows: 71 women experiencing IPV and 59 women without history of IPV as control group. All participants completed a battery of questionnaires including IPV exposure, anxiety, and depression symptoms (Beck Inventories), as well as quality of life (WHOQOL-BREF). Salivary cortisol levels in response to a cognitive test with verbal, mathematical, and abstract reasoning were measured at four time points. Results: Women exposed to IPV, with severe anxiety and depression symptoms as well as suicide thoughts, exhibited heightened cortisol response after the cognitive test and reported lower quality of life compared to (i) women experiencing IPV with moderate symptoms of anxiety and depression, who showed a blunted response, and (ii) women without history of IPV with minimal to moderate symptoms, who showed a decreased cortisol profile. Social relationships dimension was in particular the most affected aspect of quality of life. Conclusions: Our findings highlight the role of cortisol responses as a complementary biological marker to be associated with severe psychiatric disturbances in women exposed to IPV.

Are Toxoplasma-infected subjects more attractive, symmetrical, or healthier than non-infected ones? Evidence from subjective and objective measurements.

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 evidence that Toxoplasma gondii (T. gondii) manipulates phenotypic characteristics of its intermediate hosts to increase its spread. However, whether T. gondii manipulates phenotypic characteristics in humans remains poorly studied. Therefore, the present research had two main aims: (1) To compare traits associated with health and parasite resistance in Toxoplasma-infected and non-infected subjects. (2) To investigate whether other people perceive differences in attractiveness and health between Toxoplasma-infected and non-infected subjects of both sexes. Methods: For the first aim, Toxoplasma-infected (n = 35) and non-infected subjects (n = 178) were compared for self-perceived attractiveness, number of sexual partners, number of minor ailments, body mass index, mate value, handgrip strength, facial fluctuating asymmetry, and facial width-to-height ratio. For the second aim, an independent group of 205 raters (59 men and 146 women) evaluated the attractiveness and perceived health of facial pictures of Toxoplasma-infected and non-infected subjects. Results: First, we found that infected men had lower facial fluctuating asymmetry whereas infected women had lower body mass, lower body mass index, a tendency for lower facial fluctuating asymmetry, higher self-perceived attractiveness, and a higher number of sexual partners than non-infected ones. Then, we found that infected men and women were rated as more attractive and healthier than non-infected ones. Conclusions: Our results suggest that some sexually transmitted parasites, such as T. gondii, may produce changes in the appearance and behavior of the human host, either as a by-product of the infection or as the result of the manipulation of the parasite to increase its spread to new hosts. Taken together, these results lay the foundation for future research on the manipulation of the human host by sexually transmitted pathogens and parasites.

Choosing Fighting Competitors Among Men: Testosterone, Personality, and Motivations.

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 (a rival) with or without a motivation to fight. In Study 1, a group of 119 men participated in a task for choosing a rival through pictures of men with high-dominant masculinity versus low-dominant masculinity. Participants completed three personality questionnaires and donated two saliva samples (pre-test and post-test sample) to quantify their testosterone levels. We found that the probability of choosing high-dominant masculine men as rivals increased with higher aggressiveness scores. In Study 2, the task of choosing rivals was accompanied by motivations to fight (pictures of women with high or low waist-to-hip ratio [WHR]). In this context, we observed that the probability of choosing dominant masculine men as rivals depended on the WHR of the women. Overall, average levels of post-test testosterone, aggressiveness, and high self-esteem increased the probability to fight for women with low WHR independently of the dominance masculinity of the rivals. Our results indicate that human decisions, in the context of intrasexual competition and mate choice, are regulated by physiological and psychological mechanisms allowing men to increase their biological fitness. We discuss our results in the light of the plasticity of human behavior according to biological and environmental forces.

Stress and cortisol responses in men: differences according to facial symmetry.

Stress response is associated with increased activity in the hypothalamic-pituitary-adrenocortical axis. Chronic stress-induced elevation in cortisol may alter its own negative regulation with multiple long-term consequences for physical and psychological health. One of the most reliable physical traits associated with mental, apparent physical health, and competitiveness is the degree of facial fluctuating asymmetry. However, to our knowledge there are no studies regarding the relationship between cortisol levels, facial symmetry and male competitiveness, and how cortisol changes after a stressful test depending on these traits. Here, a group of 100 college men were photographed to obtain their facial asymmetry levels. They then, answered the perceived stress scale and the intrasexual competition test and donated two saliva samples (pre-and post-test sample) to measure the change in their cortisol levels after a stressful test. We found that basal cortisol levels were positively correlated with both perceived stress and competitiveness, but not with facial fluctuating asymmetry. Cortisol levels increased in most symmetrical men after a short stressful test, but it decreased in most asymmetrical men. The results suggest differences in endocrine responses according to facial fluctuating asymmetry in men and how these responses could be related to the maintenance of social status.

[Cortisol reactivity and adult mental health in adults exposed to early violence: a systematic reviewReatividade do cortisol e saúde mental em adultos com exposição precoce à violência: uma revisão sistemática]. / Reactividad del cortisol y salud mental en adultos expuestos a violencia temprana: revisión sistemática.

OBJECTIVE: Analyze results with respect to cortisol reactivity (CR) in experimental stress paradigms in adults with or without a psychiatric disorder who suffered violence in early developmental stages (infancy or early adolescence); and use these results to propose a clinical tool to determine biological stress indicators. METHODS: A systematic review was conducted using several databases and following PRISMA criteria; of a total of 231 articles, 16 satisfied the inclusion criteria and the results were analyzed qualitatively. RESULTS: Despite heterogeneity, the results suggested that the people who suffered violence at an early age present a pattern of low CR. In contrast, people who also developed symptoms of post-traumatic stress disorder and depression, regardless of the type of violence, showed increased CR. The majority of studies focused on people who suffered childhood sexual abuse and half of the articles supported the hypothesis that CR is more pronounced in men than in women. CONCLUSIONS: The results of this review suggest that cortisol hyperreactivity can be considered a biomarker for treatment and intervention in people with post-traumatic stress disorder and depression who suffered violence at an early age. The results also support evidence that experiencing violence alters stress response and mental health in the long term. However, it is necessary to conduct more studies, in particular studies on hyporeactivity and gender differences.

OBJETIVO: Analisar os resultados da reatividade do cortisol segundo um modelo de estresse experimental em adultos com ou sem transtorno psiquiátrico que foram precocemente expostos à violência durante o desenvolvimento (infância e início da adolescência) e propor um instrumento clínico para determinar indicadores biológicos de estresse. MÉTODOS: Uma revisão sistemática foi conduzida em diferentes bases de dados conforme os critérios PRISMA. Dos 231 artigos selecionados, 16 satisfizeram os critérios de inclusão. Foi realizada uma análise qualitativa dos resultados. RESULTADOS: Apesar de serem heterogêneos, os resultados indicam que adultos com exposição precoce à violência apresentam baixa reatividade do cortisol. De maneira oposta, os indivíduos que desenvolveram sintomas de transtorno de estresse pós-traumático e depressão, independentemente do tipo de violência sofrida, apresentaram elevada reatividade do cortisol. A maioria dos estudos se centrou em vítimas de abuso sexual na infância e, em metade dos artigos, sustentou-se a hipótese de que a reatividade do cortisol é mais acentuada no sexo masculino que no feminino. CONCLUSÕES: Os resultados deste estudo de revisão apontam que se pode considerar a hiper-reatividade do cortisol como biomarcador para o tratamento e a intervenção de pacientes que foram expostos precocemente à violência e que apresentam transtorno de estresse pós-traumático e depressão. Além disso, é reforçada a evidência de que sofrer violência afeta a resposta ao estresse e a saúde mental a longo prazo. Porém, fazem-se necessários mais estudos, sobretudo investigando hiporreatividade e diferenças de gênero.

Reactividad del cortisol y salud mental en adultos expuestos a violencia temprana: revisión sistemática / Cortisol reactivity and adult mental health in adults exposed to early violence: a systematic review / Reatividade do cortisol e saúde mental em adultos com exposição precoce à violência: uma revisão sistemática

RESUMEN Objetivo Analizar los resultados con respecto a la reactividad del cortisol (RC) ante un paradigma de estrés experimental en adultos con o sin algún trastorno psiquiátrico que sufrieron violencia en etapas tempranas de desarrollo (infancia y adolescencia temprana) y con ello proponer una herramienta clínica para el establecimiento de indicadores biológicos de estrés. Métodos Se realizó una revisión sistemática en diversas bases de datos, siguiendo los criterios PRISMA; de un total de 231 artículos, 16 cumplieron los criterios de inclusión y los resultados fueron analizados de manera cualitativa. Resultados A pesar de la heterogeneidad, los resultados sugieren que las personas que sufrieron violencia temprana presentan un patrón de baja RC. Contrariamente, la población que además desarrolló síntomas de trastorno de estrés postraumático y depresión, independientemente del tipo de violencia, mostró incrementada RC. La mayoría de los trabajos se centraron en población que sufrió abuso sexual en la infancia y la mitad de los artículos apoya la hipótesis de que la RC es más pronunciada en hombres que en mujeres. Conclusiones Los resultados de esta revisión nos permiten sugerir que es posible considerar la hiperreactividad del cortisol como un biomarcador para el tratamiento e intervención de población con trastorno de estrés postraumático y depresión que sufrieron violencia temprana. Además, apoyan la evidencia de que sufrir violencia altera la respuesta del estrés y la salud mental a largo plazo. Sin embargo, es necesario realizar más estudios principalmente los que se refieren a la hiporreactividad y a las diferencias de género.

ABSTRACT Objective Analyze results with respect to cortisol reactivity (CR) in experimental stress paradigms in adults with or without a psychiatric disorder who suffered violence in early developmental stages (infancy or early adolescence); and use these results to propose a clinical tool to determine biological stress indicators. Methods A systematic review was conducted using several databases and following PRISMA criteria; of a total of 231 articles, 16 satisfied the inclusion criteria and the results were analyzed qualitatively. Results Despite heterogeneity, the results suggested that the people who suffered violence at an early age present a pattern of low CR. In contrast, people who also developed symptoms of post-traumatic stress disorder and depression, regardless of the type of violence, showed increased CR. The majority of studies focused on people who suffered childhood sexual abuse and half of the articles supported the hypothesis that CR is more pronounced in men than in women. Conclusions The results of this review suggest that cortisol hyperreactivity can be considered a biomarker for treatment and intervention in people with post-traumatic stress disorder and depression who suffered violence at an early age. The results also support evidence that experiencing violence alters stress response and mental health in the long term. However, it is necessary to conduct more studies, in particular studies on hyporeactivity and gender differences.

RESUMO Objetivo Analisar os resultados da reatividade do cortisol segundo um modelo de estresse experimental em adultos com ou sem transtorno psiquiátrico que foram precocemente expostos à violência durante o desenvolvimento (infância e início da adolescência) e propor um instrumento clínico para determinar indicadores biológicos de estresse. Métodos Uma revisão sistemática foi conduzida em diferentes bases de dados conforme os critérios PRISMA. Dos 231 artigos selecionados, 16 satisfizeram os critérios de inclusão. Foi realizada uma análise qualitativa dos resultados. Resultados Apesar de serem heterogêneos, os resultados indicam que adultos com exposição precoce à violência apresentam baixa reatividade do cortisol. De maneira oposta, os indivíduos que desenvolveram sintomas de transtorno de estresse pós-traumático e depressão, independentemente do tipo de violência sofrida, apresentaram elevada reatividade do cortisol. A maioria dos estudos se centrou em vítimas de abuso sexual na infância e, em metade dos artigos, sustentou-se a hipótese de que a reatividade do cortisol é mais acentuada no sexo masculino que no feminino. Conclusões Os resultados deste estudo de revisão apontam que se pode considerar a hiper-reatividade do cortisol como biomarcador para o tratamento e a intervenção de pacientes que foram expostos precocemente à violência e que apresentam transtorno de estresse pós-traumático e depressão. Além disso, é reforçada a evidência de que sofrer violência afeta a resposta ao estresse e a saúde mental a longo prazo. Porém, fazem-se necessários mais estudos, sobretudo investigando hiporreatividade e diferenças de gênero.

Waist-to-Hip Ratio, but Not Body Mass Index, Is Associated with Testosterone and Estradiol Concentrations in Young Women.

We studied if testosterone and estradiol concentrations are associated with specific female waist-to-hip ratios (WHRs) and body mass indices (BMIs). Participants were 187 young women from which waist, hips, weight, and height were measured. In addition, participants informed on which day of their menstrual cycle they were and provided a 6 mL saliva sample. Ninety-one of them were in the follicular phase and 96 in the luteal phase. Only in the fertile phase of the menstrual cycle we found a significant interaction between testosterone and estradiol affecting WHR (b ± s.e. = -0.000003 ± 0.000001; t 94 = -2.12, adjusted R (2) = -0.008, P = 0.03). Women with the highest levels of both hormones had the lowest WHRs, while women with low estradiol and high testosterone showed the highest WHRs. BMI significantly increased as testosterone increased in female in their nonfertile days.

Effect of photoperiod on characteristics of semen obtained by electroejaculation in stump-tailed macaques (Macaca arctoides).

Some environmental variables determining seasonal reproduction in mammals are temperature, humidity, food availability, and photoperiod. Among these, photoperiod is considered the main regulator of primates' seasonal reproduction, thus the latitudinal distribution of primate populations is a key factor determining the appearance of seasonal reproduction. The present work presents supporting discrete seasonality in male stump-tailed macaques (Macaca arctoides). We investigated whether semen quality and testosterone covaried with Mexico City's photoperiod and relative humidity by analyzing variations in the portions that form the ejaculate: the seminal liquid, the seminal coagulum, and the copulatory plug. Five male adult stump-tailed macaques were electroejaculated once a month, obtaining three semen samples per male, from August 2011 to July 2012 (except for December 2011) (n = 165). Our results showed that stump-tailed macaque sperm counts were significantly different between the portions of the ejaculate. The seminal coagulum contained the significantly largest number of spermatozoids, followed by the copulatory plug and the seminal fluid. Photoperiod and relative humidity had major influence on the sperm count in the seminal coagulum and the testosterone concentrations. Testosterone reached its highest values around the time when days and nights lasted the same hours, decreasing when days either grew longer or became shorter. Concerning relative humidity, sperm counts in the seminal coagulum were highly variable on dry days, but decreased as the relative humidity increased. We conclude that stump-tailed macaques have a discrete seasonality, occurring in spring and fall when macaques' reproductive condition and readiness for postcopulatory intrasexual competition increase.

Changes in Men's Salivary Testosterone and Cortisol Levels, and in Sexual Desire after Smelling Female Axillary and Vulvar Scents.

Several studies have shown that a woman's vaginal or axillary odors convey information on her attractivity. Yet, whether such scents induce psychoneuroendocrinological changes in perceivers is still controversial. We studied if smelling axillary and vulvar odors collected in the periovulatory and late luteal phases of young women modify salivary testosterone and cortisol levels, as well as sexual desire in men. Forty-five women and 115 men, all of them college students and unacquainted with each other, participated in the study. Female odors were collected on pads affixed to the axilla and on panty protectors both worn the entire night before experiments. Men provided five saliva samples, a basal one before the smelling procedure, and four more 15, 30, 60, and 75 min after exposure to odors. Immediately after smelling the odor source, men answered a questionnaire rating hedonic qualities of scents, and after providing the last saliva sample they answered questionnaire on sexual desire. We found that periovulatory axillary and vulvar odors increased testosterone and cortisol levels, with vulvar scents producing a more prolonged effect. Luteal axilla odors decreased testosterone and cortisol levels, while luteal vulva odors increased cortisol. Periovulatory axilla and vulva scents accounted for a general increase of interest in sex. These odors were also rated as more pleasant and familiar, while luteal vulvar odors were perceived as intense and unpleasant.

La selección sexual en los humanos / Human sexual selection

Human reproduction involves, as in many other mammal species, a sexual selection process. Some of the features chose in a reproductive mate are intelligence, reliability, health, access to resources and others. However, the ultimate individuals' decision depends on her or his reproductive strategy. Several works have demonstrated that human beings cannot be characterized by a single strategy; people can decide for a long-term commitment mating, a short-term mating or both. However, there are some psychobiological aspects that underlie such decision making and apparently they are universal for human beings. In this review we present results, including our own, which illustrate the set of characteristics that are involved in human mate choice. In order to acquire an appropriate understanding of human behavior, it is necessary to consider those psychological adaptations which operate at both conscious and unconscious levels, evolved to deal with the most elementary demands to survive and reproduce.

La reproducción en los seres humanos, al igual que en otras muchas especies, implica un proceso de selección sexual que incluye la evaluación de factores como la inteligencia, la confiabilidad, la salud, la posibilidad de aportar recursos y las características físicas, entre otras. Sin duda, la decisión de la elección depende de la estrategia reproductiva que cada individuo elija pues diversos estudios sobre selección sexual humana muestran que las personas hacen uso de más de una estrategia reproductiva, lo que explica por qué algunos individuos prefieren tener varias relaciones a corto plazo, otros se deciden por una sola relación a largo plazo y otros más mantienen ambas, es decir, una a largo plazo y varias a corto plazo. Como consecuencia, las características que cada uno podría buscar en sus parejas potenciales resultan ser muy diversas. Sin embargo, existen algunos factores biológicos que subyacen a la toma de decisiones y que son aparentemente universales. En esta revisión presentamos los resultados obtenidos en algunos trabajos, incluyendo los nuestros, con la finalidad de dar a conocer, desde la perspectiva biológica, cuáles características resultan imprescindibles para seleccionar una pareja y porqué. Desde luego, sin perder de vista que para conseguir un mejor entendimiento de la conducta humana es necesario considerar que las adaptaciones psicológicas en los seres humanos, las cuales operan de forma consciente o inconsciente, están encaminadas a resolver los problemas más elementales de sobrevivencia y reproducción.

Seasonality of LH, testosterone and sperm parameters in spider monkey males (Ateles geoffroyi).

There are no reported data on hormonal fluctuations in black-handed spider monkey males. On previous research about the reproductive physiology of this monkey we have found that during the dry season females show ovulatory estrogen peaks and males present the best quality semen. As part of an ongoing research, in this study we assessed seasonal variations in the concentration of serum luteinizing hormone (LH) and testosterone (T) in three adult spider monkey males to corroborate the seasonal reproductive synchrony. At the same time sperm count and motility were evaluated to search for any correlation between those sperm parameters and hormonal concentrations. We took blood and semen samples (by electroejaculation) of anesthetized males throughout the rainy (June-September) and dry (October-May) months. Our results revealed that T and LH were higher throughout the dry season and there was a significant correlation between T concentration and sperm count. Although higher during the dry season, sperm motility tended to correlate with testosterone and LH levels. These results demonstrated that black-handed spider monkeys have a tendency to show a seasonal pattern of reproduction being the dry season the most likely time to achieve fertilization.

The seminal coagulum favours passage of fast-moving sperm into the uterus in the black-handed spider monkey.

In addition to gametes, mammalian internal fertilisation has required the evolution of assorted anatomical, physiological and biochemical devices to deal with intra- and inter-sexual conflict such as sperm competition and female cryptic choice respectively. The seminal coagulum of primates and other mammals is viewed as one of such devices. Among primates, the seminal coagulum characteristically occurs in multi-male and multi-female species, leading us to suppose that it intervenes in sperm competition. However, it can also provide cues to the female reproductive tract about male desired or undesired traits, and therefore deter or favour sperm survival and migration. The present work investigates whether the seminal coagulum of the black-handed spider monkey enhances sperm fertilisation chances by improving the female reproductive tract conditions, and if the female reproductive tract is 'blind' to semen or behaves selectively towards ejaculates of different males. A series of artificial inseminations were done in five females, using the ejaculates of three different males, one at a time, and measuring the presence of distinct types of sperm inside the uteri at 10, 30 and 60 min following the insemination. The presence of coagulum, menstrual phase, and male and female identity only affected fast, straight-moving sperm, with larger amounts of fast sperm appearing inside the uteri when ejaculates had seminal coagulum, as well as when in the periovulatory phase. There was great intra-uterine fast-sperm variation regarding which male's semen inseminated which female. The results provide evidence to account for sexual conflict in the spider monkey as well as a methodological approach to this kind of study.

Endocrine changes in male stumptailed macaques (Macaca arctoides) as a response to odor stimulation with vaginal secretions.

In mammalian species, social chemosignals are important in modulating endocrine reproductive functions. In nonhuman primates, previous studies have described a high frequency of mounting behavior by females in the follicular and periovulatory phases of the menstrual cycle. Stumptailed macaque females do not signal receptivity by means of sexual swellings, as do others macaques, therefore providing a good model in which to study chemical signaling of reproductive status. We exposed anesthetized stumptailed males to vaginal secretions of either late follicular or menses phase or to saline solution to determine the endocrine changes promoting male sexual behavior. In males exposed to follicular secretions, plasma testosterone concentrations were sustained up to 120 min after exposure. Such an effect was not observed in animals exposed to menses or saline odor sources. A luteinizing hormone surge, occurring 30 minutes after exposure to late follicular phase secretion swabs, preceded this sustained testosterone effect. The fact that late follicular scents induce sustained testosterone concentrations provides support to the idea that stumptailed males draw information concerning female reproductive status from the female's vaginal odor.

Sperm quality differences between the rainy and dry seasons in captive black-handed spider monkeys (Ateles geoffroyi).

The present work provides an assessment of sperm measures (concentration, motility, viability, etc.) of three black-handed spider monkeys (Ateles geoffroyi) during the rainy and dry seasons in Mexico City, as well as an evaluation of the between-subjects variability of sperm quality. Twenty samples obtained by rectal electroejaculation and digested with trypsin were evaluated. The results showed that during the dry season (n = 9) the semen samples were of better quality than those obtained during the rainy season (n = 11). The individual animals showed differences in sperm concentration, although there were no differences in sperm quality.

Comunicación química en primates / Chemical communication in primates

El sistema olfatorio de los mamíferos se ha especializado en la percepción de componentes químicos que regulan una gran diversidad de funciones. Uno de los componentes químicos que más utilizan las distintas especies es la feromona, cuyos efectos se pueden encontrar en el ámbito fisiológico o conductual, dependiendo del mensaje que se emita y del contexto en el cual se perciba.El uso de las feromonas en la comunicación química de los mamíferos tiene importantes funciones reguladoras de procesos reproducticos, que pueden afectar las interacciones sociales dentro de las poblaciones. Las feromonas que más emplean los mamíferos se encuentran en la orina y en las secreciones vaginales. La percepción de estos componentes químicos se lleva a cabo por el epitelio olfatorio y el órgano vomeronasal, que establecen conexiones neurales con diferentes núcleos cerebrales vinculados con la regulación del proceso reproductivo y las emociones. Sin embargo, hay controversia sobre la presencia de las feromonas en los antropoides del Viejo Mundo y en los seres humanos. En los primates, como los prosimios y los monos del Nuevo Mundo, se acepta su función en las conductas de marcaje territorial, en el reconocimiento entre conespecíficos y en la conducta sociosexual. En los primates catarrinos, en los póngidos y en los seres humanos se ha generado controversia sobre la participación de las feromonas en la atracción sexual. En primer lugar, debido a que esos grupos de primates muestran una disminucion de la región olfatoria, tanto nasal como cerebral, en comparación con el resto de los mamíferos. En segundo lugar, porque hasta ahora no se ha demostrado la funcionalidad del órgano vomeronasal, supuestamente especializado en la percepción de las feromonas en los demás mamíferos, que se considera como vestigial en los monos catarrinos y en los simios. Hay algunos trabajos sobre los seres humanos que muestran que dicho órgano no es completamente vestigial, como se consideraba, sino que es una estructura especializada en la percepción de feromonas, capaz de promover cambios fisiológicos dependientes del sexo.