Human Love Styles and Attitudes toward Pets

Pets have a positive influence on humans’ physical and psychological wellbeing, as well as their close relationships. In general, people who hold a positive view of people in turn hold a favorable view of pets. Despite this, previous studies on the relationship between love toward people and love toward pets were inconclusive. In this study, we take a fresh look at the nexus of the domains of love and pets by exploring whether people’s views of love with a romantic partner are associated with attitudes toward their pets. To answer this question, we administered scales to assess human love styles and attitudes toward pets. Participants completed measures on their attitudes toward romantic love, romantic relationship satisfaction, amount of social support, self-esteem, and attitudes toward pets. Human love styles assessed include Eros (passionate), Ludus (game-playing), Storge (friendship), Pragma (practical), Mania (obsessive), and Agape (selfless). Factor analyses of the pet attitudes measure revealed two factors—positive and negative attitudes toward pets. An erotic love style was linked to the endorsement of favorable pet attitudes, while a ludic love style was associated with the endorsement of unfavorable pet attitudes. Subsequent gender-specific correlations indicated that favorable pet attitudes were associated with high levels of social support for men, but low levels of support for women. Future research might address whether pets are instrumental in the development of love styles, whether love styles change after adoption of a pet, and if attitudes toward a romantic partner are similar to attitudes toward a particularly close companion animal.     

Romantic love modulates women's identification of men's body odors

Romantic love is one of our most potent and powerful emotions, but very little is known with respect to the hormonal and psychological mechanisms in play. Romantic love is thought to help intimate partners stay committed to each other and two mechanisms have been proposed to mediate this commitment: increased attention towards one's partner or deflected attention away from other potential partners. Both mechanisms find support in the literature. We explored the potential influence of each of these mechanisms by assessing women's ability to identify (ID) body odors originating from their boyfriend, a same-sex friend, and an opposite-sex friend and the relationship between this ability and the degree of romantic love expressed towards their boyfriend. We hypothesized that an increase in attention towards one's partner would render a positive correlation between ID of a boyfriend's body odor and degree of romantic love; conversely, we hypothesized that attention deflected away from other potential partners would render a negative correlation between ID of an opposite-sex friend's body odor and degree of romantic love for the boyfriend. Our results supported the deflection theory as we found a negative correlation between the degree of romantic love for the subjects' boyfriends and their ability to ID the body odor of an opposite-sex friend but not of their boyfriend or same-sex friend. Our results indicate that romantic love deflects attention away from potential new partners rather than towards the present partner. These changes are likely mediated by circulating neuropeptides and a testable model is suggested.     

An open-label trial of L-5-hydroxytryptophan in subjects with romantic stress

This open-label trial assessed the clinical efficacy of L-5-hydroxytryptophan (5-HTP), a natural serotonin precursor, in nondepressed young subjects with high levels of romantic stress. Since both neurotrophins and serotonin have been linked to human romantic attachment, we sought to investigate the changes in serum brain-derived neurotrophic factor (BDNF) levels and platelet serotonin content in relation to the changes in romantic stress throughout the study. A total of 15 healthy subjects (11 females and 4 males, mean age: 23.3 ± 2.1 years) who experienced a recent romantic break-up or reported recent romantic problems took part in the study. The participants were treated openly for 6 weeks with L-5-hydroxytryptophan (60 mg Griffonia simplicifolia extract containing 12.8 mg 5-HTP b.i.d., Amorex, Coropharm, Villach, Austria). The subjects were evaluated at baseline, at 3 weeks and at the end of the 6-week trial using an adapted version of the Seiffge-Krenke's Problem Questionnaire. BDNF and platelet serotonin content were determined at baseline, at 3 weeks, and after the completion of the 6-week trial. We observed significant improvements in romantic stress scores from weeks 0 through 3 (p=0.007) but no further significant improvement was evident from weeks 3 through 6 (p=0.19). At 6 weeks, subjects had a significant increase from baseline in both BDNF and platelet serotonin values. Our data suggest that direct modulation of the serotonergic system may have use for the treatment of psychological suffering associated with unreciprocated romantic love.     

Romantic love: a mammalian brain system for mate choice

Mammals and birds regularly express mate preferences and make mate choices. Data on mate choice among mammals suggest that this behavioural 'attraction system' is associated with dopaminergic reward pathways in the brain. It has been proposed that intense romantic love, a human cross-cultural universal, is a developed form of this attraction system. To begin to determine the neural mechanisms associated with romantic attraction in humans, we used functional magnetic resonance imaging (fMRI) to study 17 people who were intensely 'in love'. Activation specific to the beloved occurred in the brainstem right ventral tegmental area and right postero-dorsal body of the caudate nucleus. These and other results suggest that dopaminergic reward and motivation pathways contribute to aspects of romantic love. We also used fMRI to study 15 men and women who had just been rejected in love. Preliminary analysis showed activity specific to the beloved in related regions of the reward system associated with monetary gambling for uncertain large gains and losses, and in regions of the lateral orbitofrontal cortex associated with theory of mind, obsessive/compulsive behaviours and controlling anger. These data contribute to our view that romantic love is one of the three primary brain systems that evolved in avian and mammalian species to direct reproduction. The sex drive evolved to motivate individuals to seek a range of mating partners; attraction evolved to motivate individuals to prefer and pursue specific partners; and attachment evolved to motivate individuals to remain together long enough to complete species-specific parenting duties. These three behavioural repertoires appear to be based on brain systems that are largely distinct yet interrelated, and they interact in specific ways to orchestrate reproduction, using both hormones and monoamines. Romantic attraction in humans and its antecedent in other mammalian species play a primary role: this neural mechanism motivates individuals to focus their courtship energy on specific others, thereby conserving valuable time and metabolic energy, and facilitating mate choice.     

Incidence and duration of romantic attraction in students progressing from secondary to tertiary education

There is increasing interest in the nature and biological significance of romantic love but few quantitative data are available for testing specific hypotheses. This paper describes the use of a survey instrument to assess incidence and duration of romantic attractions over a 2-year period amongst students (121 male; 162 female) progressing from school to university education. The results for males and females were similar and schooling single-sex or co-educational--had little effect. Students averaged 1.45 romantic episodes per year and 93% of students reported at least one episode over the survey period. Duration of attraction was around 9 weeks if never reciprocated and around 12 weeks if reciprocated. There was seasonal variation of onset of episodes with peak incidence over the summer or early autumn seasons. Collectively the results accord with the view that frequent, short-duration romantic episodes could have a role in selection of appropriate long-term reproductive partnerships.     

Between nurture and nature: the shifting determinants of female fertility in Danish twin cohorts

Behaviors related to fertility constitute primary candidates for investigating the relevance of evolutionary influences and biological dispositions on contemporary human behaviors. Using female Danish twin cohorts born 1870-1968, we document important transformations in the relative contributions of "nurture" and "nature" to within-cohort variations in early and complete fertility, and we point toward a systematic relation between the socioeconomic context of cohorts and the relevance of genetic and shared environmental factors. This transformation is most striking for early fertility where genetic factors strengthen over time and are consistent with up to 50 percent of the variation in early fertility in most recent cohorts. Understanding this emerging relevance of genetic factors is of central importance because early fertility constitutes an important determinant of complete fertility levels in low-fertility societies, and because teenage motherhood and early childbearing are often associated with negative life-cycle consequences. Moreover, our results emphasize the need for socially and contextually informed analyses of nature and nurture that allow both factors to influence human reproductive behavior over time.     

Men in committed, romantic relationships have lower testosterone

Variation in human male testosterone levels may reflect, and effect, differential behavioral allocation to mating and parenting effort. This proposition leads to the hypothesis that, among North American men, those involved in committed, romantic relationships will have lower testosterone levels than men not involved in such relationships. Our study is the first to examine whether being in such a relationship (rather than being married) is the meaningful predictor of male testosterone levels. To test this hypothesis, 122 male Harvard Business School students filled out a questionnaire and collected one saliva sample (from which testosterone level was measured). Results revealed that men in committed, romantic relationships had 21% lower testosterone levels than men not involved in such relationships. Furthermore, the testosterone levels of married men and unmarried men who were involved in committed, romantic relationships did not differ, suggesting that, at least for this sample, male pair bonding status is the more significant predictor of testosterone levels than is marital status.     

Reverse Correlating Love: Highly Passionate Women Idealize Their Partner’s Facial Appearance

A defining feature of passionate love is idealization—evaluating romantic partners in an overly favorable light. Although passionate love can be expected to color how favorably individuals represent their partner in their mind, little is known about how passionate love is linked with visual representations of the partner. Using reverse correlation techniques for the first time to study partner representations, the present study investigated whether women who are passionately in love represent their partner’s facial appearance more favorably than individuals who are less passionately in love. In a within-participants design, heterosexual women completed two forced-choice classification tasks, one for their romantic partner and one for a male acquaintance, and a measure of passionate love. In each classification task, participants saw two faces superimposed with noise and selected the face that most resembled their partner (or an acquaintance). Classification images for each of high passion and low passion groups were calculated by averaging across noise patterns selected as resembling the partner or the acquaintance and superimposing the averaged noise on an average male face. A separate group of women evaluated the classification images on attractiveness, trustworthiness, and competence. Results showed that women who feel high (vs. low) passionate love toward their partner tend to represent his face as more attractive and trustworthy, even when controlling for familiarity effects using the acquaintance representation. Using an innovative method to study partner representations, these findings extend our understanding of cognitive processes in romantic relationships.     

Loving recognition: a proposal for the practical efficacy of love as a public virtue

The anthropology of love has tended to focus on the romantic, and to explore its universality. In this article I ask a different kind of question of love. How might love be recruited as a moral force and deployed as a public virtue? I conceive of love not solely or principally as a private and domestic virtue but as a public and civil practice: a structuring of social interaction by means of affective appreciation of individual others. I understand love as the human capacity and the human practice of respecting the individuality of other lives. The desirous appreciation and affirmation of another ‘I’ – the loving attention – serves to surmount the customary ‘category‐thinking’ by which the world is normally apprehended: the generalizing, homogenizing, and stereotyping that characterize a culture's symbolic identification of the world. Loving recognition is such that the individuality of another life, its precious integrity and uniqueness, may be socially accommodated.     

Attentional Biases toward Attractive Alternatives and Rivals: Mechanisms Involved in Relationship Maintenance among Chinese Women

A long-term romantic relationship can offer many benefits to committed individuals. Thus, humans possess relationship maintenance mechanisms to protect against threats from those who serve as attractive alternatives or intrasexual rivals. Many studies have indicated that romantic love can act as a commitment device to activate these mechanisms. To examine the attentional bias associated with relationship maintenance among 108 college students (49 single and 59 committed females) in China, we used a semantic priming procedure to activate mental representations associated with romantic love and then asked participants to complete a dot-probe task for the purpose of making a distinction between the engage and disengage components of attention. No significant engaging effects toward attractive faces were observed among committed females, but the following significant disengaging effects were found: when primed with romantic love, single females showed increased attention toward and difficulty in disengaging from attractive male faces, whereas females already in a committed relationship did not alter their attention, remaining as inattentive to attractive alternatives as they were in the baseline condition. In addition, committed females responded to love priming by exhibiting difficulty in disengaging from attractive rivals. The present findings provide evidence in the Chinese cultural context for the existence of early-stage attentional processes in the domain of relationship maintenance that committed Chinese females protected an ongoing relationship by not only being inattentive to attractive males who could serve as attractive alternatives, but also being more attentive to attractive females who could be potential rivals when mental representations associated with romantic love were primed.     

Oxytocin and vulnerable romantic relationships

Oxytocin (OT) has been implicated in the formation and maintenance of various social relationships, including human romantic relationships. Competing models predict, alternatively, positive or negative associations between naturally-occurring OT levels and romantic relationship quality. Empirical tests of these models have been equivocal. We propose a novel hypothesis (‘Identify and Invest’) that frames OT as an allocator of psychological investment toward valued, vulnerable relationships, and test this proposal in two studies. In one sample of 75 couples, and a second sample of 148 romantically involved individuals, we assess facets of relationships predicting changes in OT across a thought-writing task regarding one's partner. In both studies, participants' OT change across the task corresponded positively with multiple dimensions of high relationship involvement. However, increases in participants' OT also corresponded to their partners reporting lower relationship involvement. OT increases, then, reflected discrepancies between assessments of self and partner relationship involvement. These findings are robust in a combined analysis of both studies, and do not significantly differ between samples. Collectively, our findings support the ‘Identify and Invest’ hypothesis in romantic couples, and we argue for its relevance across other types of social bonds.     

Developmental Changes in Expression of a 60-kDa Somatostatin Receptor Immunoreactivity in the Rat Brain

Abstract: The neuropeptide somatostatin (SRIF) exerts several important physiological actions in the adult CNS through interactions with membrane-bound receptors. SRIF expression is developmentally regulated and this regulation is most apparent in the cerebellum, where SRIF immunoreactivity is expressed at early postnatal ages and then disappears toward adulthood. The transitory nature of SRIF expression at a time of major changes in cerebellum suggests that this peptide may have a role in cerebellar development. To further investigate the role of the SRIF transmitter system during development, we have examined the levels of expression of SRIF receptors in the developing rat brain by immunoblotting using antiserum selective for a 60-kDa brain SRIF receptor. In whole rat brain, SRIF receptor immunoreactivity first appears at embryonic day 13 (E13), is elevated at E16. increases at birth, peaks at early postnatal ages, and then gradually declines with age. No apparent changes in size of the receptor occur with age. No consistent changes in levels of SRIF receptor immunoreactivity are detected from early postnatal ages to adulthood in the hippocampus, cerebral cortex, and striatum, but levels gradually decline in the hypothalamus. In contrast, SRIF receptor immunoreactivity is expressed transiently in cerebellum. SRIF receptor immunoreactivity is detectable in cerebellum at E16, increases in levels at birth, is apparent from postnatal day 3 to postnatal day 8, and then disappears. The transitory nature of SRIF receptor expression in cerebellum is unique and parallels the expression of SRIF immunoreactivity in this brain region. These findings support the hypothesis that SRIF has a role in cerebellar development.     

TNF-alpha stimulates the ACAT1 expression in differentiating monocytes to promote the CE-laden cell formation

High levels of the inflammatory cytokine tumor necrosis factor-α (TNF-α) are present in atherosclerotic lesions. TNF-α regulates expression of multiple genes involved in various stages of atherosclerosis, and it exhibits proatherosclerotic and antiatherosclerotic properties. ACAT catalyzes the formation of cholesteryl esters (CE) in monocytes/macrophages, and it promotes the foam cell formation at the early stage of atherosclerosis. We hypothesize that TNF-α may be involved in regulating the ACAT gene expression in monocytes/macrophages. In this article, we show that in cultured, differentiating human monocytes, TNF-α enhances the expression of the ACAT1 but not ACAT2 gene, increases the cholesteryl ester accumulation, and promotes the lipid-laden cell formation. Several other proinflammatory cytokines tested do not affect the ACAT1 gene expression. The stimulation effect is consistent with a receptor-dependent process, and is blocked by using nuclear factor-kappa B (NF-kappa B) inhibitors. A functional and unique NF-kappa B element located within the human ACAT1 gene proximal promoter is required to mediate the action of TNF-α. Our data demonstrate that TNF-α, through the NF-kappa B pathway, specifically enhances the expression of human ACAT1 gene to promote the CE-laden cell formation from the differentiating monocytes, and our data support the hypothesis that TNF-α is proatherosclerotic during early phase of lesion development.     

Amino acid and manganese supplementation modulates the glycosylation state of erythropoietin in a CHO culture system

The manufacture of secreted proteins is complicated by the need for both high levels of expression and appropriate processing of the nascent polypeptide. For glycoproteins, such as erythropoietin (EPO), posttranslational processing involves the addition of oligosaccharide chains. We initially noted that a subset of the amino acids present in the cell culture media had become depleted by cellular metabolism during the last harvest cycle in our batch fed system and hypothesized that by supplementing these nutrients we would improve EPO yields. By increasing the concentration of these amino acids we increased recombinant human erythropoietin (rHuEPO) biosynthesis in the last harvest cycle as expected but, surprisingly, we also observed a large increase in the amount of rHuEPO with a relatively low sialic acid content. To understand the nature of this process we isolated and characterized the lower sialylated rHuEPO pool. Decreased sialylation correlated with an increase in N-linked carbohydrates missing terminal galactose moieties, suggesting that beta-1,4-galactosyltransferase may be rate limiting in our system. To test this hypothesis we supplemented our cultures with varying concentrations of manganese (Mn(2+)), a cofactor for beta-1,4-galactosyltransferase. Consistent with our hypothesis we found that Mn(2+) addition improved galactosylation and greatly reduced the amount of rHuEPO in the lower sialylated fraction. Additionally, we found that Mn(2+) addition increased carbohydrate site occupancy and narrowed carbohydrate branching to bi-antennary structures in these lower sialylated pools. Surprisingly Mn(2+) only had this effect late in the culture process. These data indicate that the addition of Mn(2+) has complex effects on stressed batch fed cultures.     

Linking brains and brawn: exercise and the evolution of human neurobiology

The hunting and gathering lifestyle adopted by human ancestors around 2 Ma required a large increase in aerobic activity. High levels of physical activity altered the shape of the human body, enabling access to new food resources (e.g. animal protein) in a changing environment. Recent experimental work provides strong evidence that both acute bouts of exercise and long-term exercise training increase the size of brain components and improve cognitive performance in humans and other taxa. However, to date, researchers have not explored the possibility that the increases in aerobic capacity and physical activity that occurred during human evolution directly influenced the human brain. Here, we hypothesize that proximate mechanisms linking physical activity and neurobiology in living species may help to explain changes in brain size and cognitive function during human evolution. We review evidence that selection acting on endurance increased baseline neurotrophin and growth factor signalling (compounds responsible for both brain growth and for metabolic regulation during exercise) in some mammals, which in turn led to increased overall brain growth and development. This hypothesis suggests that a significant portion of human neurobiology evolved due to selection acting on features unrelated to cognitive performance.     

A simple method to improve probe set estimates from oligonucleotide arrays

A popular commercially available oligonucleotide microarray technology employs sets of 25 base pair oligonucleotide probes for measurement of gene expression levels. A mathematical algorithm is required to compute an estimate of gene expression from the multiple probes. Previously proposed methods for summarizing gene expression data have either been substantially ad hoc or have relied on model assumptions that may be easily violated. Here we present a new algorithm for calculating gene expression from probe sets. Our approach is functionally related to leave-one-out cross-validation, a non-parametric statistical technique that is often applied in limited data situations. We illustrate this approach using data from our study seeking a molecular fingerprint of STAT3 regulated genes for early detection of human cancer.     

Adventures in Neural Plasticity, Aging, and Neurodegenerative Disorders Aboard the CWC Beagle

This article recounts some of the scientific endeavors of Carl W. Cotman (CWC) during his journeys through the cellular circuitry of the mammalian brain. I have selected for consideration his findings that have been an important impetus for my own research; in several cases our different experiments have provided complementary data to support an hypothesis. Three examples are (i) Carl's studies of the roles of glutamate in synaptic transmission and plasticity in the adult brain and my studies of how glutamate regulates neurite outgrowth and cell survival in brain development; (ii) his and our studies of the mechanisms whereby amyloid -peptide damages and kills neurons; and (iii) Carl's evidence that physical activity regulates neurotrophin levels in the brain and our evidence that dietary restriction has similar effects and is neuroprotective. In case you have not yet realized how I chose a title for this article it is because Carl has a (very distant) connection with Charles Darwin—Darwin sailed on a vessel called the Beagle and Carl has studied beagle dogs, establishing them as a model for understanding the neurobiology of human brain aging.     

Whatever happened to ecology?

The holistic ecology of the early days had much in common with the world-view of primal people and of the romantic poets. In the 1950s a revival of reductionist and mechanistic ideas took place. The living world, constantly changing in a total "chance direction", appeared by its very nature "totally indestructible". The view of ecological succession toward a "climax" (Odum) became unacceptable for its assumed metaphysical and teleological connotations. Ecological succession is indeed only one special instance of sequential development, that is a feature of all life processes at all levels of organisation. Even the principle of "balance" was rejected by reductionists, because it recalled divine-order. Finally, the principle that "the whole is more than the sum of its parts" was abandoned, thus denying the most basic feature of the living world: organisation. Mainstream scientific ecology no longer reflects the ecological movement of today and may serve to justify the destruction that the irresponsible activities of the multinationals are giving rise to.