Tag Archives: #aggression

When Your Partner Won’t Change (Psychology)

Have you said something like this about your partner? “He really wants to change; he just can’t seem to.”

Sometimes we begin relationships with people we hope will change. If we go into it with our eyes open, it’s on us if change doesn’t happen. We knew what we were getting into.


But sometimes a partner’s troubling behavior doesn’t show up right away. And when it does, it can threaten the future of the relationship.

The most obvious example is aggression.

If your partner starts being physically or verbally aggressive toward you, that needs to change if you’re going to stay together. Nobody deserves to be abused by someone they’re in a relationship with.

With deal-breaking behavior like aggression, it’s reasonable to ask your partner to change. If she knows the relationship is on the line, it will give her an opportunity to address something that clearly needs her attention.

But once you’ve asked for change, that’s when the rubber either meets the road or keeps on spinning in the air.

Can’t vs. Won’t

The reasons why people don’t change are complex. But it’s safe to say that both ability and willingness to change are influenced by our mental and emotional health.

If your partner seems to really want to change but keeps falling back into the same old habits, that seems more like a matter of “can’t” than “won’t.”

He would if he could, right? He’s even said things like, “If I could snap my fingers and be different, I would do it.”

You don’t doubt his sincerity. But it raises a question. If your partner shares your desire for change but can’t deliver, what then?

For some people, just knowing your partner genuinely wants to change is enough. You’ll put up with unwanted behavior for an unspecified period of time, as long as he’s trying.

But that puts both of you in an unhappy position. You’ve got a partner who’s not behaving well, and he’s got a partner he’s regularly disappointing.

And because there’s no deadline for change, this can go on for years. It’s a bumpy ride, with bad times and better times, and occasionally even wonderful times.

But ultimately, you’ll still wish your partner would change.

The fact is, if your partner’s poor behavior isn’t changing, it doesn’t matter whether it’s because she won’t or she can’t. You’re not obligated to stay with someone who’s trying (and failing) to do the right thing.

Motivation itself will not fix the problem. Only better behavior can fix poor behavior.

Require Change

Sometimes the only way to get change is to require it. Again, we’re talking about deal-breaking behaviors here, so don’t assume you’re being demanding if the change you’re requesting isn’t optional.

If your partner’s behavior is hurting you, then change should be required.

You don’t have to make demands. All you need to do is be clear that change is required if the relationship is to continue. And hold that boundary.

Keep these three things in mind:

Set a deadline. If you don’t, your partner could be “working on changing” for years to come. For some behaviors, a deadline is a reasonable compromise.

But if the behavior is extremely harmful, you don’t have to stick around until an arbitrary date. Make it a one-strike-and-you’re-out deal instead. This is totally reasonable when it comes to abuse.

Be specific. Make it clear that a particular behavior (describe it so it’s clear to your partner) is unacceptable.

Create consequences. Tell your partner what you’ll do if the above behavior happens again. Then follow through if necessary.

If your partner won’t change, and you don’t require her to, it’s not your partner’s fault if you’re continually mistreated. Take charge of your experience by setting and holding healthy boundaries.

You can be compassionate with a partner who’s trying, unsuccessfully, to change. But allowing him to continue to hurt you every time he fails is not helpful for either of you.

Sometimes the only thing to do when your partner can’t or won’t make reasonable changes is to walk away.

This article is originally written by Tina Gilbertson, who, is the author of Reconnecting with Your Estranged Adult Child and Constructive Wallowing: How to Beat Bad Feelings By Letting Yourself Have Them. She hosts the Reconnection Club Podcast for parents of estranged adult children and offers consultation by distance. This article is republished here from psychology today under common creative licenses

Why Do Girls Like Pink? (Neuroscience)

Recent research on gender development is reviewed.

In a recent article, published in the November 2020 issue of Neuroscience and Biobehavioral Reviews, Melissa Hines of the University of Cambridge reviews the latest findings on the development of gender, such as the role of testosterone and socialization and how the two interact (e.g., why girls tend to like the color pink). The present post is a selective summary of this review.

Girl in a pink dress ©Freedesignfile

Testosterone and gender development

Let us begin with hormones. Hormones can have a temporary effect on development—an effect that rises and falls depending on the hormone concentration. For instance, estrogen has feminizing effects (e.g., breast development) at puberty.

Hormones can also have organizational influences, causing changes that persist even when the hormone is no longer present.

Testosterone is one hormone with such organizational influences.

Consider the effects of testosterone early in life. The concentration of testosterone is much higher in males than females, particularly from week 8 to week 16 or 24 of pregnancy, and from the first to the third month of infancy.

These are probably the critical periods during which testosterone causes sex-related organizational influences, ultimately reducing female-typical and increasing male-typical behaviors.

Since testosterone influences attributes that show sex differences, it may be helpful to know which behaviors show the largest average sex differences. Those would be gender role behaviors (e.g., preferred toys, sex of playmates), sexual orientation, and gender identity (one’s sense of self as female or male or both). Other characteristics often showing large sex differences include cognitive spatial abilities, empathy, dominance, and physical aggression.

Most of the findings on the effects of testosterone come from animal research or the study of genetic variations in humans. One such genetic variant is congenital adrenal hyperplasia (CAH).

CAH is associated with high levels of testosterone exposure. Compared to unaffected females, females with CAH show more male-typical gender role behaviors and are more likely to be bisexual or homosexual. It has been estimated that about 2 percent ultimately identify as men, which is a much larger percentage than the overall population estimate.

Socialization and gender development

Early testosterone exposure is not the only factor influencing gender behavior. Both self-socialization and external socialization are important too.

External socialization refers to the effects of encouragement of particular kinds of activities by other people (e.g., parents, friends, classmates, teachers).

For example, parents often buy their children toys perceived as gender-appropriate. A recent study of the room contents of 2- to 6-year-old American children found “boys’ rooms contained more play guns, tools, and machines for pretend play; spatial-temporal objects; sports equipment; and vehicles,” while “girls’ rooms contained more dolls, costume jewelry and dress-up clothes, ruffles, and floral furnishings.”

Once they know their sex, children also self-socialize, meaning they imitate the choices of people of their own sex in order to behave in ways expected of them. For instance, they prefer activities and objects favored by those of their sex and show a liking of objects they are told are for their sex (e.g., “dolls are for girls, not boys”).

Interactions of testosterone and socialization: Pink vs. blue

Gender development is also shaped by the interaction between socialization and testosterone. A good illustration concerns color preference (i.e., pink for girls and blue for boys).

Color preference appears to be mostly absent in children younger than 2, even though they seem to show a preference for gender-typical objects (e.g., toys vs. dolls).

The gender difference in color preference seems to emerge between ages 2 and 3. During the next couple of years, this difference becomes larger as children become more deeply aware of themselves as boys or girls, “learning that this will not change over time or if they engage in other-gender activities.”

By adulthood, the pink/blue color preference shows less of a sex difference. Though women, compared to men, still show a marginally greater preference for pink, both male and female adults prefer blue to pink.

This suggests a female preference for pink is not hardwired or sculpted by evolution. So how does this interest for pink develop?

One theory suggests color preference results from the association between colors and emotionally pleasant experiences. And this is partly due to socialization.

Specifically, as Hines notes, “children may learn to like the colors of the toys that are typed for their own sex, pink for girls, and anything but pink for boys, contributing to the stronger preference for pink in girls than in boys.”

In addition, “Girls also may identify strongly with their assigned sex during early childhood, and so may show particularly strong preferences for pink compared to older ages.”

The female preference for pink declines over time as girls have more opportunities to engage with objects not color-coded for their use and as they develop a deeper understanding of their gender.

Concluding thoughts on gender development

Some people believe gender-related behaviors are mainly caused by biological factors (nature), while others believe they are mainly caused by social and environmental factors (nurture).

However, if we were to think of gender-related behaviors in developmental terms, we could see how gender development is affected by numerous influences that interact. An early change in one part of the system, especially during critical periods in development, might significantly reduce or increase the effect of another factor later on.

These changes might concern seemingly trivial differences, like color preference (pink vs. blue), or more significant ones, like empathy, spatial ability, and aggression.

This article is originally written by Arash Emamzadeh and is republished here from psychology today under common creative licenses. To read original click here.

Autism Study Suggests Connection Between Repetitive Behaviors, Gut Problems (Psychology)

In children with autism, repetitive behaviors and gastrointestinal problems may be connected, new research has found.

The study found that increased severity of other autism symptoms was also associated with more severe constipation, stomach pain and other gut difficulties.

The research, which appears in the journal Autism, found no association between social and communication difficulties and gastrointestinal symptoms.

The study doesn’t explain the biological mechanism for the relationship between repetitive behaviors, such as rocking back and forth and hand flapping, and gut problems. But it helps establish that gastrointestinal symptoms may exacerbate repetitive behaviors, or vice versa, a finding that could one day help lead to helpful interventions, said Payal Chakraborty, a graduate student in The Ohio State University College of Public Health who led the study.

Children with autism spectrum disorder are more likely than their typically developing peers to experience a range of gastrointestinal abnormalities, including chronic diarrhea, constipation, food sensitivities and abdominal pain. These symptoms have been associated with higher levels of irritability and aggressive behavior, but less is known about their relationship with other autism spectrum disorder symptoms.

“In the general population, there’s a fair amount of evidence about the connection between mood and mental disorders and gastrointestinal difficulties. In autism, we wonder if the gut problems children experience are a core part of the disease itself or whether they’re brought on by other symptoms that children with autism experience,” Chakraborty said.

Chakraborty began the study as a student at Duke University, where she worked at the Center for Autism and Brain Development and became interested in the potential connection between the gut and other characteristics of the developmental disability.

Using data from a study designed to test the viability of cord blood transplants as an autism treatment, Chakraborty looked at detailed clinical measures and reports provided by the families of 176 children who were two to seven years old to see if she could find any insights into the drivers of gastrointestinal problems. Almost all of the children, 93%, had at least one gastrointestinal symptom.

“GI problems are a significant issue for many people with autism and there’s evidence that these symptoms might exacerbate certain autism behaviors, which can lead to greater developmental challenges,” she said.

The specifics of the relationship are unclear, but it’s possible that repetitive behaviors in children with autism could be a coping mechanism that helps them manage their gastrointestinal discomfort, Chakraborty said, adding that the symptoms of autism often emerge at a time when children aren’t in a position to adequately communicate their physical suffering with words.

“Gastrointestinal problems are a major concern for many children with autism and we still have a lot to learn about the complicated gut/brain axis,” she said.

References: Payal Chakraborty et al. Gastrointestinal problems are associated with increased repetitive behaviors but not social communication difficulties in young children with autism spectrum disorders, Autism (2020). https://journals.sagepub.com/doi/10.1177/1362361320959503 DOI: 10.1177/1362361320959503

Provided by Ohio State University

Where Does Morality Come From? (Psychiatry)

The natural origins of the human moral sense.

In the popular imagination, there is still quite a widespread assumption that religion is the source of morality. This is typically based on a belief that religion transmits the moral edicts of a divine creator of the universe. Despite the fully natural origins of morality having been very well established by scholars and widely accepted in the academic world, many people are surprisingly uninformed about this subject and are at a loss to even begin to explain the origins of morality in non-supernatural terms. This blog post will briefly sketch the outline of this vast topic in an attempt merely to orient readers to the scientific study of the human moral sense.1

Source: Paul Fleet /Adobestock

Understanding the origins of morality, like all behavioral traits, requires an evolutionary perspective, taking into account both biological and cultural evolution.

I find it helpful to simplify this subject by considering first the individual characteristics and then the group dynamics that shape human morality. The individual characteristics include instinctual and emotional traits such as empathy and guilt, as well as higher cognitive capacities such as the ability to inhibit impulses and the capacity to reason. The group dynamics revolve around cooperation and competition, and the ways in which societal and cultural norms and rules evolve. All these individual and group factors are, of course, intertwined.

Instinctual and Emotional Traits

  • Empathy
  • Guilt and conscience
  • Shame (and concern for reputation)
  • Disgust
  • Outrage and inequity aversion

All of these emotions and their behavioral correlates can be demonstrated in simpler form in other animals, particularly in other primates.

There is a large body of research demonstrating and delineating the complex moral instincts of young children, including babies far too young for these to have been socialized into them. Babies exhibit empathy, fairness, justice, and the ability to judge “goodness” and “badness” of human behavior.

Some of these emotions, such as disgust and outrage, can fuel either compassion or cruelty. Even empathy has the potential to fuel aggression, as when someone’s empathic identification with an in-group victim leads them to exact revenge on a perceived out-group perpetrator.2


Considering, as one example, the instinctual basis of empathy, primatologist Frans de Waal and others have provided compelling evidence of empathic behavior in our closest relatives, chimpanzees and bonobos, as well as in other animals.4 Certainly, chimps are also highly aggressive (much more so than bonobos, to whom we are equally related), mainly between groups and when hunting—for example, chimps catch and eat monkeys. But chimps also provide food for older or weaker members, without expectation of reciprocity. Chimps and other apes comfort fellow apes who are distressed.

What appears to motivate this kind of altruistic behavior is intense empathic distress—a literal case of “I feel your pain.” Neuroscientific experiments indicate that in humans, the same emotional brain circuits are activated when we ourselves feel pain and when we observe others feeling pain.5 Empathy is a very physical reaction and is closely related to unconscious mirroring behavior or imitation. It is frequently automatic and involuntary, such as when we wince or flinch when we see someone get injured. We smile automatically when smiled at—a hardwired developmental milestone at four to six weeks of age. Empathy also manifests as emotional synchrony, mood convergence, and contagion—such as occurs in crowds, audiences, large groups of spectators, and religious congregations.

Unbalanced, indiscriminate empathy would not have been adaptive for evolutionary survival. Natural selection in primates has produced both empathy and aggression, as well as cooperativeness and competitiveness.

Empathy is strongest when one identifies with the “other.”6

Cognitive Capacities

Individual characteristics giving rise to the human moral sense also include higher cognitive capacities, particularly:

Self-control is a crucial faculty among complex animals. It allows an animal to suppress acting on an urge, or to delay gratification in order to achieve a greater goal—doing a more difficult thing for a larger but delayed reward. For example, self-control allows a predator to stalk its prey rather than pounce immediately. Self-control as a brake on aggression is crucial for cooperation in social animals.7

Humans excel at self-control, which can take very elaborate forms. Often referred to as willpower, it varies in strength between individuals, mostly determined by inborn temperament. Its relative strength or weakness in a given individual is remarkably stable across their lifespan, but it can be strengthened by the environment and learning/conditioning.

The role of reason or rationality in shaping the human moral sense is self-evident, and had generally been thought in the past by philosophers and psychologists to be the main factor shaping human morality before the central role of instinct and emotion was fully appreciated and understood. There is debate now about whether emotion or reason holds the greater sway over the human moral sense. While emotion is often more powerful than reason, reason is far more versatile and adaptable than emotion, and is capable of overriding emotion when deliberately and carefully deployed by the individual (aided by self-control).

Group and Sociocultural Factors

Socialization and education clearly play a major role in shaping our innate moral instincts into the differing forms particular morals take within different societies and cultures. An analogy has been made to human language, which is the product of a universal instinct determined in part by certain inborn grammatical rules, shaped into different final forms by a child’s learning within their particular culture.

Enlightened self-interest and reciprocity

Social factors shaping morality center on cooperation. Cooperation is strongly influenced by self-interest and reciprocity. Game theory applies mathematical models to study rational decision-making in situations of competition and cooperation, and is central to understanding fields such as economics, sociology, politics, and international relations.

The relative success of cooperative, trusting strategies versus uncooperative, self-interested strategies has been extensively tested in computerized “tournaments.” It turns out that a “tit-for-tat” strategy of reciprocity wins most of the time: be nice and cooperate, but if the other player becomes uncooperative, be provocable to immediate retaliation. Then return to cooperation as soon as the other player does—be quick to forgive and to be “nice” again.

Reciprocity forms the basis of the “golden rule” that is a central tenet of most religions. It is a universally discoverable strategy for the fostering of cooperative societies.8

Expanding notions of “within-group”

In all primates, including humans, aggression is more commonly displayed between groups, with relatively more cooperativeness within groups. Humans have a greatly enhanced capacity for cooperation within groups due to language.9 With the advent of agriculture around ten thousand years ago, human groups grew larger as previously small hunter-gatherer groups transitioned to large settlements. Religion may have emerged around that time as a very effective means to bind expanding groups together. Groups further enlarged over time as cultural, economic, and technological advances led to increased specialization, trade, and interdependence.

In the last several centuries, the expansion of literacy was an important additional factor contributing to an expanding notion of “within-group” and the consequently expanding circle of empathy. People became much more able to put themselves in the shoes of those vastly different from themselves. The popularity of fiction in the form of the novel in the eighteenth century may have played no small part in this process.

Another very influential factor driving societal reductions of violence in the last several decades has been the increasing empowerment of women.

authority to the centralized authority of the state, as a contract between rational groups, so that the state can protect the individuals’ rights to life, liberty, and property. The power to punish transgressors is ceded by individual citizens to the state.

Democracy, prosperity, education, secularism

Certain societal conditions clearly favor cooperation and compassion over aggression, including socio-economic-political stability, prosperity, democracy, a well-educated citizenry, and universally accessible high-quality health and social services. Additionally, the most peaceful, tolerant, compassionate societies in the world today tend to be very secular. However, secularism on its own cannot yield peaceful and compassionate societies; the other conditions are crucial, especially democracy. Over the last few centuries and decades, most Western societies, and a great many Eastern societies, have evolved from predominantly autocratic, authoritarian regimes to more or less democratic societies.

There is remarkable commonality and consistency in the laws of all effective democratic societies, despite cultural differences. The development of increasingly rational systems of law is achieved through sophisticated, informed debate in highly educated democratic societies.

Open information flow (greatly accelerated by the internet) is another crucial ingredient, making it much harder for totalitarian states to control the minds of their citizenry through propaganda.10

In Summary

Morality can be understood as a natural characteristic emerging from traits that are based on instinct and emotion and shaped by reason, evolving in an intensely social context. Humans certainly also have natural tendencies toward violence, cruelty, and selfishness, but prosocial, cooperative traits have held the overall advantage over antisocial, violent tendencies, in both biological and cultural evolutionary adaptation. Cooperation and compassion have taken an especially strong lead over violence and cruelty in modern educated secular democratic societies, when contrasted with most of human history. Reason and rigorous critical thinking are our best tools in this ongoing process of societal improvement.

Societal progress in our modern era has been uneven and faltering; catastrophic derailments have occurred along the way and will always be a risk. But the long-term positive trend toward more compassionate, cooperative societies has been strong and unmistakable. Societal ethics and compassion are achieved solely through human action—we have only ourselves and our fellow human beings to rely on in this collective human project. 


1. Chapter 9 of my book Finding Purpose in a Godless World: Why We Care Even If The Universe Doesn’t (Amherst, NY: Prometheus Books, 2018) provides a more in-depth understanding and substantiation of the arguments that are merely summarized in this blog post. This post is adapted from that chapter. More substantial source materials are referenced in that chapter’s Notes section at the end of the book. The book is a deeper dive into questions of purpose, meaning and morality in a random, purposeless, godless universe.

2. More generally, human interpersonal violence is often carried out by people acting impulsively, insecurely, passionately, vengefully, or misguidedly. Only some is premeditated, calculated, or predatory.  Much human violence is driven by ideology or intergroup conflict. Some premeditated violence is merely opportunistic—for personal gain, sometimes even trivial gain. Occasionally violence may be motivated by sheer callousness or even sadistic pleasure. However, as the social psychologist Roy Baumeister has showed, this last category is a lot less common than the cultural ‘myth of pure evil’ has led most people to believe [Roy F. Baumeister, Evil: Inside Human Violence and Cruelty (New York: W. H. Freeman, 1997)]. Most acts of apparent ‘evil’ are better accounted for by the aforementioned factors and motives.

Sadistic, predatory, psychopathic personalities lacking empathy or conscience are a small proportion of the population, but those individuals cause disproportionate pain and suffering for the rest of the population.

3. Empathy is the state of experiencing emotions that match another person’s emotions, or knowing at an emotional level what the other person is thinking or feeling without the other person having explicitly communicated this. Empathy may be thought of as a more fundamental, automatic reaction than sympathy, which is a more conscious feeling of compassion and concern for another. Sympathy is an attitude that one adopts toward another; it is often (but not always) strengthened when a feeling of empathy is also present. Many empathy researchers consider empathy to have two components: affective (emotional) and cognitive. Cognitive empathy is sometimes equated with social cognition or ‘theory of mind.’ Here we are focusing more on affective empathy.

4. The evolution of empathy may have its origins partly in maternal-infant care. Females who were sensitive to their offspring and who reacted instantaneously to their distress, perhaps because this induced distress in themselves, would have out-reproduced those who were cold and distant, passing on this trait to their offspring. Mother-infant bonding is mediated by the hormone oxytocin, which has also been extensively studied in adult human and animal relationships, trust and empathy.

5. The motivation to relieve one’s own distress by relieving someone else’s pain has been shown to be even more powerful than obtaining a ‘selfish’ food reward at the expense of another. Experiments have revealed that animals—including apes and some other mammals—will actually starve themselves if their eating is directly linked to causing another’s pain. Watching another animal in pain is unpleasant and aversive to many higher animals.

6. Failure to identify with other people, seeing them as fundamentally different from oneself, will reduce or neutralize empathy. Racist nationalistic political regimes exploit this lack of identification with, and dehumanization of, other racial groups through xenophobic propaganda and indoctrination. An extreme example was the Nazi propaganda process of dehumanizing Jews by labeling them as subhuman vermin, pollution, a pathogen, or a malignant presence. Similar political strategies have been used prior to other orchestrated genocides, such as in Rwanda in 1994. As the Harvard psychologist Steven Pinker has noted, disgust by one group about another becomes a particularly potent force when combined with irrational beliefs such as utopian ideologies. Practically any means can come to be ‘rationally’ seen as a regrettable but justifiable action toward achieving an imagined utopian end. From this perspective, utopian ends are seen as infinitely good, and the extermination of a group of people who are believed to be preventing the achievement of a perfect, pure society appears to be justifiable [Steven Pinker, The Better Angels of Our Nature: Why Violence Has Declined (New York: Viking, 2011), pp. 320–43.]

The Nazi genocide of Jews and other ‘contaminating’ groups also illustrates how charismatic individuals with antisocial and narcissistic traits can hijack entire societies under certain conditions—especially societies that have suffered humiliating defeats and crushing loss of status and quality of life, such as Germany had after WWI and during the Depression. The co-opting of large numbers of people into actively perpetrating such atrocities—or simply looking the other way and compartmentalizing their moral sense—illustrates how societies can be seduced by irrational, even bizarre, uncritical belief systems and rigidly excessive forms of morality obsessed with utopian purity.

7. In complex social animals, self-control allows a group member to remain disciplined as the pack or troop hunts or defends itself in a coordinated, strategic effort. Discipline is reinforced by others in the group, often in accordance with a dominance hierarchy. Aggression between members within the group may occur, in competition for food, mates, and dominance, but ultimately, a strong level of group cooperation, cohesion, and discipline is required for the survival of the group. Therefore, self-control is a crucial brake on aggression, at least within the group—most aggression is directed at rival groups or other species.

8. Religion, rather than being the source of morality, has simply coevolved with human cultures over time, incorporating our natural moral sense (as well as our between-group enmity and our disgust-based obsessions with purity).

9. Language also powerfully magnifies the importance of reputation, as people’s behavior is not only directly witnessed but is spoken about far and wide (including through gossip). Language also amplifies the power of reciprocity, for the same reasons.

10. We have witnessed in our lifetimes the massive effects of the internet on myriad aspects of society—just like the impact of the invention of the printing press in the fifteenth century. Clearly, the internet has strengthened human cooperation and expanded people’s general knowledge. It has of course unfortunately also bred and emboldened hatred and vitriol (often under the cover of anonymity, with the usual restraining effects of reciprocity and reputation stripped away). It has locked many ordinary people’s minds into echo chambers of filtered information and confirmation bias, and it has fed limitless nonsense to the gullible. But the net effect of the internet has undoubtedly been a vast expansion of cooperation, useful information flow and knowledge.

This article is originally written by Ralph Lewis, who is an assistant professor in the Department of Psychiatry at the University of Toronto and is republished here from psychology today under common creative licenses.

What Do Guys Think of Other Guys’ Beards? (Psychology)

A new study suggests men have stronger opinions about beards than women do.

Somewhere in our evolutionary past, hair provided humans with warmth and protection against the elements. Today, it has become more of a fashion statement than a survival feature.

As we have evolved, so too have our views on the attractiveness of body hair — especially male facial hair. For instance, psychologists have found: article continues after advertisementnull

  • Women associate men’s facial hair with aggressiveness and dominance.
  • Facial hair is related to men’s success on the marriage market.
  • Men with facial hair are judged by women to have higher social status and better parental skills.

A new study published in the journal Evolutionary Psychology takes this research one step further.

A team of scientists led by Lukasz Jach of the University of Silesia in Poland conducted two studies to better understand the preferences for male facial hair among men and women. They found that women’s preferences for male facial hair were ambiguous; in some cases they liked it, in other cases they didn’t. Men, on the other hand, preferred facial hair for themselves but not for other males.

The finding that men prefer facial hair for themselves but not for others has a clear Darwinian explanation.

“These results are in accordance with a signaling role of beardedness in intrasexual competition,” say the researchers. “Men may prefer having facial hair to deter their enemies and display greater masculinity or a higher social position.”

This is consistent with other research that has found angry faces to be recognized more quickly when they are accompanied by a beard.

Moreover, the lack of consistent results among women underscores just how context-dependent ratings of attractiveness can be. In Poland, for instance, researchers found women to prefer clean-shaven faces over faces with stubble or full beards. Research in the United Kingdom has found British women to prefer light stubble over full beards and clean-shaven faces.

In this study, the researchers recruited 287 men and 285 women to take part in a short survey. The researchers asked women to indicate whether, in general, they liked men to have clean-shaven faces or faces with facial hair. They asked male participants the same question in relation to their own faces.

They found that 57% of women indicated a preference for facial hair while 43% preferred clean-shaven male faces. Among men, 77% preferred facial hair for themselves while 23% preferred a clean-shaven look.

The scientists conducted a second study in which male and female participants were asked to view five visual examples of male facial hair (clean-shaven, light stubble, heavy stubble, light beard, and full beard) and were asked to indicate which look they preferred.

Preferences differed by gender. The authors write, “The majority of women preferred clean-shaven male faces (43.84%), followed by heavy stubble (26.03%) and light stubble (16.44%). Faces with light beard (10.96%) and full beard (2.74%) were the least preferred.”

For men, approximately 60% preferred some type of facial hair for themselves while 40% preferred a clean-shaven look. When judging other men, the results narrowed: approximately 50% of men preferred other males to have a clean-shaven look while 50% preferred some type of facial hair.

Perhaps the most convincing finding in this research is that women care a lot less about men’s facial hair than men might think they do. “The hypothesis that men’s preference to have facial hair is greater than the female preferences associated with male facial hair was supported,” write the authors.

References: Jach, Ł., & Moroń, M. (2020). I Can Wear a Beard, but you Should Shave… Preferences for Men’s Facial Hair From the Perspective of Both Sexes. Evolutionary Psychology, 18(4), 1474704920961728.

This article is originally written by Mark Travers, who is a psychologist and writes about human potential and the science of reaching it and is republished here from psychology today.

Very Hungry And Angry, Caterpillars Head-butt To Get What they Want (Biology)

Inspired by his own butterfly garden at home, a Florida Atlantic University neuroscientist got a unique look at how monarch butterfly (Danaus plexippus) caterpillars behave when food is scarce. The results look something like a combination of boxing and “bumper” cars.

When food is scarce, monarch butterfly caterpillars go from docile to domineering. ©Florida Atlantic University

With less access to their favorite food – milkweed – they go from docile to domineering, aggressively head-butting, lunging and knocking aside other caterpillars to ensure their own survival. And, they are most aggressive right before the final stages of their metamorphosis. A lack of nutrition during larval stages has been shown to delay larval development as well as reduce adult body size, reproductive performance and lifespan.

“Aggression is common in insects, including fruit flies, where single-pheromone receptors or single genes have been shown to trigger their aggression,” said Alex Keene, Ph.D., lead author and a professor of biological sciences, FAU’s Charles E. Schmidt College of Science. “I decided to investigate monarch caterpillars because I was intrigued by their combative behavior, which I observed first-hand in my own garden. They are large and easily recognizable compared to many other insects. These are charismatic animals that everyone loves, and there’s a growing appreciation for their potential to tell us about how the brain controls behavior.”

For the study, published in the journal iScience, researchers faced a number of challenges maintaining a population of monarchs while trying to model resource limitation. To encounter these challenges, Keene and his team built an open milkweed garden behind their Boca Raton-based lab and let nature do the work of collecting caterpillars. Back in the lab, the researchers placed caterpillars into groups with different amounts of milkweed. The results were clear – the less food, the more likely caterpillars were to try to head-butt each other out of the way to get their fill.

The process of getting to that result also was challenging. The researchers had difficulty breeding the monarchs in the lab, and found that almost every nursery sells their milkweed with pesticides. That’s why they ended up growing their own milkweed.

To examine whether caterpillars display aggressive behavior, Keene and collaborators quantified the presence of aggressive lunges under a number of conditions, as well as the effect of attacks on target conspecifics. Monarch caterpillars predominantly feed on milkweed and often strip entire plants bare of leaves over a two-week period. In many locations, milkweed is only available for part of the year, placing a significant constraint on monarch development. Monarchs also impact the milkweed plants they consume – at their largest and hungriest phase, a single caterpillar may devour an entire milkweed leaf in under five minutes.

©Joseph Collie et al.

“If you compare a monarch caterpillar to a fruit fly where there are lot of larvae on one piece of rotting fruit, you’ll find that they feed socially with little evidence of territoriality,” said Keene. “But each of these caterpillars will at some point in their developmental cycle encounter resource limitation because they can strip an entire milkweed of leaves.”

While observing the caterpillars, researchers noticed that the monarch’s tentacles, large mechanosensory appendages, were not utilized when they were being combative. This finding suggests that alternative sensory modalities, such as pheromonal, olfactory or tactile cues that are independent of the tentacles initiate aggression. The researchers believe that aggression induced by limited food availability in monarch caterpillars are likely present in many different species throughout the animal kingdom.

“While our research showed that the caterpillars respond aggressively to limited food, we still hope to learn more about what drives this response in their brains, which is important for learning more about how these responses work outside the lab,” said Keene. “One of the fundamental problems with work like this is that we’re testing animals in a very derived setting. And that’s not what brains evolved to do. So now that we have this invertebrate model in a relatively controlled setting, but doing an ecologically relevant behavior, that becomes important in terms of looking at the mechanism and function of this behavior in more complex organisms.”

The less food, the more likely caterpillars were to try to head-butt each other out of the way to get their fill, lunging and knocking aside other caterpillars to ensure their own survival. And, they are most aggressive right before the final stages of their metamorphosis. ©Florida Atlantic University

Beyond the study of aggression in caterpillars, monarchs present an emerging model for studying the molecular mechanisms underlying behavior and set the stage for future investigations into the neuroethology of aggression in this system.

References: Joseph Collie, Odelvys Granela, Elizabeth B. Brown, Alex C. Keene et al., “Aggression Is Induced by Resource Limitation in the Monarch Caterpillar”, IScience, 2020. https://www.cell.com/iscience/fulltext/S2589-0042(20)30988-3?utm_source=EA DOI:https://doi.org/10.1016/j.isci.2020.101791

Provided by Florida Atlantic University

How Aggression Leads to More Aggression? (Neuroscience)

Like a champion fighter gaining confidence after each win, a male mouse that prevails in several successive aggressive encounters against other male mice will become even more aggressive in future encounters, attacking faster and for longer and ignoring submission signals from his opponent.


This phenomenon is interesting to people who study the neuroscience of behavior, because aggression is an innate, hard-wired behavior in the brain. This means that a mouse does not need to learn aggressive behaviors before it engages in them; aggression is instinctive upon reaching adulthood. However, experiences (say, repeated successful aggressive encounters) are able to alter this innate behavior.

Now, a team of Caltech researchers has discovered that hard-wired neural circuits governing aggression in mice are strengthened following their victories in aggressive encounters, and has identified a learning mechanism operating in the hypothalamus—a brain region traditionally viewed as the source of instincts, rather than learning.

The research was conducted in the laboratory of David Anderson, Seymour Benzer Professor of Biology, Tianqiao and Chrissy Chen Institute for Neuroscience Leadership Chair, Howard Hughes Medical Institute Investigator, and director of the Tianqiao and Chrissy Chen Institute for Neuroscience at Caltech.

A paper describing the research appears in the journal Proceedings of the National Academy of Sciences on September 24.

There is a difference between innate behaviors and those that are learned. For example, mice can be taught that performing certain behaviors (for example, pulling a lever) can result in a positive outcome (such as receiving food). On the other hand, innate behaviors like aggression are instinctive to male mice; the mice do not need to learn how to lunge and attack when confronted with other mice they deem a threat—they just react.

Previous studies have shown that a male mouse, once it has won in several aggressive encounters with other males, will exhibit increased aggression in future encounters. In other words, an innate behavior is altered by experience. This effect is termed “aggression training.”

Led by postdoctoral scholar Stefanos Stagkourakis, the Caltech team examined a particular connection in the mouse brain where a group of synapses transfer signals from a little-studied region at the junction between the amygdala (a brain region notable for its role in fear-related behaviors) and the hippocampus (which plays a role in short-term memory) to a specific subdivision of the hypothalamus called the ventromedial hypothalamus (VMH), which controls aggressive behaviors in mice. (The hypothalamus also contains neurons in other subdivisions that mediate other social and homeostatic behaviors, such as mating, parental behavior, feeding, and thermoregulation, but these were not studied.)

The team found that after aggression training, these synapses show signs of long-term potentiation (LTP), which is similar to turning the volume knob up on the signal. Instead of just talking to the neurons in the hypothalamus, these synapses are shouting at them, causing them to react more strongly.

Using the Caltech Brain Imaging Center, the team studied the dendrites of neurons, protrusions extending from neurons that receive signals from other neurons, and in particular the dendrites’ spines, structures that act like miniature radio antennae on the hypothalamic neurons to detect input from other brain regions. They examined the number, size, and shape of these structures before and after aggression training. They found that aggression training caused the growth of many additional dendritic spines on hypothalamic neurons. Such structural changes are expected to make these neurons more sensitive to incoming signals, and therefore more easily activated.

The team also experimentally prevented LTP from forming on these synapses during aggression training, and found that aggression-training no longer led to an increase in aggressive behaviors in these mice.

Although all of the male mice tested were genetically identical, about 25 percent never showed aggression and also were “immune” to the behavioral changes caused by aggression training. The authors further found that such behavioral heterogeneity among genetically identical mice is due to naturally occurring variations in serum testosterone levels: the non-aggressive mice had, on average, lower levels of testosterone than their aggressive siblings. Administration of supplemental testosterone to the non-aggressive mice caused both the appearance of aggressive behavior and LTP at the amygdala-hypothalamic synapses.

This work identifies changes in a very specific brain region after aggression training, but the adaptations that mediate the behavioral effect of aggression training likely occur at multiple sites in the brain. In future work, the team will examine how neural activity in different brain areas changes following social experience and will attempt to identify brain nodes of high significance in the neural circuit of aggression. The team also hopes to investigate how testosterone levels can vary among otherwise genetically identical mice, since the hormone is synthesized by genetically encoded enzymes.

References: Stagkourakis, Stefanos and Spigolon, Giada and Liu, Grace and Anderson, David J. (2020) Experience-dependent plasticity in an innate social behavior is mediated by hypothalamic LTP. Proceedings of the National Academy of Sciences of the United States of America . ISSN 0027-8424. (In Press) link: https://www.pnas.org/content/early/2020/09/23/2011782117 doi: DOI: 10.1073/pnas.2011782117

Provided by California Institute Of Technology