– by Oliver Sng & Krystina Boyd-Frenkel

If you think about the last stranger you met, you will likely remember their race. But why do we care and think about others’ race? Laypersons sometimes suggest that humans have evolved to be racist. Evolutionary scholars know that the truth is far more complex. Instead, the somewhat surprising answer (at least to laypersons) is that, without modern transportation, our ancestors rarely encountered individuals who looked phenotypically different enough to qualify as a different ‘race’. As a result, natural selection couldn’t have shaped a psychology for interacting specifically with different races.

Why, then, do people care about others’ race today? One prominent answer has been that race is a cue to coalition—the groups that we work with, compete against, and generally solve life’s problems with. Our families, work colleagues, and political groups are all examples of coalitions. Considerable research has accumulated supporting the race-as-coalition perspective, including replications and re-analyses. Our recent work offers a second, complementary answer to this question: that race is a cue to ecology.

The “race-as-ecology” perspective proposes that people pay attention to and think about others’ race because people assume different races live in different (social) ecologies. In the U.S., people assume that Black individuals, relative to White individuals, live in harsher ecologies. Living in harsh ecologies – where early death from unavoidable causes like disease or violence is common – has been linked to traits including an earlier age of first reproduction, a more present-focused time perspective, and less investment in skill accumulation (e.g., education) (see two recent reviews here and here). If living in harsher ecologies influences people’s behaviors, then knowing about another person’s ecology may help us understand and predict their behavior.

We are aware of the ongoing debates in the life history literature, with important issues such as exactly why and how people respond to harsh ecologies, or whether life history “strategies” exist in our species. However, these do not necessarily affect our current work, as we focus on people’s perceptions of others, based on what people think others’ ecologies are. From our perspective, as long as (1) individuals living in harsher ecologies adopt different behaviors, and (2) certain racial groups are presumed to be living in ecologies of varying harshness, then it follows that (3) people will categorize others by their racial group because they assume different racial groups to be living in ecologies of different harshness. If so, one critical implication is that when individuals of different racial groups are presented as equally living in harsh ecologies (or not), people should care about their race less. In the presence of direct information about another’s ecology, their race isn’t useful information anymore. This is the essence of the race-as-ecology perspective.

In a set of three studies, we test these implications. Using a widely used method in the literature, sometimes referred to as the “who-said-what” method, American participants viewed photos of Black and White individuals paired with sentences presumably spoken by each person. Each Black or White person was randomly presented multiple times. After that, participants were given a surprise memory test, in which they were shown the sentences again, but now tried to remember who said each sentence. In our research, what matters are the mistakes participants make. If a participant misremembered what a Black person said as being said by a different Black person, they essentially confused the two Black individuals (a within-race confusion). However, if the participant misremembered what a Black person said as being said by a White person, they have instead confused two individuals of different races (a between-race confusion). More within-race (vs. between-race) confusions indicate that a person categorizes others by race, mentally grouping Black individuals together and White individuals together.

In our studies, half of our participants saw Black and White individuals presented with just their faces. The critical manipulation is that the other half of our participants saw the same Black and White individuals, but now presented in the ecologies/neighborhoods that they supposedly live in. Importantly, both Black and White individuals were presented evenly in both relatively harsh (or the opposite, referred to as “hopeful”) ecologies (see example photos below).

Sample race-with-ecology photos used in studies

What do we observe? First, participants categorized these individuals by their ecologies. In other words, they were more likely to confuse individuals living in harsh (or hopeful) ecologies with other individuals also living in harsh (or hopeful) ecologies. Second, participants categorized these individuals by their race, but they did so less when the Black and White individuals were shown in both harsh and hopeful ecologies. Hence, ecology information leads to the reduction of racial categorization.

Could just telling people to not pay attention to others’ race have the same effect? Past research has tried this and failed. In fact, getting people to stop thinking about race isn’t easy. The current “race-as-ecology” perspective provides insights into one way in which this can be achieved, complementing work from the “race-as-coalition” perspective.

There are puzzles that remain, and new puzzles that emerge. For example, even when race is paired with ecology, we do not see racial categorization completely disappearing (as is sometimes observed in work from the race-as-coalition perspective). So, people are still categorizing others by their race in the presence of ecology information. This suggests that other processes (like race-as-coalition) are still at play.

So, can race be “replaced”? Our answer is a partial yes. When people see others of different races, but living in different ecologies, they group others by their ecologies. In the minds of perceivers then, race is replaced by ecology. In other recent work, we also find that people hold ecology stereotypes—general beliefs about what individuals who live in harsh ecologies are like—and that these stereotypes exist across multiple societies. To the extent that people around the world think about others in terms of their ecology, there may be a range of other social categories, beyond race, that also have the potential to be “replaced” by ecology.

Read the original article: Sng, O., Boyd-Frenkel, K. A., & Williams, K. E. G. (2024). Can race be replaced? Ecology and race categorization. Evolution and Human Behavior, 45(6), 106630.

– by Marta Kowal

We might not spend much time thinking about how much we pursue beauty, yet we undoubtedly spend a lot of time actually doing it. In one of our large-scale, cross-cultural quantitative studies, 99% of our sample (93,158 participants from 93 countries) reported spending more than 10 minutes a day enhancing their physical attractiveness. These results were remarkable! Yet, after conducting that large-scale study, we couldn’t help but wonder: did we miss something? Or more precisely, what did we miss?

To explore this question, we adopted an emic approach, which emphasizes understanding cultures from an insider’s perspective. We conducted semi-structured, in-depth interviews with people from four distinct societies: the Cook Islands, Guatemala, Pakistan, and Poland. We asked three core questions: What do people do to enhance their physical attractiveness? How intensely do they engage in these behaviors? And why do they do it? This approach allowed us to go beyond predefined survey questions and uncover a richer, more nuanced understanding of beauty-enhancing behaviors around the world.

Our new study brought several fascinating findings.

First, enhancing physical attractiveness emerged as a universal behavior. Whether in Poland, Guatemala, Pakistan, or the Cook Islands, people actively engaged in practices to improve their appearance.

Second, we found a consistent gendered pattern: women spent more time than men improving their appearance, though the exact amount of time varied by culture. For instance, Cook Islander women reported typically spending 15–20 minutes a day on their appearance, while Polish and Guatemalan women reported dedicating around 30 minutes. Pakistani women topped the list, averaging 45 minutes daily. In contrast, men reported spending significantly less time—between 5–10 minutes in the Cook Islands and 15–30 minutes in Pakistan. This disparity reflects societal expectations and evolutionary pressures, as women’s physical appearance tends to play a larger role in mate selection and social evaluation across cultures.

Third, while many beauty-enhancing activities were universal—such as maintaining hygiene, hairstyling, wearing makeup, and choosing clothing—how people approached these behaviors varied widely across cultures. In Pakistan, gold jewelry and well-groomed beards were particularly emphasized, while in the Cook Islands, floral adornments held cultural significance. Poles prioritized body shape and balanced makeup, whereas Guatemalans focused on fashionable clothing.

Summarizing our findings, at its core, the drive to enhance physical appearance seems to serve two primary evolutionary purposes: competing for mates (inter-sexual competition) and outperforming rivals (intra-sexual competition). Whether it’s through a perfectly tailored outfit or shiny, well-kept hair, these efforts signal health, vitality, and desirability—traits that are universally valued.

On a more immediate level, participants identified different reasons for engaging in beauty-enhancing behaviors. Social media emerged as a powerful influence, with participants frequently citing it as both an inspiration and a source of pressure. However, motivations extended beyond digital trends.

Cultural and social norms often dictated how individuals presented themselves and the consequences of deviating from those norms. Religious beliefs also played a role, especially among Christian and Muslim participants, who mentioned spiritual motivations for enhancing their appearance. For example, a Guatemalan participant (Man11) reflected, “The way I look talks about my dad [God] in heaven.” Similarly, a Pakistani participant (Man6) explained, “We want to look good to God.” In the Cook Islands, a participant (Woman25) noted, “Because I am a bride. A bride for God, for Jesus.” These responses show how deeply cultural and religious values can influence the desire to look attractive.

One particularly striking finding came from the Cook Islands, where historical norms surrounding weight revealed a very different perspective on attractiveness. Traditionally, a man’s social status was linked to his wife’s size. A larger wife symbolized prosperity and the ability to provide. One participant (Man24) explained, “They [our fathers and grandfathers] praised themselves if their wives were big. My grandfather used to say things like, ‘I don’t want my wife to get blown away by the wind.’ … It’s hard to explain, but I’m more proud to have a big wife.” Another participant (Woman22) elaborated, “If your wife is skinny, you’re not feeding her. So, you know, it’s like a competition type of thing.”

These perspectives highlight how beauty standards are deeply rooted in cultural and historical contexts, challenging the notion of a single, universal standard of attractiveness.

While this research offers valuable insights, it’s important to acknowledge its limitations. The study relied on self-reported data, which can be influenced by memory biases and social desirability. Additionally, the four cultures studied—though diverse—don’t represent the full spectrum of human societies. Further research could explore other cultural contexts or use observational methods to provide a more nuanced understanding of beauty-enhancing behaviors.

So, why do people strive to enhance their physical attractiveness? From an evolutionary perspective, the ultimate goal is competitive advantage—whether in mate selection or social standing. However, the immediate reasons people cite often reflect cultural norms, personal preferences, and social influences. Ultimately, beauty is not just about appearances. It’s a complex interplay of biology, culture, and individual choice. The way we present ourselves to the world communicates who we are, what we value, and how we navigate our social and cultural environments.

The next time you pick out an outfit, apply makeup, or even choose a pair of shoes, you may want to take a moment to reflect. What message are you sending to the world? And how does your culture, your biology, and your personal preferences shape that message? In the end, the pursuit of beauty is as much about understanding ourselves as it is about appealing to others.

Read the original article here: Kowal, M., Sorokowski, P., Cardona, S. M., Castaňeda, A., & Faisal, C. M. N. (2024). Sex and cross-cultural comparison of self-enhancement practices: data from four distinct societies. Evolution & Human Behavior, 45(6), 106627.

– by Sarah Peacey

‘Witchcraft’ has a variety of associations, from pointed hats and broomsticks to the nature-focused, neopagan religion of Wicca. The oldest and most universal definition is the darkest: the idea that people – perhaps members of your community including relatives and neighbours – are secretly working harmful magic to hurt you. In communities where they exist, these beliefs can create fear and mistrust, and can lead to horrific harm coming to those suspected of witchcraft.

But how did belief in witches and the folklore and imagery surrounding them become so widespread? My co-authors and I examined the ancestry and transmission of the ‘witchcraft phenotype,’ or the collection of ideas and beliefs about witches, in linguistically and culturally-related societies in sub-Saharan Africa.

Our study population consisted of Bantoid and Bantu-speaking societies. Bantoid languages are spoken in parts of Nigeria and Cameroon, and approximately 5,000 years ago, people from this region began migrating and settling in places throughout central, eastern and southern sub-Saharan Africa, and started speaking Bantu languages. This vast population movement was a key event that significantly changed Africa’s cultural and biological landscape. As they settled in varied locations, the cultures retained ancestral traits but also began to diversify.

We created our sample of 13 Bantu and Bantoid witchcraft traits by coding information from historical records dating from the 19^th-mid-20^th century. If there is a linguistic phylogeny (an evolutionary tree showing how languages are historically related to one another like biological species), then cultural traits can be mapped on to the tips. We could then trace their likely patterns of evolution backwards over several thousand years. How were these beliefs transmitted between societies? Were they present in the more ancestral groups or did they arrive more recently?

Belief in witchcraft is widespread in these groups and many have similar words for harmful magic, suggesting an ancient origin. In line with this, witchcraft beliefs were present in all 84 societies which we could acquire data on. The idea that witchcraft belief is globally ancient is echoed by recent archaeological research from Australia, that was able to match artefacts from a ‘witchcraft ritual’ dating back 11,000-12,000 years to a description from the 19^th century.

Every society with these beliefs has its own ‘witchcraft phenotype’. In our sample, some hold women are more likely to be sorcerers than men, although others believe witchcraft is a predominantly male undertaking. The elderly may be accused, or the young, as in the disturbing phenomenon of ‘child witches’. Some communities believe witches have familiars (magical helpers) – hyenas and aardvarks in Tanzania can be seen as having the same role as toads and cats in England. Societies often have tests or ordeals for whether an individual is guilty of causing harm through magic. Many societies in our sample had a poison ordeal, where the suspect was given a drink with a noxious substance in it. Guilt was determined by how they responded: the drink itself could kill them or they might suffer ill effects and then be executed. Only those who were not seriously affected were deemed innocent.

The traits we examined were almost all ‘successful’ in cultural evolutionary terms: the results suggest some lasted for hundreds of years in multiple societies, although others appeared to be more recent. It might seem likely beliefs would spread between neighbouring cultures, through trade or other contact, but geographic proximity alone largely couldn’t explain similarity in beliefs between societies. Instead some traits, such as the poison ordeal and belief in familiars, seemed to be passed down from generation to generation, following the divergence of Bantu societies along the tree.

Exceptionally, the evil eye belief may have been transferred between neighbouring societies. It is related to the concept of witchcraft: the idea that a single glance in someone’s direction can cause them mystical harm. We found no evidence that it was ancestral or that its distribution fitted the structure of our tree. An explanation may lie in the fact it was present in societies such as the Kikuyu in Kenya and others who live near groups of Nilotic-language speakers, among whom belief in the evil eye is more prevalent.

Some groups viewed witchcraft as a physical substance in the body, often described as having a greyish appearance and being found above the liver or the heart. This trait had a unique distribution. Our results suggest it has a deep ancestry and was present before the Bantu migration. But at a later point when Bantu populations split again, with one group heading east and another west, the trait disappeared. Why this happened can only be speculated on, but its sudden disappearance is striking.

Who is targeted in accusations probably depends on multiple factors including the structure of relationships within societies.  Where an accusation can free up resources, it may be more beneficial to accuse individuals from some groups than others. It is not that accusations are necessarily cynical, as fear of witchcraft is often deeply held, but they may be associated with various forms of competition. We found that accusations of children appear comparatively recent, which aligns with other research indicating that this has developed in parts of Africa since the late 20^th century. Perhaps surprisingly, accusations of men appear not to have been present ancestrally. Even some of the most well-known, stereotypical traits of witches – being elderly and female – appear neither ancestral nor inherited from society to society intergenerationally. Patterns of accusation may change quite rapidly in response to socioecological factors. This appears to have been the case in modern Tanzania and in the European witch trials of the 16^th and 17^th centuries, where accusations increased during periods of poor harvests.

So what does our study suggest overall about the cultural transmission of witchcraft beliefs? Some traits appear to have a deep ancestry and were stable enough to exist in societies for hundreds if not thousands of years. Some may evolve independently in numerous cultures: this may be because they produce fitness benefits in certain environments. Some (such as the recurrence of familiars) can perhaps best be explained as appealing to pre-existing cognitive processes, while others appear to be preserved and passed down from generation to generation. Therefore the diverse traits in witchcraft phenotypes appear to differ in their patterns of evolution and their likely functions: further research may provide deeper insights into this.

Read the original article: Peacey, S., Wu, B., Grollemund, R., & Mace, R. (2024). The cultural evolution of witchcraft beliefs. Evolution & Human Behavior, 45(5), 106610.

– by Robin Dunbar

Solving the problem of how to live in large, demographically stable groups is probably the single most important achievement of anthropoid primates, and especially so of humans. Group-living does not come for free. A variety of centrifugal forces constantly threaten to destabilise groups. One of these is the infamous public goods dilemma. Being willing to live in a group with others involves – necessitates, in fact – an implicit promise not to cheat on the deal. I have to allow you a fair share of the benefits, just as you have to allow me a fair share. However, as we all know, it always pays me to take a bit more than my fair share because, by doing so, I gain a modest but significant fitness advantage on you – at your expense, of course!

If access to benefits is a function of physical strength, then it will always pay those who can get away with it to use a little extra force to extract a few extra benefits. The issue for everyone else is how much exploitation should you be prepared to put up with as the price of living in the group – given that the opportunity cost (or, as economists used to call it with a lot more literary imagination, your regret) is to live alone and miss out on all the genuine benefits of group life?

The Norse world of medieval Iceland was the archetypal example of the problem. With no formal political structures (it was the Wild West of the early medieval period), it lacked judges and police to enforce good behaviour. The result was that violence was endemic and very disruptive. It spawned psychopaths with fiercesome reputations. One such individual was Egil Skallagrimsson, who made himself very rich by shamelessly helping himself to a lot of other people’s land and property (and occasionally wives). If necessary, he simply killed you. Such behaviour often generated vendettas that dragged on for years. In one such case, a third of all the adult males in the community were killed in a vendetta that lasted a generation. Of 23 families, four lost all their males; only 11 survived without losing any. Analysis of data from hunter-gatherer societies indicates that the proportion of all deaths that are due to homicide increases linearly with living group size, such that in bands of just 50 people half of all deaths are due to homicide (Dunbar 2022). Why do small scale societies put up with this?

In one sense, of course, they don’t. As I have shown (Dunbar 2022), what they do is introduce social institutions that allow them to manage violent behaviour, especially among the young males. These include marital arrangements that increase the number of people who can lean on badly behaved individuals, charismatic leaders (whose friendly advice we heed out of respect), communal feasts (where we bond) and, especially, men’s clubs (where boys who fall out are made to sit down together to make peace – without, by the way, actually talking about it, just by bonding).

This is all very well, of course, but it ignores the elephant in the room: bad behaviour pays. This raises the intriguing question as to whether there is a significant selection factor favouring bad behaviour that promotes whatever genes might be involved, despite the costs to the rest of the community?

Many studies have tried to determine whether violence pays by determining whether males who murder gain more wives and/or reproduce more often. Broadly speaking, they do. But, as the ecologist David Lack (of Lack’s Principle) reminded us back in the 1950s, pumping out babies doesn’t necessarily translate into loads of grandchildren. As often as not, having too many babies results in many dying, such that fitness is lower.

At this point, the medieval Icelanders come to our rescue, because they left us an amazing literary record of their daily lives – the family sagas (or histories) that recount in considerable detail the goings-on in the various communities and families, not to mention who married (or otherwise) who and what offspring they had. Using these records, the Viking Age historian Anna Wallette (of Lund University, Sweden) and I have been able to place all the family pedigrees into a single interlinked database of over 1200 males, for a great many of whom we can trace their ancestry, siblings and descendants over 3-5 generations. We used a sample of 13 known killers (who had killed 1-19 other men) and 31 non-killers to test whether killers had higher fitness than socially matched non-murderers – not just in terms of their own descendants but also in terms of the fitness of their collateral male relatives. In other words, for the first time, we were able to test the hypothesis that violence pays by examining inclusive fitness.

The results (Dunbar & Wallette 2024) revealed that, despite having a 40% higher risk of being themselves killed than the average non-killer, killers had twice of many wives and offspring as matched non-murderers (men who were never recorded as murdering anyone) and nearly four times the inclusive fitness through their male siblings – providing they themselves survived to die in their own beds. More importantly, the brothers benefitted enormously: if the killer survived, their inclusive fitness was around three times that of the brothers of a non-killer.

In other words, violence does pay. This does not, however, mean runaway selection in favour of ever more violent individuals. Too many violent individuals would cause the collapse of communal life. Since our capacity to survive and reproduce depends on the group, this would negatively impact our fitness. In the end, it is a balance of the costs and benefits. Humans seem to be especially good at finding social controls that allow us to live in unusually large groups – not because we are naturally altruistic, but because we are good at finding workable solutions. Viking Iceland offers us a glimpse of how bad it can become when the social controls are absent.

Read the original article: Dunbar, R.I.M. & Wallette, A. (2024). Are there fitness benefits to violence? The case of medieval Iceland. Evolution & Human Behavior 45: 106614

Image: woman in Uganda

– by Alessandra Cassar

Women around the world experience maternal depression, particularly around the time of pregnancy and childbirth. With around 10-15% of mothers in high-income countries and up to 25% in low- and middle-income countries experiencing depression during or after pregnancy, it is essential that we understand its causes and effects. But from an evolutionary perspective, why would such a costly condition even exist, if it affects not only the mother and her infant but potentially the entire family?

Patricia Schneider, Chukwuemeka Ugwu, and I decided to explore one specific theory rooted in evolutionary psychology: that maternal depression may not be solely a dysfunction but an evolved mechanism. We tested whether maternal depression could act as an unconscious bargaining strategy for mothers who had exhausted all other strategies to elicit help and support from their social network, particularly the baby’s father. This idea is controversial but offers a potential explanation for why a condition so detrimental could have persisted over evolutionary time.

Evolutionary Perspectives on Depression. Several evolutionary hypotheses suggest that depression might have evolved as an adaptive response. Depression could enable individuals to obtain help from others, encourage cognitive changes to solve social problems, or prevent individuals from engaging in risky behaviors. In other words, while depression is painful, it might serve important functions, especially when faced with adverse social situations. This idea gains more traction when we look at maternal depression, where a mother’s wellbeing directly impacts her offspring’s chances of survival.

Perinatal depression, occurring during pregnancy or shortly after birth, presents a particular challenge. Symptoms like sadness, fatigue, and loss of interest in usual activities make it hard for mothers to care for their infants. This has led some researchers to propose that maternal depression might serve as a signal—a costly, honest cry for help—that triggers increased investment from others, particularly those closest to the mother (and genetically closest to the infant).

The Bargaining Model Hypothesis. The bargaining model of maternal depression advanced by Edward Hagen proposes that depression acts as an unconscious strategy for a mother to elicit support. In evolutionary terms, a mother who experiences adversity—such as a lack of support from the baby’s father or social group—could “bargain” for more help by stopping activities that are beneficial to the baby and even to herself. This behavior, costly to everyone, herself included, would signal, through her visible depressive symptoms, that she cannot continue to care for the baby on her own and she truly needs help. This could encourage the father or others to step in and provide the necessary assistance, ensuring the survival of the offspring.

Our Work. To test this hypothesis, we conducted a study in Uganda, involving nearly 300 women around the time of giving birth. Our focus was on whether women showing signs of depression received more cooperation from their social network—specifically, their spouse, kin, and other close individuals—compared to those who did not display such symptoms. In our work, we propose to use a quasi-experimental method called regression discontinuity design (RDD), an empirical method to estimate the potentially positive causal effect of perinatal depression on cooperation within a mother’s social group, despite an expected negative relationship between the two. The negative relationship between social support and maternal well-being is bi-directional: lack of support can cause depression, while depression may reduce support as individuals tend to isolate themselves. This well-known relationship can be seen in the downward sloping predicted lines in Figure 1. However, the bargaining hypothesis suggests that depressive symptoms may also increase cooperation from others, adding a positive effect from depression to support. But how could we test for that since one cannot randomize who is depressed and who is not? Our proposed method is based on the assumption that around the threshold for depression advised by psychiatrists, being a few points below or a few points above is almost random. In this case, we could estimate whether there is a positive “jump” in support between the women right below and those right above such threshold.

Key Findings. Our findings provide some evidence in favor of the bargaining hypothesis. Comparing women just below and just above the threshold for potential depression, we observed that mothers who were at the threshold of displaying depressive symptoms did indeed receive more help, particularly from their spouse (see the positive jump/discontinuity at the threshold in the graphs of Figure 1), maternal grandparents, and a few other close kin. These results suggest that, at least in some cases, maternal depression might trigger increased cooperation from key individuals in a mother’s network.

Interestingly, non-kin such as neighbors and friends, while generally supportive, did not seem to react as strongly to a mother’s depressive symptoms. This aligns with the idea that depression’s signaling function might be more effective among genetic relatives, whose fitness is directly tied to the survival of the child.

Figure caption: Discontinuity plot: Spouse. Each graph represents the predicted line resulting from a linear regression of the corresponding support type on the depression index with a structural break at 0 (equivalent to EPDS=10), and a 95% confidence interval. The vertical axis shows the respondent’s assessment of how often (Always=5, Most of the times=4, Some of the time=3, Rarely=2, Never=1) the individual named above typically: watched children for her (Watch), helped take care of her or the baby in case of sickness (Care), gave guidance about taking care of the baby (Guide), talked with the respondent (Talk), and would give money in case of need (Money). See the original EHB article for other relationships.

The Role of the Spouse: A Critical Relationship. Among all relationships, the one with the baby’s father appeared to be the most important. Women with more support from a loving and helpful partner were at significantly lower risk for depression. Conversely, conflicting or controlling relationships elevated the risk of depression. The baby’s father not only provided the most help but also responded most strongly to his partner’s early signs of depression. This was especially true if the relationship with the mother was one of conflict (a paradox at first, but precisely what is predicted by the bargain idea). This could highlight the evolutionary significance of pair bonding and cooperative parenting.

In ancestral environments, where raising a child often required contributions from both parents (and others), depression could have evolved as a strategy for mothers to secure greater investment from their partner, ensuring the survival of their offspring. Our findings support this idea, suggesting that perinatal depression may indeed catalyze cooperation from fathers and close kin.

Implications for Mental Health and Public Health Policy. While our study provides some evidence for the bargaining model, it’s important to emphasize that the findings do not imply that maternal depression is beneficial or should be left untreated. Depression is a painful condition that requires serious attention and care. However, understanding its potential evolutionary roots could open new avenues for treatment, particularly in the realm of family and marital therapy.

If maternal depression serves as a signal of need within a social group, then interventions that focus on improving relationships and increasing support from family members could be particularly effective. For example, recent research has shown that psychotherapy interventions, such as cognitive behavioral therapy (CBT), can have positive and lasting effects on women’s mental health and their children’s well-being. Our findings suggest that incorporating family therapy, especially to address conflicts with a spouse or other family members, could further enhance these treatments.

Conclusion: Depression as a Call for Cooperation. Maternal depression remains a complex and multifaceted condition. While much of the focus has been on its negative consequences, our research adds to the growing body of evidence suggesting that it may also serve an adaptive function. By acting as a catalyst for increased cooperation, maternal depression might help mothers in challenging environments secure the support they need to care for their offspring.

Understanding depression through an evolutionary lens doesn’t diminish the suffering it causes but offers a deeper perspective on why such a costly condition might exist. As we continue to explore the relationship between mental health and social support, this knowledge could pave the way for more effective treatments that not only address the symptoms of depression but also the underlying social dynamics that contribute to its persistence.

Read the original article: Cassar, A., Schneider, P.H., & Ugwu, C. (2024). Maternal depression as a catalyst for cooperation: evidence from Uganda. Evolution & Human Behavior, 45(4), 106575.