Childcare at HBES 2024 Aarhus

Dear HBES members,

We are pleased to announce that HBES will be offering a childcare option for parents attending the HBES 2024 conference in Aarhus. The Society has contracted with the Nanny Agency, based in Copenhagen and Aarhus, to provide childcare services:

https://www.thenannyagency.dk/en/forside-1

The hourly rate for childcare will be $20 USD during the day from 8am-7pm. There is also a possibility of childcare during the evening at a higher rate.

We will ask HBES attendees to sign up for child care by April 15 in order for the Agency to be able to guarantee the required staff and hours. By that date, we will ask parents to commit to their preferred childcare schedule (dates and times) and pay for the hours specified in that schedule.

For parents traveling with children, HBES strongly recommends that parents obtain travel insurance for themselves and their children, in order to have full coverage for possible accidents and hospitalization. The childcare agency has required liability coverage under Danish law, but it is limited to accidents caused by agency staff during hours of supervision.

As part of the registration process, HBES will provide a portal for parents to register and pay for childcare service. Stay tuned!

The Ups and Downs of Fieldwork – A Personal “Dispatch From the Field”

– by Nicole Hess

[Communication Officer’s Note: Readers of Evolution & Human Behavior are used to reading the results of fieldwork when the papers get published. However, unless they themselves are field researchers, readers of E&HB may not be as familiar with the *process* of fieldwork and what it’s like to collect such data (I count myself in this category). This blog entry is a personal account of the fieldwork process for one of the papers in the recent special issue on “Dispatches From the Field”. It highlights some of challenges and joys of fieldwork and of adapting protocols from MTurk into the field. Of course, every field site is unique, so anthropologists’ experiences will vary as much do the cultures they study – this is just one illustrative experience. The paper described herein is: Hess, NH, & Hagen, EH (2023). The impact of gossip, reputation, and context on resource transfers among Aka hunter-gatherers, Ngandu horticulturalists, and MTurkers. Evolution and Human Behavior, 44(5), 442-453.]

In the summer of 2012, when our daughters were 2 and 6, my spouse was preparing to head to the Central African Republic (CAR) to continue his fieldwork on recreational drug use by Aka hunter-gatherers. This was his 3rd or 4th trip, and I would be staying home (again) with our young children. I also have a PhD in Anthropology, so as he applied for visas and secured research materials, I wondered if I could join to work with one of the few foraging groups left in the world, the Aka, and revitalize my evolutionary psychological research on gossip as reputational competition. My teaching responsibilities would not be disrupted, because we’d be back just before our university’s fall term started.

We could not take our young children to the field for safety reasons, mainly the high child mortality rate (5 children in the village died during our field season). Inconveniences included limited dietary options and a lack running water or electricity for cooking or personal use. We were fortunate to have reliable grandparents and great-grandparents two states away who were willing to help, and a satellite phone to call twice a week. My matriline agreed to do most of our girls’ caretaking, and my paternal grandparents (who were approaching their 90s) agreed to give them breaks by taking the girls for a day at a time over the month that we would be in Africa.

It is harder to make last-minute changes to fieldwork than lab work due to additional health, governmental, and logistical challenges. We adjusted our travel dates, applied for my visa, and added my name to research permit applications that were about to be processed by the CAR government. I took the risk of getting several vaccines at once so that all the immunities would be in effect by the time we arrived in CAR. We got all that in order, flew to Los Angeles to drop our girls off with my mother, got right back on a plane to Paris for a connecting flight to Bangui (CAR’s capital) for our permits, food, gasoline, and gifts for our hosts such as soap and medicines (aspirin, antiseptics, bandages), and finally drove to our field site; that’s over 48 hours of flights, connections, and driving.

We arrived in the Ngandu village of Bagandou, CAR in late July. The Ngandu are small-scale horticulturalists growing manioc, corn, plantains, and other crops in extensive gardens surrounding the village. They have some market integration, with families producing some cash crops, like coffee for sale outside of the village. Ngandu also trade their crops, money, and small gifts like salt and tobacco with the Aka for net-hunted small game and labor (e.g., Aka work in Ngandu gardens for manioc).

We happened to arrive in Bagandou in the middle of caterpillar season, a short period when most Aka are focused on moving far and wide in the forest to collect caterpillars to use as food. Caterpillars are consuming plant matter prior to metamorphosis into moths and butterflies; they literally rain from the trees as they feast. Caterpillar season had come unusually early this year, so we had to put our primary study, which involved reputation and access to resources, on hold because most adult Aka were not accessible. We decided to run our secondary study first, working with Ngandu participants to replicate an MTurk experiment we’d run earlier.

The MTurk resource allocation experiment involved participants being exposed to stimuli including a vignette with a fictional target individual, followed by several negative vs. positive and relevant vs. irrelevant gossip statements about the target. Participants indicated their opinions of the target, as well as their likelihood of allocating a valuable resource to the target.

The MTurk experiment used stimuli suitable to a WEIRD population. To run it with the Ngandu, we had to create new vignettes, gossip content, and dependent measures that were consistent with Ngandu culture. Initially I created vignettes involving witchcraft, as this is a common precursor to gossip in Ngandu daily life. For example, witchcraft accusations often involve jealousy over accumulations of material wealth. But our Ngandu research assistants quickly vetoed those vignettes, sternly warning us to “never talk about witchcraft” because witchcraft and witchcraft accusations led to serious consequences. They provided several accounts of witchcraft that resulted in painful losses, dangerous behavior, illness, and even death. So we brainstormed for several days with our field assistants, developing vignettes, gossip statements, and dependent measures. The Ngandu value a reputation for generosity, and resource transfers among paternal and maternal relatives are routine. With this in mind, our assistants helped us develop vignettes that reflected common local experiences: inheriting valued items and sharing them with family, and also hiring Aka laborers with whom they often shared gifts like clothing. Our assistants also helped us generate several gossip statements that were to be manipulated. To check the validity of the statements, we recruited dozens of locals to evaluate the negativity and positivity of each statement. So just adapting our stimuli to the local context took an immense amount of work – and we hadn’t even started the actual experiment!

We shared many laughs with our assistants about what kinds of behaviors were associated with “good” and “bad” reputations in our cultures. Some behaviors they viewed as important were not ones we expected; other behaviors that we thought would surely be “good” and “bad” were insignificant to the Ngandu. They told us gripping stories about encounters lions, hippos, crocodiles, and apes; we told them that, where we were from, movies and amusement parks exposed people to such animals as a form of entertainment. They laughed in disbelief at my description of the “Jungle Cruise” ride at Disneyland—and when I convinced them it really existed (with fake animals), and was an experience for which people paid a lot of money, they asked “why would you want to scare a child with this?”.

Once the study was designed, I got to work putting the materials together to present to participants, which was another challenge in the field context. We couldn’t collect data on laptops because of the limited electricity, so I cut uniform 2×6 inch strips of paper out of a flimsy, lined cahier (notebook) from the tiny local market, and neatly hand-wrote our experimental stimuli on them. Then, making good use of my packing tape, I laminated each slip, front and back. The gossip statements written on the slips were to be used hundreds of times in different random combinations for our between-subjects design, so they needed to be sturdy. I made one set in English, and one in French.

Then there was the actual running of the study. We needed translators to present our stimuli to participants who spoke the Ngandu language (diNgandu) or Sango, the main language in CAR. Not all of our research assistants spoke English, so in running our experiment, my spouse/coauthor worked with a translator who spoke diNgandu, Sango, and English, and I worked with one who spoke diNgandu, Sango, and French – some of which I thankfully still remembered from 25 years ago. With the help of our tireless translators, we were able to efficiently run our Ngandu experiment with enough participants to fill our conditions. We found that hearing more positive gossip relative to negative gossip led to a higher likelihood of giving the benefit. And, when gossip content was relevant the context of the competition (family or work), the effect was stronger.

Surprisingly, we still had about a week left before our flight home (only one plane left Bangui for Paris each week, and we could not miss it). We decided to attempt to run our Aka study. By this time, caterpillar season was coming to a close, and the Aka were returning to their camps which were located along trails that radiated from Bagandou into the forest. One of our research assistants who also spoke diAka helped us run this study with adult Aka participants from camps along 2 trails. This study involved non-experimental methods where participants peer-rated one another in response to a small number of questions related to reputation and access to resources (along with age, sex, and relatedness). We investigated the relationships between participants’ peer-rated contributions to their group, reputations, costs imposed on the group, and receipt of benefits from the group. Unlike typical groups of adults in the US, such as co-workers, the Aka in our study had lifelong relationships with each other, and many were biological kin. Aka results showed that contributions to family and community were associated with a good reputation, which in turn was associated with receiving benefits.

Although there were many challenges, this field experience was not just fruitful, but enjoyable. I had been expecting a physically uncomfortable site with hard-to-access participants, where language barriers would limit my ability to study gossip. But the living conditions and climate were pleasant, and language, thanks to our competent and enthusiastic assistants, was no problem at all. Members of the communities were warm, authentic, and willing to share themselves and their cultures with us, and they were curious about what we were up to; this made data collection breezy and gratifying. We wanted to return to CAR soon.

Unfortunately, a few months after these studies, CAR plunged into a civil war that is still ongoing. We get infrequent updates from our research assistants about their lives and the local political climate. Diamonds and gold were discovered in the region around the time we were there, and jobs for men in mining (a dangerous venture that can result in windfalls, but also injuries and death) dramatically increased cash flowing into Bagandou. Beyond disruptions due to civil war and dangerous mining practices, interest from international mining groups in diamonds and gold are increasingly impacting in the region. We have not been able to return in over 10 years.

Read the published paper described in this blog: Hess, NH, & Hagen, EH (2023). The impact of gossip, reputation, and context on resource transfers among Aka hunter-gatherers, Ngandu horticulturalists, and MTurkers. Evolution and Human Behavior, 44(5), 442-453.

Arranged and Self-Choice Marriage: Implications for Child Outcomes

– By Kristin Snopkowski & Annemarie Hasnain

While free choice of spouses (i.e., the love marriage) is the norm in western countries today, arranged marriage has historically been a common form of marriage.  We see this today in some cultures, like India and Pakistan where it is still common, and in the past century in many other parts of the world, including many small-scale foraging populations. Given the interest of evolutionary researchers on the topic of mate choice, which requires that individuals choose their own mates, do arranged marriages lead people to marry less preferred partners and what are the implications? Research in our recent Evolution and Human Behavior article, “Maternal investment in arranged and self-choice marriages: A test of the reproductive compensation and differential allocation hypothesis in humans,” seeks to understand the role arranged marriage plays in reproductive and child outcomes.

Research has shown that the mate one would choose for themselves may be different from the one that would be chosen as a son- or daughter-in-law. Most of this research comes from surveys that ask individuals for their preference in a mate and their preferences for a son or daughter’s spouse or those that separately ask parents and adult children for their preference in the adult child’s spouse. These studies tend to find differences, where people prefer attractiveness and an exciting personality in a potential spouse, but instead prefer similar ethnic background, religion, and social class in a potential son- or daughter-in-law.

Mating preferences likely evolved because of the fitness implications of these choices. Evidence from the non-human animal literature shows that when individuals are forced to mate with less preferred or unattractive partners, their offspring do worse (i.e., have reduced fitness).  This may be because attractiveness is an honest signal of immune function or that preferred partners have better territory that allow them to invest more in offspring or that preferred mates are more likely to produce offspring that are then preferred by individuals in the next generation, increasing their chance of finding mates. Regardless of the mechanism, these findings suggest that arranged marriage may impede an individual’s choice of an optimal partner.

There are two hypotheses that have been developed to explain investment patterns in offspring from non-preferred or unattractive partners.  The first hypothesis is the differential allocation hypothesis, which argues that individuals will invest less in the offspring of unattractive mates.  Conversely, the second hypothesis, called reproductive compensation, states that individuals will invest more in the offspring of non-preferred mates as a means to compensate for their offspring’s likely reduced prospects. These hypotheses have not previously been tested in humans, but arranged marriage may provide an opportunity to explore these hypotheses in humans. This requires that the spouse of individuals in arranged marriages are in some way less preferred, which some empirical evidence suggests given two assumptions: first, that mating preferences are evolved to optimize mate choice and, in turn, offspring outcomes and second, the preferences for a mate are different than the preferences for a son- or daughter-in-law.

Our paper tests whether there are any differences in how mothers invest in their offspring depending on their marital status (arranged marriage or self-choice marriage). The sample included about 8400 women living in Indonesia who were surveyed longitudinally from 1993 to 2015.  We examined factors like prenatal checkups, birth weight, breastfeeding duration, children’s height-for-age and weight-for-age, to determine if there are differences based on whether the parents were in an arranged marriage. We also examined fertility outcomes including the number of live births, the number of living children, marital fertility (number of births per years married), and the number of stillbirths and miscarriages.

The results show that arranged marriage is decreasing in Indonesia.  For women born prior to 1930, about 55% reported their marriage as arranged, but for those born after 1990, this has fallen to 6.7%.  When maternal investment is examined for women in arranged vs. self-choice marriages, there are no significant differences in the number of prenatal checkups, birth weight of children, breastfeeding duration, or offspring height and weight.

When the number of children is examined (live births, living children, marital fertility), results show slightly fewer children for those couples in arranged marriages. There is a significant reduction in the number of living children and a marginally significant reduction in live births and marital fertility.  Interestingly, arranged marriage couples also have a marginally higher number of stillbirths.

These results suggest that being in an arranged marriage or a self-choice marriage results in few differences in how women invest in their children. Being in an arranged marriage does not appear to significantly increase or decrease investment that influences child size, for instance through prenatal check-ups, breastfeeding, or height and weight in childhood. The only factor that had any significant effect was number of living children, which suggests some support for the differential allocation hypothesis, that individuals who choose their mates invest in having more offspring. There is no evidence supporting the reproductive compensation hypothesis, that people are increasing investment in the offspring of less preferred partners. This finding also supports research from other species that free mate choice is associated with increased reproductive success. The reasons for this effect could relate to genetic incompatibility which makes it harder to conceive or less likely to bring offspring to term for couples in arranged marriages. It is also possible that self-choice partners begin reproduction sooner because they begin their marriage well-acquainted with each other and may experience greater marital satisfaction.

Why would someone agree to an arranged marriage if it hinders their reproductive success?  While people who come from cultures where arranged marriage is rare may find the practice unappealing, it is important to point out the numerous benefits of arranged marriage. In many cultures that practice arranged marriage, it is believed that arranged marriage is an optimal family strategy, allowing more experienced parents to identify good partners for their children. Further, there is some evidence that parents provide more support to their adult children if they choose their partners, especially as parents may feel some responsibility for the success of the marriage.  There are likely tradeoffs people experience in terms of alloparental and social benefits that result from engaging in arranged marriage (especially when it is the dominant marriage pattern in a community) even though there may be slight costs to reproductive success.  A detailed examination of the costs and benefits of different marriage strategies provides a fuller understanding of the variation we see in marriage patterns across the world.

Read the original paper: Hasnain, A.M., & Snopkowski, K. (2024). Maternal investment in arranged and self-choice marriages: a test of the reproductive compensation and differential allocation hypothesis in humans. Evolution and Human Behavior, 45, 99-110.

crowd of participants in speed-dating

Funny How? Humour as an Evolved Trait

– by Henry Wainwright

Humour is an everyday part of our lives and is present in virtually all human cultures, seemingly both past and present; the oldest known surviving joke being from Bronze Age Sumer, circa 1900 B.C. And while what we find funny is likely culturally and socially influenced, the fact that we all have a sense of humour, irrespective of culture, strongly suggests that humour evolved for some purpose.

One among many evolutionary explanations is that humour may have helped our ancestors to attract a mate. Indeed, individuals today consistently report a preference for humour in a romantic partner. However, it remains unclear why, in an ultimate sense, humour is considered an attractive quality. Humour is enjoyable, of course – but there is nothing inherently enjoyable or attractive about what we describe as funny. The question becomes, why did we evolve to find certain things funny and to be attracted to funny individuals?

The ‘fitness indicator hypothesis’ argues that humour aided ancestral courtship because being funny signals underlying genetic quality. Specifically, the idea is that funniness requires mental performance (e.g. speed, intelligence, creativity), which in turn requires a high-functioning brain, which in turn requires a low load of genetic mutations. Therefore, both being funny and being attracted to funny people are evolutionarily favoured because offspring of these couplings will inherit lower mutation loads and pass on their parents’ genes more effectively.

We tested predictions from the fitness indicator hypothesis by having participants – undergraduate students from the University of Queensland – report their preferences for humour in a romantic partner (i.e. their stated preferences) before engaging in a multiple unscripted, three-minute speed dates with each other, for a total of 860 unique dates. After each date, participants rated their partner on several characteristics including their funniness, their  humour receptivity (they found me funny), and their overall attractiveness.

Audio from these interactions were also surreptitiously recorded for a subset of 563 dates, which enabled the use of an additional, objective measure of humour, in the form of laughter frequency. From there we tested the central predictions of the fitness indicator hypothesis: that funniness and humour receptivity are attractive traits. We were also interested in additional predictions of the hypothesis, namely, that in accordance with parental investment theory, there should be a sex differences in how men and women respond to humour. That is, men should be attracted to humour receptivity in a partner more than women, whereas women, more so than men, should value funniness in a partner.

Indeed, results from stated preferences were largely consistent with these predicted sex differences. However, relying on stated preferences alone is problematic because doing so assumes that participants have sufficient, bias free insight into their own preferences. In practice, stated preferences often fail to predict individuals’ evaluations of potential partners (i.e. their revealed preferences). Therefore, we continued our investigation by looking at revealed preferences using laughter as well as ratings of humour .

We began by looking at how strongly participants’ ratings of their partners’ funniness or humour receptivity correlated with their ratings of the partners’ overall attractiveness. This allowed us to first check the basic premise of the fitness indicator hypothesis: that funniness is actually attractive. Consistent with this premise, partners who were rated as funnier were also rated as having greater overall attractiveness. Notably, the same was not found for humour receptivity – partners rated as more receptive were rated no more or less attractive overall. More damaging for the fitness indicator hypothesis, though, is that the predicted sex differences were not observed at all: the associations of both funniness and humour receptivity with overall attractiveness were similar in men and women.

Using ratings as a sole assessor of revealed preferences can be troublesome, as post-interaction ratings are possibly subject to a halo effect, whereby participants might rate a partner as funnier simply because they were more physically attractive, for instance. Therefore, we examined revealed preferences using laughter as a real-time, behavioural measure of both funniness and humour receptivity. After first establishing that at-partner-laughter (i.e. participant laughter following something their partner said) was positively associated with ratings of funniness, thus partially validating laughter as a measure of humour, we found that neither funniness nor humour receptivity, as measured by laughter, predicted ratings of overall attractiveness. Furthermore, using laughter, we found no evidence that men value humour receptivity in a speed-date partner more than women do, or that women value funniness in a speed-date partner more than men do.

In summary, we found that while stated preferences largely supported the sex differences predicted by the fitness indicator hypothesis, results from revealed preferences, which are taken as more valid than stated preferences, did not support these predicted sex differences and offered only mixed support for the central premise of the hypothesis, that funniness is attractive.

Overall, our results call into question not only the fitness indicator hypothesis, but also (or alternatively) the degree to which parental investment theory can be applied to sex differences in humans’ preferences for fitness indicators. The absence of significant sex differences in revealed preferences alone does not necessarily exclude humour as a fitness indicator; instead, it may be that the degree to which parental investment theory predicts sex differences in human fitness indicators has been overestimated. Humans exhibit mutual mate choice, and as a result, fitness indictors are still expected to evolve, but not necessarily with large (or any) sex differences. So the possibility remains that humour may be a fitness indicator, but men and women differ little, if at all, in their attraction to it. The current study is partially consistent with this possibility, as there is evidence that both funniness was a desirable trait to both sexes similarly. However, further investigation, especially into the role that humour plays in romantic attraction over longer periods of acquaintance, is needed to fully investigate this possibility, as well as to comprehensively test the fitness indicator hypothesis.

Read the original article: Wainwright, H.M., Zhao, A.A.Z., Sidari, M.J., Lee, A.J., Roberts, N., Makras, T., & Zietsch, B.P. (2024). Laughter and ratings of funniness in speed-dating do not support the fitness indicator hypothesis of humour. Evolution and Human Behavior, 45(1), 75-81.

Connections beyond blood: chosen kin are integral to human social life

– by Ollie Shannon & Anne Pisor

The Vatican made it official: transgender individuals can now serve as godparents.

But what is a godparent and why are godparents important? Ultimately, answering this question requires us to think about the evolution of human social life – and the importance of chosen kin.

Humans raise children cooperatively, with alloparents – people other than the parents – usually involved. Born helpless and with long childhoods, our kids need all the help they can get.

Evolutionary social scientists have traditionally focused on biological kin as helpers, much as bio kin are the primary helpers in other cooperative breeders like crows and meerkats. But the Vatican’s declaration reminds us that in humans, the question of who helps is more complicated.

Choosing kin

Humans have a diversity of non-kin alloparents – a rich tapestry of social relationships and reciprocal obligations. Non-bio kin can be especially involved when bio kin aren’t available to help, like in communities with high residential mobility or in the Queer community, when bio kin sometimes aren’t interested in helping their Queer kids. In marginalized communities facing systematic challenges such as poverty or discrimination, individuals may face limitations in the support they can offer due to these systemic factors and may rely on a combination of bio-kin and non-kin alloparents to help everybody’s children thrive.

When humans lack needed family support, we often create the family we need. In the Black community, for example, churches and religious institutions offer a sense of community during tough times and joyful occasions. The use of kinship terms such as “brother” and “sister” in a religious context affirms and strengthens these relationships. For this reason, non-bio alloparents are often called chosen kin or, using an older term from anthropology, fictive kin.

Compadres, padrinos, and ahijados

Godparents are chosen or bio kin who commit to being a child’s alloparent, usually through a ritual – by being present at a birth, for example, supporting a child’s graduation party, or being present at a child’s baptism. In Latin America, where godparenthood (compadrazgo) is widespread in the Catholic church, the choice of godparent is often guided by a mix of considerations, including the social standing of the godparent and their ability to provide help and resources.

In rural Bolivia, the focus of our recent paper in Evolution & Human Behavior, the support and resources godparents provide is sometimes day-to-day, like after-school care, but can also be rare but big infusions of help. Godparents who live in the city, for example, can house an adult godchild when they go to university, provide help with bureaucracy, or send packages of things not available rurally, like cheap smartphones or other household items.

Given the importance of godparents in this context, we asked: how might godparents impact child outcomes? For example, if godparents often provide after-school care or house their grown godchildren, does this impact godchildren’s educational outcomes? Studying how and the degree to which godparents impact child outcomes across societies could unlock key insights – like the benefits of non-kin alloparental support to kids, parents, and the alloparent themselves – that are still not a common focus in the evolutionary literature.

In 2017, one of us (AP) led a research team that interviewed 148 adults about their children, including their adult children: we wanted to know not only whether their kids had godparents, but where those godparents lived, and what their kids’ educational outcomes were. Among the 210 adult children discussed, 163 had at least one godparent. However, these godparents didn’t have detectable impacts on their godchildren’s education in our statistical models – not on years of education, high school completion, or even pursuing a university degree. It didn’t matter if the godparent lived in the same community – where the godchild’s high school was located – or somewhere else, or even whether the godparent was actually bio kin who had been given godparent status.

Instead, we found that adult children with more older siblings were likely to have more years of primary and secondary education, complete high school, and pursue higher education. Older siblings are important alloparents in many contexts, with varying impacts on child outcomes – including educational attainment.

What next in the study of chosen kin as alloparents?

Our findings underscore that chosen kin may not have measurable effects in all domains of a child’s life – but, as captured by our ethnographic data, are still making things easier for parents and children alike, by providing care, resources, and even housing. Whether through quantitative or qualitative data collection, focusing on impacts on children or even on their parents, there is still much to be done in understanding why chosen kin are so prevalent in human societies.

In the rich tapestry of human sociality, the concept of chosen kinship serves as a testament to the flexible nature of human relationships. By embracing the complexity of chosen kinship, we honor the resilience and diversity of human social bonds, fostering a more inclusive and compassionate approach to human relationships.

Read the original article: Hubbard, E.B., Shannon, O., & Pisor, A.C. (2023). Non-kin alloparents and child outcomes: older siblings, but not godparents, predict educational attainment in a rural context. Evolution & Human Behavior, 44(6), 597-604.

Is the Mind a Swiss-Army Knife or a Crowbar?

Image: A vintage and somewhat unscientific map of mental functions. But how fine grained are these adaptations?

– by Thomas J. H. Morgan

From the outside, the brain is a medium sized, pinkish-grey blob. At the microscopic level, it’s a densely woven mesh of countless neurons. In between these two extremes is the brain’s functional structure – the mind, or more concretely, how those neurons are wired together to solve problems and manage behavior.

A popular metaphor for the mind is the Swiss-army knife. Like the brain, the Swiss-army knife has a large-scale external appearance (red, cigar-shaped, with silver rotating appendages) and a microscopic constitution (atoms and molecules). However, it also has a functional mid-level structure, being composed of subunits that solve particular problems – opening bottles, filing nails, driving screws, scaling fish, cutting wires, and so on.

As useful as it is, the Swiss-army knife has limitations. Screwdrivers and fish scalers aren’t much use without screws or a means to catch fish. Someone heading out into the unknown might instead prefer a kit of fewer but more widely applicable tools. Say, an axe and a crowbar. Rather being designed for specific problems, these items can be put to work in many contexts and so can handle unforeseen situations more successfully.So, what does the mind look like – a bespoke Swiss-army knife with many task-specific solutions, or an adaptable survival kit of just a few broadly applicable tools? This is the question we set out to answer. We recruited groups of participants and had them collectively complete a task. The task we chose was mate-choice copying – participants evaluated how attractive they found photos of other people, and then they saw what other participants thought and could alter their decision.

Mate-choice copying is particularly relevant to this question as it sits at the interface of two fields – evolutionary psychology, which has collected lots of data on human mate choice, and cultural evolution, which has extensively studied copying and social influence. In addition, while some prior work on mate choice copying has suggested it is managed by a mental adaptation evolved specifically for this task, other work has argued the mental system is broader and handles decision making and learning more generally.

Prior work led by Dr. Sally Street had already found that humans were equally influenced by what others thought about the attractiveness of human faces, human hands and abstract art, but we wanted to dig into the details. Studies of copying across many other contexts have documented that humans are influenced by majorities (“conformity”) as well as by successful individuals (“prestige”). We tested whether these same patterns occurred in mate-choice copying. In addition, we collected data from both men and women to see if there were gender differences in copying. Our reasoning was that the more mate-choice copying differed between genders or from copying in other contexts then the more likely it was underpinned by a mate-choice specific adaptation.

Our results showed the opposite. Participants were influenced by each other’s decisions, and analysis of the patterns in this copying found strong evidence of both conformity and prestige. In addition, there was strong evidence that both men and women copied in the same way. We thus concluded that rather than a bespoke system, mate choice-copying is underpinned by the same copying mechanisms that are active in other contexts – it’s a crowbar, not a Swiss-army knife.

There are two important points though. First, although we suggest the mind is made of general-purpose systems, these systems are still adaptations – they are just adaptations for broad classes of problems, as opposed to specific tasks. Second, even broadly applicable systems can be flexibly tuned to meet particular needs. For instance, copying is known to be adjusted according to factors like confidence and risk. Through factors like these, even broad ranging systems can be adaptively tuned for particular tasks, just like a crowbar can be applied with different amounts of force. Thus, the mind might have fewer solutions than the Swiss-army knife metaphor suggests, but its adaptive power comes from the flexible use of the tools at its disposal.

Read the original article: Foreman, M., & Morgan, T.J.H. (2024). Prestige, conformity and gender consistency support a broad-context mechanism underpinning mate-choice copying. Evolution and Human Behavior, 45(1), 58-65.

An issue of EHB

New E&HB article format: Short Reports

The official HBES journal, Evolution and Human Behavior, has created a new report format: short reports. Short reports, created in honor of John Tooby, are intended to expedite the publication of concise reports of original research. Short reports contain no more than 3000 words in the introduction, methods, results and discussion combined, an abstract of 200 words or less, and a maximum of 30 references. The introduction, only a few paragraphs in length, should state concisely the evolutionary rationale for the project (for example, the relevant selection pressure/adaptive problem and proposed behavioral/cognitive solution), a very brief description of the methods used, and specific empirical predictions. Short reports may have online-only supplements that contain full materials, supplemental tables, and details of complex methods. However, the supplement may not be used to circumvent the word count. A reviewer/reader of EHB should be able to evaluate the science of a short report solely from the main paper. Members of the Editorial Review Board and Invited Reviewers of short reports will be notified of this new format to ensure appropriate appreciation of its concise nature. Details will appear soon on the EHB website.

Take part in a commentary article on John Tooby quotes

– by Deb Lieberman, Editor-in-Chief, Evolution & Human Behavior

In honor of John Tooby (1952-2023) and his contributions to our field, members of HBES and invited guests are welcome to pick a quote(s) from any Tooby publication of any year and take up to 350 words to state its importance or its impact on science. The 350-word runway is firm, no matter how many quotes you pull. You need not include a discussion of the quote if you do not wish; you can simply include your favorite quotes or passages. Whatever the case, your all-in word limit including any quotes is a firm 350 words. This is to allow as many HBES members to contribute as possible.

FAQ:

How many submissions per scholar?
One

How many authors per submission?
One. Single author submissions only.

Can the same quote be used by multiple contributors?
Yes. Of all the sentences written, we are hoping there is a wealth of options. However, we also know that people will have different interpretations and comments on similar quotes. The editorial team will organize submissions.

How many references are allowed?
The only references allowed will be for the quote(s) used.

What is the word limit?
350 words. All in. Firm.

How do I submit?
Complete the form using the Qualtrics link or QR code below: https://umiami.qualtrics.com/jfe/form/SV_bgA7sgv20cJsvmm

QR code for submissions

Will the submissions be reviewed?
Yes, by members of the Editorial Board. HBES membership will be verified. Submissions from non-HBES members (or individuals who have not been personally invited by the Editor) will be rejected. If you’d like to renew your HBES membership prior to submission, visit: https://www.hbes.com/membership-join/

Where can I find all of John Tooby’s publications?
Here is a link to the Center for Evolutionary Psychology Publication list, where you can find most of John’s publications. (https://www.cep.ucsb.edu/publication/)

When are submissions due?
Submissions are due by March 31st and notification of acceptance will be rolling. The link for submissions will be disabled after this date.

When will the tribute be published?
The editorial team will collect and compile the submissions, with the aim of publishing the collection as a single on-line article in the third or fourth issue of 2024. Details will be sent to contributors.

Deb Lieberman
Editor-in-Chief, EHB

Dates, deadlines, & info about HBES 2024 (Aarhus, Denmark)

We are fast approaching the 35th Annual Meeting of the Human Behavior & Evolution Society in Aarhus, Denmark! It will be held at Aarhus University from May 22-25, 2024. Here are some important dates to know about HBES 2024:

  • Abstract submission deadline: Feb 1st
  • Final abstract acceptance confirmations: March 1st
  • Last day for Early Registration: March 31st
  • Regular Registration begins: April 1st
  • Childcare registration deadline: April 15th
  • Regular Registration ends: May 21st
  • Late Registration begins: May 22nd
  • Conference dates: May 22-25

We have an exciting lineup of plenaries: Brian Nosek will give the keynote, and we will have plenaries by Dorsa Amir, Lisa Feldman Barrett, Nicolas Baumard, Judith Maria Burkart, Joseph Carroll, Jaimie Krems, and Manvir Singh.

Bookmark the conference website for updates and the most recent information.

Looking forward to seeing you in Aarhus!

Tsimane woman gardening while younger females watch

Cultural transmission: Who learns what from whom? When, how, and why?

– by Eric Schniter, Michael Gurven, & Hillard Kaplan

Humans depend on culturally transmitted knowledge and skills crucial for their survival. But how is essential culture transmitted?

In economically modern human societies, most youngsters are formally educated alongside their similar-aged peers by unrelated teachers from an older generation. Adults in modern societies often develop into specialists, learning novel specialized skills from their coworkers and prestigious peers. But is this pattern of “horizontal” and “oblique” transmission from unrelated others the most fundamental mode of human culture transmission?

Evidence from subsistence groups like the Tsimane suggest that the patterns of cultural transmission, schooling, and skill development seen in economically modern society are not universal to all humans and were likely uncommon among our ancestors who relied on multi-generational broad social structures of kin-based exchange.

In our recent study in Evolution & Human Behavior, we brought a life history approach to the study of transmission vectors that considers how changes in embodied capital, combined with gender and relatedness, affect the costs and benefits to both the influencer and the learner. We emphasize the investments made in knowledge and skill across the human lifespan, and the returns on these investments at different ages that manifest in the array of competencies we see in a cross-section of society. We adapt the vector framework introduced by Luigi Cavalli-Sforza and Marcus Feldman to describe vertical, oblique, and horizontal cultural transmission relationships (see Figure 1).

Figure 1. Schematic representation of the intra- and inter-generational cultural transmission vectors, both related and unrelated that potentially influence receivers’ culture acquisition. Our cultural transmission study focuses on the relationships in bold fonts and colors.

So, what did we find? When do people learn, from whom, and how?

Our study focusing on 421 adult Tsimane forager-farmers native to Bolivia sheds light on how essential skills and specific domains of knowledge find their way from person to person and from one generation to the next. We examined the transmission vectors and styles of influence behind Tsimane people’s acquisition of 92 skills, ranging from those involving foraging, domestic chores, crafts and tool manufacture, childcare, music, and more. This transitioning community, living at the intersection of traditional foraging and farming practices and the rapidly changing demands of market integration, provides a unique lens to understand the vectors and influences driving cultural transmission.

We used a survey approach to gather knowledge about the skills that people had, their proficiency with those skills, and their reports of who influenced their skill acquisition by teaching, correction, helpful example, encouragement, or discouragement. Tsimane people report acquiring basic competency with most skills by the end of childhood and developing their skill proficiency further throughout adulthood.

Older, same-sex relatives predominantly influence Tsimane culture transmission, and in a variety of ways. They lead by example, directly instruct, correct learner’s mistakes, and sometimes just encourage and positively reinforce behaviors. Older adults are named most for these influences, despite the greater amount of time that kids spend interacting with same-generation peers while developing proficiency with most skills.

95% of culture transmission is reported as coming from within families (87% blood relatives, 8% related by marriage) and 75% from older kin. Vertical transmission from parents is most common, followed by oblique transmission from older kin. For example, grandparents –revered for their wisdom and experience—play a crucial role in imparting difficult-to-acquire skills that demand less physical strength but more complex knowledge, such as music performance, storytelling, and crafting. In contrast, peers of the same generation tend to positively influence the acquisition of modern, market-oriented skills, like finding wage labor opportunities and using machines for farming.

While similar-aged peers facilitate the acquisition of modern skills, they are reported to be the least helpful when it comes to positively influencing traditional skill acquisition. Unlike older kin, peers of the same generation are more likely to be competitors during the skill acquisition process, explaining why they are reported to be the mostly likely contributors of discouragement, a negative influence intended to inhibit skill acquisition.

We examined a diverse set of essential Tsimane skills and types of knowledge that has been conserved for untold generations, underscoring the important role of older adults and the multi-generational support of youngsters and young adults. This dominant pattern of kin-biased cultural transmission from older to younger generations mirrors the Tsimane pattern of kin-biased net food transfers between generations and within extended families (see here and here).

In subsistence societies, essential skills continue to develop for decades after they have been acquired (e.g., see here), forming older adults into “banks” of accumulated cultural solutions and practical knowledge (e.g., see here, and here). Our findings are consistent with the view that older-to-younger cultural transmission is the result of selection for a long lifespan favoring peak abilities for information retrieval and transmission to younger kin at late ages.

Generations of cultural isolation likely helped the Tsimane conserve their multigenerational system of cooperation and downward traditional culture transmission. However with rapid modernization, the current and future generations will face new challenges. Older adults’ contributions to their forager-farmer economy have been possible because of their comparative advantages and accumulated experience that comes with age. As transitioning societies increasingly value novel skillsets, and as younger generations develop comparatively greater proficiency and productivity with these modern skills, the opportunities for positive cultural influence and transfers from younger to older generations will grow. These results suggest that successful aging among adults, in both Tsimane and economically modern societies, will hinge on both upward inter-generational flows of knowledge and resources, and younger generations maintaining an appreciation for older adults’ roles as trusty helpers, educators, and experts of cultural traditions.

Read the original paper: Schniter, E., Kaplan, H. S., & Gurven, M. (2023). Cultural transmission vectors of essential knowledge and skills among Tsimane forager-farmers. Evolution and Human Behavior.