UMN Search for a Biological Anthropologist in 2025-2026

– by Dor Shilton, Aniruddh D. Patel, Kim Hill, and Chris von Rueden

Many think that music evolved to promote or signal social cohesion. However, there are several societies in which group singing and dancing are extremely rare. Why is that the case, and what does it mean for our theories of music evolution? We examined four indigenous societies in which collective music-making is rare, assembling evidence concerning three non-mutually exclusive hypotheses:

1. Collective action hypothesis: collective music-making is less likely where there is less collective action in general
2. Musical expertise hypothesis: collective music-making is less likely if music is normally performed by people with special expertise or used to signal individual status
3. Musical style hypothesis: collective music-making is less likely if the predominant musical styles are less suitable for coordinated singing and dancing

Our case studies

Using previous cross-cultural studies, we narrowed in on societies in South America and Siberia:

1. the Tsimane of lowland Bolivia
2. the Ache of eastern Paraguay
3. the Ayoreo of Bolivia and Paraguay
4. the Tuvans of the Russian Republic of Tyva

We aimed to create a detailed portrait of each society and its music-making practices using both ethnographic materials and first-hand reports. The latter were essential, since music-making practices are often not a major focus of ethnographies — especially in cultures in which music is not a central feature of collective behavior. Two of our co-authors had extensive relevant knowledge: Chris von Rueden, who worked with the Tsimane since 2005, and Kim Hill, who worked with the Ache from 1977 to 2020. We also corresponded with over a dozen anthropologists and other people familiar with these societies.

In the process of assembling these portraits, we became cognizant of the diverse histories underlying each culture and its musical customs. We did, however, find some convergent evidence for our hypotheses.

Collective action

This was the best supported hypothesis. In all the societies we examined, collective action related to subsistence was mostly limited to small groups and extended families, inter-tribal warfare was either non-existent or limited to small parties, and collective religious action was either suppressed significantly (limiting the scope of attendance) or was altogether absent.

Musical expertise

The influence of expertise was supported only in relation to religious activity. Among the Tsimane, Ayoreo, and Tuvans, the songs involved in religious rituals are potent and potentially dangerous, and require a level of expertise and knowledge.

Musical style

While we found evidence of solo-oriented musical styles (drone-overtone singing, ad-libbing), cases like the Tuvans made it clear that these do not prevent other singing styles from being used when circumstances encourage people to sing together. We therefore concluded that musical style is the consequent rather the antecedent of collective music-making prevalence.

Cultural loss

Cultural loss is a factor we haven’t initially considered, but which surfaced as a result of our study. Whether religious practices were suppressed by external forces (which is the case with the Tsimane, Ayoreo, and Tuvans), or were lost along with other cultural traits (as is the case with the Northern Ache), it certainly seemed to influence the overall prevalence of collective music-making.

Key Takeaway

Overall, our findings suggest that the scale and religiosity of collective action may be the most important explanatory factors for the prevalence of collective music-making, but other factors, like cultural loss and religious expertise, also play a role. While collective music can benefit social well-being, it is evidently not essential, as the four societies we studied sustained many key aspects of their social life with little to no collective music-making. One important takeaway from this study is that music evolution theories need to look more deeply into the relationship between music and religion, which could turn out to be a big part of the puzzle.

Finally, we invite readers to listen to some of the songs of the Tsimane, Ache, and Tuvans:

1. A female Tsimane singer (link), from McDermott, J. H., Schultz, A. F., Undurraga, E. A., & Godoy, R. A. (2016). Indifference to dissonance in native Amazonians reveals cultural variation in music perception. Nature, 535(7613), 547–550. https://doi.org/10.1038/nature18635
2. Northern Ache songs (link), from Singh, M., & Hill, K. (2025). Loss of dance and infant-directed song among the Northern Aché. Current Biology. https://doi.org/10.1016/j.cub.2025.04.018
3.  An album of Tuvan singing (link), audio companion to Levin, T. (2010). Where Rivers and Mountains Sing: Sound, Music, and Nomadism in Tuva and Beyond (PAP/COM edition). Indiana University Press.

Read the original paper here: Dor Shilton, Aniruddh D. Patel, Kim Hill, Chris von Rueden. (2025) Why collective music-making is sometimes rare: A study of four indigenous societies. Evolution and Human Behavior, 46(4), 106695.

— by Maria Brackin

Neither a borrower, nor a lender be;
For loan oft loses both itself and friend,
And borrowing dulls the edge of husbandry.

– William Shakespeare, Hamlet

Suppose that you borrow money from a friend and you promise to repay them soon. Wait, you might be thinking, you would never do this! You would avoid having to borrow—for instance, by saving money, or delaying whatever purchase you were planning. This may be the case, but a majority of people in the world do borrow informally, whether by choice or necessity.

Entertain me for a moment and imagine this is really happening. If the thought of borrowing makes you feel uncomfortable, you’re not alone. In a theoretical, economic sense, borrowing is a straightforward, amoral transaction—the only details that should matter are the willingness of the lender to give you the money, and the terms of repayment. If your friend is offering, and you are confident that you will repay, why worry?

But worry we do. Borrowing can prompt a range of different emotions: relief and gratitude towards the person who is loaning you money, anxiety and guilt about your debt to them, and a gnawing awareness that there is now an imbalance between you. Research suggests that, understandably, informal debt damages social relationships when loans are not repaid, but even the act of borrowing itself has varied outcomes: interpersonal conflict and negative emotions on the one hand; stronger relationships and positive feelings on the other.

Your next thought might be that you need more information: why are you borrowing the money? From which friend? Context is essential, and your emotional reaction will likely depend on what you imagine the situation to be: borrowing from a rich friend feels different than borrowing from a poor friend, and borrowing to meet an urgent need feels different than borrowing to purchase something unimportant.

In our recent paper, Hugo Mercier and I point towards a potential explanation for such emotional reactions. Our core claim is that informal, interpersonal borrowing is not just an economic transaction, but a social interaction. As humans, our cognitive systems are highly attuned to fairness in our social lives—this is why we keep track of how people behave towards us and others, and the consequences of their actions.

When we borrow, we risk not just our wallets but our reputations. The strong feelings that emerge include “social emotions” that have evolved to regulate interpersonal relationships, such as gratitude, guilt, anger and shame. These emotions all respond to the welfare tradeoff ratio (WTR): the costs we feel we should pay to benefit someone else, or the costs we feel they should pay to benefit us. In the case of borrowing:

• A loan that imposes too high a cost on the lender (such as taking money that they have specifically set aside for something else), or delivers too low a benefit for the borrower (such as a frivolous purchase), is indicative of a low WTR and can generate emotions such as guilt (if we are the borrower) and anger (if we are the lender).
• A loan that imposes only a low cost (such as borrowing from someone with money to spare), or delivers a high benefit (such as an essential purchase), suggests a high WTR, causing positive emotions like gratitude.

In a series of online experiments, we asked participants to imagine, as you just did, that they had borrowed money from a friend, or that they had loaned money to a friend. We provide the crucial context outlined above: the costs to the borrower or the benefits to the lender. In the first study, we measured social emotions for both lenders and borrowers, comparing high and low benefits and high and low costs. In the second study, we measured the change in social emotions after contextual information about the loan was revealed. In the third study, we measured social emotions and repayment intention, relative to two potential lenders.

In the first study, we found that people emotionally respond to welfare tradeoffs in interpersonal borrowing scenarios. For a huge majority of participants, emotions tracked the WTR: they anticipated higher negative emotions (guilt, shame, anger) when the benefit to the borrower was low or the cost to the lender was high, and higher positive emotions (gratitude) when the benefit to the borrower was high or the cost to the lender was high.

The second study explored indebtedness in the context of social emotions. We found that negative emotions (guilt) related to borrowing increased significantly more when the benefit of the loan was revealed to be low rather than high, while positive emotions (gratitude) increased more when the benefit was revealed to be high. Indebtedness increased in both situations, suggesting that it can be triggered by increases in either positive emotions or negative emotions.

In the final study, we found initial evidence that welfare tradeoffs influence not just emotions, but actual borrowing choices. When comparing two potential lenders, participants expected to feel more of all the social emotions (both positive and negative) when the lender asked for nothing in return (besides repaying the loan). These stronger emotions were linked to a curious choice: nearly a third of participants preferred to take on a loan from the other lender, who asked for a favor in addition to repayment, presumably to avoid anticipated negative emotions like guilt.

Despite how common informal borrowing is, it is little-studied compared to formal credit from banks or microfinance institutions. More research is needed in this area. Studying a wider range of cultures is particularly important: if borrowing activates our evolved cognitive systems, we would expect to see cross-cultural similarities in emotional responses. Future research might also explore the role of social emotions in formal borrowing. Most of the evidence about emotional reactions to borrowing comes from surveys about bank loans, with people reporting strong feelings that are linked to social context and responsibility. If social emotions also emerge in the context of formal credit, this suggests that social and reputational concern represents an additional, unappreciated element of financial inclusion.

Read the original paper here: Brackin, M., & Mercier, H. (2025). Owing others: debt, welfare tradeoffs, and the social emotions. Evolution and Human Behavior, 46(4), 106690.