Biological Markets
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Phelps, Ng,  Musolesi & Russell (2018). Precise time-matching in chimpanzee allogrooming does not occur after a short delay. PLOS ONE, 13(9), e0201810

Phelps, Ng,  Musolesi & Russell (2018). Precise time-matching in chimpanzee allogrooming does not occur after a short delay. PLOS ONE, 13(9), e0201810 | Biological Markets | Scoop.it
Allogrooming is a key aspect of chimpanzee sociality and many studies have investigated the role of reciprocity in a biological market. One theoretical form of reciprocity is time-matching, where payback consists of an equal duration of effort (e.g. twenty seconds of grooming repaid with twenty seconds of grooming). Here, we report a study of allogrooming in a group of twenty-six captive chimpanzees (Chester Zoo, UK), based on more than 150 hours of data. For analysis, we introduce a methodological innovation called the “Delta scale”, which unidimensionally measures the accuracy of time-matching according to the extent of delay after the cessation of grooming. Delta is positive when reciprocation occurs after any non-zero delay (e.g. A grooms B and then B grooms A after a five second break) and it is negative when reciprocation begins whilst the original grooming has not yet ceased. Using a generalized linear mixed-method, we found evidence for time-matched reciprocation. However, this was true only for immediate reciprocation (Delta less than zero). If there was a temporal break in grooming between two members of a dyad, then there was no evidence that chimpanzees were using new bouts to retroactively correct for time-matching imbalances from previous bouts. Our results have implications for some of the cognitive constraints that differentiate real-life reciprocation from abstract theoretical models. Furthermore, we suggest that some apparent patterns of time-matched reciprocity may arise merely due to the law of large numbers, and we introduce a statistical test which takes this into account when aggregating grooming durations over a window of time.
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Noë & Kiers (2018). "Mycorrhizal markets, firms, and co-ops." Trends in Ecology & Evolution (online) ScienceDirect

Noë & Kiers (2018). "Mycorrhizal markets, firms, and co-ops." Trends in Ecology & Evolution (online) ScienceDirect | Biological Markets | Scoop.it
Highlights:
 The mutualism between plants and arbuscular mycorrhizal fungi shows several market characteristics, including partner choice and adjustments to supply and demand.

Nutrient exchanges via communally formed arbuscules reduce trading costs the same way the formation of firms reduces ‘transaction costs’ on human markets.

Plants may discriminate among individual arbuscules, which are associated with subsets of the many nuclei found in a single fungus.

Subsets of polymorphic nuclei acting in unison are like co-ooperatives (‘co-ops’), institutions midway between independently acting traders and firms, that help traders coordinate their trading strategies and reduce competition among themselves.

Future models of the evolution of mycorrhizal mutualisms should concurrently incorporate their market-, firm-, and co-op-like characteristics.

Abstract: The nutrient exchange mutualism between arbuscular mycorrhizal fungi (AMFs) and their host plants qualifies as a biological market, but several complications have hindered its appropriate use. First, fungal ‘trading agents’ are hard to identify because AMFs are potentially heterokaryotic, that is, they may contain large numbers of polymorphic nuclei. This means it is difficult to define and study a fungal ‘individual’ acting as an independent agent with a specific trading strategy. Second, because nutrient exchanges occur via communal structures (arbuscules), this temporarily reduces outbidding competition and transaction costs and hence resembles exchanges among divisions of firms, rather than traditional trade on markets. We discuss how fungal nuclei may coordinate their trading strategies, but nevertheless retain some independence, similar to human co-operatives (co-ops).

Keywords: arbuscular mycorrhizal fungibiological market theorymycorrhizal mutualismnutrient exchange mutualism
Ronald Noë's insight:
I perhaps better don't comment on my own papers, except perhaps to say that this is a special paper in several ways, among other things because it is the fruit of a cooperation between a mycorrhiza expert and an (ex-) primatologist and because it came online the last day before my retirement.

I hope it contains a few ideas worth giving a bit of thought.
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Jiang, Xia, Wang, Zhang, Sun & Li (2018). Interchange between grooming and infant handling in female Tibetan macaques (Macaca thibetana). Zoological Research, 79-

Jiang, Xia, Wang, Zhang, Sun & Li (2018). Interchange between grooming and infant handling in female Tibetan macaques (Macaca thibetana). Zoological Research, 79- | Biological Markets | Scoop.it
Abstract: In some nonhuman primates, infants function as a social tool that can bridge relationships among group members. Infants are a desired commodity for group members, and mothers control access to them. The biological market theory suggests that grooming is widespread and represents a commodity that can be exchanged for infant handling. As a limited resource, however, the extent to which infants are interchanged between mothers (females with an infant) and non-mothers (potential handlers, females without an infant) remains unclear. In this study, we collected behavioral data to investigate the relationship between grooming and infant handling in free-ranging Tibetan macaques (Macaca thibetana) at Mt. Huangshan, China. Our results showed that females with infants received more grooming than females without infants. After her infant was handled, mother females received more grooming than they did during daily grooming interactions. However, with the increasing number of infants within the social group, both the grooming that mothers received and the grooming that non-mothers invested for handling infants decreased. We also found that non-mothers invested more time in grooming to gain access to younger infants than older infants. Our results provide evidence that infants are social commodities for both mother and non-mother females. Mothers use infants for obtain grooming and non-mothers use grooming to gain access to infants. The current study implies a bidirectional and complex interchange pattern between grooming and infant handling to compensate for the dyadic grooming disparity in non-human primates.

Keywords: Tibetan macaques (Macaca thibetana) Interchange Infant handling Grooming Biological market theory
Ronald Noë's insight:
Monkeys, and especially female monkeys, are very eager to inspect and handle newborn babies, but in many species they have to groom the mother in order to get permission to do so. The amount of grooming they have to spend most often depends on three factors: the dominance relationship between handler and mother (the 'grooming-up-the-hierarchy' effect; the age of the infant (the younger, the higher the value) and the number of infants relative to the number of would-be handlers (the effect of supply and demand). The authors of this study managed to show all three effects convincingly in the rarely studied Tibetian macaque.
The keyword they did not use, but under which this phenomenon is often described is 'baby market'.
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Ueno & Nakamichi (2018). Grooming facilitates huddling formation in Japanese macaques. Behavioral Ecology and Sociobiology, 72(6), 98

Ueno & Nakamichi (2018). Grooming facilitates huddling formation in Japanese macaques. Behavioral Ecology and Sociobiology, 72(6), 98 | Biological Markets | Scoop.it

Abstract: Some animals conserve body heat through physical contact with conspecifics (i.e., huddling) under cold climate conditions. However, the factors that promote huddle partner selection have not been clarified. We hypothesized that exchanging grooming for huddling is a beneficial strategy used by female Japanese macaques (Macaca fuscata) to withstand cold temperatures. In this study, we undertook focal sampling of 17 female macaques at Katsuyama, Okayama Prefecture, Japan, between April 2012 and March 2013. We used generalized linear mixed models and determined influential factors based on the Akaike information criterion. As a result, we found that female Japanese macaques were likely to participate in grooming interactions before huddling with adult females, but that they rarely did so before huddling with their young (1-year-old or younger) offspring. In particular, adult females tended to huddle with other adult females after unreciprocated grooming bouts. Moreover, they solicited return grooming less frequently when females huddled after grooming interactions than when they did not huddle after grooming interactions. Finally, we evaluated whether grooming improved huddling position. Immediately after grooming, females huddled at advantageous positions more often than they huddled without grooming, and relative benefit by huddling position in the groomer was likely to be larger than the groomee. In contrast, when females huddled after reciprocal grooming, females tended to huddle in positions that were equally beneficial to both females. Overall, our results suggest that female Japanese macaques, particularly those without young offspring, exchange grooming for huddling with other adult females.


Keywords: thermoregulation reciprocity cooperative behaviors young offspring primates

Ronald Noë's insight:
Over the years many commodities have been mentioned that primates can trade against their 'common currency' grooming: support in fights, tolerance in food patches, access to infants, sex etc. These authors add another one that is of special interest for a primate that lives in a cold climate: huddling.
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D'Souza, Shitut, Preussger, Yousif, Waschina & Kost (2018). Ecology and evolution of metabolic cross-feeding interactions in bacteria. Natural Product Reports, 35(5), 455-488

D'Souza, Shitut, Preussger, Yousif, Waschina & Kost (2018). Ecology and evolution of metabolic cross-feeding interactions in bacteria. Natural Product Reports, 35(5), 455-488 | Biological Markets | Scoop.it

Abstract: Literature covered: early 2000s to late 2017

Bacteria frequently exchange metabolites with other micro- and macro-organisms. In these often obligate cross-feeding interactions, primary metabolites such as vitamins, amino acids, nucleotides, or growth factors are exchanged. The widespread distribution of this type of metabolic interactions, however, is at odds with evolutionary theory: why should an organism invest costly resources to benefit other individuals rather than using these metabolites to maximize its own fitness? Recent empirical work has shown that bacterial genotypes can significantly benefit from trading metabolites with other bacteria relative to cells not engaging in such interactions. Here, we will provide a comprehensive overview over the ecological factors and evolutionary mechanisms that have been identified to explain the evolution and maintenance of metabolic mutualisms among microorganisms. Furthermore, we will highlight general principles that underlie the adaptive evolution of interconnected microbial metabolic networks as well as the evolutionary consequences that result for cells living in such communities.

Ronald Noë's insight:
This is a somewhat overwhelming (433 refs!) review of trading among baxcteria and between bacteria and other organisms. Trade doesn't necessarily to markets, but in combination with partner choice, which is also extensively reviewed, one is close enough even if the word 'market' doesn't appear in the text. In any case a rich source for all those struggling to keep up with the recent literature on trade involving bacteria.
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Shu, Zhang, Queller & Strassmann (2018). Burkholderia bacteria use chemotaxis to find social amoeba Dictyostelium discoideum hosts. The ISME Journal

Shu, Zhang, Queller & Strassmann (2018). Burkholderia bacteria use chemotaxis to find social amoeba Dictyostelium discoideum hosts. The ISME Journal | Biological Markets | Scoop.it

Abstract: A key question in cooperation is how to find the right partners and maintain cooperative relationships. This is especially challenging for horizontally transferred bacterial symbionts where relationships must be repeatedly established anew. In the social amoeba Dictyostelium discoideum farming symbiosis, two species of inedible Burkholderia bacteria (Burkholderia agricolaris and Burkholderia hayleyella) initiate stable associations with naive D. discoideum hosts and cause carriage of additional bacterial species. However, it is not clear how the association between D. discoideum and its carried Burkholderia is formed and maintained. Here, we look at precisely how Burkholderia finds its hosts. We found that both species of Burkholderia clones isolated from D. discoideum, but not other tested Burkholderia species, are attracted to D. discoideum supernatant, showing that the association is not simply the result of haphazard engulfment by the amoebas. The chemotactic responses are affected by both partners. We find evidence that B. hayleyella prefers D. discoideum clones that currently or previously carried Burkholderia, while B. agricolaris does not show this preference. However, we find no evidence of Burkholderia preference for their own host clone or for other hosts of their own species. We further investigate the chemical differences of D. discoideum supernatants that might explain the patterns shown above using a mass spectrometry based metabolomics approach. These results show that these bacterial symbionts are able to preferentially find and to some extent choose their unicellular partners. In addition, this study also suggests that bacteria can actively search for and target phagocytic cells, which may help us better understand how bacteria interact with immune systems.

Ronald Noë's insight:
This is not really about tiny markets, but shows that bacteria can exert partner choice very well. The amoeba of this paper are known for their habit of 'farming' bacteria. Farming is made possible with the help of the Burkholderia-bacteria, which are not suited as amoebe-food themselves. In this paper the authors show that two species of Burkholderia actively seek out their amoebe-hosts by chemotaxis. This mechansism of partner choice is also know from other mutualistic bacteria, such as the rhizobia (attracted to plant roots where they become N-providers in nodules formed on the roots) and Vibrio that enter the light organs of bobtail squids where they take care of the light production (bioluminiscence) their hosts need as a kind of camouflage.
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Smith, Larroucau, Mabulla & Apicella (2018). Hunter-gatherers maintain assortativity in cooperation despite high-levels of residential change and mixing. bioRxiv

Smith, Larroucau, Mabulla & Apicella (2018). Hunter-gatherers maintain assortativity in cooperation despite high-levels of residential change and mixing. bioRxiv | Biological Markets | Scoop.it

Abstract: Widespread cooperation is a defining feature of human societies from hunter-gatherer bands to nation states. But explaining its evolution remains a challenge. While positive assortment of cooperators with cooperators is recognized as a basic requirement for the evolution of cooperation, the mechanisms governing assortment are debated. Moreover, the social structure of modern hunter-gatherers, characterized by high mobility, residential mixing and low genetic relatedness, undermine assortment and add to the puzzle of how cooperation evolved. Here, we analyze four years of data (2010, 2013, 2014, 2016) tracking residence and levels of cooperation elicited from a public goods game (PG), in Hadza hunter-gatherers of Tanzania. Data were collected from 56 camps, comprising 383 unique individuals, 137 of whom we have data for two or more years. Despite significant residential mixing, we observe a robust pattern of assortment necessary for cooperation to evolve: In every year, Hadza camps exhibit high between-camp and low within-camp variation in cooperation. We further consider the role of homophily in generating this assortment. We find little evidence that cooperative behavior within individuals is stable over time or that similarity in cooperation between dyads predicts their future cohabitation. Both sets of findings are inconsistent with homophilic models that assume stable cooperative and selfish types (e.g. partner choice). Consistent with social norms, culture and reciprocity theories, the data suggest that the strongest predictor of an individual's level of cooperation in any given year is the mean cooperation of their campmates in that year. These findings underscore the adaptive nature of human cooperation - particularly its responsiveness to social contexts - as a feature important in generating the assortment necessary for cooperation to evolve.


Keywords: evolution of cooperation, homophily, partner choice, social influence, social norms, hunter-gatherers

Ronald Noë's insight:
The authors measured the tendency of Hadza hunter-gatherers from northern Tanzania to form groups living together in camps on the basis of cooperativeness. I listed this paper here, because it tests ‘partner choice models’, among others, and refers to BMT as one of those. The tendency of to cooperate is measured as an individual’s contribution in a public goods game (PGG) over several years. The authors neither find assortment on the basis of average contributions in the PGG (‘homophily’), nor a tendency to move to camps with generous contributors or to stay with the latter. They interpret this as lack of support for partner choice models.
I am not sure that I indeed recognise BMT as a model tested here. BMT is about dyadic cooperation and I am not convinced an n-player game tests the tendency to cooperate in a two-player situation very well. BMT also doesn’t predict choice on the basis of cooperativeness as such, but on the basis of profitability as a partner, which also depends on factors such as the partner’s status, skill, knowledge etc.. The authors indeed mention this problem. Moreover, BMT would only predict assortment in the sense measured here, if cooperativeness would be the major factor determining profitability AND competition over partners would force less cooperative ‘choosers’ to settle for less cooperative partners. It is not clear to me, however, that such competition takes place, i.e. that individuals are forced out of groups or that group sizes are strictly limited. In short, I find the paper highly interesting as such, but I am not convinced it reports a valid test of BMT.
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Finkenwirth & Burkart (2018). Why help? Relationship quality, not strategic grooming predicts infant-care in group-living marmosets. Physiology & Behavior

Finkenwirth & Burkart (2018). Why help? Relationship quality, not strategic grooming predicts infant-care in group-living marmosets. Physiology & Behavior | Biological Markets | Scoop.it
Abstract: Cooperatively breeding common marmosets raise their infants with the help of other adult group members, but individual care-taking contribution can vary considerably. We tested four hypotheses that may explain this variation within marmoset family groups. The pay-for-help hypothesis argues that allogrooming is used strategically by parents to pay helpers for helping. The pay-for-infant-access hypothesis claims that helpers use allogrooming as payment for infant-access. The intrinsic predisposition hypothesis suggests that more affiliative individuals are also more motivated for infant-care, and the relationship quality hypothesis that individuals involved in highly affiliative relationships with main caregivers contribute more to infant-care. To test these hypotheses, we followed five marmoset family groups over a total of eight reproductive cycles, and quantified affiliative behavior, infant-carrying, and food sharing over six to 12 weeks around infant-birth. We found no evidence for either the pay-for-help or pay-for-infant-access hypotheses nor did intrinsic prosocial predisposition determine individual infant-care. Mutual dyadic affiliation, however, was positively linked to infant-carrying and food sharing in female and male breeders and in male helpers. This suggests that cooperation during infant-care is mediated by relationship quality rather than strategic grooming in marmosets. Overall, these results may also contribute to a better understanding of cooperation in humans.

Keywords: Common marmoset; Infant-care; Prosociality; Relationship quality; Pay-for-infant-access; Pay-for-help
Ronald Noë's insight:
The authors show (and explain why) cooperative breeding common marmoset helpers neither pay for access to infants, nor - as has been reported previously - are paid for their help in caring for the infants. Rather than using grooming strategically as a payment for some othre commodity, the marmoset seem to base their grooming decisions on individual relationship quality.
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Hunt, Ortiz-Hunt & Lerner (2018). Entrepreneurial action among non-humans. Conference paper for: Babson College Entrepreneurship Research Conference, Waterford, Ireland, June 2018

Hunt, Ortiz-Hunt & Lerner (2018). Entrepreneurial action among non-humans. Conference paper for: Babson College Entrepreneurship Research Conference, Waterford, Ireland, June 2018 | Biological Markets | Scoop.it
Our study in first to undertake a comprehensive investigation that relaxes the central assumption that entrepreneurial activity is the exclusive domain of human beings. Doing so illuminates new frontiers regarding the biological origins of innovation and entrepreneurship. Using a database consisting of 134,000 coded behaviors from 2,572 hours of activity by chimpanzees, elephants, canines, rabbits, woodpeckers, and wrasses, we sought evidence regarding six forms of entrepreneurship: rent-seeking, social, cultural, institutional, environmental and inter-species. Our findings suggest, to varying degrees, that all six forms are observable in non-human species.
Ronald Noë's insight:
Three authors from economics departments and business schools wade into the world of non-human trade and markets. By grazing through the biological literature, which must be a daunting task for them, they attempt to assess whether non-human organisms can be classified as 'entrepreneurs' (a word that has no equivalent in French, as George W. Bush once remarked).

The present paper is obviously a work in progress and the authors will probably find that there is a lot more to discover, but they already get a long way.
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The Invisible Paw - on Freakonomics Radio

The Invisible Paw - on Freakonomics Radio | Biological Markets | Scoop.it
Humans, it has long been thought, are the only animal to engage in economic activity. But what if we've had it exactly backward?
Ronald Noë's insight:
Stephen Dubner interviews a number of economists and biologists (including myself) about the economic behaviour of non-human animals and biological markets in general.

This is a podcast of about 50 min, but you can also read the transcript (eventually while listening of course).

Something completely different: ScoopIt suddenly changed its policy, forcing me to discard the 100+ older posts on these pages. I am sorry for that.
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Bliege Bird, Ready & Power  (2018). The social significance of subtle signals. Nature Human Behaviour

Bliege Bird, Ready & Power  (2018). The social significance of subtle signals. Nature Human Behaviour | Biological Markets | Scoop.it

Abstract: Acts of prosociality, such as donating to charity, are often analysed in a similar way to acts of conspicuous advertising; both involve costly signals revealing hidden qualities that increase the signaller’s prestige. However, experimental work suggests that grand gestures, even if prosocial, may damage one’s reputation for trustworthiness and cooperativeness if they are perceived as prestige enhancing: individuals may gain some types of cooperative benefits only when they perform prosocial acts in particular ways. Here, we contrast subtle, less obviously costly, interpersonal forms of prosocial behaviour with high-cost displays to a large audience, drawing on the example of food sharing in subsistence economies. This contrast highlights how highly visible prosocial displays may be effective for attracting new partners, while subtle signals may be crucial for ensuring trust and commitment with long-term partners. Subtle dyadic signals may be key to understanding the long-term maintenance of interpersonal networks that function to reduce unanticipated risks.A highly interesting review in which two rather distinct forms of signalling by showing generous (‘altruistic’) behaviour are compared, notably in the context of food sharing: public displays of superior abilities of producing and offering resources, such as the Meriam turtle hunters giving away their complete catch and much more private gifts, which are often reciprocal and can even consist of exchanges of food of the same quality and quantity, such as by Martu women exchanging lizards. The authors propose that the function of the blatant public form is to advertise one’s value as a partner, which notably plays a role in the context of partner choice. They suggest the second, more subtle form plays a role in the maintenance of existing relationships, both among kin and non-kin. Such relationships are valuable, not because of the daily food exchanges, but as an assurance of support in unexpected disastrous events. The latter reminds of the use of grooming in primates, which is also a low cost, regular investment in partners that can eventually be important as supporters in unexpected conflicts. Grooming can also be used to pay up front for privileges that are immediately obtained, such as being allowed to enter a food patch, holding an infant or being allowed to mate. Improved reproductive success is also one major reward for skilled hunters doling out meat in several hunter-gatherer societies. Unsurprisingly, non-human and human primates are very similar; the latter only do everything in a more exaggerated and over-the-top way, it seems.

Ronald Noë's insight:
A highly interesting review in which two rather distinct forms of signalling by showing generous (‘altruistic’) behaviour are compared, notably in the context of food sharing: public displays of superior abilities of producing and offering resources, such as the Meriam turtle hunters giving away their complete catch and much more private gifts, which are often reciprocal and can even consist of exchanges of food of the same quality and quantity, such as by Martu women exchanging lizards. The authors propose that the function of the blatant public form is to advertise one’s value as a partner, which notably plays a role in the context of partner choice. They suggest the second, more subtle form plays a role in the maintenance of existing relationships, both among kin and non-kin. Such relationships are valuable, not because of the daily food exchanges, but as an assurance of support in unexpected disastrous events. The latter reminds of the use of grooming in primates, which is also a low cost, regular investment in partners that can eventually be important as supporters in unexpected conflicts. Grooming can also be used to pay up front for privileges that are immediately obtained, such as being allowed to enter a food patch, holding an infant or being allowed to mate. Improved reproductive success is also one major reward for skilled hunters doling out meat in several hunter-gatherer societies. Unsurprisingly, non-human and human primates are very similar; the latter only do everything in a more exaggerated and over-the-top way, it seems.
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Schweinfurth & Taborsky (2018). Reciprocal trading of different commodities in norway rats. Current Biology

Schweinfurth & Taborsky (2018). Reciprocal trading of different commodities in norway rats. Current Biology | Biological Markets | Scoop.it

Highlights:

 •Norway rats reciprocally trade food for allogrooming, and vice versa

•Experimental proof of tit-for-tat-like exchange of different services in animals

•The study suggests that reciprocal commodity trading in animals may be common 


Summary: The prevalence of reciprocal cooperation in non-human animals is hotly debated [ 1, 2 ]. Part of this dispute rests on the assumption that reciprocity means paying like with like [ 3 ]. However, exchanges between social partners may involve different commodities and services. Hitherto, there is no experimental evidence that animals other than primates exchange different commodities among conspecifics based on the decision rules of direct reciprocity. Here, we show that Norway rats (Rattus norvegicus) apply direct reciprocity rules when exchanging two different social services: food provisioning and allogrooming. Focal rats were made to experience partners either cooperating or non-cooperating in one of the two commodities. Afterward, they had the opportunity to reciprocate favors by the alternative service. Test rats traded allogrooming against food provisioning, and vice versa, thereby acting by the rules of direct reciprocity. This might indicate that reciprocal altruism among non-human animals is much more widespread than currently assumed.


Keywords: reciprocity, Rattus norvegicus, allogrooming, food provisioning, cooperation, helping, exchange, trade

Ronald Noë's insight:
This is not a market experiment, but nevertheless an interesting study that shows that rats, as many other organisms, can trade commodities of different kinds with each other.

The authors discuss the possibility of using rats in experiments in which partner choice is possible. I can only hope that they'll do so soon, since this would increase the validity for our understanding of the evolution of cooperative behaviour considerably.
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Claessens (2017). The benefits of being seen to be cooperative. MRes thesis. Dept. Evolution and Human Behaviour, Newcastle University

Claessens (2017). The benefits of being seen to be cooperative. MRes thesis. Dept. Evolution and Human Behaviour, Newcastle University | Biological Markets | Scoop.it
Abstract: Cooperation is an evolutionary puzzle as individuals pay fitness costs to benefit others. Yet cooperative behaviour is widespread in human society. One possible explanation is reputation-based partner choice (RBPC): cooperation acts as an honest signal of one's intentions to be generous in the future, and cooperators can then benefit by being chosen more often as interaction partners. Here, across two experiments, empirical support is provided for an agent-based model of RBPC, using a two-stage economic game where individuals could first use generosity to signal their intentions to cooperate, and then choose partners for a dyadic interaction. In Experiment 1, cooperation in the first stage acted as an honest signal of cooperative intentions, and individuals chose partners on the basis of these signals. However, contrary to the model's predictions, individuals also signalled when the cost of doing so outweighed the benefits of the partnership, and these signals remained honest even when they were inexpensive. In Experiment 2, partner choice was also based on signals of cooperative intent, even when wealth was varied. However, partners were also chosen on the basis of wealth, and when there was a trade-off between cooperative reputation and wealth participants showed no marked preference for either. These results broadly fit with an RBPC account of human cooperation, but amendments to the theory are offered, as well as suggestions for future modelling and empirical work.
Ronald Noë's insight:
This is a master thesis supervised by Gilbert Roberts describing two experiments to test a yet unpublished model by Gilbert (entitled "Reputations as signals of commitment"). This model is based on the idea of "competitive altruism" (CA) (Roberts, G. (1998). Competitive altruism: from reciprocity to the handicap principle. Proceedings of the Royal Society, London, B., 265, 427-431). The idea is basically the same as of BMT, but specifically for humans and more focussed on the effect of reputation. Pat Barclay nicely explains the connection between CA and BMT in several of his papers (see below for a reference to one of them).

One interesting conclusion is summed up in the following sentence: "Both these findings together highlight the importance of considering RBPC (= reputation-based partner choice) within the wider umbrella of biological market theory, where potential social partners are evaluated on the basis of not just willingness to give, but also ability to give (40)." (Ref 40 = Barclay P. Strategies for cooperation in biological markets, especially for humans. Evolution and Human Behavior. 2013;34(3):164-75.)

In other words: repuation is certainly important, but to be chosen as a partner one should not only have a good repuation but notably a better reputation than those competing for the same partnership. Moreover, a good reputation alone doesn't necessarily makes one a desired partner; one must also have the capacity of delivering benefits. Margaret Tatcher already had this insight according to a quote in the thesis. Worth reading!
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"Not your typical fish market" by Rebecca Parsons (Georgia Dolphins Ecology Program)

"Not your typical fish market" by Rebecca Parsons (Georgia Dolphins Ecology Program) | Biological Markets | Scoop.it

First par.: Obviously, we here at GDEP have a lot of love for big, charismatic, marine animals. Marine mammals such as orcas and dolphins are known for their intelligence, complex social structure, and beauty. We could go on and on about the interesting facets of cetacean species (and we have), but today we’re taking a moment to appreciate the not-so-glamorous little guys, the unsung heroes of the deep sea.

Ronald Noë's insight:
A popular science-style account of "fish markets"in the sense of BMT. Unfortunately there is one consistent misspelling: Redouan's surname is Bsary, not Bshari
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Mielke, Preis, Samuni, Gogarten, Wittig & Crockford (2018). Flexible decision-making in grooming partner choice in sooty mangabeys and chimpanzees. Royal Society Open Science, 5(7)

Mielke, Preis, Samuni, Gogarten, Wittig & Crockford (2018). Flexible decision-making in grooming partner choice in sooty mangabeys and chimpanzees. Royal Society Open Science, 5(7) | Biological Markets | Scoop.it

Abstract: Living in permanent social groups forces animals to make decisions about when, how and with whom to interact, requiring decisions to be made that integrate multiple sources of information. Changing social environments can influence this decision-making process by constraining choice or altering the likelihood of a positive outcome. Here, we conceptualized grooming as a choice situation where an individual chooses one of a number of potential partners. Studying two wild populations of sympatric primate species, sooty mangabeys ( Cercocebus atys atys ) and western chimpanzees ( Pan troglodytes verus ), we tested what properties of potential partners influenced grooming decisions, including their relative value based on available alternatives and the social relationships of potential partners with bystanders who could observe the outcome of the decision. Across 1529 decision events, multiple partner attributes (e.g. dominance ranks, social relationship quality, reproductive state, partner sex) influenced choice. Individuals preferred to initiate grooming with partners of similar global rank, but this effect was driven by a bias towards partners with a high rank compared to other locally available options. Individuals also avoided grooming partners who had strong social relationships with at least one bystander. Results indicated flexible decision-making in grooming interactions in both species, based on a partner's value given the local social environment. Viewing partner choice as a value-based decision-making process allows researchers to compare how different species solve similar social problems.


Keywaords: grooming bystanders sooty mangabey chimpanzee decision-making

Ronald Noë's insight:
What is really nice about this paper, is that the authors consider the decisions of primates who to groom when and for how long, as a result of a dynamic decision process the outcome of which can be different from day to day and situation to situation. The paper gives the impression that we are finally approaching the end of a long road that started with tit-for-tatting individuals taking always the same kind of decisions based on rigid rules that took a limited number of parameters such as kinship, rank-distance and the (recent) experiences with the same partner into account.
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Thomson, Yuki, Talhelm, Schug, Kito, Ayanian, . . . Visserman (2018). Relational mobility predicts social behaviors in 39 countries and is tied to historical farming and threat. Proceedings of the ...

Thomson, Yuki, Talhelm, Schug, Kito, Ayanian, . . . Visserman (2018). Relational mobility predicts social behaviors in 39 countries and is tied to historical farming and threat. Proceedings of the ... | Biological Markets | Scoop.it

Abstract: Biologists and social scientists have long tried to understand why some societies have more fluid and open interpersonal relationships—differences in relational mobility—and how those differences influence individual behaviors. We measure relational mobility in 39 societies and find that relationships are more stable and hard to form in east Asia, North Africa, and the Middle East, while they are more fluid in the West and Latin America. Results show that relationally mobile cultures tend to have higher interpersonal trust and intimacy. Exploring potential causes, we find greater environmental threats (like disease and warfare) and sedentary farming are associated with lower relational mobility. Our society-level index of relational mobility for 39 societies is a resource for future studies.Biologists and social scientists have long tried to understand why some societies have more fluid and open interpersonal relationships and how those differences influence culture. This study measures relational mobility, a socioecological variable quantifying voluntary (high relational mobility) vs. fixed (low relational mobility) interpersonal relationships. We measure relational mobility in 39 societies and test whether it predicts social behavior. People in societies with higher relational mobility report more proactive interpersonal behaviors (e.g., self-disclosure and social support) and psychological tendencies that help them build and retain relationships (e.g., general trust, intimacy, self-esteem). Finally, we explore ecological factors that could explain relational mobility differences across societies. Relational mobility was lower in societies that practiced settled, interdependent subsistence styles, such as rice farming, and in societies that had stronger ecological and historical threats.


Keywords: relational mobility culture socioecology multicountry interpersonal relationships

Ronald Noë's insight:
The link between this paper and BMT is perhaps not obvious, but recognized by the authors: more relational mobility means more freedom to choose social partners, which translates into a more open and volatile market of relationships.

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Kern & Radford (2018). Experimental evidence for delayed contingent cooperation among wild dwarf mongooses. Proceedings of the National Academy of Sciences (PNAS)

Kern & Radford (2018). Experimental evidence for delayed contingent cooperation among wild dwarf mongooses. Proceedings of the National Academy of Sciences (PNAS) | Biological Markets | Scoop.it

Abstract: Humans frequently trade goods and can track the amount they owe using memories of past exchanges. While nonhuman animals are also known to be capable of trading cooperative acts immediately for one another, more contentious is the possibility that there can be delayed rewards. We use detailed field observations, social-network analyses, and a playback experiment to demonstrate that wild dwarf mongooses provide more grooming to those groupmates who contribute more to sentinel behavior (acting as a raised guard to look out for danger). We therefore provide experimental evidence of delayed contingent cooperation, and cross-commodity exchange, in a wild nonprimate.

Many animals participate in biological markets, with strong evidence existing for immediate cooperative trades. In particular, grooming is often exchanged for itself or other commodities, such as coalitionary support or access to food and mates. More contentious is the possibility that nonhuman animals can rely on memories of recent events, providing contingent cooperation even when there is a temporal delay between two cooperative acts. Here we provide experimental evidence of delayed cross-commodity grooming exchange in wild dwarf mongooses ( Helogale parvula ). First, we use natural observations and social-network analyses to demonstrate a positive link between grooming and sentinel behavior (acting as a raised guard). Group members who contributed more to sentinel behavior received more grooming and had a better social-network position. We then used a field-based playback experiment to test a causal link between contributions to sentinel behavior and grooming received later in the day. During 3-h trial sessions, the perceived sentinel contributions of a focal individual were either up-regulated (playback of its surveillance calls, which are given naturally during sentinel bouts) or unmanipulated (playback of its foraging close calls as a control). On returning to the sleeping refuge at the end of the day, focal individuals received more grooming following surveillance-call playback than control-call playback and more grooming than a matched individual whose sentinel contributions were not up-regulated. We believe our study therefore provides experimental evidence of delayed contingent cooperation in a wild nonprimate species.


Keywords: biological markets delayed rewards economic behavior reciprocity social information

Ronald Noë's insight:
The authors report both observational data and the results of a beautiful experiment showing that dwarf mongooses reward group members with grooming before going to bed for their sentinel duties during the day. Sentinel behaviour is typical for social mongooses: one or two animals stand on a higher position and look out for the raptors that are ready to attack any time. Sentinels advertise their work with a special call and their group members regularly check the presence of sentinels. The 'sentinel call' is what is used in this study: by using playbacks one can suggest additional duties of an individual that is in fact quietly going about in his daily business.

Compared to primates, with whom a number of more or less comparable studies have been done, the dwarf mongooses have a number of advantages: (1) one can more easily work with multiple groups (here 12 groups in total; playback trials done in 5), (2) doing sentinel duty is a public good that benefits all group members equally and (3) sentinel behaviour is shown during the day, while the grooming is done in the evening at the den, so quite a bit of time may pass between service and reward.

All together the result show that the market value of diligent sentinels increases. All group members are inclined to reward them and not only the dominants or their best friends or their close kin. Worth reading!
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Freitas, DeScioli, Thomas & Pinker (2018). Maimonides’ ladder: States of mutual knowledge and the perception of charitability. Dept. Psychology, Harvard, Dept Political Science, Stony Brook (draft)

Freitas, DeScioli, Thomas & Pinker (2018). Maimonides’ ladder: States of mutual knowledge and the perception of charitability. Dept. Psychology, Harvard, Dept Political Science, Stony Brook (draft) | Biological Markets | Scoop.it
Abstract: Why do people esteem anonymous charitable giving? We connect normative theories of charitability (captured in Maimonides’ Ladder of Charity) with evolutionary theories of partner choice to test predictions on how attributions of charitability are affected by states of knowledge: whether the identity of the donor or of the beneficiary is revealed to the other. Consistent with the theories, in Experiments 1-2 participants judged a double-blind gift as more charitable than one to a revealed beneficiary, which in turn was judged as more charitable than one from a revealed donor. We also found one exception: Participants judged a donor who revealed only himself as slightly less, rather than more, charitable than one who revealed both identities. Experiment 3 explains the exception as a reaction to the donor’s perceived sense of superiority and disinterest in a social relationship. Experiment 4 found that donors were judged as more charitable when the gift was shared knowledge (each aware of the other’s identity, but unsure of the other’s awareness) than when it was common knowledge (awareness of awareness). Experiment 5, which titrated anonymity against donation size, found that not even a hundredfold larger gift could compensate for the disapproval elicited by a donor revealing his identity. Experiments 6-7 showed that participants’ judgments of charitability flip depending on whose perspective they take: observers disapprove of donations that they would make as donors and would prefer as beneficiaries. Together, these experiments provide insight into why people care about how a donor gives, not just how much.

Keywords: Charity; partner choice; reciprocity; common knowledge
Ronald Noë's insight:
This draft paper departs from the idea that people choose their partners on a market of potential candidates, based on the information they have of the latters' cooperative and altruistic behaviour. But what is the criterion for preferring one person over another? This depends on the chooser's estimates of the motives for altruism, but also on knowledge of the relationship between donor and receiver and so forth.

The authors use a classification proposed by the 12th century philosopher Maimonides as inspiration for a series of experiments in which they manipulated the various relevant parameters. The result is a rather long paper that I will soon read in more detail.
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Geoffroy, Baumard & André (2018). Why cooperation is not running away. bioRxiv

Geoffroy, Baumard & André (2018). Why cooperation is not running away. bioRxiv | Biological Markets | Scoop.it

Abstract: A growing number of experimental and theoretical studies show the importance of partner choice as a mechanism to promote the evolution of cooperation, especially in humans. In this paper, we focus on the question of the precise quantitative level of cooperation that should evolve under this mechanism. Using a classic adaptive dynamics model, we first highlight the existence of a paradox. When individuals compete to be chosen by others, their level of investment in cooperation evolves towards ever-higher values, a process called competitive altruism, or runaway cooperation. Our model shows that this runaway process leads to a profitless escalation of the level of cooperation, up to the point where the cost of cooperation exactly cancels out its benefit. In other words, at first sight, under the effect of partner choice we predict that cooperation should have no benefit at ESS. Second, importing models from matching theory in economics we, however, show that, when individuals can plastically modulate their choosiness in function of their own cooperation level, partner choice stops being a runaway competition to outbid others, and becomes a competition to form the most optimal partnerships. Assortative partner choice then leads to the evolution of the socially optimum level of cooperation. This result could explain the observation that human cooperation seems to be often constrained by considerations of social efficiency.


Keywords: partner choice, biological markets, matching models, competitive altruism, human cooperation

Ronald Noë's insight:
This what looks like – to me at least – a very elegant model of the effects of partner choice and the levels of cooperative investment on the evolution of cooperation. The work builds on an extensive number of previous theoretical studies of the same problem, notably those of McNamara etal 2008 and previous work of the same group (Debove, André & Baumard), as well as ‘search and matching’ models from economics

The authors obviously had human cooperation in mind, but their results are much more general than that and could apply to many more intra- and inter-specific biological markets. The authors do not simply try to explain whether cooperation can emerge and remain stable as such, but notably at what level of investment in choosiness and cooperation it should stabilise. With the help of a first model they show the risk of runaway processes that end up in such a high investment in partner choice that the costs are no longer compensated by the benefits of cooperation. This problem will look familiar to those who remember the early days of sexual selection models.
They then introduce a more elaborate model in which the level of choosiness is coupled to the level of cooperative investment, which shows phenotypic variation. In this model assortative matching occurs whereby partners match each other in the level of investment and the runaway problem disappears.
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Christian & Bever (2018). Carbon allocation and competition maintain variation in plant root mutualisms. Ecology and Evolution

Christian & Bever (2018). Carbon allocation and competition maintain variation in plant root mutualisms. Ecology and Evolution | Biological Markets | Scoop.it
Abstract: Plants engage in multiple root symbioses that offer varying degrees of benefit. We asked how variation in partner quality persists using a resource‐ratio model of population growth. We considered the plant's ability to preferentially allocate carbon to mutualists and competition for plant carbon between mutualist and nonmutualist symbionts. We treated carbon as two nutritionally interchangeable, but temporally separated, resources—carbon allocated indiscriminately for the construction of the symbiosis, and carbon preferentially allocated to the mutualist after symbiosis establishment and assessment. This approach demonstrated that coexistence of mutualists and nonmutualists is possible when fidelity of the plant to the mutualist and the cost of mutualism mediate resource competition. Furthermore, it allowed us to trace symbiont population dynamics given varying degrees of carbon allocation. Specifically, coexistence occurs at intermediate levels of preferential allocation. Our findings are consistent with previous empirical studies as well the application of biological market theory to plantroot symbioses.

Keywords: biological market theory cheating preferential allocation resource competition species coexistence
Ronald Noë's insight:
At first I was a bit irritated to see "biological market theory" in the keywords and all over the text, but without any reference to the source of the concept. This is science culture I cannot get used to.

However, after reading the paper, I rather prefer BMT not to be associated with this kind of approach. BMT assumes adaptation at the individual level due to partner choice. One known problem of partner choice models, including sexual selection models, is that at some point the variation in the partner trait on which the choice is based may disappear from the population of potential partners to choose from. One therefore has to explain how variation is maintained, since this also explains why partner choice itself is maintained in spite of fitness costs compared to no choice (i.e. a random choice of partners).

Oddly enough, the authors mention this problem, but then build a model on the basis of a population of potential partners that consists of only two types: mutualists and non-mutualists. By doing that they eliminate the variation that is important to BMT. One cannot really understand how the price of bread is determined by the choices clients make if one models the bakery-market with only two types of shops: those that sell bread for a uniform fixed price and those that sell no bread at all. In other words, I have the impression that adaptation due to partner choice is placed at the wrong level here: populations rather than individuals. I acknowledge that one runs into problems with the concept ‘individual’ in the case of mycorrhizal fungi, but that doesn’t mean that one should resort to a kind of selection at the species level as if ‘Williams 1966’ was never written.
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Pleasant & Barclay (2018). Why hate the good guy? Antisocial punishment of high cooperators is greater when people compete to be chosen. Psychological Science, 0956797617752642

Pleasant & Barclay (2018). Why hate the good guy? Antisocial punishment of high cooperators is greater when people compete to be chosen. Psychological Science, 0956797617752642 | Biological Markets | Scoop.it
Abstract: When choosing social partners, people prefer good cooperators (all else being equal). Given this preference, people wishing to be chosen can either increase their own cooperation to become more desirable or suppress others’ cooperation to make them less desirable. Previous research shows that very cooperative people sometimes get punished (“antisocial punishment”) or criticized (“do-gooder derogation”) in many cultures. Here, we used a public-goods game with punishment to test whether antisocial punishment is used as a means of competing to be chosen by suppressing others’ cooperation. As predicted, there was more antisocial punishment when participants were competing to be chosen for a subsequent cooperative task (a trust game) than without a subsequent task. This difference in antisocial punishment cannot be explained by differences in contributions, moralistic punishment, or confusion. This suggests that antisocial punishment is a social strategy that low cooperators use to avoid looking bad when high cooperators escalate cooperation.

Keywords: public-goods games, biological markets, partner choice, competitive altruism, do-gooder derogation
Ronald Noë's insight:
Aleta Pleasant and Pat Barclay report a new test of Pat's version of BMT for humans: do people compete to look better under the pressure of being chosen as a (cooperative) partner?

The authors rightly remark that one cannot only compete by being more generous than the next guy, but also by suppressing the generosity of that next guy. Although instances of this mechanism have been reported for animals (see Zahavi-reference in the paper), it is no doubt much more likely to see 'competitive altruism' (Gilbert Roberts' term) among humans.

The experiment consists of a public goods game (PGG; 5 rounds, 4 players) with an Observer in the 'market condition' and no Observer in the control condition. The Observer gets information about the participants contributions in the PGG and can then choose one of the 4 participants to play a Trust game in which extra money can be gained.

Both low and high contributions to the common pot attract punishment, but 'antisocial punishment' (paying a small amount to take away a bigger amount from someone who contributes above average) is seen much more in the market condition than in the control condition, as predicted.
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Intragroup social dynamics vary with the presence of neighbors in a cooperatively breeding fish | Current Zoology | Oxford Academic

Intragroup social dynamics vary with the presence of neighbors in a cooperatively breeding fish | Current Zoology | Oxford Academic | Biological Markets | Scoop.it

Abstract: Conflict is an inherent part of social life in group-living species. Group members may mediate conflict through submissive and affiliative behaviors, which can reduce aggression, stabilize dominance hierarchies, and foster group cohesion. The frequency and resolution of within-group conflict may vary with the presence of neighboring groups. Neighbors can threaten the territory or resources of the whole group, promoting behaviors that foster within-group cohesion. However, neighbors may also foster conflict of interests among group members: opportunities for subordinate dispersal may alter conflict among dominants and subordinates while opportunities for extra-pair reproduction may increase conflict between mates. To understand how neighbors mediate within-group conflict in the cooperatively breeding fish Neolamprologus pulcher, we measured behavioral dynamics and social network structure in isolated groups, groups recently exposed to neighbors, and groups with established neighbors. Aggression and submission between the dominant male and female pair was high in isolated groups, but dominant aggression was directly primarily at subordinates when groups had neighbors. This suggests that neighbors attenuate conflict between mates and foster conflict between dominants and subordinates. Further, aggression and submission between similarly-sized group members were most frequent when groups had neighbors, suggesting that neighbors induce rank-related conflict. We found relatively little change in within-group affiliative networks across treatments, suggesting that the presence of neighbors does not alter behaviors associated with promoting group cohesion. Collectively, these results provide some of the first empirical insights into the extent to which intragroup behavioral networks are mediated by intergroup interactions and the broader social context.


Keywords: exponential random graph model, Neolamprologus pulcher, colony, network, conflict, affiliation

Ronald Noë's insight:
A study of the effect of outside options on helpers in cichlid fish. I did not have the time to read this yet, but it looks interesting.
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McFarland (2018). Grooming. In: The International Encyclopedia of Biological Anthropology (Wiley)

McFarland (2018). Grooming. In: The International Encyclopedia of Biological Anthropology (Wiley) | Biological Markets | Scoop.it
Abstract: Grooming behavior is seen throughout the animal kingdom, but is particularly prevalent among the primates. Primate grooming is typically a bimanual process, whereby the groomer sweeps through the pelt with their hands, while removing dirt and ectoparasites from the skin or hair fibers with their hands or mouth. Grooming is thought to have evolved primarily for its hygienic function. The persistence of grooming in the absence of a hygienic demand, and its tactical importance to primate group members, however, supports the view that grooming also plays an important role in servicing social relationships and, in turn, can have a positive impact on an individual's reproductive fitness.

Keywords: behavior biological markets fitness hygiene social relationships
Ronald Noë's insight:
This is a short review of grooming in primates of the kind one can expect is such a reference work. Here is a small excerpt of the section relevant here:

"Grooming as a social commodity is based on the notion that each primate group serves as its own biological market (Noë & Hammerstein 1995). Commodities that exist in such a marketplace, and can potentially be exchanged for grooming, include, for example, reduced aggression, tolerance, agonistic support, access to mating opportunities, food sharing, and infant handling. The framework of a biological market explains how, and to what extent, grooming is exchanged within the group. The biological market approach stresses that individuals differ in the types of commodity they exchange with one another, that different commodities hold different values, and that the value and exchange rate of the commodity is also contingent on the value the recipient attributes to any given social partner. No two individuals are likely to value each other to the same degree, which means grooming exchange is unlikely to be symmetrical."
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Watanabe, Yoshimura & Hasegawa (2018). Ants improve the reproduction of inferior morphs to maintain a polymorphism in symbiont aphids. Scientific Reports, 8(1), 2313

Watanabe, Yoshimura & Hasegawa (2018). Ants improve the reproduction of inferior morphs to maintain a polymorphism in symbiont aphids. Scientific Reports, 8(1), 2313 | Biological Markets | Scoop.it

Abstract: Identifying stable polymorphisms is essential for understanding biodiversity. Distinctive polymorphisms are rare in nature because a superior morph should dominate a population. In addition to the three known mechanisms for polymorphism persistence, we recently reported a fourth mechanism: protection of the polymorphism by symbionts. Attending ants preferentially protect polymorphic aphid colonies consisting of green and red morphs. Here, we show that attending ants manipulate the reproductive rate of their preferred green morphs to equal that of the red morphs, leading to the persistence of the polymorphism within the colonies. We could not, however, explain how the ants maintained the polymorphism in aphid colonies regardless of inter-morph competition. Manipulation by symbionts may be important for the maintenance of polymorphisms and the resulting biodiversity in certain symbiotic systems.

Ronald Noë's insight:
Ants selecting among aphids that they protect in return for honeydew provide perhaps the best examples of what I call 'market selection' (selection due to partner choice in cooperative, mutualistic and symbiotic partnerships). This paper describes a particularly neat example, even though without ever using the term market. The aphid species in question has two colour morphs, green and red. The ants prefer the green ones because they give more honeydew of higher quality and therefore protect them more. Providing more honeydew goes at a reproductive cost, but this is compensated by the better protection. The authors speculate that the ants don't select the red morph out of existence (they prefer mixed colonies with 2/3 green and 1/3 red aphids), because the red morphs are better at overwintering, hence assuring the honeydew production for the next year.
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Everett, Faber, Savulescu & Crockett (2018). The costs of being consequentialist: Social perceptions of those who harm and help for the greater good. psyarXiv

Everett, Faber, Savulescu & Crockett (2018). The costs of being consequentialist: Social perceptions of those who harm and help for the greater good. psyarXiv | Biological Markets | Scoop.it
Abstract: Previous work has demonstrated that people are more likely to trust “deontological” agents who reject instrumentally harming one person to save a greater number than “consequentialist” agents who endorse such harm in pursuit of the greater good. It has been argued that these differential social perceptions of deontological vs. consequentialist agents could explain the higher prevalence of deontological moral intuitions. Yet consequentialism involves much more than decisions to endorse instrumental harm: another critical dimension is impartial beneficence, defined as the impartial maximization of the greater good, treating the well-being of every individual as equally important. In three studies (total N = 1,634), we investigated preferences for deontological vs. consequentialist social partners in both the domains of instrumental harm and impartial beneficence, and consider how such preferences vary across different types of social relationships. Our results demonstrate consistent preferences for deontological over consequentialist agents across both domains of instrumental harm and impartial beneficence: deontological agents were viewed as more moral and trustworthy, and were actually entrusted with more money in a resource distribution task. However, preferences for deontological agents were stronger when those preferences were revealed via aversion to instrumental harm than impartial beneficence. Finally, in the domain of instrumental harm, deontological agents were uniformly preferred across a variety of social roles, but in the domain of impartial beneficence, people prefer deontologists for roles requiring direct interaction (friend, spouse, boss) but not for more distant roles with little-to-no personal interaction (political leader).

Keywords: consequentialism deontology impartiality moral dilemmas morality partner choice person perception
Ronald Noë's insight:
A new paper on partner choice and morality in humans. Comments may follow.
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