hundo-E

Costly Signaling, Culture & Cooperation

Is costly-signaling adaptive? To answer this question, this paper will review: natural selection, Tinbergen’s evolutionary questions, cultural evolution, costly signaling theory (CST), and markers & norms. That theoretical foundation will be used to analyze three case studies and consider them from Tinbergen’s framework.

The hypothesis of this review is that costly-signaling is adaptive. The belief is that costly-signaling encourages & maintains cooperation. This functional perspective does go against the grain of some “natural selection” interpretations, but there is also literature that persuasively argues that cultural group selection (CGS) is inadequately accounted for in these classical interpretations (i.e., Richerson et al., 2016). Whether it be individual, group, or multi-level selection/fitness, costly-signaling can be evaluated for its adaptive/behavioral functionality.

Culture & Evolution

What would it mean for a behavior to be adaptive? Let’s clearly define natural selection. Smith & Winterhalder documented that three conditions are required for natural selection: (1) phenotypic variation, (2) some of that variation being heritable, and (3) that “variants differ in their ability to survive/reproduce” (1992). Natural selection is the evolutionary phenomena where traits/genes that are most adaptive (helping individuals survive and reproduce) are the ones that proliferate into a population, eventually (Smith & Winterhalder, 1992). The differences between traits/genes are called variation (with mutations ranging from helpful, to neutral, to harmful) (Smith & Winterhalder, 1992). If they do not help individuals survive & reproduce, then they are not naturally selected. Individuals can be out-competed by those with more adaptive variation. Alternatively, they may simply be unable meet the demands of their environment. The genes/traits that are harmful (or otherwise less advantageous) fall out of the gene pool as individuals are unable to survive & reproduce. There may be periods of time where environmental demands differ and greater selection occurs.

Smith & Winterhalder juxtaposed Tinbergen’s (1968) evolutionary questions & Mayr’s (1976) forms of explanation (which will provide a backdrop for the purposes of this discussion) (2000). Regarding ultimate analysis in the Neo-Darwinian process, Tinbergen was concerned with how behavior influences the survival/success of an animal and Mayr posited that ecology was the ultimate driver (Smith & Winterhalder, 2000). In terms of proximate analyses of mechanisms, Tinbergen wondered what it was that makes a given behavior happen (how its “machinery” works) and Mayr believed that there were intrinsic (i.e., photoperiodicity & bird migration patterns) & extrinsic (i.e., cold temperatures cue a bird to migrate) physiological causes (Smith & Winterhalder, 2000). With regard to proximate analyses of ontogeny, Tinbergen asked “How does the behavior machinery develop as the individual grows up?” (Smith & Winterhalder, 2000). Lastly, in considering ultimate analyses in terms of evolutionary history (phylogenetic/functional/adaptionist), Tinbergen questioned how “behavior systems of each species evolved until they became what they are now” while Mayr supported the notion that genetic causes answer this question best (i.e., having the genetic constitution to “respond appropriately to the proper stimuli from the environment”) (Smith & Winterhalder, 2000).

Henrich & McElreath wanted to understand both “the evolution of the psychological mechanism that underlie human social learning and the evolutionary (population) dynamics of cultural systems (2003). These were prerequisite in the aspiration to understand “how and when such culturally evolved adaptations arise” (Henrich & McElreath, 2003, p.123). Probability of an individual learner acquiring an adaptive behavior was juxtaposed with the frequency of cultural learning in Box 2, with Henrich & McElreath having written that “Natural selection favors cultural learning only when the costs of developing and maintaining cultural learning mechanisms are smaller than the benefits gained by acquiring simple behaviors that could be learned on one’s own.” (2003, p. 127). They added, “But, despite being difficult to get started, once a reliance on cultural learning is common in the population, it is easy to sustain.” (Henrich & McElreath, 2003, p. 127). Box 3 introduced frequency-based biases (conformity and rarity) and model-based biases (prestige, success, similarity, and others) (Henrich & McElreath, 2003, p. 129). On success and prestige, McElreath & Henrich wrote, “The greater the variation in acquirable skills among individuals, and the more difficult those skills are to acquire via individual learning, the greater the pressure to preferentially focus one’s attention on and imitate the most skilled individuals,” (2003, p. 130).

 Boyd & Richerson defined culture as “information – skills, attitudes, beliefs, values – capable of affecting individuals’ behavior, which they acquire from others by teaching, imitation, and other forms of social learning,” (1987). Critiques against cultural evolution essentially argue “transmitted culture, if it exists, lacks the properties to evolve in a Darwinian fashion at all, much less at the group level,” but this critique fails to consider that culture may influence selection via proximate mechanisms or ontogeny (rather than as an ultimate cause) (Richerson et al., 2016). Boyd & Richerson posited that a “‘dual inheritance’ theory of the interaction of genes and culture” further substantiates the defense against claims that culture is either constrained to genetics or varying independently from genetic fitness (1987). Richerson et al. noted, “Groups exhibit variation in behaviors that affect the rate at which they grow, produce daughter groups, overcome resource constraints, avoid internal political conflict, succeed in war, and ultimately replace other groups,” (2016). The debate is still on-going, but research has made it clear that this is far from an “open & shut case.”

“Niche construction is the process whereby organisms modify selective environments, thereby affecting evolution,” (Laland & Brown, 2006). Laland & Brown argued “against the hypothesis that modern humans experience an atypically large adaptive lag,” (2006). They hypothesized that humans frequently buffer adaptive lag through cultural niche construction and that “niche-constructing activity increases the match between an animal’s behavior and its environment,” (Laland & Brown, 2006). Laland and Brown put forward 3 reasons as to “why human niche construction should be typically adaptive”: (1) “Humans construct their world to suit themselves,” (2) “Humans frequently buffer adaptive lag through cultural niche construction,” and (3) “When humans are unable to buffer adaptive lag fully through further cultural niche construction, natural selection on genes ensues,” (2006). Human global population growth supports the assertions of Laland & Brown (2006). We’ll address cultural lags again when discussing ethnic markers.

To briefly present multi-level selection (MGS), it may be beneficial to entertain the possibility that CGS can be acting on multiple groups or sub-cultures (e.g., corporate kin groups, nations, ethnicities, classes, castes, religions, clubs, and empires) (Richerson et al., 2016). Cultures/groups & the behaviors they normalize can affect their outcomes. It stands to reason that individuals within these systems would also have some skin in the game (or fitness to increase/decrease). Cultures are part of human environments. How individuals behave within those environments matters (for both the group and themselves). McAndrew wrote, “a growing number of researchers have come to believe that the concept of natural selection can be meaningfully applied at the group level, and they maintain that group selection may be more common and more important than previously thought,” (2002). David Sloan Wilson (as cited in McAndrew, 2002) highlighted the need to distinguish between in-group competition (between individuals that are members of the same group) and out-group competition (between individuals in different groups) because MST postulates that “groups do not evolve into adaptive units for all traits, but only for those traits that increase the fitness of some groups relative to other.” McAndrew also explicitly noted that MST doesn’t assume that organisms act for “the good of the species,” (2002). Rather, MST suggests that individual-level selection occurs faster than at the group-level and that “it is the individual’s membership in a group faced with particular selection pressures that causes the group to become the vehicle for behaviors that benefit each individual,” (McAndrew, 2002).

Costly Signaling

          McAndrew said that “CST is about truth in advertising” and “it proposes that individuals often engage in behaviors that are very costly as a way of signaling honest information about themselves,” (2002). Smith & Bliege Bird said that CST “offers an explanation of generosity and collective action that contrasts sharply with explanations based on conditional reciprocity,” (2000). Costly-signals can range from mate choice to prey telling a predator not to bother pursuing them (Zollman et al., 2012). McAndrew listed four qualities that a behavior must have in order to be qualified as a costly-signal: (1) “the behavior must be observable by others”; (2) “it must be costly to the actor in resources, energy, or some other significant domain”; (3) “the signal must be a reliable indicator of some trait or characteristic of the signaler, such as health, intelligence, or access to resources”; and (4) the behavior in question must lead to some advantage for the signaler,” (2002). Within a group, altruism can be a “good hedge against future calamities” and induce reciprocity (McAndrew, 2002). With group competition, a more cooperative group may be less dysfunctional/selfish and therefore more likely to outcompete a less cooperative group.

          Religion is a useful group investigate with regard to costly-signals. Sosis found that religious rituals “promoted group cohesion by requiring members to engage in behavior that is too costly too fake,” (2004). Some people shave their heads, others surgically alter themselves (Sosis, 2004). Some take ice baths, others are required to lie still while hordes of ants bite them (Sosis, 2004). Sosis asked, “If our species is designed to optimize the rate at which we extract energy from the environment, why would we engage in religious behavior that seems so counterproductive?” (2004). Furthermore, why has natural selection “favored a psychology that believes in the supernatural and engages in the costly manifestations of those beliefs” (Sosis, 2004). Instead of abiding by the “primitive equals irrational” equation, Sosis sought to explain from a functional perspective (2004). Religious practices and their costs solve the adaptive problem that William Irons (as cited in Sosis, 2004) suggested as the “universal dilemma” of “promotion of cooperation within a community.” Irons (as cited in Sosis, 2004) pointed out that “although everyone is better off if everybody cooperates, this ideal is often very difficult to coordinate and achieve.” Sosis elaborated, “The problem is that an individual is even better off if everyone else does the cooperating while he or she remains at home enjoying an afternoon siesta,” (2004). With costly-signals of religious groups, the signal is worth more than if someone with no commitment signals. The problem of Zahavi’s (as cited in Sosis, 2004) dishonest signals is mitigated by worthy signals being costly, they’re supposed to be reliable indicators and the cost helps makes sure of that. Costly-signals can also be things like: monogamous marriage, living as a nuclear family, not consuming coffee/alcohol/tobacco/meat, not wearing certain jewelry, not owning certain technology, enduring public sessions of criticism, wearing certain clothes, fasting, learning a body of knowledge, trial periods for membership, and surrendering of belongings (Sosis, 2004).    

Sosis ran an experimental series of games where two members received higher payoffs when they requested less (2004). Both members were presented with 100 shekels and their requests affected the amount of shekels the received at the end of the game (Sosis, 2004). If they requested less than or equal to 100 shekels, the remaining money would be increased by 50% and split between the members, but requests greater than or equal to 100 would results in 0 shekel payoffs (Sosis, 2004). Sosis found that religious kibbutzniks were more cooperative than secular kibbutzniks on average (2004). The incentive structure was equal for the secular kibbutzniks, but they made less cooperative/beneficial decisions. Sosis also found that the men that attended synagogue most requested the fewest shekels (2004). Sosis ended his journal article with some caution: “If the intragroup solidarity that religion promotes is one of its significant adaptive benefits, then from its beginning religion has probably always played a role in intergroup conflict,” (2004).

Hall et al. ran their own experiments and demonstrated that there may be room for optimism with regard to intra-religious cooperation (2015). The goal of the study was to examine how costly-signaling related to Muslim & Christian perceived trustworthiness (Hall et al., 2015). Experiments 1 & 2 operationalized costly-signaling as “giving to religious charities,” Experiment 3 used dietary restrictions, and Experiment 4 differed in that it used an indirect measure of the association between trustworthiness and costly-signaling (Hall et al., 2015). Although all of the participants were university students, this research could be done with other samples. Hall et al. found that religious costly-signaling increased self-reporting trust in Experiments 1-3 (regardless of affiliation) and Experiment 4 revealed similar findings (not engaging in costly signaling was correlated with much more low trustworthiness (2015). Trust is important for cooperation, culture, and the individuals in those cultures.

Zollman et al. argued that signals can be partial/cheap, in addition to costly or not sent (2012). Sometimes signals can be informative, but lacking high costs (Zollman et al., 2012). Zollman et al. made notice that CST operates on a Nash equilibrium and argued that a “hybrid” signaling equilibrium needed to be theoretically implemented (that most empirical studies fail to discriminate between classical CST equilibrium and their hybrid one) (2012). Differential cost models & differential benefit models characterize the hybrid equilibrium employed by Zollman et al. (2012). Zollman et al.’s models take lying signals into account (which impacts the signal receiver’s responsiveness to signals) and partial/cheaper information/signaling (which allows signalers to potentially position themselves for greater benefit/payoff) (2012). There is greater incentive to signal partially when signals are being ignored because of false signalers diluting the “game.” They reported that their “hybrid equilibria are general features of the costly signaling [sic] games studied in evolutionary biology” and that “they arise and facilitate low-cost, low-fidelity communication not only in differential benefit games used to model nestling begging, but also in differential cost games used to model sexual signaling [sic] and prey-to-predator communication,” (Zollman et al., 2012). Zollman et al. concluded their journal article by noting that “differential signaling [sic] is at least as plausible as” the traditional CST models, might correspond with observed CST data, and “may represent a superior theory to traditional handicap theory,” (2012). Costly-signaling may still be an adaptive behavior, but there may still be more theoretical development to come.

Markers & Norms as Signals

          In this section, ethnic markers & social norms will be considered in light of CST. The markers and norms are operationalized as being under the broader umbrella of signals. They may serve similar behavioral functions, operate on similar proximate mechanisms, and develop through similar ontogenetic processes.

          Boyd & Richerson reported, “The chance that individual A will adopt an innovation modeled by individual B often seems to depends upon: (1) how successful B is, and (2) the similarity of A to B,” (1987). This helps to explain how ethnic markers can evolve in a culture/population. Boyd & Richerson used two hypothetical niches/habitats (one moist and the other dry) to demonstrate how they might differentially value traits (related to pastoralism & horticulture) (1987). Marker traits can be obtained ontogenetically via socializers (& their respective preponderance/frequency) (Boyd & Richerson, 1987). Adaptive traits are acquired later in development, after observing a wider range of behavioral models (Boyd & Richerson, 1987). Imitation is large part of the dynamic here. “Individuals modify both their adaptive and marker traits by imitating the successful individuals among their local young adult peers,” (Boyd & Richerson, 1987). A successful strategy in one situation does not necessarily mean it will be successful in a dissimilar context. Since we would expect adaptive traits to be naturally selected, it would also make sense that marker traits would covary based on niche/habitat. Boyd & Richerson stated that their research suggests a “subdivision of a population into culturally semi-isolated groups based on arbitrary symbolic traits such as dialect can result from using the success and similarity choice rules” (1987). Additionally, they wrote: “The process of imitating people like oneself sets up a self-reinforcing process, which causes sub-populations occupying different habitats, or pursuing different economic strategies in the same environment, to become culturally isolated,” (Boyd & Richerson, 1987).

It seems fair to venture that markers could be adaptive signals if they predict adaptive traits reliably. Boyd & Richerson said conclusively, “Once a portion of a population has adapted genetically to a particular niche, selection will favor mechanisms that prevent mating with individuals living in some other niche because the offspring that result from such matings will be inferior in both niches,” (1987). The same argument can be levied behaviorally for CGS & inter-group competition (marker traits can be informative signals & selection would favor those traits that reliably predict adaptive traits). Richerson & Boyd (as cited in Laland & Brown, 2006) also reported that “selection cannot always eliminate the spread of maladaptive cultural variants because adaptive information is costly to evaluate, making the spread of some maladaptive traits an unavoidable byproduct of a generally adaptive cultural capability.” This supports the notion that costly-signals can be adaptive because the cost can maintain the reliability/value of markers/signals. Fitzgerald wrote:

“Culture is often seen metaphorically as a group’s own ‘property.’ In the process, identity becomes confused with culture; and ethnic markers associated with a particular group come to be viewed as its unique ‘property.’ Any outsider want to use, say an art form (dress, dance, language), may find his/her efforts greatly resented by the other group, almost as if on had attempted a form of cultural theft.” (1995).

Protection of signal/marker quality & reliability may help researchers understand out-group hostility. This defensiveness may prove to be adaptive in certain exogenous circumstances.

          Themes of success, similarity, & imitation are also seen in literature regarding norms. McElreath listed 3 empirically plausible conditions that might explain how marked groups can arise & persist: (1) “social behavior in groups is regulated by norms in such a way that interactions between individuals who share beliefs about how people should behave yield higher payoffs than interactions among people with discordant beliefs,” (2) “people preferentially interact with people with whom they share easily observable traits like dress, style, or dialect,” and (3) “people imitate successful people, with the result that behaviors that lead to higher payoffs tend to spread” (2002). According to McElreath, marker traits are observable indicators for behavioral traits (2002). As adaptive behaviors spread with payoffs, they become norms in their given niches/habitats. If the covariance between marker and behavior is zero, these markers are useless (McElreath, 2002). This also applies to signals. Similarly, the covariance between norm compliance and signal reliability is of crucial import for any receiver considering acting upon the norm-signal. So, what about costly-norms?

Eriksson pointed out some interesting problems with sanctions, norms, and non-compliance (2019). For McElreath, punishment was operationalized similarly to cost in CST (2002). However, there are some CST limitations that this review has not taken into account yet. Eriksson does so with particular regard to social norms (2019). Social norms can often resemble costly-signaling in that they often discount the present for the future (Eriksson, 2019). Complying with a social norm can signal one’s discount rate (lower meaning that one gives less weight to the future benefits while giving more to immediate benefits & higher meaning less weight to future benefits than to immediate benefits) (Eriksson, 2019). Using CST, Eriksson wrote that finding cooperation partners can be difficult due to two problems: (1) being able to identify reliable partners so that one doesn’t get cheated and (2) one wants to be chosen amongst other potential cooperative partners (2019). Signal receivers “generally only pay attention to credible signals” and “it is the fact that the behavior [sic] is costly, but differentially so, that makes the signal credible,” (Eriksson, 2019).

High levels of compliance/signaling can mean one of two things according to Eriksson: (a) “almost everyone has trait T” or (b) “even those without trait T comply with the social norm” (2019). In this instance, receivers wouldn’t be taking much of a risk by selecting a partner at random and signalers have little incentive if nobody is paying attention (Eriksson, 2019). Here is where sanctions come into play. “What sanctions against social norm violators do, is to create short-term costs for violating social norms,” (Eriksson, 2019). This aligns with CST, but it isn’t quite so black-and-white. Here are some of the problems Eriksson noted about sanctioning: it can be costly, one’s willingness to sanction can depend on others’ compliance with the norms, efforts could be directed toward helping instead (although there isn’t much consideration here for how sanctioning might be seen as helpful behavior), signaling discount rate gives enough incentive to comply (therefore making sanctions unnecessary for sustaining norms), sanctioning risks ruining relationships (& possible retaliation), and sanctioning can undermine the signal sent by compliance with the norm (2019). It is also less likely that instances of required sanctioning will arise with high levels of compliance (Eriksson, 2019). Low compliance can make a signal more valuable, but it wouldn’t be a social norm at that point (Eriksson, 2019).

It seems fair to consider markers & norms as signals, but there is theoretical ambiguity like CST. That said, future theoretical development and research with regard to one should be able to contribute to the others.

Case Specific Analyses

Sugiyama & Chacon observed two East Amazonian communities (the Yora & Shiwiar) and their experiences with pathology (2017). Pathology was studied as an adaptive problem for human social relations (Sugiyama & Chacon, 2017). The Yora were observed for 59 days (using scan sampling, focal person follows, and departure/return records (Sugiyama & Chacon, 2017). The Shiwiar were observed (using focal person follows) and departure/return records) for 133 hunts across 89 days (two field seasons) (Sugiyama & Chacon, 2017). Hazards of the hunter-gatherer lifestyle included: infections, fractures, venom, enemies/feuds, and pathogens/illnesses (with fieldwork even knocking some men out of commission for weeks) (Sugiyama & Chacon, 2017). Minimum requirements for the populations (m) were used to compare the costs of losing average hunters against the best hunters (Sugiyama & Chacon, 2017). For the Shiwiar, the best represented a 32% loss (and an additional 4% for every average hunter thereafter), while the Yora’s best hunters represented 37% of the avg. per capita protein consumption (with an additional 7% for each average hunter) (Sugiyama & Chacon, 2017). Losing an average hunter alone cost about 18% for each community (Sugiyama & Chacon, 2017). Do these hunters & gatherers signal their commitment to their groups/cultures? The real risk of being “out of commission” presents some real environmental demand to share. Endogenous proximate explanations might point to satiation. Exogenous might point to a culture with cooperative norms and ontogeny might develop those through socializing marker traits. At phylogenetic level of analysis: non-cooperative people may have left (unwilling to pay costs or comply with norms), they may have been less cared after (sanctioned), or mates may have been able to reliable select for signal due to a previously low level of compliance.

Smith & Bliege Bird explored (CST) with regard to the Meriam’s (of Torres Strait, Australia) expensive death ceremonies and feasting events (boods) (2000). CST offered an explanation of generosity & collective action by meeting four conditions with their turtle hunting: “1) an honest signal of underlying abilities such as strength, risk-taking, skill, and leadership; (2) costly in ways not subject to reciprocation; (3) an effective means of broadcasting signals, since the collective good (a feast) attracts a large audience; and (4) seems to provide benefits to signalers (turtle hunters) as well as recipients (audience),” (Smith & Bliege Bird, 2000). Upon notice of a death, kin groups elect a leader to follow and to elicit donations/contributions to pay for mortuary expenses and the next day the immediate family feeds all of the guests (Smith & Bliege Bird, 2000). The bood lasts for several days and a temporary burial is erected (Smith & Bliege Bird, 2000). The bood is concluded with a public feast and it can be quite costly (Smith & Bliege Bird, 2000). Then, 2-5 years later, the permanent tombstone is treated with a grand-opening (& another feast) (Smith & Bliege Bird, 2000). How can such expensive signaling be adaptive? An intrinsic physiological cause for the prevalence of such behavior might operate at the level of individuals’ mental health & coping (and subsequent ability to continue cooperating and performing effectively). These endogenous proximate mechanisms can aggregate and influence the culture (thereby reducing stress & encouraging continued adaptive behavior despite the grief/loss). Additionally, these costly-signals seem impossible to fake (making signals more reliable and giving strong models for what behaviors are to be normed [ontogeny], sparking self-reinforcing processes that tend to keep adaptive traits in the mating pool [phylogeny]).

Alvard & Nolin used game-theory to explore the decision-making with regard to prey-choice in the village of Lamalera (of Nusa Tenggara Timur, Indonesia) (2002). Nash equilibria (a combination of players’ choices that are best against one another & where neither can do better by changing their decision unilaterally), Pareto optimums (the set of strategies that maximizes group benefit), and Pareto equilibria (it is impossible for a player to increase their payoff without making the other player worse off) were used to question the supposed irrationality that happens in prey-choice, within this case study (in particular) (Alvard & Nolin, 2002). They noted that people readily fail to achieve Pareto optimums, but Lamalera seemed to be oriented toward one (Alvard & Nolin, 2002). We’re left to ask, “Why?” “Focal points” or “shared notions of prominence” appear to be possible explanations for shared information & conformist cultural transmission (Alvard & Nolin, 2002). Alvard & Nolin argued that “pregame communication” plays a crucial role in coordination and “may have been one selective pressure favoring the evolution of language and culture” (2002). There is some phylogenetic & ontogenetic significance. The primary prey for both of their seasons are ray & sperm whales (Alvard & Nolin, 2002). Sperm whales were successfully killed 3 times over 853 hunts (across 80 different hunting days) while 52 rays were caught (Alvard & Nolin, 2002). Return rates (kg/hr) were compared between hunting & fishing, showing that whale-hunting was “no more profitable” or “marginally more profitable” than fishing (Alvard & Nolin, 2002). Why not just go fishing? Hunting is risky and usually unsuccessful. If too many people fish, then there may be fewer whale kills. Are hunters signaling their fitness for status & prestige (phylogeny)? Development & culture surely play a role (ontogeny). Going hunting might be enough of a signal in this instance, but that is also a cooperative feat.

Conclusion

Costly-signaling can be adaptive (across each of Tinbergen’s criteria). However, CST is still developing. Models are useful, but limited. Specific models appear to be necessary to determine where/when/how they are adaptive. Research regarding norms and markers may be relevant to CST’s theoretical progression. Likewise, the role of culture looks to be significant. The cost/benefit differential are informed by culture and should also be considered.

References

Alvard, M. S., & Nolin, D. A. (2002). Rousseau’s whale hunt? Coordination among big-game hunters. Current Anthropology, 43(4), 533–559.

Boyd, R., & Richerson, P. J. (1987). The evolution of ethnic markers. Cultural Anthropology, 2(1), 65–79. http://www.jstor.org/stable/656396

Eriksson, L. (2019). Social norms as signals. Social Theory and Practice, 45(4), 579–599. http://www.jstor.org/stable/45276661

Fitzgerald, T. K. (1995). Ethnic markers: Media & changing metaphors of ethnicity & identity. Race, Gender & Class, 3(1), 113–122. http://www.jstor.org/stable/41675350

Hall, D. L., Cohen, A. B., Meyer, K. K., Varley, A. H., & Brewer, G. A. (2015). Costly signaling increases trust, even across religious affiliations. Psychological Science, 26(9), 1368–1376. http://www.jstor.org/stable/24544077

Henrich, J., & McElreath, R. (2003). The evolution of cultural evolution. Evolutionary Anthropology: Issues, News, and Reviews, 12(3), 123-135.

Laland, K. N., & Brown, G. R. (2006). Niche construction, human behavior, and the adaptive-lag hypothesis. Evolutionary Anthropology: Issues, News, and Reviews, 15(3), 95-104.

McAndrew, F. T. (2002). New evolutionary perspectives on altruism: Multilevel-selection and costly-signaling theories. Current Directions in Psychological Science, 11(2), 79–82. http://www.jstor.org/stable/20182772

McElreath, R., Boyd, R., & Richerson, P. J. (2003). Shared norms and the evolution of ethnic markers. Current Anthropology, 44(1), 122–130. https://doi.org/10.1086/345689

Richerson, P., Baldini, R., Bell, A. V., Demps, K., Frost, K., Hillis, V., Mathew, S., Newton, E. K., Naar, N., Newson, L., Ross, C., Smaldino, P. E., Waring, T. M., & Zefferman, M. (2016). Cultural group selection plays an essential role in explaining human cooperation: A sketch of the evidence. The Behavioral and brain sciences, 39, e30. https://doi.org/10.1017/S0140525X1400106X

Sosis, R. (2004). The adaptive value of religious ritual: Rituals promote group cohesion by requiring members to engage in behavior that is too costly to fake. American Scientist, 92(2), 166–172. http://www.jstor.org/stable/27858365

Smith, E. A., & Bliege Bird, R. L. (2000). Turtle hunting and tombstone opening: Public generosity as costly signaling. Evolution and Human Behavior, 21(4), 245-261.

Smith, E. A., & Winterhalder, B. (1992). Natural selection & decision-making: Some fundamental principles. In E. A. Smith & B. Winterhalder (Eds.), Evolutionary Ecology and Human Behavior (pp. 36). Routledge.

Sugiyama, L. & Chacon, R. (2017). Effects of illness and injury on foraging among the Yora and Shiwiar: Pathology risk as adaptive problem. An Anthropological Perspective. 10.4324/9781351329200-22.

Winterhalder, B., & Smith, E. A. (2000). Evolutionary ecology and the social sciences. In L. Cronk, N. Chagnon, & W. Irons (Eds.), Adaptation and human behavior: An anthropological perspective (pp. 1-26). Aldine de Gruyter.

Zollman, K. J. S., Bergstrom, C. T., & Huttegger, S. M. (2013). Between cheap and costly signals: The evolution of partially honest communication. Proceedings: Biological Sciences, 280(1750), 1–8. http://www.jstor.org/stable/41727594

______________________________________________________

This still needs some work, but the hypotheses production might be the most valuable objective available (here).