There are basic facts related to decision making and the idea of "free choice" that everybody should know. Experiments have proven that we are victims of ourselves, and therefore we can fall victims of others. This book presents the mechanisms that guide our behaviors and the techniques that can help influence it, so that the reader can be aware of the traps that awaits him in his day-to-day life.

How the brain works - resilience of decisions

Our choices are influenced by prior decisions, whether they were conscious or unconscious decisions. And these individual behaviors impact group decisions as well, and points to the fact that in a group, the analysis of the impact of a decision should always be done by people other than the ones involved in the decision.

Examples of such self manipulation can be seen in 3 types of behaviors:

• Escalating Commitment
• Sunk Cost
• Escalating Conflict

Escalating Commitment

When people agree to a small request, they feel committed, and will make sure that they do the right thing even if it costs them more than they originally expected or intended. For example if someone is asked to look after a bag, chances are that he/she will run after a robber trying to get away with this bag. Under the same circumstances but without a prior request from the owner of the bag, the same person may not have done it. An example of such a mechanism can be found in a study by Staw published in 1976 "knee deep in the big muddy: a study of escalating commitment to a chosen course of action".

Sunk cost

When people make a choice, they tend to choose based on what did cost them more instead of what would be the best for them. For example if people make a reservation (and pay) for two events that turn out to be on the same day, they will tend to choose to go to the one that did cost more rather than the one they would most interested in, even though the money was spent and the overall cost is the same regardless of the choice made. An example of such a mechanism can be found in a study by Arkes and Blumer published in 1985 "the psychology of sunk cost"

Escalating Conflict

When a person has to take a additional decision to get out of a situation in which he is trapped, it is very hard to make such decision. If the opportunity to re-evaluate the original choice is not given, people will tend to stick to their original choice way beyond the point when this choice starts costing them more than they would ever have committed. An example of such a mechanism can be found in a study by Brockner, Shaw, and Rubin published in 1979 "factors affecting withdrawals from an escalating conflict: quitting before it's too late"

How manipulation works: from Self-manipulation to Manipulation

Preparatory steps

All the behaviors presented earlier are the result of self manipulation, but they open the door for actual manipulation by others. Somebody can easily exploits these type of behaviors, and introduce preliminary steps in an interaction so as to condition a person to fall later into one of the response mechanism described earlier. The initial preparatory decision should be the result of free choice, which can be induced:

• through a plain lie, for example offering a product that is not available or promising a deal that does not exist
• by controlling how the information is released, for example ask the subject to make a decision first, then provide him with more details that include changes to the original deal (low ball technique)
• by using a teaser, for example offering a sale on a pair of shoes with only large sizes left

It has been shown that in addition to decision being resilient, people also tend to stick to this original decision even after they have been informed of a change to the original deal. An example of this mechanism can be found in a study by Cialdini published in 1978 "low ball procedure for producing complaince: commitment then cost"

Engagement

What makes all these processes work is the effect of "engagement", which precedes the "resilience of decision", as demonstrated in a study by Kiesler published in 1971 "The psychology of commitment - Experiments linking behavior to belief"

Engagement can be reinforced, and there can be several levels of engagement:

• signing a petition is a low entry level, and providing name/address/profession is another level
• how public is the engagement or how often the engagement is requested also impacts the level of engagement.

As a result of this engagement process the reality is that "free choice" is actually "free will submission". The perception from the decision maker is that he is making a free choice, but the reality is that he can be influenced by a simple request.

The consequences of engagement

It has been shown that the preparatory steps work better when engagement is reinforced by action. More specifically, experimentation has shown the following:

• When there is engagement into an action that is in tune with what the person thinks, it reinforces the conviction of this person.
• When there is engagement into an action that conflicts with what the person thinks, it results in an adaptation of the convictions

Engagement into a non-conflictual decision, followed by an action makes the choice more resilient. This can go as far as creating boomerang reactions to opinions that go against the original choice. For example it has been shown that people asked to sign a petition for a cause that they are supporting will become stronger supporters of that cause after they have signed than they were before.

The interesting part is that the effect of engagement being reinforced by actions applies someone regardless of the original point of view of the person. This can regarded as a good thing or as a bad thing depending on how one wants to look at it:

• when engagement is for a good cause, it is usually considered to be leadership - the person engages in an action
• when engagement is for a "bad" cause, it is usually called being brain washed, or manipulated - the person has been engaged into an action

But the mechanism behind remains the same.

Techniques of manipulation

Several techniques can help prepare the context for a better compliance to a later request:

• The "Foot-in-the-door" technique
• The "Door-in-the-face" technique
• Touch
• The "Foot-in-the-mouth" technique
• The "Fear-then-relief" technique
• The "But you are free of" technique
• The "A little is better than nothing" technique

The "Foot-in-the-door" technique

In this technique, the preparatory step consist in getting the person engaged into a low cost action as a way to prepare for a much more costly one. For example asking for the time of the day before asking for some money to pay for a phone call - such examples can be found in a study by Freedman and Frazer published in 1966 "compliance without pressure: the foot-in-the-door technique", and by Pliner Host Kohl and Saari published in 1974 "compliance without pressure: some further data on the foot-in-the-door technique".

This technique works even better if you follow up with an "attribution", by commenting on the person's action and by making them feel good about such action (Attribution technique - see below)

The "Door-in-the-face" technique

This technique consist in asking for something totally unrealistic as a way prepare for a much more resonable request. For example asking for a large sum beyond the means of a person before asking for $100. Such examples can be found in studies by Cialdini, Vincent, Lewis, Catalan, Wheeler and Darby published in 1975 "a reciprocal concessions procedure for inducing complaince: the door-in-the-face technique"

Touch

This technique consist in touching the person for a few second as a preparatory step for a later request. As strange as it may seem it does make real difference. Examples of results from such a technique can be found in a study by Kleinke published in 1973 "compliance to requests made by gazing and touching experimentaters in field settings"

The "Foot-in-the-mouth" technique

This technique consist in inquiring about the person and showing interest in the answer as a preparatory step for a later request. Examples of results from such a technique can be found in a study by Howard published in 1990 "the influence of verbal responses to common greetings on compliance behavior: the foot-in-the-mouth effect"

The "Fear-then-relief" technique

This technique consist in creating stress before providing relief as a preparatory step for a later request. However unpopular it might be, examples of this technique can be found in police questioning procedures.

The Attribution technique

This technique consist in commenting on the person's action to give them a good image of themselves. Examples of results from such a technique can be found in a study by Millet, Brickman and Bolen published in 1975 "attribution versus persuasion as a means for modifying behavior"

The "But you are free of" technique

This technique consist in clarifying after a request that the person should feel free to not comply to this request. Examples of results from such a technique can be found in a study by Guegen and Pascual published in 2002 "evocation of freedom and compliance: the but ou are free of... technique".
This technique also works on the web (for example by changing the wording of a button to "feel free to click here" instead of just "click here"). In one experiment from Guegen, LeGouvello, Pascual and Morineau published in 2002 "request solicitation and semantic evocation of freedom: an evaluation in a computer mediated communication context", it was shown to move the success rate from 65% to 82%.

The "A little is better than nothing" technique

This technique consist in adding to the request that a little will be better than nothing, thus removing the excuse of cost from the possible answers. Example of results from such a technique can be found in a study from Cialdini and Shroeder published in 1976 "increasing compliance by legitimazing paltry contributions"

"This is not all" technique

This technique consist in offering additional items that were not requested originally to justify the high cost of the request. This is a classic, and we are exposed to in our everyday shopping.

The "Foot-in-the-memory" technique

This technique consist in asking the person to remember when they did not comply in the past with something that they approve of in general, or try to ask them to visualise situations that would not be conform with a given policy. An example of results from such a technique can be found in a study by Dickerson, Thibodeau, Aronson and Miller published in 1992 "using cognitive dissonance to encourage water conservation"

Once all these techniques have been identified, it is then possible to mix and match to try to optimise results. An example of such mix and match and the results that it yielded can be found in a study by Joule published in 1989 "Tobacco deprivation: the foot in the door technique versus the low ball technique". In this experiment, the goal was to have students agree to stop smoking for 18 hours. In the control group, 12% of the students selected agreed to the request, and only 4% actually complied. But after two "foot-in-the-door" steps followed by 2 engagements 95% of the students selected agreed to the request, and 90% complied.

Possible Applications

An obvious application of all these techniques is Marketing.
Management and Child Education are the other areas where they can be useful.

Management

Organizations of all kinds all require that a group of individuals work towards a common goal. And even when the culture inside the organization is very open (what the authors call industrial democracy), we are still in a configuration were people are being asked to do, or maybe they are being influenced into doing, something that makes sense for the organization as the best way to reach the goal.

Research by Kurt Lewin (1947 "group decision and social change") gave birth after the war to the practice of group decision making in industrial organizations. But what remains today from this orginal theory has been dilluted into two main versions that were further advertised, one with a "management" bias, and the other one with a "democratic" bias.

To understand how these versions differ (or not), one has to look at two important parameters within the entreprise:

• the internal social weight - impact on employees
• the organizational efficiency weight - impact on production

The "management" version of the original theory has been presented by Norman Maier who was studying group decision for better management. According to him:

• If a change has no internal social weight and no organizational efficiency weight (for example the color of the paint on the walls), then who makes the decision does not matter, and coin tossing is a good method
• If a change has no internal social weight but has organizational efficiency weight, then the decision should be taken by experts
• If a change has internal social weight but no organizational efficiency weight, then the decision should be taken as a group decision
• If a change has internal social weight and organizational efficiency weight, then there is potential conflict, and the situation requires a "moderator" to drive the group towards the decision that makes most sense for the organization, while it is taken with buy-in from the group. This means using techniques to guide the free choice, to gain engagement, and therefore through manipulation.

The "democracy" version of the original theory favors "listening to the group", by analysing the organization constraints and the personal conflicts within the group. And from this analysis it is expected that a solution will emerge at some point in time.

But while it seem to be a friendlier approach, this also can be seen as another form of manipulation: even if the intent is sincere, the fact that the indivudual agrees to get into the process means he has been "engaged". And from that point, he can be guided as well (and the organization needs it if we do not want the process to take forever), which is again manipulation, but using a psychologist instead of a moderator.

Education

In Education, well intended parents want their child to have choice. But it should not be choice betwen many options, but rather the choice to do or not to do: when somebody makes a choice, they internalize this choice and then rationalize it. This mechanism makes them more apt at making similar choices in the future. So in the case of a child, asking him/her to do the right thing (rather than giving them a real choice or trying to impose an action) and then doing an Attribution, will condition them to make similar decision in the future. During the internalization process, they will associate the behavior to the fact that they were doing the right thing because this is who they are rather than because they were doing what they are told.

Conclusion

Manipulation and propaganda are everywhere, and people usually feel unconfortable with the concept of manipulation. But Marketing propaganda is forcing commercials into a consumer brain without regard for his/her own interest while well intended manipulation can be seen as just another act of selling. Architecting behaviors should not be consider as bad as manipulating people by lying on the virtues of a product or trying to brain wash them through force fed commercials. In fine, and despite the unpopularity of the word "manipulation", using technologies of comportment is probably a more ethical choice, as long as the preliminary steps to engage the person are not based on lies or abuse.

Regardless of what one would like to think, it is clear that we are subject in our everyday life to manipulation. So people making decisions should always keep in mind of the following:

• be aware of the mechanism behind various behaviors
• do not hesitate to re-consider a decision
• learn to consider each decision individually (and not take into account previous decision)
• do not overestimate your freedom of choice

Freedom does not prevent us from doing things that are costly to us personnally and that are the result of somebody else expectation. From a political point of view, it means that one should not confuse living in a liberal society and living in a true democracy.

Bacteria colonies that migrate and forage and form joint structures via chemical signaling, social insects that engage in joint problem solving behaviors via chemical signaling, symbiotic relationships between ruminants from termites to cattle with cellulose-digesting bacteria, Margulis' evidence for the symbiogenesis of mitochondria and hypthoses that flagella originated from the joining of free-swimming spirochetes with energy-producing but less-mobile microorganisms, the probably evolution of flight from a suite of synergistic functional changes, the emergence of protohumans are all cited by Corning as evidence that synergies play a central, not a peripheral role in evolution of complex life forms: "Synergy has played a key role in the progressive evolution of complex systems in nature. However, complexity is not an end in itself; it's a consequence of the innovations that produce more potent forms of synergy. Synergy is the 'driver.'"

William E. Hamilton's papers on "The Genetical Evolution of Social Behavior" in 1964 formalized the neo-Darwinian explanation of altruistic behavior as conferring benefits on close kin, but Robert Trivers' 1964 "Evolution of Reciprocal Altruism" decoupled kinship, cooperation, and altruism by offering evidence that the helping organism acts with the assumption that low-cost, low-risk assistance to another now will be repaid later – reciprocity.

Game theoretic models were driven to more realistically match human and biological behavior than Axelrod's and Hamilton's models when zoologist Martin Nowak and mathematician Karl Sigmund created "Pavlov," a Prisoner's Dilemma strategy based on "win-stay, lose-shift" that introduces punishment. Corning objects to inclusive fitness theory, reciprocal altruism, tit-for-tat as adequate explanatory frameworks because they exclude interactions that provide synergistic combined effects and are self-policing because they are interdependent – the way two oarsman are interdependent when trying to cross a river if they each have one oar. Corning claims "The intellectual fascination of the Prisoner's Dilemma game may have led us to overestimate its evolutionary importance."

Rejecting single-cause "prime mover" hypotheses for either biological or cultural evolution, Corning lists "five maybe six distinct paths to cooperation and complexity in evolution:" altruism, reciprocity, functional interdependence, mutualism, and parasitism.

In regard to humans, Corning points to specific probable synergistic packages that enabled proto-humans to evolve from tree-dwelling primates, for language to evolve as an adaptation on precursors, for hunting and gathering culture to dominate and spread, for fire use to be culturally maintained, and for settled agriculture to take root and replace nomadic foraging and hunting as the dominant human form of social organization. Asking how a small, lightweight primate that can't fly or run very fast, lacking natural defensive weapons, but having bipedal gait, manipulative hands, omnivorous digestive system and large brain managed to shift to an earthbound habitat, broaden its resource base, and expand its range, Corning proposes that "In a patchy but relatively abundant woodland environment that was also replete with predators, competitors , and sometimes hostile groups of conspecifics, group foraging and collective defense/offense was the most cost-effective strategy. There were immediate payoffs (synergies) for collective action that did not have to await the plodding pace of natural selection….There may well have been group selection, but it was not based on altruism. It involved what the economists call 'collective goods' or 'public goods.'"

Corning agrees with Jared Diamond that the emergence of agricultural civilization, empires, and wars of conquest in the fertile crescent 10,000 years ago was due to what Diamond himself called a "package" of ecological circumstances and cultural inventions that worked together synergistically: domesticated, genetically altered plants and animals, draft animals, technologies for plowing, cutting, threshing, grinding, food transport and storage, cooking, processing hides and fibers, sewing, manufacturing tools of stone, bone, and wood, as well as access to reliable fresh water sources, abundant fuel, long-distance trade, and defense against raiders. As a result, ten to one hundred times more people can be fed from one acre than from hunting-gathering, and a settled lifestyle permitted a reduction of the spacing of births from a four year separation among nomads to two years, leading to rapid population growth.

Corning cites contemporary examples of synergistic cultural evolution involving the creation of new forms of collective action, together with new toolsets. The Igorot people of the remote mountains of Luzon, in the Philippines, use a vast, elaborate, intricately constructed combination of terraces, dams, canals, and ponds to grow rice sustainably and with remarkable efficiency. It was originally thought that the system was thousands of years old, but anthropologist Charles Drucker turned up evidence indicating that lowlanders who had practiced slash-and-burn agriculture for millennia were forced to migrate to the highlands when Spanish invaders seized choice lowlands. The sustainable high yields of Igorot rice farming depends on constant replenishment of soil nitrogen in places where there is not a natural abundant supply. The Igorot use ponds of blue-green algae that live in symbiosis with the rice plants, receiving carbon dioxide from the rice in exchange for fixing nitrogen. In order to use and maintain this new, complex technological and ecological system the former slash-and-burn lowlanders had to invent a new social and political system involving the disciplined coordination of many family groups.

The Great Basin Shoshone of North America, studied by Julian Steward in the 1930s, forage in very small family groups, with plants providing 80% of their calories. In winter, however, several families gather in larger camps near an abundant resource and trade information, teach each other skills, and find mates. During rabbit drives, groups of 75 or more coordinate efforts deploying nets hundreds of feet long. A division of labor is temporarily established between net holders and beaters, under the supervision of a temporary rabbit boss.

Work by Gintis, Bowles, Fehr and Gächter indicate that strong reciprocity among humans is egoistic, not altruistic or cooperative, and depends on aggressive punishment of cheaters. This is related to work by Boyd and Richerson on group-serving norms of "fairness." Corning notes: "…the principle of fairness came to play a central role in reconciling conflicting claims of self-interest within the groups/bands/tribes that were indisipensable to our ancestors' survival and reproductive success over many thousands of generations."

The self-regarding and outcome oriented picture of human behavior presented in traditional economics does not explain why humans care so much about each other and about how social interaction is carried out, not just the end goals. The Ultimatum Game, designed by Werner Guth, is just one illustration of how real people will not always follow the dictates of self-interested rationality. Two subjects are given a sum of money, one is given the power to divide the sum, and the other can either accept or reject (in which case neither get any money). Research from conducting hundreds of trials of the game with thousands of students in Europe, Japan and the USA has shown that the responders frequently reject low offers and proposers frequently propose near equal divisions, even though it is to their monetary disadvantage. While early experiments on undergraduates seemed to suggest that there was a universal sense of fairness, extended research in different cultures (hunter-gatherers, slash-and-burn agriculturists, nomadic pastoralists) has exposed much cultural variation in responses, indicating that local cultural conditions play an important role in how people approach cooperation.

While mean proposals for university students from all over the world was usually between 42 and 48 percent, mean proposals from this cross-cultural study varied from 25 to 57 percent. Rejection rates, the action of the responders, also varied considerable between groups. Individual-level economic and demographic variables did not explain behavior as well as group-level behavior, and game play often could be connected to the people's common patterns of interaction. For example, the Orma recognized that one of the experiment's games was similar to the harambee, a local institution of giving to public goods like roads and schools. They began calling it 'the harambee game' and displayed highly prosocial behavior. In other groups, like the Au and Gnau, frequent rejection of generous offers can be explained by a cultural association with gift-giving: accumulating gifts, even if unsolicited, can imply a lowered status and force the receiver into future obligations or political alliance. The cross-cultural study showed that, in the case of groups at the extremes of behavior, "contrasting behaviors seem to reflect their differing patterns of everyday life, not any underlying logic of hunter-gatherer life ways."

The effect of market integration on cooperation to obtain a monetary reward can be explained easily: individuals from market-oriented societies when put in the context of one of the games are able to seek analogues in their daily activities of using and trading money with strangers. "Those who do not customarily deal with strangers in mutually advantageous ways may be more likely to treat anonymous interactions as hostile or threatening, or as occasions for the opportunistic pursuit of self-interest."

Social psychological research has a long tradition of interest in cooperative behavior and commons dilemmas, beginning with Von Neumann and Morgenstern's 1944 book, Theory of Games and Economic Behavior. It is convenient to summarize the way psychological studies have attacked the commons problem through nine variables (social motives, gender, payoff structure, uncertainty, power, status, group size, communication, causes, frames) divided into three groups (individual differences, situational factors of the task structure, and the perceived effects of situational factors.) Although behavior elicited in a controlled lab environment is never the same as that observed in field research, lab research is an indispensable tool for teasing out causal relations from the larger number of interacting influences. Attention to the findings of psychological research relevant to the specific instance of a commons dilemma can make the difference in generating positive collective action.

Studies on social motives have found correlations between motives and choice behavior and interpretation of others' behavior. Liebrand et al. (1986) demonstrated that "people with individualist social motives tend to interpret behavior along the might dimension (what works), whereas cooperators tend to view cooperation and competition as varying on the moral dimension (what is good or bad)." Less intuitive findings have come out of research into social rewards for cooperative behavior. Gachter and Fehr (1999) conducted a study around public goods dilemmas with an anonymous group, a group that met beforehand to establish a group identity, a group that had a chance to interact after playing, and a group that met before and after. They found that neither the second nor the third groups had significant improvements in cooperation, but that the fourth option resulted in "significantly higher levels of contribution."

Uncertainty of resource size may play a detrimental role in commons dilemmas for multiple reasons. Any factor which threatens to bring an end to the resource will decrease interest in one's reputation and therefore with the relations that support the resource's maintenance. Uncertainty also helps diffuse personal responsibility, since overusers can try to justify their actions through their ignorance of the current resource size.

Experimenters have also uncovered interesting effects from varying groups size on self-efficacy, an individual's sense of their own competence in taking effective action. Smaller groups were found by Kerr (1989) to have higher averages when testing "collective" efficacy, the sense that the group could carry out effective actions to achieve a desired outcome. In groups with a relatively low provision point, the percentage of cooperating members necessary to support the public good, small group size was associated with a sense of "collective" efficacy.

Voting can significantly improve efficiencies in commons dilemmas by acting as a form of communication. Collective learning of general information "extends to subsequent situations and enables people to coordinate their activities even in rounds when no proposals are made."

Evolutionary psychology has been portrayed as justifying or implying a lot of bad ideas in the 20th century, but it need not suffer from these mistaken linkages and can potentially shed light on how to build better social institutions. Although the claim has been made, evolutionary psychology is not consistent with the tenets of Social Darwinism. Whether a trait or behavior survives the process of natural or cultural selection has no bearing over our discourse on whether it is morally justified. Nor does it mean that we are determined like machines to act out these behaviors in every case, a theory termed 'behavioral determinism' by those criticizing evolutionary psychology or its earlier form, sociobiology. Any reputable biologist, or sociobiologist, would acknowledge that the fitness of a behavioral trait is dependent on the interaction between that trait and a given environment, so saying that a certain psychological predisposition in humans is the product of an evolutionary process does not mean that it is good, justifiable or useful in the world we live in. Evolutionary science stresses that fitness is fundamentally contingent. Furthermore, humans have a cultural inheritance that dictates in subtle ways how and when we should express or repress our behavioral traits, making the interaction between trait and environment even more complex. Evolutionary psychologists suggest that we pay close attention to the basic human behaviors that through cross-cultural analysis appear 'hard-wired', because it is these behaviors, such as sympathy for those in pain or identification with one's kin or tribe, that we want to either channel or suppress in order to reap the benefits of cooperation.

This article isolates four mechanisms that promote cooperation in the absence of a central authority: kin selection, cooperation for mutual advantage, reciprocal altruism, and group selection. Kin selection implies a kind of utilitarian genetic calculus, that sacrificing one's life for the right number of relatives will be favorable for one's genes. A sibling shares on average half of one's genes, so sacrificing one's life for two or more siblings makes evolutionary sense. An example of a behavior that might be explained by kin selection is the warning call of ground squirrels; a ground squirrel that notices a hawk circling will call out to warn its family, although it increases its likelihood of being noticed and eaten by the hawk. This form of cooperation requires enough brain or nose power to be able to determine who is a relative.

The second form, cooperation for mutual advantage, occurs when a particular given end (critical for survival) is easier to accomplish with a group working together. The quintessential example of this mechanism is group hunting; wolves (and our hunter-gatherer ancestors) hunt in packs because they will end up with a portion of the large game, which can be much larger than the small game they would be able to catch on their own and not have to share. This benefits of this mechanism is not as immediate or certain as those of kin selection, because the stronger hunters could potentially share nothing with the weak who helped. This article cites field studies of monkeys, lions, and fish, which show that group hunting generally only occurs when environmental conditions make it economically more efficient that hunting alone. While cooperation for mutual advantage is an important surplus-generating mechanism in nature, we should not expect this mechanism to form the basis of modern human cooperation. Modern human cooperation cannot be pared down to a single one-shot end, and it could be argued the developments of civilization we are most proud of, charity for the poor or sick, go against the logic of mutual advantage.

Reciprocal altruism looks similar to the mechanism of mutual advantage, except the benefits are spread over time rather than through a single interaction. One individual helps another individual with the expectation that in the future the gesture will be repaid. Reciprocal altruism works best when developed alongside "a large number of supplementary psychological and social institutions." Enduring reputation and social traditions such as gift-giving foster relationships of reciprocal altruism. This kind of a relationship requires a bigger brain to remember who gave you what and who has mooched off you for too long, but can generate a big societal payoff. "By allowing trade over a period of time, reciprocal altruism opens up the possibility of a division of labor and credit-based relationships. These innovations make possible the recognition of the gains from specialization, comparative advantage, and the insurance and risk-shifting elements of inter-temporal trade."

While reciprocal altruism is most compelling in small groups with face-to-face interaction, the final mechanism, group selection, treats populations as the unit of measure. Proponents of group selection argue that a population of individuals with altruistic traits would fare better than less altruistic populations, reaching the big payoffs described in the above paragraph. The traits in question could be genetically inherited or culturally inherited. Arguing for cultural group selection, "[g]roups that adopt 'better' cultural practices will again tend to grow healthier, wealthier, and more populous, gradually supplanting less efficient cultures through conquest, migration, or conscious adoption." This kind of cooperation requires even more specific conditions than the other three mechanisms. Because the scale of group selection is so much larger than the other mechanisms, it is still a controversial theory in natural and social sciences. The argument against cultural and biological group selection is based on problem of free riders without altruistic traits who might take advantage of the social surplus generated by their altruistic neighbors. While human populations have reached impressive levels of cooperation in modern societies, one can imagine natural disasters or devastating world wars that would eliminate the evolutionary strength of group selection.