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."

Analytical results from modeling the fitness consequences of two decision-making mechanisms, despotism and democracy, shows that generally despotic models leads to higher costs than democratic models because despotism produces more extreme decisions than democracy. "Even when the despot is the most experienced group member, it only pays other members to accept its decision when group size is small and the despot's average error is lower than the average median error of all other group members."

Research has largely assumed despotism because social structures among animals are commonly hierarchical and the ability to vote and to count votes is not obvious. However, there is mounting empirical evidence of voting in the animal world by body postures, ritualized movements, and vocalizations, as well as vote counting in the form of summing up votes, integration of votes up to an intensity threshold, and averaging of votes.

An important context in which social animals have to make group decisions is activity synchronization, e.g. red deer herds have to decide when to end rumination and move on. The model assumes that (1) synchronization costs increase linearly with the difference between when an individual would have preferred to stop and when the group actually stops, and (2) costs of stopping to early or too late are symmetrical. Even when relaxing assumption (1) costs are still higher for despotic than for demographic groups in most cases. When relaxing assumption (2) a democratic majority rule different from simple majority that reflects the asymmetry between "too early" and "too late" costs is least costly.

These results are fairly robust with respect to group heterogeneity, energy needed for enforcement, and individuals having incomplete information about their own optimal activity duration. The model predicts that democracy gives groups a competitive advantage and due to natural selection should be quite common in social groups of animals.

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.