The Evolution of Darwinian Liberalism

In December of 2013, I participated in a workshop on "Liberalism and the Evolutionary Agenda" in Freiburg, Germany.  I wrote a series of six posts on that workshop.

Now, the Journal of Bioeconomics (volume 17, number 1, 2015) has published some of the papers from that workshop, along with a paper by David Sloan Wilson.  Here is my article, which is a shortened version of the long paper that I presented at the workshop.

The evolution of Darwinian liberalism

Larry Arnhart

 

Abstract  From John Locke and Adam Smith to Herbert Spencer and Friedrich Hayek, the central idea of classical liberalism has been the thought that the social orders of morals, markets, laws, and politics can emerge as spontaneous orders—as largely self-regulating and unintended orders arising from the interaction of individuals pursuing their individual ends.  Darwinian evolutionary science supports this idea by showing how evolutionary order can arise from the evolution of self-ownership, property, and mammalian sociality and the evolution of exchange and the division of labor.  In developing these points, I argue for a Darwinian liberalism.

 

Keywords  Darwinism, Division of Labor, Evolutionary Psychology, Liberalism, Neuroscience, Property

 

The fundamental idea of classical liberalism is that society is largely a self-regulating, unintended order—a largely self-enforcing order created unintentionally by the free exchanges of individuals seeking to satisfy their individual desires (Barry 1982; Hamowy 1987; Raico 2012).  In this paper, I argue that Darwinian evolutionary science supports this fundamental idea of classical liberalism by sustaining an evolutionary liberalism as based on two evolutionary foundations--the evolution of self-ownership, property, and mammalian sociality and the evolution of exchange and the division of labor.  I thus add to the work of a few other scholars who have suggested ways in which an evolutionary science of human nature confirms liberal social thought (Rubin 2002; Turner and Maryanski 2008).

 

1  The evolution of self-ownership, property, and mammalian sociality

 

If classical liberalism is correct in assuming that society can arise as a largely self-regulating, unintended order from the actions of individuals seeking only the satisfaction of their individual desires, then the naturally self-seeking desires of individuals must lead them into social cooperation with others.  Adam Smith explains this as an expanding circle of human care rooted in care for oneself and then extended to care for one’s property, one’s family, and wider groups. Darwinian science supports this individualistic explanation of social order by showing how individuals are inclined by their evolved human nature as social mammals to care first for themselves, and then to extend that self-care into caring for property and for other individuals to whom they are attached.

 

1.1  Self-ownership as liberalism’s first principle of human nature

 

Classical liberalism teaches us that even if the cosmic order of the world does not care for or about us, we care for ourselves.  Consequently, the moral order of human social life conforms to the order of human care.  And having evolved to be the smart social mammals that we are, our human societies organize themselves through an expanding circle of human care.  Human beings naturally care first and foremost for themselves as individuals.  But as social animals who cannot live or thrive without the cooperative concern of others, human beings also care for and about others, and consequently they care for how they appear to others—seeking their approval and avoiding their disapproval.  Finally, through the power of our human imagination, we project our desire for social approval into a desire for the approval of an impartial spectator, which gives us a moral sense or conscience.

          Smith sketched that naturally expanding circle of human care.  Every person is first and primarily recommended to his own care, Smith observed, because every person is better situated to care for himself than for any other person, and because every person feels his own pleasures and pains more sensibly than those of others.  One’s feelings of one’s own pleasures and pains are the “original sensations,” and what one feels of the pleasures and pains of others is only “the reflected or sympathetic images of those sensations.”  After one’s care for oneself, one extends one’s affections first to one’s family—parents, children, siblings, and more distant relatives—then to one’s closer friends and neighbors, then to social relationships of gratitude and reciprocity, then to those individuals of high rank whom one admires, then to people whose suffering elicits one’s fellow-feeling, then to one’s country as stirring patriotic love, and finally, there can be some universal benevolence for all sensible beings insofar as they are brought to our attention (Smith 1982, pp. 219-35).

At the center of Smith’s expanding circle of care is one’s natural self-ownership, which is the first principle of liberalism.  Perhaps the earliest clear statement of this liberal principle was by Richard Overton in 1646.  Writing as one of the Levellers in the English Civil War, Overton began a political pamphlet by declaring: “To every individual in nature is given an individual property by nature not to be invaded or usurped by any.  For everyone, as he is himself, so he has a self-propriety, else could he not be himself.”  He saw this claim of self-ownership as an instinctive natural desire.  And insofar as every individual can recognize that every other individual naturally asserts the same claim to self-ownership, everyone can see that he must respect the natural liberty of others if he expects them to respect his natural liberty.  For if he infringes on the natural liberty of others, he will provoke their resentment and retaliation (Overton 1998, pp. 55-57).

          Later, Locke adopted this same principle of self-ownership as the ground of natural rights (Zuckert 2002, pp. 3-7, 193-97, 324-26).  In his Second Treatise of Government, Locke asserts: “Though the Earth, and all inferior Creatures be common to all Men, yet every Man has a Property in his own Person.  This no Body has any Right to but himself.  The Labour of his Body, and the Work of his Hands, we may say, are properly his.  Whatsoever then he removes out of the State that Nature has provided, and left it in, he hath mixed his Labour with, and joined to it something that is his own, and thereby makes it his Property” (par. 27).  Locke thought it self-evident that though the resources of nature are available in common for all, each man as master of himself and proprietor of his own person could extend himself through labor to claim property in those natural resources (par. 44).

Later, in the nineteenth century, British liberals like Auberon Herbert (1978) elaborated this principle that each person as “self-owner” was the “owner of his own mind and body and his own property” (pp. 369-75).  Today, classical liberals like Charles Murray (1997) continue to appeal to this principle of self-ownership.

          Locke’s understanding of self-ownership was founded in a biological conception of embodied self-awareness.  Locke was a medical doctor and a biomedical researcher who worked closely with some of the leading medical scientists of his day, such as Thomas Sydenham, Robert Boyle, and Thomas Willis (Dewhurst 1963; Woolhouse 2007).  For example, he contributed to Boyle's experiments with his air-pump to explore how air provided some element necessary for respiration, which apparently sustained the natural heat of the heart that was necessary for life.  Thus, Boyle and Locke were close to the discovery of oxygen's role in sustaining animal life.  One of Locke's earliest writings was a draft manuscript on the importance of air in respiration.  He wrote: "Nature's aim seems to have been to foster that universal heat or fire of our life. For we live as long as we burn, and are nourished by the same fire” (Woolhouse 2007, p. 68).   Here he saw the natural teleology of functional processes in biology.

Locke also learned about how the human mind emerges from the brain and nervous system from Willis, who was the founder of modern neurology (Zimmer 2004).  Like Aristotle, Willis dissected monkeys and apes to study their neurological similarities to human beings, while also looking for differences that would explain the distinctiveness of the human mind.

In his Essay Concerning Human Understanding, Locke identified a "person" or "self" as "a thinking intelligent being, that has reason and reflection, and can consider itself as itself, the same thinking thing, in different times and places."  All the parts of a human body are vitally united to this thinking self, "so that we feel when they are touched, and are affected by, and conscious of good or harm that happens to them, are a part of ourselves; i.e. of our thinking conscious self."  So that "the limbs of his body are to every one a part of himself; he sympathizes and is concerned for them."  "Self is that conscious thinking thing . . . which is sensible or conscious of pleasure and pain, capable of happiness or misery, and so is concerned for itself, as far as that consciousness extends.  Thus every one finds that, whilst comprehended under that consciousness, the little finger is as much a part of himself as what is most so” (1959, II.xxvii.9, 11, 17).

This Lockean conception of individual personhood as embodied self-conscious awareness of, and emotional concern for, the survival and well-being of the body can now be understood as rooted in the mammalian evolution of the human nervous system.

1.2  The neurobiology of care

The biological psychology of human care can be illuminated through Antonio Damasio’s  (1994) "somatic marker hypothesis" for explaining the importance of emotion in decision-making and consciousness.  Building on an idea proposed by William James and Carl Lange, Damasio believes that emotions arise from physiological states of the body, so that, for example, the emotion of fear arises from the physiological disturbance of the body associated with some fearful event.  Emotions help us to make decisions by assigning emotional valence to our choices. Through imaginative projection, we can foresee the emotional outcome of a choice by anticipating how we will feel--our somatic markers--if we make that choice, and thus we might avoid a choice with fearful associations.  Ultimately, this emotional decision-making mechanism is an evolutionary adaptation to secure the survival and well-being of the body.

This line of thought has been extended by A. D. (Bud) Craig, a functional neuroanatomist.  He has traced out the fundamental neuroanatomical basis for all human emotions, and he has argued that this shows how the neural substrates for human self-awareness or consciousness are based on the neural representation of the physiological state (the homeostasis) of one's body.  This manifests the embodiment of emotional self-consciousness.  In particular, he argues that there is a phylogenetically novel sensory pathway in primates, most fully developed in human beings, that provides for a self-conscious integration of the physiological condition of the body (the material "self") with one's sensory environment, with one's motivational condition, and with one's social situation in the anterior insular cortex (AIC) (Craig 2002, 2003, 2008).

In imaging studies of emotion, the AIC is jointly activated with the anterior cingulate cortex (ACC).  The AIC seems to be the primary site for generating self-awareness from representations of the feelings from the body, while the ACC seems to be the site for the initiation of behavior, which thus provides volitional agency.

This could be the evolutionary neurophysiological basis for Locke's account of natural rights.  Reasoning about natural rights ultimately depends on discerning natural human inclinations, such as self-preservation, property, social attachment, practical judgment, and intellectual understanding, which correspond to what I have identified as the twenty natural desires.  Evolutionary neuroscience explains how the human nervous system has evolved to serve those natural inclinations or desires.  The concrete expression of those natural inclinations varies according to individual temperament, individual life history, and cultural circumstances.  But there is a universal human pattern that manifests the evolved natural needs of human beings as the smart social mammals that they are.

The evolution of mammalian social behavior depends on the evolution of pain or "negative affect," which includes pain, fear, panic, and anxiety.  In all vertebrates, fear and pain are represented in the brainstem and hypothalamus as signals to elicit self-preserving behavior.  In mammalian evolution, these neural mechanisms are modified so that animals care for their offspring as well as themselves.  This includes modifying the cortex of the mammalian brain to elaborate the representation of pain to include anxiety tied to separation from or threat to loved ones.

Craig's research clarifies this neural evolution of pain by classifying pain as a homeostatic emotion rather than as a sensation of touch.  Pain belongs to "interoception"--the sense of the physiological condition of the body--and it is therefore part of the evolved mechanisms for self-preservation.  The insular cortex receives signals from all the tissues of the body, and these signals are integrated with physical and social stimuli from outside the body and with the memory of past experiences as well as imaginative projections of future experiences.  This supports a general awareness of the body's condition in space and time.  The ACC can then be activated to motivate behavior to correct whatever is wrong.  This neural processing mechanism seems to be unique to primates, but it's more highly developed in human beings.

Both the insular cortex and the ACC respond not only to physical pain from bodily injury but also social pain from social injury.  In mammalian evolution, the neural circuitry for physical pain was appropriated for registering social pain in animals adapted for social attachment.  Mammals have evolved to care for the survival and well-being not only of themselves, but also of others to whom they are attached.  Extending the neural mechanisms originally evolved for individual self-preservation to include the welfare of offspring and social partners secures mammalian social order.  The uniquely human evolution of the neocortex elaborates this mammalian development to sustain human love and concern for others.  When we use the language of physical pain to metaphorically describe our social pain, as when we speak of suffering "a broken heart,” we suggest the embodiment of our natural social consciousness, in which our mind, our brain, our body, and our social life are inseparably intertwined.  After all, being rejected by others really does hurt us, and we can see how this is rooted in our evolved nervous system (Eisenberger and Lieberman 2004).

Social neuroscience is beginning to explain the neurochemistry of mammalian attachment as the natural ground for human morality and social order as rooted in human care (Zahn, Oliveira-Souza, and Moll 2011; Churchland 2011, 2013).  As shaped by evolutionary history, nervous systems are organized to take care of the body.  Animals with neural adaptations inclined to care for themselves and for their well-being are selected over those that neglect their self-preservation.   In mammals, this caring for oneself is extended into care for others--for one's offspring, for one's mate, for one's kin, and for others in one's group.  We are now beginning to explain how this works through the neurochemistry of factors such as oxytocin and vasopressin, which support attachment and bonding.  This sustains the basic social desires or sentiments that lead to human morality.   This neurobiology of mammalian sociality confirms the argument of Locke, Smith, and other liberal thinkers about the importance of mammalian biology as the natural ground for the unintended social order of family life (Locke 1988, I.86-88, II.77-79; Smith 1982b, pp. 141-43, 438).

Because of our evolved human nature, we care not only for ourselves and other persons to whom we are attached, but also for the physical goods that have some value for us, and thus we have a natural desire for property.

 

1.3  The biology of property

A Darwinian view of human nature sustains the liberal commitment to private property as a natural propensity that is diversely expressed in custom and law.  The particular rules for property rights are determined by customary traditions and formal laws that vary across history and across societies, but that variation is constrained by the natural desire for property.  We need to understand the complexity of property across three levels--natural property, customary property, and formal property (Arnhart 2009, pp. 59-67).

This is illustrated in the historical case of mining law in California.  Once gold was discovered in northern California in 1848, hundreds of thousands of people went there to search for gold, and they showed their natural instinct for property by claiming land for mining by taking possession of it, although they were only squatters on land officially owned by the federal government of the United States.  To settle disputes over mining claims, the miners developed customary rules that they enforced among themselves by social tradition.  Then, finally, in 1866, the United States Congress passed a federal mining law that formally legalized these local customs of the miners.

Thus, the property claims of the miners moved through three levels--natural possession, customary rules, and formal laws.  This manifests the general structure of Darwinian social order as the joint product of natural desires, cultural practices, and deliberate judgments.

In recent years, a growing number of law professors have become interested in the evolutionary analysis of law, and one prime area of research has been the evolutionary analysis of property law.  This research confirms the Darwinian account of property (Krier 2009; Stake 2004; DeScioli and Wilson 2011).

This research provides a scientific confirmation for the evolutionary explanation of property laid out originally by Locke (in his Two Treatises of Government), William Blackstone (in his Commentaries on the Laws of England), and Adam Smith (in his Lectures on Jurisprudence) (Smith 1982b, pp. 13-39).   First, among ancient foraging bands, hunting territory was owned communally by the band--excluding other bands--and personal property (such as weapons, tools, and clothing) was owned individually.  These original claims to property were based on possession and occupancy, so that the first person or group to take and hold possession of some scarce resource was presumed to own it.  This was enforced by customary agreement.  But, then, when agriculture was developed, the growing scarcity and demand for land made it necessary to settle property disputes through the formal institutions of government, and the invention of writing facilitated this.  Finally, with the expansion of commerce and trade, property rights became ever more subject to rules of sale, grant, or conveyance.

We might explain part of the evolutionary logic for property through John Maynard Smith's (1982) evolutionary game theory analysis of how the "bourgeois" strategy develops among animals to settle disputes over territory and resources.  If we imagine two animals competing for access to a particular breeding territory, and if they have an equal opportunity of arriving first and possessing it or arriving later and being an intruder, we might imagine two possible strategies: the Hawk who fights until one animal is injured and retreats, and the Dove who bluffs but never fights. Under certain conditions, the best strategy is a "bourgeois" strategy that mixes the other two: "if owner, play Hawk; if intruder, play Dove."  In fact, many animals do seem to play this strategy, so that the possessor of a territory tends to have an advantage over an intruder, and consequently there is a kind of instinctive rule of property that favors possessors over intruders, because possessors will risk injury to defend their possessions, while intruders will retreat in response to the threat of injury.  Of course, explaining territorial behavior among animals requires weighing many factors that influence the costs and benefits of defending territory, which goes beyond a simple choice between two strategies (Alcock 2013, pp. 142-52).  But the general point is that it is adaptive for animals to defend their possession of appropriated resources.

The primacy of possession runs through much of our property law, and this could be because it is rooted in the evolved structure of our brains so that it feels right to us.  One lawyer concludes: "Possession, as any property lawyer knows, remains the cornerstone of most contemporary property systems--nine points of the law, the root of title, and the origin of property” (Krier 2009, p. 159).  Included in the right of possessing property is the right of exchanging one’s property for the property of others, which allows for the mutual gains from trade (Westermarck 1906, vol. 2, pp. 1-71).

2  The evolution of exchange and specialization

 

The liberal idea of society as a largely self-sustaining order assumes that this arises as an unintended outcome of the actions of individuals naturally inclined to mutual exchange and a division of labor.  Smith explained this in The Wealth of Nations as rooted in the human “propensity to truck, barter, and exchange.”  Darwinian science confirms this liberal idea by showing how a natural propensity to exchange and specialization arose in human evolution, and how the modern cultural evolution of exchange and specialization explains the explosive growth in the prosperity, population, and liberty of the modern world. 

2.1  The evolution of the “propensity to truck, barter, and exchange”

 

Smith claims in The Wealth of Nations that the "propensity to truck, barter, and exchange one thing for another" is uniquely human and not found in any other animals (1981, p. 25).  Is this true, and, if true, what would it mean for our understanding of human social life?

Haim Ofek (2001) and Matt Ridley (2010) have argued that what we now know about human evolution confirms Smith's insight about the unique importance of exchange for human history.  The whole of human history for the past 200,000 years can be understood as the progressive extension of human cooperation through exchange and the division of labor--from foraging bands to agrarian states to modern commercial societies in global networks of trade.  Both Ofek and Ridley see this as arising from a human propensity to exchange that cannot be seen in any other animal.

In the first chapter of The Wealth of Nations, Smith explains the division of labor as the primary cause for the increasing productivity, which includes the famous example of the pin factory.  In the second chapter, he explains how this division of labor arose in human history:  "This division of labour, from which so many advantages are derived, is not originally the effect of any human wisdom, which foresees and intends that general opulence to which it gives occasion.  It is the necessary, though very slow and gradual consequence of a certain propensity in human nature which has in view no such extensive utility; the propensity to truck, barter, and exchange one thing for another” (p. 25).   Smith does not see this propensity in other animals: “Nobody ever saw one animal by its gestures and natural cries signify to another, this is mine, that yours; I am willing to give this for that” (p. 26).   Animals beg for help, and human beings also do this as well.  But in a large civilized society, human beings require the cooperation of a great number of strangers who feel no love, friendship, or benevolence for them.  Consequently, in such a large human society, we must secure the cooperation of strangers through mutually beneficial trading:  “Give me that which I want, and you shall have this which you want, is the meaning of every such offer; and it is in this manner that we obtain from one another the far greater part of those offices which we stand in need of.  It is not from the benevolence of the butcher, the brewer, or the baker, that we expect our dinner, but from their regard to their own interest” (pp. 26-27).

Smith then indicates that the emergence of a division of labor through exchange appears originally among savages living as hunter-gatherers, where someone might specialize in making bows and arrows that he can trade for some meat captured by a hunter, so that each fills a particular occupation, and thus their joint labor becomes more productive than would be the case if each were working only for himself (1981, pp. 27-28; 1982b, pp. 347-49).  This is part of Smith's understanding of human social evolution as passing through four stages of social life--from foraging to herding to farming to commerce.  Smith and other Scottish philosophers developed a theory of the four stages in social evolution from their study of the reports about the native Americans in the New World.  This was the beginning of evolutionary anthropology (Meek 2011).

At the beginning of The Wealth of Nations, we see the fundamental idea that is common to Smith's social thought and Darwin's biology--the possibility of design-without-a-designer ("not originally the effect of any human wisdom") through emergent or spontaneous order.   Smith then poses an evolutionary question: Was the propensity to exchange an original principle of human evolution, or was it a late by-product of earlier evolved "faculties of reason and speech"?  Although he chooses not to take up this question here, he considers it more probable that reason and speech came first, and then the propensity to exchange came later as a by-product.  In the Lectures on Jurisprudence, Smith says that the "real foundation" of exchange and the division of labor is "that principle to persuade which so much prevails in human nature” (1982b, p. 352).   Like Aristotle, Smith believes that human beings are more political than other political animals because human beings have a capacity for logos--reason or speech--that allows them to persuade one another to cooperate for common ends, which makes exchange and the division of labor possible.  Ofek argues, however, that the evidence of human evolutionary history now suggests that exchange was an early agent of human evolution that favored the evolution of human reason and speech.

Smith goes on to suggest that while other animals can seem to act in concert when they are in passionate pursuit of the same object--like greyhounds chasing the same hare--this is the consequence not of any contract or deliberate choice but of "the accidental concurrence of their passions" in pursuing the same object at the same time.  Non-human animals are unable to communicate with one another well enough to say: "this is mine, that yours; I am willing to give this for that."

Smith does think that non-human animals can engage in persuasion by begging for attention within their families or their groups or even to elicit benevolent care from human beings.  But the range of benevolence for all animals--including human beings--is limited.  In human civilization, individuals need "the cooperation and assistance of great multitudes," and for this they must appeal not to benevolence but to self-love, by persuading other individuals to engage with them in mutually beneficial exchanges.  Indeed, Smith points out that among human beings, even beggars cannot rely totally on charitable benevolence to secure their needs, because they beg for money that they use to buy what they need.

We might wonder whether Darwin would agree with Smith about barter or exchange being unique to human beings in giving rise to the division of labor as a spontaneous order.  Remarkably, Darwin says little about exchange in human evolution.  But there are at least two passages in Darwin's writings that both Ofek and Ridley cite as supporting their arguments about the human evolution of exchange.

In the Voyage of the Beagle, Darwin described the savage people that he saw at Tierra del Fuego, at the far southern tip of South America.  He thought the Fuegians showed the most primitive level of human social life.  "Some of the Fuegians plainly showed that they had a fair notion of barter. I gave one man a large nail (a most valuable present) without making any signs for a return; but he immediately picked out two fish, and handed them up on the point of his spear. If any present was designed for one canoe, and it fell near another, it was invariably given to the right owner” (2004a, p. 201).  Darwin seems, then, to agree with Smith that even those living in the most primitive foraging societies show "the propensity to truck, barter, and exchange one thing for another."

In The Descent of Man, Darwin described how man became "the most dominant animal" through technological inventions such as tools:

To chip a flint into the rudest tool, or to form a barbed spear or hook from a bone, demands the use of a perfect hand; for, as a most capable judge, Mr. Schoolcraft, remarks, the shaping fragments of stones into knives, lances, or arrow-heads, shews 'extraordinary ability and long practice.' This is to a great extent proved by the fact that primeval men practised a division of labour; each man did not manufacture his own flint tools or rude pottery, but certain individuals appear to have devoted themselves to such work, no doubt receiving in exchange the produce of the chase (Darwin 2004b, p. 69).

Darwin implies that the complexity of artifacts in the archaeological record could be interpreted as evidence for a division of labor that promotes the dexterity and inventiveness that comes from specialization.  Ofek and Ridley have adopted this line of reasoning in arguing that the explosion of technological complexity in the Upper Paleolithic record of human evolution is a consequence of exchange and specialization, which is confirmed by evidence that some of the material in the human artifacts was transported over long distances, apparently through trade.

Darwin does not indicate, however, that this propensity for exchange and a division of labor is uniquely human, as Smith does.  Ridley argues that recent research on the evolution of cooperation confirms Smith's view.  Other animals cooperate with one another based on kinship, relatedness, and reciprocity (direct and indirect), and human cooperation shows these same evolved mechanisms at work.  But cooperation based on exchange or barter is uniquely human, and it cannot be explained as a form of reciprocity.  Reciprocity means giving each other the same thing.  I'll scratch your back if you scratch mine (direct reciprocity).  Or I'll scratch your back because you have a reputation for scratching the backs of others (indirect reciprocity).  But exchange means giving each other different things.  As Smith puts it, "Give me that which I want, and you shall have this which you want."  Other animals can't do this.

To support this conclusion, Ridley cites some experiments with chimpanzees:

The primatologist Sarah Brosnan tried to teach two different groups of chimpanzees about barter and found it very problematic. Her chimps preferred grapes to apples to cucumbers to carrots (which they liked least of all). They were prepared sometimes to give up carrots for grapes, but they almost never bartered apples for grapes (or vice versa), however advantageous the bargain. They could not see the point of giving up food they liked for food they liked even more. Chimpanzees and monkeys can be taught to exchange tokens for food, but this is a long way from spontaneously exchanging one thing for another: the tokens have no value to the chimpanzees, so they are happy to give them up. True barter requires that you give up something you value in exchange for something else you value slightly more (Ridley 2010, p. 59).

Here Ridley is obscuring some of the complexity in these experiments (see Brosnan 2008).  Brosnan and her colleagues apparently showed that chimps do barter, at least in a situation where they can trade very low valued items (carrots) for very high valued items (grapes).  But they do not barter where the gains from barter are small--as in trading valuable apples for slightly more valuable grapes.  One possible explanation that they suggest is that the chimps are less inclined to take the risk from giving up a valued food item if the possible gains are too small.

Nevertheless, these experiments do provide some support for the Smith/Ridley position.  Even if these chimps can learn to barter under some special conditions in the laboratory, they don't seem to spontaneously barter in the wild.  This is in contrast to the human situation where bartering comes easily as a spontaneous behavior, even in the most primitive human conditions, as with Darwin's Fuegians.

2.2  The neurobiology of exchange

 

If exchange has been an important factor for human evolution for a hundred thousand years or more, then we can expect that human neurobiological systems support the disposition to exchange.   Paul Zak (2012) has performed some game-theory experiments that seem to show that this disposition to exchange as based on trust is supported by the neuroactive hormone oxytocin, which is found in all mammals, and which evolved originally to support maternal care of offspring.   The ancient evolution of oxytocin in human beings and other mammals suggests deep evolutionary roots for extended human cooperation.

Zak argues that economic exchange depends upon moral values, because it depends upon the trust that makes cooperation possible.  There is evidence that this disposition to trust and cooperation has evolved to be part of human nature, although the expression of that disposition varies in response to the cultural environment.  We are now beginning to explain the neural mechanisms of this evolved moral nature.  In particular, Zak has shown experimentally that oxytocin supports moral cooperation by promoting attachment to offspring, to reproductive partners, to friends, and even to strangers.  What originally evolved to promote mammalian maternal care for offspring has been extended to embrace ever wider groups of individuals who benefit from exchange.

Zak sees economic exchange as rooted in evolved human nature:

Values are not specific to the West or East, nor are there broadly distinct Western and Eastern economic institutions.  Rather, values across all cultures are simply variations on a theme that is deeply human, strongly represented physiologically, and evolutionarily old. Similarly, the kinds of market institutions that create wealth and enable happiness and freedom of choice are those that resonate with the social nature of human beings who have an innate sense of shared values of right, wrong, and fair.  Modern economies cannot operate without these (Zak 2008, p. 276).

Zak agrees with Friedrich Hayek (1991) in seeing the modern transition from personal exchange to mostly impersonal exchange in markets as making possible the great increases in wealth and population since the Industrial Revolution.  But in contrast to Hayek, Zak sees this cultural tradition of impersonal exchange as developing an innate potentiality of evolved human nature.

One can see this in the research of Joseph Henrich and his colleagues (2010) who studied the play of the Ultimatum Game in small-scale societies around the world. Variations in the play of the game manifested variations in the cultural norms of the societies.  The higher rates of fair offers in the game were associated with those societies that had high levels of market activity.  It seemed that people who regularly engaged in trade learned that successful trading required that traders agree on a fair distribution of gains.  The genetically evolved neural mechanism of oxytocin as favoring trust will fluctuate in response to the culturally evolved social environment.  Thus, a Darwinian explanation of exchange behavior requires a coevolutionary explanation of the interaction between genetic evolution and cultural evolution, in which cultural evolution taps into human genetically evolved psychology.

 

3  Conclusion

In one of the first reviews of Darwin’s Origin of Species, Thomas Henry Huxley (1860) declared that “every philosophical thinker hails it as a veritable Whitworth gun in the armory of liberalism.”  The Whitworth gun was a new kind of breech-loading cannon.

          If the fundamental idea of liberalism is that social order can arise as a largely self-regulating and unintended order from the free exchanges of individuals seeking to satisfy their individual desires, then Darwinian evolutionary science truly is a powerful weapon for liberalism insofar as it supports that idea.  It does that by showing how an evolutionary liberalism can be grounded on the evolution of self-ownership, property, and mammalian sociality and on the evolution of exchange and the division of labor.

  

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