The Neolithic Revolution: Epigenetics and Rousseau's 'Natural Man'

 

Preface

Contrary to the Enlightenment faith in the clear and inevitable progress of humanity, Jean Jacques Rousseau suggests in his 1755 Discourse on the Origin of Inequality Among Mankind that humans have not only lost their way, but that they have also been on a course of self-alienation for quite some time. Indeed, Rousseau tells his readers that he has peered into the “book of nature which never lies” (177) and discovered there, in a time long ago and far away, a profile of man in his best and most natural state. That creature, he says, is nothing at all like the rationalistic and pampered person of modern Europe. Rather, he is a being entirely devoid of the accouterments of civilization, especially those degenerate faculties of “foresight [and] curiosity” (190) peculiar to modern man. For Rousseau, savage, 'natural man' is the happiest, most robust, most well-supplied, and greatest advantaged life form to issue from the earth's womb. Furthermore, he in no way resembles the pathetic, fearful, and brutish figure given by Hobbes. So convinced is Rousseau of this underlying truth about the human as he really is, and even as he ought to be, that he is positive that we too, upon hearing his account, will lament the disappearance of that golden age being and rue the degradation of his descendants, namely, us.

 

While many of Rousseau’s details are, in his words, “hypothetical and conditional reasonings” meant to get at “the nature of things” (176) rather than to offer scientific or historical facts, it is fairly impressive just how close to the facts, as we now see them at least, many of those ‘reasonings’ actually are. Indeed, current anthropological accounts of the relatively more holistic and egalitarian lifestyles of our immediate ancestors, that is, the hunter-gatherers of the Paleolithic era, jibe nicely if not perfectly with much of Rousseau’s portrayal of savage man. Yet what is perhaps even more striking is the confluence between the reports given by modern anthropologists regarding the rise of agricultural society and Rousseau’s account of the ‘fall’ of the free and noble savage into the seemingly intractable ills that are the necessary effects of property ownership, stratified society, and the “slavery and misery” (220) associated with the onset of agriculture.

 

The unhappy fallout of that shift is today being critically examined, among others, by researchers who bridge the worlds of genetics and anthropology, such as the population geneticist Spencer Wells (Jared Diamond and Yuval Harari likewise document the effects of the Neolithic Revolution). In his thoroughly compelling 2010 book on human evolution, Pandora’s Seed: Why the Hunter-Gatherer Holds the Key to Our Survival,  Wells offers a bleak prognosis for our species that can be seen as an echo or ripple effect of the events found in Rousseau’s account of the demise of 'prelapsarian', non-agricultural savage man.

 

Wells’ genetic data also gives rise to other interesting questions about that momentous historical transition and what it might say about our ‘true’ nature, especially if that loaded term is understood to mean "grounded in our biological makeup." In particular, what Wells and others alternatively call the ‘Neolithic Revolution’ or the ‘Big Bang’ (a period that began roughly 10,000 years ago) has recently been shown to coincide with marked genetic selection within our species, something which has long been thought to require at least 1000 generations to manifest.

 

While the findings do identify numerous changes in the human genome beginning around that time – primarily related to skin pigmentation, lactose persistence, and other factors connected to the metabolizing of food and the resistance to disease– not much has been said about the possibility that it may have likewise coincided with alterations in human phenotypic expressions, especially those connected to personal and/or interpersonal psychology. Those familiar with Rousseau’s Discourse on Inequality will of course remember his focus on the transition of the natural human as a creature who was ruled by real, healthy self-love - or 'amour de soi' - to one in which an ugly and warped self-regard - or 'amour propre' - began to dominate his consciousness. This paper will consider the possibility that this proposed shift may not only be an accurate reflection of what happened in the hypothetical Rousseauean sense, but also perhaps in the ‘factual’ scientific sense.

 

In order to do this, the relatively new field of epigenetics will be explored for clues regarding the effects of environment on phenotypic expression and also for information regarding the heritability of those effects. The paper will then propose a number of extrapolations that might follow from the epigenetic findings, especially as they relate to the thoughts of Rousseau and his ruminations on 'natural man' vs. 'civilized man'. Because the overlap between Rousseau’s depiction of natural man and the modern notions of Paleolithic hunter-gatherers is so striking, however, this paper will first investigate that overlap with an eye towards demonstrating, in Rousseau’s words, “How much you are changed from what you once were” (177).

 

Natural Man

 

In the mind’s eye of Rousseau, the original human, the natural man, is a naked and almost entirely instinctual creature, much like the wild animals around him. He differs from them, says Rousseau, only in this respect: he “appropriates to himself those [instincts] of all the other animals” (179) and thus is capable of a greater flexibility in attaining his subsistence. Savage man slakes his thirst at the clear waters of the babbling brook and satisfies his hunger wherever he finds food, depending entirely upon nature to meet his every need. Similarly, says Wells, our species’ most distant cousins, the homo sapiens that show up in Africa some 200,000 years ago, were hunter-gatherers who “lived much the same way as any other [species], relying on the whims of nature to provide [them] with food and water” (24). This they did up until around 10,000 years ago when, for reasons related to climate change and shifts in population size, they began to produce rather than find their food.

 

Prior to becoming thus ‘civilized’, says Rousseau, man in the state of nature was the very picture of health, as he met “few sources of sickness, [and thus had] no great occasion for physic, and even less for physicians” (184). Similarly, in a startling graph reprinted in Wells’ book showing the differences between the skeletal remains of hunter-gatherers and their immediate agricultural descendants, it is revealed that both median life span and average height of both men and women decrease significantly after the rise of agriculture. This trend reaches a low point in the late Neolithic, around the time the Sumerian and Egyptian civilizations begin, and slowly reverses until it sharply alters during the 20th century and the development of modern medicine.

 

The bottom line, in the words of Wells, is that “hunter-gatherers had an overall 22 percent health advantage over Neolithic agriculturalists” (24), and more importantly, that “every single major disease affecting modern human populations […] has its roots in the mismatch between our biology and the world we have created since the advent of agriculture” (90). One must give credit to Rousseau for intuiting this truth over 250 years ago when he stated that natural men were “strangers to almost every disease, except those occasioned by wounds and old age, [and that] the history of human disease might be easily written by pursuing that of civil societies” (183). Yet the rise in maladies concomitant with the shift to an agricultural society is certainly not limited to those affecting the physical body. Indeed, both Wells and Rousseau are keen to speculate, as we will see next, about a perhaps even more insidious decline in human mental and emotional health in the wake of the Neolithic ‘Big Bang’. 

 

Amour de Dementia

 

After the Neolithic Revolution the hunter-gatherer individual/band lost the option of entertaining “any and all cultural possibilities”, gradually finding that they were instead like zoo animals, “caged, limited in both geography and focus”  (Wells 113). In addition to this, the hardwired biological comfort zone of human sociability, which is maximized when living in groups of 150 or fewer people, became quickly overwhelmed as the Neolithic societies grew. According to Wells, when this happens (or happened) only two options are open to the socially inundated human: 1) you and your group move elsewhere, or 2) you and your group join with the other groups to form institutions that will maintain and regulate the swelling ranks. Hunter-gatherers primarily took the first option; Neolithic peoples could only choose the second. As a result, says Wells, Neolithic man began “to dehumanize one another, and [his] behavior [thus] becomes decidedly unnatural” (120). Now, I might quibble with Wells over his employment of the modifier "unnatural" since, as far as I can tell, any behavior exhibited by humans must be "natural" in the sense that it is made possible by his biological makeup. Yet I nonetheless agree that the dehumanizing tendency fostered by social overwhelm is at the very least problematic and, not infrequently, dangerous.

 

Wells says further that the density of agricultural societies is so at odds with the sparse populations of hunter-gatherers, i.e., the societies in which our species developed biologically, that “this is almost certainly one of the reasons for the psychological unease felt” (120) by people living in agricultural or other extremely ‘noisy’ societies, i.e., in post-industrial settings. In a similar passage in the Discourse, Rousseau imagines the changes taking place within humans as they begin to settle in one location, joining with those who were once strangers into a “distinct nation, united in character and manners […] by the same way of life, and alimentation, and the common influence of the climate” (218). In this new arrangement, men “continue to shake off their original wildness” (218) and find themselves in an unfamiliar and difficult psychological climate in which “public esteem [now] acquire[s] a value” (218).

 

This unfortunate situation, says Rousseau, sets mankind irrevocably on the path toward the twin evils of inequality and vice; thus, says Rousseau, natural man in the newly formed nation is still 'man' but he is no longer 'natural'. Like Wells, he insists that this degradation takes place primarily because “the society now formed and the relations now established among men required in them qualities different from those which they derived from their primitive constitution” (219).

 

If we take these observations seriously, as we ought, we might be inspired to posit a number of important questions about this ‘civilizing’ Neolithic transition and its possible effects on our ancestors. Two of the most compelling, as far as this paper is concerned are: 1) ‘If our biology is indeed mismatched with our cultural environment, and if it is true that the only significant genetic selection that has occurred since the Neolithic Revolution shows up in genes connected to skin pigmentation and the metabolizing of food, then what other non-genetic yet still biologically important effects might that mismatch be responsible for?’ and 2) ‘Is there anything that epigenetics can tell us about question 1?’ It is to these two questions that this paper will now turn.

 

Epigenetics and Inequality

 

In the Introduction to her 2012 book The Epigenetic Revolution, author and virologist Nessa Carey identifies epigenetics as “the set of modifications to our genetic material that change the way the genes are switched on or off, but which don’t alter the genes themselves” (7). She also remarks that “[w]hen a change in environment has biological consequences that last long after the event itself has vanished into distant memory, we are seeing an epigenetic effect in action” (6). Without rehearsing the molecular mechanisms by which such epigenetic effects arise, fascinating as they are, we may nonetheless take little risk in suggesting that the above description of the transition from hunter-gatherer/natural man to agricultural/civilized man would qualify as a significant change in the environment that had biological consequences. As already mentioned in the Introduction, the evidence for genetic selection during (and since) the Neolithic Revolution is fairly uncontroversial. Evidence of epigenetic changes regarding the same, however, is somewhat scarce.

 

Scarcer still is the evidence, biologically speaking, that personal and interpersonal ills such as those described by Rousseau, i.e. “vanity and contempt [and] envy and shame” (218), came into being, or at least became more intransigent, after the Neolithic Revolution. Lack of evidence notwithstanding, Wells remarks that today’s increased use of prescription psychoactive drugs in the battle against anxiety and depression reflects a somewhat backward attempt to address the problems that are “part of the continuing fallout of the Neolithic population explosion” (121). Is it possible that both Rousseau and Wells have correctly, if indirectly, identified a suite of psychological disorders that are linked to or even rooted in epigenetic 'mutations' whose foundations lie in social inequality, especially, as Rousseau says, “that kind of inequality which obtains in all civilized nations” (246)? In the absence of any direct evidence to confirm or disconfirm this notion, and as a tip of the hat to Jean Jacques, the remainder of this paper will indulge in a few its own Rousseauean ‘hypothetical and conditional reasonings’.

 

The Book of Epigenetics

 

“O man, of whatever country you are, whatever your opinions may be, attend to my words; here is your history such as I think I have read it, not in books composed by your fellow men […] but in the book of [epigenetics] which never lies” (Rousseau 177).

Though we may be in the dark regarding our most ancient selves, it is nonetheless a fact that “modern man is, in a fundamental, biological sense, a hunter-gatherer” (Mayor 485). And it is also an inescapable fact that at a deep level we are creatures accustomed to a great deal of personal freedom. Indeed, “the anthropological evidence is overwhelming that for seven million years man had a level of individual autonomy in decision making that far exceeded anything experienced since the introduction of extensive agriculture” (491). Yet that level of freedom has long since disappeared, as we all know. Some consolation may be found, however, in the knowledge that our basic approach to affairs of the heart has remained unaltered over the ages.

 

We know this because most hunter-gatherer interband conflicts were not caused by disputes over resources or territory, but rather by personal grievances, especially “disputes over women and the […] capturing of women [which] were prominent causes of warfare” (Mayor 487). Some things never change. Still, despite this powerful link to the past, you may rightly feel that you have gotten something of a raw deal on personal freedom and psychological health ever since the Neolithic Revolution. This, after all, was when it first became possible for “powerful warlords with the necessary leverage to dominate settled agricultural communities, establish the first states, restrict individual autonomy, and abolish the individual’s right to his own production” (499).

 

But you may not fully grasp just how raw that deal is. To wit: have you ever considered that those restrictions brought about not by ‘nature’, per se, but rather by those imbalances of power in agricultural societies and their descendants, have insidiously bored their way into your fundamental, biological self? That is, have you ever wondered if the human genome was 'hijacked' long ago by a cultural larcenist that has since kept the wheels of our DNA rolling squarely in the ditches of physical and, most relevant here, psychological health? If not, perhaps the following will assist you in imagining how such a distressing process might have occurred.

 

Trapped, Like Rats

 

Consider, if you will, the question of childhood trauma. Now it is well known that “an abusive or neglectful environment when [one is] young is clearly a major risk factor for the development of later neuropsychiatric disorders” (Carey 234). And though still in the early stages of research, it is hypothesized that on the molecular level such childhood traumas, and the subsequent neuropsychiatric disorders associated with them, have a strong epigenetic component. This is primarily because of the long span of time taking place between the specific trauma and the manifestation of the related, and biologically identifiable, disorders – a relationship that is, by definition, epigenetic in nature. Most of the studies performed thus far regarding this relationship have focused on the differences in cortisol levels of adult rats who as babies were given either high or low levels of rat ‘mother love’, which is expressed primarily through the licking and grooming activities of the mother on the baby rat.

 

The findings show that rats given proper levels of maternal care as babies grew into adults who exhibited much lower base stress levels and a matching capacity to handle novel situations without freaking out. There is evidence from studies of human adult victims of childhood abuse or neglect that show similarly high cortisol levels. This means that they, like the above 'love-deprived' adult rats, live their lives in a chronically higher than normal state of stress. Because of this, they are at a greater risk of developing some form of mental illness than those who were lucky enough to have escaped highly traumatic childhoods. Neurological studies of suicide victims who experienced childhood abuse or neglect have also revealed the presence of higher than normal DNA methylation levels (an epigenetic marker) at the cortisol receptor gene in the hippocampus. This suggests that there may be an epigenetic component to the mental illnesses that can lead to suicide.

 

You may at this point be wondering what all this talk of stressed rats and childhood trauma has to do with the Neolithic Revolution, social inequality, and the ‘truth’ about your fundamental self. The answer, to put it plainly, is this:

The transition from small, egalitarian hunter-gatherer societies to heavily populated and stratified agricultural societies forced into existence negative epigenetic changes in the genomes of a vast population of susceptible individuals that linger to the present day. Those qualifying as ‘susceptible’ would be anyone whose individual autonomy in decision making was made subservient to the now ‘too-large for the brains of homo-sapiens to handle’ collective. The pressure to conform to the demands of this new collective, which was dominated by a small elite, brought about levels of stress so high in much of the populace as to increase, among other dysfunctional attempts at coping, the incidences of child abuse and or neglect at home (the kick-the-cat syndrome). This rise in childhood trauma in agricultural societies thus manifested in epigenetic changes in those children, and those changes led in turn to a plethora of intrapsychic and interpersonal disorders. Most importantly, those changes, it is proposed, have been passed on through subsequent generations all the way to the present via the quasi-Lamarckian mechanism known as epigenetic inheritance.

 

For those of you having doubts about this proposition, consider what one epigenetics researcher has recently written: “In addition to prenatal chemical and dietary influences, early caregiving can have long-term effects on epigenetic markers, neurophysiology, and behavior in offspring” (Masterpasqua 200). Of course, such a statement is tempered by the circumspection required in a field of research still in its infancy, but there is nonetheless some concordance in the writings of current anthropological thinkers. One such thinker, Melvin Konner, notes that the “[d]epartures from the [child rearing practices of hunter-gatherers] since the end of the hunting-gathering era constitutes a discordance and may have psychological and biological consequences that merit further study” (64).

Another thinker, Darcia Narvaez of Notre Dame, has made the case more directly, stating that

"[...] we [moderns] live and raise children in an environment that is opposite to the small-band hunter-gatherer, with relative physical comfort but with enormous built-in social distress […] Poor early environments, as in many settled societies, lead the brain to […] develop all sorts of strange beliefs to keep painful reality at bay […] The strange beliefs we see in complex societies, including in the West, also correspond to the trauma that children and/or adults have undergone, perhaps through coercion of some sort, which is a rare occurrence in small-band society," (44-45). 

 

As Rousseau so insightfully remarks in his Second Discourse, “the equality [of preagricultural society] once broken was followed by the most terrible disorders” (225), so too does Narvaez aver that the abandonment of child-rearing practices found in hunter-gatherer societies has lead “to the rampant and increasing ill health and psychopathology in Western cultures that is unknown in ancestral environments” (Moral 31). Similarly, this paper insists that evidence for epigenetic transgenerational effects, though only suggestive at this time, will in the future reveal the truth of the above ‘hypothetical and conditional reasonings’ regarding the epigenetic legacy of the Neolithic Revolution. In other words, they will no doubt validate Rousseau’s account of the manner and degree to which “[…] you are changed from what you once were” (177).

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Works Cited

 

Carey, Nessa. The Epigenetics Revolution: How Modern Biology Is Rewriting Our Understanding of Genetics, Disease, and Inheritance. New York: Columbia University Press, 2012.

Konner, Melvin. “Hunter-Gatherer Infancy and Childhood: The !Kung and Others.” HunterGatherer Childhoods: Evolutionary, Developmental, and Cultural Perspectives. Eds. Barry S. Hewlett and Michael E. Lamb. New Brunswick: Transaction Publishers, 2005. Print.

Narvaez, Darcia. “Restoring Personal Knowledge and Virtue: Response to Commentary.” Tradition and Discovery: The Polyani Society Periodical, 2011-2012, Vol. 38, No. 2, 44- 46.

Masterpasqua, Frank. “Psychology and Epigenetics.” Review of General Psychology, 2009, Vol. 13, No. 3, 194-201.

Mayor, Thomas. “Hunter-Gatherers: The Original Libertarians.” The Independent Review, Vol.16, No. 4, Spring 2012, 485-500.

Rousseau, Jean Jacques. The Social Contract and Discourse on the Origin of Inequality. New York: Simon and Schuster, 1967.

Wells, Spencer. Pandora’s Seed: Why the Hunter-Gatherer Holds the Key to Our Survival. New York: Random House, 2010.