How did humans come to do this so predictably all over the world? Much of the answer has to lie in biology. If we are to explain conscience evolution, I believe that initially we must look to natural selection processes that came to favor individuals who had the advantage over their fellows in the matter of controlling their own aggressions, for that is one very basic job that an evolutionary conscience does. If an individual lives in a society where subordinates can gang up and hurt the fitness of dominant individuals who rub them the wrong way, obviously such self-control can be quite useful to fitness.
After thinking for years about environmental changes that might have triggered such selection processes, I have decided that it could have been not so much a change in the physical environment itself as a change in what human groups did to exploit it—specifically, large-game hunting—that helped to do the trick. As we’ll see, this particular ecological pursuit would have made some very specific demands on the people involved in terms of major social adjustments that would allow such a subsistence practice to flourish.
In considering the actual selection processes that might have supported the emergence of a conscience, I shall go beyond Darwin’s rather tentative byproduct theory, and even beyond much of contemporary evolutionary thinking, to create a distinctive and multifaceted version of “social selection” theory as an explanation for the rather unusual set of agencies that created this moral faculty for us. In the next two chapters, my hypothesis will be that if earlier humans hadn’t already had an ancestral head start in the form of nonmoral group social control, today we might be just as amoral as any of the great apes that still live in sub-Saharan Africa, species that continue to live a life based on dominant power and still do so in top-heavy hierarchies that, compared to ourselves, are only rather moderately modified by subordinate rebellions.
Our human ancestors also lived in Africa, and for that reason our search for a scientific Eden will take us not into a lush paradisiacal garden perhaps at the confluence of the Tigris and Euphrates rivers, with trees bearing tempting fruit on all sides, but rather out onto the hot dry plains of Africa where wild game abounded. There are very good reasons to believe that these large mammals had to be killed and carefully shared by entire groups of people—and not just by individuals or small “families”—if our ancestors were to depend on their meat. And this, I believe, will provide an important key to explaining the evolution of morals.
A NATURAL GARDEN OF EDEN
6
A REALLY SERIOUS HUNTER ARRIVES
Our moral origins story begins 8 million years ago, plus or minus, when the lineage of the Common-Ancestor figure that Richard Wrangham identified for us was, as we’ve seen in Figure 1, splitting in two. At that branching point one of the two new lineages led to today’s gorillas, and to judge from what these apes do in the wild, this gorilla-based lineage either developed or retained a basically vegetarian approach to eating, along with a lack of territorial defense of natural resources and a haremic social structure. This will not concern us here, for it’s our more recent direct predecessor, Ancestral Pan, that we’re interested in because of its more developed talent for social control.
It’s very likely that Ancestral Pan continued all of the CA behaviors we’ve met with. To know with a high degree of probability what else this more recent ancestor was doing behaviorally, all that’s needed is to look for major patterns of behavior that are present unanimously in bonobos, chimpanzees, and humans—but not in gorillas. Again, the evolutionary principle of parsimony applies in reconstructing the behaviors of this ancestor,1 and, again, it will be useful to keep the analysis as conservative as possible since we are working with a small clade of only three species here. For that reason I will be looking for the least common denominator, wherever unanimity exists, and projecting only it into the past.
TERRITORIALITY, XENOPHOBIA, AND MORALITY
Thus, it will be Ancestral Pan who is the original inhabitant of our Natural Garden, while eventually we will have to include archaic Homo sapiens as well. For Ancestral Pan, the existence of natural-resource defense was significant.2 This became humanly important because territoriality and warfare pose such a profound practical problem for our own species.3 From the standpoint of evolutionary biology, such conflict between groups might also have contributed to moral evolution—if the group selection Darwin spoke of was activated sufficiently to have significant effects.4 But to start with, we must ask exactly how “territorial” and xenophobic the three extant descendants of Ancestral Pan are, respectively, and then look for the least common denominator.
Wild chimpanzee communities predictably stalk and kill their neighbors, and they may eventually wipe out an entire group and take over its resources.5 LPA human foragers, although often fairly peaceful, sometimes have intensive warfare that also rises to the level of genocide.6 However, bonobos’ territoriality is a far paler version of what chimpanzees and humans do, even though a similar basic pattern is readily discernible.7 When sizable foraging parties from neighboring communities meet near the edges of their territories, the xenophobic males are prone to vocalize hostilely with the smaller party withdrawing, and in one instance an injured bonobo male was observed afterward,8 so apparently the bonobos’ intergroup antagonism is not limited entirely to bluffing. On the other hand, some bonobo groups are reported to join up together amicably.9
With bonobos as the least common denominator, this means that Ancestral Pan’s territorial tendencies were setting up groups to actively dislike their socially distant neighbors, with at least some possibility of limited physical conflict. Conservatively, with this least common denominator Ancestral Pan, though xenophobic, was not a serious warrior.
It seems likely that contemporary very inconsistent LPA forager warfare levels may not be representative for frequent junctures in the Late Pleistocene, when our predecessors were facing dire scarcity due to climate change and group competition was likely to have been seriously exacerbated.10 One of the remarkable things about xenophobic tendencies in contemporary hunter-gatherers, and for that matter in all humans, is that our moral codes apply fully only within the group, be it a language group, a nonliterate population that shares the same piece of real estate or the same ethnic identity, or a nation.11 There seems to be a special, pejorative moral “discount” applied to cultural strangers—who often are not even considered to be fully human and therefore may be killed with little compunction.12
This moral downgrading of out-groupers generalizes beyond warfare between groups of coresident armed males, for today it can feed not only into genocide against the helpless, but also into terrorism that targets civilians. More generally, standard military ideologies make the “necessary” killing of civilian enemies palatable, even if they aren’t being used as human shields. “Regrettable, but acceptable” seems to define the collateral damage situation unless inflicting civilian casualties becomes a deliberate instrument of national policy, as with indiscriminant World War II bombing of cities like Nanking, London, Dresden, and Tokyo, with enormous and deliberate civilian losses, or as with the American attacks on Hiroshima and Nagasaki, which may have destroyed military targets but also killed similar numbers of civilians.
The underlying raw xenophobia can be traced directly back to Ancestral Pan. However, once culturally modern humans began to “moralize” their fear of or contempt for strangers, this gave us ethnocentrism.13 This culturally refined motivating force helps to support intensive conventional warfare and conquest, along with genocide as a particularly destructive type of warfare. Ethnocentrism, with its moral condescension factor, obviously has been important in establishing the sometimes quite deadly warfare patterns that some hunter-gatherers engage in today, but it may be difficult to estimate exactly how far back this violent, morally based type of cultural behavior reaches, how widespread it might have been in the Late Pleistocene at times when climates were more favorable,14 and, at the bottom line, to what degree it could have boosted Pleistocene group
selection that favored the evolution of altruism.15
I must emphasize that the Pleistocene was different, even though conditions that would have spurred warfare were not constant. In that epoch, climate fluctuations could have led to recurrent situations of population growth and then, with dwindling resources, crowding, and serious political competition. If small groups were annihilating each other at sufficiently high rates, a Darwinian group selection scenario that favored groups with greater numbers of morally upright, cooperative altruists, including men acting as warriors, could conceivably have been in play quite significantly.16
Here, however, we’ll be concerned with what could have been a very powerful type of social selection, one that over evolutionary time could have been far more consistent in its effects than group selection if the latter were driven by warfare spurred by cyclical climatic downturns. This means that as far as moral evolution is concerned, we’ll be much more interested in what happens within groups, than between groups. In that context, I’ll be constructing a series of tentative and sometimes partly competing hypotheses about how human evolution, with major help from social selection, could have taken a turn in the direction of morality.
ANCESTRAL PAN’S HUNTING AND SHARING PATTERNS
As I’ve said, the CA cannot be designated a hunter because gorillas don’t hunt. In contrast, Ancestral Pan was actively hunting—and sharing—some occasional small-game meat, and presently we’ll be learning about some finer details from bonobos and chimpanzees that underlie this ancestral assumption. Since then, at some point weapons-bearing humans began to regularly and actively scavenge, hunt and share the carcasses of animals larger than themselves; we’ve been doing this for at least hundreds of thousands of years, and as recently as 15,000 years ago human foragers, certainly the great majority, lived in mobile bands whose males hunted large mammals enthusiastically and often.
It’s possible that sometimes females were involved in this prehistoric hunting as well, for today there are a small handful of LPA bands that exhibit some female hunting,17 and both chimpanzee females and in particular bonobo females are known to hunt actively. There surely were Pleistocene junctures when human populations were being badly decimated by cold or drought and consequently some bands were becoming too small to be efficient at hunting,18 and at such times gaining extra hunters could have been useful as a way of increasing kill rates and reducing unwanted peaks and valleys in meat consumption. Thus, female hunters might have added to the general social flexibility that enabled Pleistocene humans to cope with a wide array of sometimes very sudden and often stressful environmental challenges.
LPA humans hunt large game as a dedicated activity that involves sophisticated systems of sharing. Chimpanzees and bonobos hunt casually and rather rarely, and in the absence of projectile weapons they go after smallish game.19 Bonobos hunt even less than chimpanzees, and they tend to do so as individuals, whereas sometimes chimpanzee males seem to be quite collectively oriented in their pursuit of attractive fresh meat.20 Both species appear to savor the fatty brains when it’s time to eat and share, and at Gombe what I found fascinating was the limited way that up to a dozen or more excited apes shared these carcasses; chimpanzees and bonobos have similar modes of doing this. Normally, a higher-ranking individual who captured the carcass firmly possesses the meat afterward and takes a lion’s portion, sharing with some of those who approach and beg for shares—but definitely not with others.
I’ll never forget a chimpanzee hunt I witnessed my first year at Gombe, when a foraging party with numerous adult and adolescent males aggressively captured four colobus monkeys in less than half an hour and began eating them. As a novice fieldworker, I asked Jane Goodall afterward why the alpha male, Goblin, had stayed on the ground throughout the hunt instead of climbing into the trees and participating. With the benefit of over twenty years of field experience, Jane told me that Goblin was waiting for someone else to make a kill so that he could selfishly confiscate it, and her interpretation made a perfect fit with what I had described that afternoon in my field notes. With so many kills being made, the alpha male knew he had a sure feast in his near future, so this habitual bully conserved his energy and let an adolescent male catch his meat.
It’s clear enough that meat is a prized food, for apes that are not given a share seldom leave the scene. They steadfastly bide their time hoping somehow to get some meat, and often enough these unsuccessful chimpanzee beggars become highly frustrated and prone to quarrel among themselves. In both bonobos and chimpanzees, the impression is one of gluttonously selfish possession, combined with rampant cronyism when it comes to limited sharing of this most precious of all foods. The overall sharing process seems to be shaped both by individual political power and by personal alliances.
TOLERATED THEFT OR SOCIALLY BONDED ALLIANCING?
Biologist Nicholas Blurton-Jones sees chimpanzees’ meat-sharing as a kind of “tolerated theft.”21 This means that it’s all about power, and the meat possessor isn’t really being generous at all. Rather, he or she realizes that the other hungry apes could fight to take away the carcass, so it’s best to share it with them—and thereby preempt their strike. However, in free-ranging chimpanzees I know of no record of a gang attack in which a stingy meat possessor was physically assaulted and dispossessed, even though often enough up to half or more of the apes present are being given no meat.
I have copublished a somewhat different theory, which comes from my having watched a fair number of hunts in the wild over a six-year research period, with eighteen months spent actively in the field.22 Jessica Flack and I have suggested that the possessors usually share meat with just enough partners to gain the allies needed to firmly control the carcass, but not with many others who are anxiously signaling their desire for meat as they jockey for a better position in the begging line. Thus, rather than passively “tolerating theft,” the meat-possessor, using his or her initial control of the carcass, is in fact quickly and actively buying a few allies—latent allies—who will help to balance power against the hungry nonrecipients. More generally, these allies are likely to serve as friendly political partners or as reciprocators in future hunts or sometimes as breeding partners.
Compared to tolerated theft, for chimpanzees in the wild the inferred political and emotional dynamics become rather different if we consider this balancing of power with socially bonded others.23 I believe these dynamics may hold also for the less-well-studied bonobos, for Pan paniscus follows a similar pattern of sharing with a favored few and excluding others, again without fights breaking out between the possessor and the excluded. This “alliancing” theory is congruent with the fact that at other chimpanzee field sites there is further evidence of political alliances being actively involved in meat-sharing. For instance, at the Kibale field site in Uganda, certain pairs of males enter into productive meat partnerships; if one of them controls some meat, he will share with the other—as long as such reciprocation is being continued over time.24 And at Tai Forest in West Africa, where cooperative hunting seems to be in play more than elsewhere, individuals who have allied to cooperate in killing a prey also cooperate in eating the meat, while nonparticipants are excluded.25
The distinction between tolerated theft and an alliancing approach to meat control is rather subtle, but it’s important for this evolutionary analysis because we’ll be focusing on sympathetic feelings that are involved in social bonding. Tolerated theft interpretations make possible the assumption that what appears to be “sharing” actually involves no element of perspective taking or generosity, but rather just a fearful concession to the potential power of others. In contrast, with an alliancing interpretation it makes sense that sharing with favored allies would involve some social bonding and hence, quite possibly, some ape version of sympathetic generosity that combines with political expediency.26
There’s no reason, then, that the two theories couldn’t be combined, for we might surmise that the possibility of a gang attack leads a mea
t possessor to share with just enough bonded allies to discourage active incursions by those who are excluded. But the bottom line is that the meat possessor is, in effect, using some of the meat to purchase allies, which implies positive social feelings as well as fear of an attack. This pattern of meat “bartering” sometimes can apply to securing sexual favors from females as well, as a special bonus,27 and again an emotional kind of bonding seems likely.
When humans share large game, aside from certain tensions and sometimes some superficial squabbling, there’s obvious community joy in participation—because meat is so deeply appreciated, because no one is left out, and because eating meat together is a splendid way to socialize commensally. In observing wild chimpanzees, I’ve always noticed that the sharing process itself appears to be extremely tense and hostile among the competing beggars—but at the same time both tense and amicable between the sharing partners and sometimes downright friendly. (This is only an impression.)
Field reports suggest that the same could hold true for bonobos, who also share very sizable fat-and-protein-rich fruit items as adults,28 and it’s worth noting that in both ape species, as with humans, mothers regularly share food with begging infants and—again—that such accommodation should involve substantial positive feelings. This adult meat-sharing likely involves some kind of a behavioral extension of strongly selected maternal generosity,29 but ultimately, at the level of genes, the frequent sharing with nonkin must be explained through benefits of political alliancing or through some other compensatory mechanism that repays the loss of meat when it is less than abundant.
Of course, even when ape mothers share with their infants, it’s difficult to demonstrate that sympathetic feelings are at work, and such interpretations are still more difficult with adults. But if we set aside the question of motives, it’s clear that Ancestral Pan’s rather limited sharing patterns—based on what bonobos do at their rather rare meat feasts as a least common denominator—provided an important preadaptation in terms of behavioral potential. Thus, when archaic humans finally decided to turn from hunting small game (and probably aggressively scavenging a large carcass once in a while) to actively hunting sizable ungulates as a major and regular part of their subsistence, they already had something rather significant to work with in the meat-sharing department—even though the sharing pattern would have been involved with dominant possession and the favoring of cronies and therefore would have been quite lopsided.
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