Tag Archives: social evolution

Bikers and hippies and apes

We’ll have more to say about the evolution of our very distinctive social organization as the blog carries on. But it may be informative to consider our closest relatives, chimpanzees and bonobos. The two species are closely related, having diverged only about 2 million years ago. They remain physically quite similar, and people didn’t even figure out that bonobos are a separate species until the twentieth century. There are some broad similarities in their social organization. Both species have fission-fusion societies, in which subgroups form and reform within a larger, more stable community. Both species have male philopatry: males spend their lives in the community they were born in, while females transfer out of their natal community to a new community when they reach sexual maturity. In both species, females commonly mate with many males over the course of an estrus cycle. But there are some important differences.

Jane Goodall began studying chimpanzees in the wild at Gombe National Park, Tanzania, in the 1960s. The early reports from Gombe captivated the world with stories of chimpanzee social life, tool use, and interactions with human observers. It was the 1960s, and chimpanzees – hairy, sexually promiscuous, grooving in the jungle ­– looked familiar: they were hippies.

The picture darkened a lot in the 1970s, when the community at Gombe split in two. Between 1974 and 1978, the two daughter communities were effectively in a state of war. Males from the larger of the two communities carried out a series of raids against the smaller, with raiding parties opportunistically picking off and killing isolated individuals, eventually eliminating all the males and some of the females. Subsequent studies of other chimpanzee populations have made it clear that this was not an isolated incident: intergroup warfare and group extinction are general features of chimpanzee life. Chimpanzees are still hairy, still sexually promiscuous, but they now look less like hippies and more like bikers. Really scary bikers.

Bonobos look like the real hippies. They are more peaceable. They show less violence between groups, with members of neighboring groups sometimes even feeding peacefully in proximity to one another, something unthinkable for chimps. There is also less within-community male-male violence among bonobos. Bonobo females play a major role in regulating and intervening in male-male competition, and may even be dominant to males. There are tensions within bonobo communities but these are often resolved by (non-reproductive) sexual activity. For example, females, who are generally not related to one another because they were born elsewhere, might be expected to find themselves fighting over food. Instead they settle potential feeding conflicts peaceably by “g-g (genital-genital) rubbing,” rubbing their sexual swellings together until they reach orgasm. Or do a pretty convincing job of faking it: “I’ll have what she’s having.”

However recent DNA tests have revealed an unexpected twist to the chimpanzee/bonobo comparison. In spite of the more peaceable nature of male bonobos compared to male chimps, it turns out that there is actually greater reproductive inequality among male bonobos and a stronger relationship between dominance rank and reproductive success! Dominant male bonobos are more successful than dominant male chimps in monopolizing reproduction. If bonobos still look like hippies, then they are the kind of hippies where a lot of free loving is going on, but the whole happening is run by and for the leader (backed up by his mom) and his groupies.

Bunches of monkeys

Our descent, then, is the origin of our evil passions!! The devil under form of Baboon is our grandfather.

Charles Darwin, Noteboook M

Maimoun angushti shaitan ast.

(A monkey is the devil’s fingers.)

Tajik proverb

Monkeys and apes are not only exceptionally brainy, but also distinctively social. Most mammals are solitary (apart from mothers and their juvenile offspring of course). Among a minority of mammals, adult males and females set up pairbonds. And some mammals form larger groups. In most cases, however, these are relatively unstructured aggregations: a herd of buffalo is more like a crowd of people than a human community. A handful of mammals – elephants, cetaceans, and the majority of monkeys and apes – form more structured groups, enduring and internally differentiated.

Social evolution is path dependent: primate social organization is affected by ecology, but also has a strong phylogenetic component.  This makes it possible to offer a tentative reconstruction of the stepwise evolution of stable sociality in primates. Here’s an evolutionary tree, showing inferred transitions between solitary living, and multimale/multifemale, unimale/multifemale, and pairbonded groups:

monkey society tree

A diagram of the possible evolutionary dynamics looks like this:

monkey society transition

And the accompanying story goes like this: about 52 million years ago, the solitary nocturnal ancestor of monkeys and apes switched to being diurnal. This allowed for the exploitation of a whole range of new foods, but it also exposed the ancestor to new forms of predation. The first step in the evolution of monkey and ape sociality, then, was aggregation in multimale/multifemale groups to cut predation risk. At first these groups would have been loosely structured and unstable, but eventually they would have evolved into something like what we see today among most Old World monkeys: stable (sometimes lifelong) networks of relatives and friends, dominants and subordinates, nested within enduring communities.

A later development, going back to 20 million years ago or less, was a shift, among some of these social primates, to unimale/multifemale groups, or pair-living family groups.

The inferred development of structured social groups in primates bears a remote similarity to the evolution of eusociality among social insects. According to current theories, the starting point for eusociality is the development of a defended nest site where females lay eggs and raise offspring. Sometimes an established nest site is so valuable that it’s adaptive for the next generation of offspring to stay on when they mature rather trying to found new nests. The eventual result may be the evolution of a highly structured society, with strong reproductive skew: some nest members specialize in reproduction, others in foraging or defending the nest. The latter may evolve into an obligately sterile caste.

Primates too have developed an intensified, structured sociality as a response to obligate group living. But the parallels with eusocial insects go only so far. The great majority of primates give birth to one offspring at a time. There are no queen bee baboons whelping one vast litter after another and pushing subaltern kin into caring for them. This goes for humans as well. Our species matches the social insects in the scale of cooperation, but we manage this through a complicated dance of coalition-building and reputation management. For a primate, building a honey-bee style superorganism has to be an aspiration rather than a reality.

beehive state

Proposed design for Utah state quarter

Slime had they for mortar

“And slime had they for mortar” Genesis 11:3

The last post was about a major transition in evolution, the origin of social insect colonies, in which individual ants and bees work together to make up something like a superorganism. Around the same time that this was happening we find evidence for another venture in higher-level evolution, the slime molds. (The evidence is in the form of a recently discovered 100 million year old fossil, although slime molds were probably around long before this.)

John Tyler Bonner, who died just last year, spent 70 years of a very long life studying cellular slime molds. Here are some weirdly beautiful movies he made. Cellular slime molds switch between being single cell organisms and multicellular organisms. Most of the time they live alone, looking and acting much like non-social amoebae. But when times get tough, and local food resources are exhausted, the cells start sending out chemical signals indicating they are ready to shift to another state. Individual cells aggregate to form a mass, which is capable of moving around, seeking out new food sources, even learning. (In cellular slime molds, cells retain their identity as separate cells. In plasmodial slime molds, the cells merge to form one super cell.) The mass may raise up a fruiting body atop a stem. The spores in the fruiting body may blow away, perhaps being carried some distance to a better home, where the survivors disperse and feast as the cycle begins again. There is an interesting sociobiological puzzle here: the cells forming the stalk are sacrificing themselves for the sake of the spore cells. This is probably an instance of kin selection.

Both social insects and slime molds may carry lessons for human social life, which, on a large scale, is radically different from the social life of our primate near relations. Both social insects and humans commonly build enormous social organizations with high levels of cooperation. These organizations are too large for their members to recognize one another as individuals. Instead they rely on signals to show others that they are the right sort. With social insects, these are mostly chemical signals. With humans these are the various insignia – letters of commission, uniforms, shibboleths, etc. – that mark the bearer as the occupant of a particular social role, independently of his personal character. (“You salute the uniform, not the man.”) For more on this topic, check out Mark Moffett’s The Human Swarm: How Our Societies Arise, Thrive, and Fall.

And, as with slime molds, humans seem to go through characteristic alternations in their social lives, on a time scale of multiple generations. With slime molds there is an alternation between solitary and social phases. With humans there is an alternation between phases of lesser and greater social solidarity (asabiya). Borrowing from Max Weber, we might call this an alternation between routine and charisma. In phases of routine, people learn the rules of their society, and do their best to get ahead by following the rules, or working around them. But in times of crisis, the old ways no longer serve. While slime molds secrete pheromones to instigate aggregation in hard times, humans secrete cosmologies. Prophets arise, with visions of a new order, taking their cues from divine visions, or the Book of Daniel or Revelations, or theories of political economy or race science. The great majority of such projects are stillborn, but occasionally one succeeds, subduing doubters and infidels, overthrowing the established order or leading a chosen people to a new land. The world we live in – the civilizational landscape of Eurasia, the cultural geography of the United States (I write this in Salt Lake City, Utah) – is in some degree the legacy of such projects.

The quotation above from Genesis 11:3 was used by Eric Hoffer in his book The True Believer: Thoughts on the Nature of Mass Movements, published in the early years of the Cold War, still worth reading today.

Related, here’s me on the sociobiology of “ethnic group selection.”

Consider her ways

106-100 million years ago.

There are some pieces of paleontology that really stand out in the popular imagination. Dinosaurs are so cool that even if they hadn’t existed we would have invented them. (Maybe we did, in the form of dragons. And look ahead (or back) to early April for the dinosaur-griffin connection.) Also, as I suggested in a previous post, transitions from one form of locomotion to another – flightless dinosaurs to birds, fish to tetrapods, land mammals to whales – really grab the imagination (and annoy creationists) because the largest and most distinctive named folk categories of animals (snakes, fish, birds) are built around modes of locomotion.

Evolutionary biologists tend to see things differently. Turning fins into legs, legs into wings, and legs back into flippers is pretty impressive. But the really major evolutionary transitions involve the evolution of whole new levels of organization: the origin of the eukaryotic cell, for example, and the origin of multicellular life. From this perspective, the really huge change in the Mesozoic – sometimes called the Age of Dinosaurs – is the origin of eusociality among insects like ants and bees. An ant nest or a bee hive is something like a single superorganism, with most of its members sterile workers striving – even committing suicide — for the colony’s reproduction, not their own. (100 million years ago – corresponding to March 29 in Logarithmic History — is when we find the first bee and ant fossils, but the transition must have been underway before that time.)

Certainly the statistics on social insects today are impressive.

The twenty thousand known species of eusocial insects, mostly ants, bees, wasps and termites, account for only 2 percent of the approximately one million known species of insects. Yet this tiny minority of species dominate the rest of the insects in their numbers, their weight, and their impact on the environment. As humans are to vertebrate animals, the eusocial insects are to the far vaster world of invertebrate animals. … In one Amazon site, two German researchers … found that ants and termites together compose almost two-thirds of the weight of all the insects. Eusocial bees and wasps added another tenth. Ants alone weighed four times more than all the terrestrial vertebrates – that is, mammals, birds, reptiles, and amphibians combined. E. O. Wilson pp 110-113

E. O. Wilson, world’s foremost authority on ants, and one of the founders of sociobiology, thinks that the origin of insect eusociality might have lessons for another major evolutionary transition, the origin of humans (and of human language, technology, culture, and complex social organization). In his book The Social Conquest of Earth he argues that a key step in both sets of transitions was the development of a valuable and defensible home – in the case of humans, a hearth site. Wilson returns to this argument in his book Genesis: The Deep Origin of Human Societies, just published, which I’ll get around to saying more about here eventually. On the same topic, Mark Moffett’s book The Human Swarm: How Human Societies Arise, Thrive, and Fall,  asks how it is that we somehow rival the social insects in our scale of organization.

One trait found in both ants and humans is large-scale warfare. Wilson gives an idea of the nature of ant warfare in fictional form in his novel Anthill. It’s an interesting experiment, but also disorienting. Because individual recognition is not important for ants, his story of the destruction of an ant colony reads like the Iliad with all the personal names taken out. But Homer’s heroes fought for “aphthiton kleos,” undying fame (and got some measure of it in Homer’s poem). The moral economy of reputation puts human cooperation in war and peace on a very different footing from insect eusociality. (Here’s my take on “ethnic group selection,” which depends on social enforcement, perhaps via reputation.)

Consider her ways” is the title of a short story by John Wyndham, about a woman from the present trapped in a future ant-like all-female dystopia. It was made into an episode of Alfred Hitchcock Presents. The title is from Proverbs 6:6, “Go to the ant, thou sluggard, consider her ways and be wise.”

Empires and barbarians

The fall of Rome involved the disintegration of the Roman state; the collapse of long-distance trade; the disappearance of mass-produced pottery, coinage, and monumental architecture over large areas; declining literacy among commoners and elites; great insecurity of life and property, and demographic collapse. The process was drawn out and played out differently in different regions. In the Eastern Mediterranean and Middle East, central government supported by taxation continued; in the West it largely disappeared. The nadir in the West was perhaps the tenth century. We might set the turning point at the battle of Lechfeld (955): a last set of invaders off the steppes, the Magyars, was defeated by the Emperor Otto, and then adopted Christianity, gave up nomadic marauding, and settled down as feudal lords in Hungary.

The fall of Rome illustrates a general lesson. The overall trend of history is for more complex societies to replace less complex. (Important note: “more complex” is not the same as “nicer.”) But the process is an uneven one, in part because military effectiveness is only loosely coupled with social complexity. Tribal peoples with states next door often react by developing states of their own, partly to defend against their civilized neighbors, partly to prey on them. The resulting societies – no longer tribal, not really civilized, but barbarian – have sometimes been more than a match militarily for their more complex neighbors. In Europe, the result over nearly a millennium was a great leveling process. Rome declined under barbarian assault, while state organization, class stratification, and Christianity spread eventually as far as the Slavic East and the Scandinavian North. (See Peter Heather’s Empires and Barbarians.)

By the end of the first millennium, Western Christendom had some consciousness of itself as distinct from the Islamic world; this would later help motivate the Crusades, but it would never be enough to spur unification. Much later, in the twentieth century, Europe would be divided by a different set of meta-ethnic frontiers, centered on the clash of ideologies, rather than civilization versus barbarism. But that’s a story for later.

Asabiya and metaethnic frontiers

In 390 BCE an army of Gauls, 30 thousand strong, marched out of northern Italy into Latium, an area that included Rome. They defeated a Roman army, sacked and burned Rome, and left only after being paid a large tribute. This marked a turning point for Rome, which resolved never again to allow such a disaster. Over the next century, Romans used a mixture of coercion and consent to bind their Italian allies more closely to them. Attempted secession was punished. But those who accepted their position as allies were not simply crushed and plundered (as in many other empires) but granted some or all of the privileges of Roman citizenship in return for military contributions. Membership in the Roman confederation was attractive enough that many Italian states sought it voluntarily.

The history of Greece during this period is different. Greek city-states never united. In the aftermath of the bloody Peloponnesian war, different city-states went on fighting for supremacy, until they were finally conquered by an outside power, Macedonia.

Peter Turchin is an ecologist-turned-social scientist who thinks that the contrast between Rome and Greece illustrates some general laws of history. According to Turchin, the rise and fall of empires is partly conditioned on the strength of “asabiya,” or social solidarity. (He borrows the term from the medieval Arab historian ibn Khaldun.) The strength of states depends not just on material factors like population size and wealth, but also on morale – on the willingness of citizens to work together for the common good (which includes punishing free-riders). Asabiya was high in early Rome; in Greece, by contrast, while individual city-states might evoke strong group feeling, there was little willingness to cooperate for the good of Greece as a whole.

metaethnicAsabiya in turn (according to Turchin) develops especially along “metaethnic frontiers,” where very different cultures meet and clash. The illustration (by me, writing about matrilocal asabiya, not Turchin) shows the general idea. When culture changes little, or changes gradually, with distance (a), there is little basis for uniting independent polities (stars) into enduring larger units, and alliances (dotted lines) shift constantly. Along the metaethnic frontier (b), the opposite is true (solid lines show cohesive enduring units). Think Game of Thrones versus Lord of the Rings: it’s easier to get men and elves and dwarves to work together when they are fighting an army of orcs serving the Dark Lord.

Sometimes a metaethnic frontier develops where major religions or ideologies clash. But in the Roman case, the metaethnic frontier ran along the line dividing civilized Italians from barbarian Celts. Greece, by contrast, experienced a surge in fellow-feeling when Athens and Sparta fought together to defeat Persia, but this was too short lived to lead to a unified state.

Also worth reading is Empires of Trust, tracing parallels between the expansion of early Rome and of the United States – two immense states on the western frontiers of civilization. (The book is better than most comparing America and Rome.)

Bikers and hippies and apes

Maimoun angushti shayton ast.

“A monkey is the Devil’s fingers.”

Tajik proverb

We’ll have more to say about the evolution of our very distinctive social organization as the blog carries on. But it may be informative to consider our closest relatives, chimpanzees and bonobos. The two species are closely related, having diverged only about 2 million years ago. They remain physically quite similar, and people didn’t even figure out that bonobos are a separate species until the twentieth century. There are some broad similarities in their social organization. Both species have fission-fusion societies, in which subgroups form and reform within a larger, more stable community. Both species have male philopatry: males spend their lives in the community they were born in, while females transfer out of their natal community to a new community when they reach sexual maturity. In both species, females commonly mate with many males over the course of an estrus cycle. But there are some important differences.

Jane Goodall began studying chimpanzees in the wild at Gombe National Park, Tanzania, in the 1960s. The early reports from Gombe captivated the world with stories of chimpanzee social life, tool use, and interactions with human observers. It was the 1960s, and chimpanzees – hairy, sexually promiscuous, grooving in the jungle ­– looked familiar: they were hippies.

The picture darkened a lot in the 1970s, when the community at Gombe split in two. Between 1974 and 1978, the two daughter communities were effectively in a state of war. Males from the larger of the two communities carried out a series of raids against the smaller, with raiding parties opportunistically picking off and killing isolated individuals, eventually eliminating all the males and some of the females. Subsequent studies of other chimpanzee populations have made it clear that this was not an isolated incident: intergroup warfare and group extinction are general features of chimpanzee life. Chimpanzees are still hairy, still sexually promiscuous, but they now look less like hippies and more like bikers. Really scary bikers.

Bonobos look like the real hippies. They are more peaceable. They show less violence between groups, with members of neighboring groups sometimes even feeding peacefully in proximity to one another, something unthinkable for chimps. There is also less within-community male-male violence among bonobos. Bonobo females play a major role in regulating and intervening in male-male competition, and may even be dominant to males. There are tensions within bonobo communities but these are often resolved by (non-reproductive) sexual activity. For example, females, who are generally not related to one another because they were born elsewhere, might be expected to find themselves fighting over food. Instead they settle potential feeding conflicts peaceably by “g-g (genital-genital) rubbing,” rubbing their sexual swellings together until they reach orgasm. Or do a pretty convincing job of faking it: “I’ll have what she’s having.”

However recent DNA tests have revealed an unexpected twist to the chimpanzee/bonobo comparison. In spite of the more peaceable nature of male bonobos compared to male chimps, it turns out that there is actually greater reproductive inequality among male bonobos and a stronger relationship between dominance rank and reproductive success! Dominant male bonobos are more successful than dominant male chimps in monopolizing reproduction. If bonobos still look like hippies, then they are the kind of hippies where a lot of free loving is going on, but the whole happening is run by and for the leader (backed up by his mom) and his groupies.