Take my mother-in-law

32.1 – 28.8 thousand years ago

I just posted a tweet about population structure in people thirty four thousand years ago. Like modern hunter-gatherers, people back then apparently managed to distribute their marriage alliances broadly and so keep their coefficients of inbreeding down. 

Unlike the Habsburgs. 

And also, apparently, unlike Neanderthals. It looks like Neanderthals frequently had high levels of inbreeding, evidenced by many and extensive Runs Of Homozygosity, long stretches of DNA in one individual that look the same because they trace back to the same recent ancestor showing up multiple times through several genealogical lines (e.g. a great grandma on Mother’s side is also a great grandma on Father’s side) before recombination could shuffle her genes.

In an earlier post I wrote about the evolution of pair bonds in human ancestors, associated maybe with the evolution of a sexual division of labor. (Not everyone buys this story. Some of my colleagues here at the University of Utah think that “male provisioning” in humans is more like the peacock showing off his tail than like Daddy Bird and Mommy Bird feeding the various baby birds.) But human mating is more than pair-bonding; it enlists some distinctively human social aptitudes. Previous posts have covered the human gift for sharing intentions, getting on the same page as the other person. But getting this intimate with another person is scary. It can get you in trouble, even get you killed, if you get off on the wrong foot. So we have another mode of interaction, especially with people we don’t know very well and with our social superiors, where we don’t bare our hearts, but instead follow a safe script. We treat the other person as the occupant of a social role, rather than an individual: Sir, Your Excellency, Your Majesty, Your Holiness, Professor – not Jimmy or Bill. They may wear special regalia or a uniform, and (if you’re in the army) you’re told to salute the uniform, not the man.

Building large scale societies depends on treating other people according to their social roles even when we don’t know them personally. But we were doing the whole roles-norms-and-scripts thing long before the Rise of Civilization. One of the classic topics in anthropology is the Mother-in-Law taboo, which shows up in one form or another in one society after another. You show respect to your Mother-in-Law. You don’t make ribald jokes in her presence. Maybe you don’t address her or share with her directly, but through someone else. Or maybe you avoid her company entirely. Maybe when you see her footprints around the campfire you (discretely) brush them away so you’re not looking at them. 

Long before human beings had armies, and bureaucracies, and aristocrats and commoners, they were crafting complicated marriage rules, and expanding their social universe beyond the circle of intimates, to those scary outsiders, The In-Laws. Maybe this is partly what gave our ancestors an edge over Neanderthals.

Species

We have been treating Neanderthals here as a species, Homo neanderthalensis, distinct from our own species, Homo sapiens. Some researchers elect to call Neanderthals a subspecies, Homo sapiens neanderthalensis, and classify modern humans as another subspecies, Homo sapiens sapiens.

The line between subspecies and species is not clear cut, nor – given the way evolution works – should we expect it to be. Recent work on ancient DNA recovered from fossils has shown just how complicated the subject is. The spectacular finding of the last few years is that modern humans are hybrids, getting most of their ancestry from an African founding population (we can call them Homo sapiens), but incorporating limited ancestry from close relatives. Thus human beings outside Africa have 1-4% Neanderthal DNA. So it looks as if early in the course of expansion(s) out of Africa, there was a limited amount of interbreeding with Neanderthals.* And not just with Neanderthals. Populations in Melanesia get an additional 4-6% of their DNA from a widespread East/Southeast Asian population known as Denisovans. Actually these “Denisovans” may turn out to be several high divergent populations, and some of the interbreeding with Denisovans in or around New Guinea may have happened 30-15,000 years ago. And Neanderthals and Denisovans also interbred: just recently we learned about a girl whose mother was a Neanderthal and father was a Denisovan. Meanwhile some African groups may have ancestry from non-sapiens populations in Africa. (The fossil record for Denisovans is a lot sparser than for Neanderthals, and it’s even sparser for African non-sapiens.)

This isn’t reason enough to put Neanderthals and sapiens in a single species: plenty of species occasionally hybridize with related species. And in fact the DNA evidence implies that sapiens and Neanderthals were moving toward being reproductively isolated. Specifically, we find that a lot of Neanderthal genes related to testis development and male fertility are underrepresented (i.e. at a lot less than 1-4% frequency) in modern humans. The likely explanation is that those genes didn’t work well against a H. sapiens genetic background. In other words, if you were mixed sapiens/Neanderthal man, you probably had fertility problems, albeit not to the point of complete sterility. On the other hand, other Neanderthal genes  – especially genes related to immune function – were useful to modern humans moving into Neanderthal territory and are found at high frequency in Europeans today.

There is an extensive older literature in physical anthropology on “race crossing.” Researchers were concerned with whether people with mixed racial ancestry might have reduced fitness as a result of combining incompatible genes. This literature is reviewed at book length here. The overwhelming evidence is that “race crossing” has no harmful biological consequences (in contrast to close inbreeding, which is a bad idea: check out this post on the Habsburgs.)

Put it this way: it now looks like Homo sapiens and Homo neanderthalensis evolved separately for the better part of a million years, and were some way on the path to reproductive isolation. By contrast, different populations (“races”) within Homo sapiens have been evolving separately for 100,000 years or less outside Africa. This has been enough time to evolve major differences in traits like skin color and hair form, but apparently not to create appreciable biological barriers to interbreeding.

And here’s a link covering some recent research suggesting that across a wide range of organisms it takes a surprisingly clock-like average of two million years separation to split one species into two.

* Hence, my Neanderthal name, Carg, my website, cargshome, and my Utah car license plate, NEANDR.

Australian megafauna and the sixth great extinction

40.1 – 38.0 thousand years ago

The Earth has been through a number of mass extinctions. On Logarithmic History, we covered the five greatest mass extinctions during the month of March, and into early April.

• March 3. Ordovician/Silurian 440 mya
• March 6. Late Devonian 364 mya
• March 12. Permian/Triassic 251 mya
• March 17. Triassic/Jurassic 214-199 mya
• April 6. Cretaceous/Paleocene 65 mya

For all these extinctions, the most likely cause is some kind physical catastrophe: either drastic changes in the chemistry of oceans and atmosphere, or extraterrestrial events, like asteroid strikes or, just possibly, gamma ray bursts.

Competition with other organisms is another major cause of extinctions. Usually this is just part of a steady background level of extinction. But occasionally competition – and extinction rates – increase dramatically, as during the Great American Interchange five million years ago, when South American animals were swamped by North American invaders with the establishment of the Isthmus of Panama.

Earth now may be on the edge of another episode of mass extinction, a Sixth Extinction. (although rates of species extinction don’t match those of earlier ME’s. So far). This time the cause is very different: a single species, Homo sapiens, is playing an overwhelming role. Although the pace of extinction has accelerated over the last few centuries, you can make a case that the sixth extinction began a long time ago, with the expansion of modern humans out of Africa. Australia in particular sees the disappearance of a unique fauna that evolved over more than a hundred millions of years of isolation. This fauna included monster wombats, giant kangaroos, huge flightless birds, and a marsupial version of a lion.

All of these – all land mammals, reptiles, and birds with mass of more than 200 pounds – seem to have gone extinct by around 45,000 years ago, after humans crossed the sea to settle the island continent. (Sea levels were lower then, and Australia was connected with New Guinea, but still isolated from mainland Asia.) This is not settled science. Some researchers think climate change was to blame. But I think the evidence in the case of this and later mass extinctions is strongly in favor of humans as the major agent of extinction. This is one more reason to treat the advent of our species as one of the major evolutionary transitions, comparable to the evolution of complex cells, or multi-cellular life.

Talk Like a Neanderthal Day

44.9 – 42.6 thousand years ago

Like “Talk Like a Pirate Day,” but more scientific!

Human language is probably more than One Weird Trick. It’s multiple weird tricks. We’ve already posted about phonemes, and how they can be strung together to make words. That’s (at least) one trick. And then words are strung together to make phrases and sentences: but there are a multiple weird tricks here as well. Consider this quotation from some language researchers:

Every human language sentence is composed of two layers of meaning: a lexical structure that contains the lexical meaning, and an expression structure that is composed of function elements that give shape to the expression. In the question, Did John eat pizza?, the lexical layer is composed of the words John, eat, pizza … The sentence also contains did, which has two functions: it marks tense, and by occurring at the head of the sentence, it also signifies a question. (Miyagawa et. al.)

The lexical level of language includes content words: nouns, most verbs, adjectives. The expressive level contains functional words (auxiliary verbs, conjunctions, articles, and so on), as well as tenses and other inflections, and even functional operations like moving around the parts of a phrase. We can think of a sentence like a piece of carpentry, a bookshelf, say. A typical bookshelf will consist of the parts that hold things up (shelves, sides, etc., analogous to lexical structure), and parts that fasten these parts together (dowels, screws, bolts, nuts, nails, glue, etc., analogous to expressive structure).

So language gets its open-ended expressive power by fastening together expressive and functional constructions in (more-or-less) alternating levels. Here’s an illustration, a Christmas tree of a phrase with expressive levels in green and functional levels in red:

But there are other ways to build furniture. For example, here’s a desk with no fasteners. Instead, the load bearing parts have slots and tabs that fit together. This is simpler but less flexible than having boards and fasteners that you can put together however you see fit.

The analogy with language would be a protolanguage with nothing but content words – nouns, verbs, and adjectives, say – and lexical structure. The analogy works because verbs come with built in slots that nouns can fit into, even without any extra “fasteners” to hold them together. Linguists call this the “argument structure” of a verb. (Think about functions and their arguments if you’re into math or computer science.) For example fear and frighten are both transitive verbs, but they have different argument structures

• Carg fear thunder.
• Thunder frighten Carg.

In one case the experiencer goes in the subject slot, and the agent goes in the direct object slot. In the other case it’s the reverse. Some verbs, like burn, have more than one argument structure.

• Carg burn meat.
• Meat burn.

English verbs have some tens of different argument structures. (Note that I haven’t put any tense on the verbs. That would be part of expressive structure, which we’re leaving off here.)

So a protolanguage, one step along the way to a full blown language, could consist of a bunch of verbs and their argument structures, together with nouns slotted in the appropriate spaces as needed, and adjectives added to convey additional information. Is this what Neanderthal language was like? There is evidence that Neanderthal ancestors as far back as 430,000 years had hearing specialized for the frequencies of speech. (This is not the case with chimpanzees, or earlier hominins.) But we don’t know yet how complex Neanderthal speech was. Eventually, as we figure out the genetics of language, we’ll find out. For now though, let’s make today – just about the last day on Logarithmic History that Neanderthals are around – “Talk Like a Neanderthal Day.”

Carg publish blogpost now. Carg hungry. Carg eat. Goodbye.

And then there was one

47.5 – 45.0 thousand years ago.

The broad outlines of the spread of Homo sapiens have been established for several decades now: origins in Africa, expansion out of Africa at least 50-45 thousand years ago. But we’re still arguing about the details. Just recently it was reported that modern humans reached Sumatra 73-63 thousand years ago, and that stone tools in Australia date back 60 thousand years ago.

Also, based on recent recalibrations of DNA mutation rates, it looks like the African/non-African split might have happened more like 100 thousand years ago than 50 thousand years ago. So the ancestors of non-African (or non-sub-Saharan-African) H. sapiens might have occupied a homeland somewhere north of the Sahara between 100 and 50 thousand years ago, before spreading through Eurasia. North Africa is one possibility. The Near East, maybe the Arabian peninsula, is another possibility. The (or “a”) homeland might be (gated, sorry) underwater, under the Persian Gulf (sea levels were lower then). Both possibilities have some archeological support. There might have been multiple homelands, and multiple expansions – south through Arabia and along the shores of the Indian Ocean, and north through the Levant and into Europe.

A recent (2015) redating of archeological finds suggests that the Levant-to-Europe corridor was part of the story. A modern stone tool technology, coming from Ksar Akil, just outside Beirut, Lebanon, dates to about 50,000 years ago, a little before much the same technology appears in Europe, in the form of the Upper Paleolithic.

And many other “details” remain to be resolved: What did interbreeding with non-sapiens mean for the evolution of H. sapiens? And just what advantage(s) did H. sapiens have that allowed them (us!) to replace other species? Stay tuned for more on Logarithmic History

Votes for Oysters, or The Murder of the Missing Link

50.2 – 47.6 thousand years ago

Darwin was a liberal but his theories had consequences in some degrees inimical to traditional liberalism. The doctrine that all men are born equal … was incompatible with his emphasis on congenital differences between members of the same species. There is a further consequence of the theory of evolution, which is independent of the particular mechanism suggested by Darwin. … If men developed by such slow stages that there were creatures which we should not know whether to classify as human or not, the question arises: at what stage in evolution did men, or their semi-human ancestors, begin to be all equal? Would [Homo] erectus, if he had been properly educated, have done work as good as Newton’s? Would the Piltdown Man [sic] have written Shakespeare’s poetry if there had been anybody to convict him of poaching? A resolute egalitarian who answers these questions in the affirmative will force himself to regard apes as the equals of human beings. And why stop with apes? I do not see how he is to resist an argument in favour of Votes for Oysters.

Bertrand Russell. A History of Western Philosophy

If our brothers, Australopithecus robustus, had survived for another million years, how would we treat them today? … Human equality is a contingent fact of history. Equality is not given a priori; it is neither an ethical principle (though equal treatment may be) nor a statement about norms of social action. It just worked out that way. A hundred different and plausible scenarios for human history would have yielded other results (and moral dilemmas of enormous magnitude). They didn’t happen.

Steven Jay Gould. Human equality is a contingent fact of history

Whether there are any consequential behavior-genetic differences between living human populations is an unsettled – and unsettling – question. What is firmly settled, though, is that when it comes to behavior, there is a chasm between living Homo sapiens and all other animal species, including our closest relatives, chimpanzees and bonobos, that completely dwarfs any differences between human populations. Human language provides a particularly clear demonstration of the point: every human society has a full-blown language, no other creature has anything like it. This makes it workable to extend universal human rights to all living people (with some special provisions for children and the mentally impaired).

However, as the quotations above, from two staunch liberals, indicate, it didn’t have to be that way. Homo floresiensis on Flores island, Indonesia, survived up to about 50,000 years ago. Members of the species stood about 3 feet 6 inches tall (a little over 1 meter), had tiny brains, no chins and receding foreheads. They also made stone tools and hunted dwarf elephants and giant rodents.

In a novel published in 1958 under the title “The Murder of the Missing Link,” (originally in French, also published in English as “You Shall Know Them”), explorers in New Guinea discover a population of “tropis,” diminutive human relatives very much like Homo floresiensis. This makes for a moral dilemma: what rights should tropis have? There are those who would be willing to let them be rounded up and used for forced labor or medical experiments. A scientist who fears for their future makes a desperate decision. He kills an infant tropi with a lethal injection. He is hoping to be convicted of murder, winning legal recognition of the tropis’ humanity at his own expense. After much argumentation, the tropis are deemed to be human. The deciding argument is that they seem to have a form of worship: if they’ve got religion, then they’ve got souls. (Don’t worry, the scientist gets off on a technicality.)

The goodness paradox

205 – 195 thousand years ago

We’re now doing history at ten thousand years a day.

Earth Abides is an early (1949) entry in the genre of post-apocalyptic science fiction, with some haunting reflections on what it takes to keep a civilization going, or just a human community. In this case the apocalypse takes the form of a lethal infectious disease that wipes out well over 99% of Earth’s human population, leaving scattered survivors to try and put things back together.

The drama is low-key. If you want to read about the remnants of civilized humanity defending themselves against zombies, or venomous man-eating walking plants, or a horde of cannibal anti-nuke zealots, you’ll have to look elsewhere. The threat to civilization in Earth Abides is more subtle. The generation born after the die-off has no understanding of what they have lost, of what the collapsing factories and powerlines and machines around them really were, or how they worked, or how to get them back up and running. The older generation, without the institutions of a complex society backing them up, can’t supply enough discipline and punishment to pass on the arts of civilization. The young will grow up as illiterate scavenger-foragers, skilled with bow and arrow, well-adapted in their own way to a rewilding Earth. Ish, the protagonist, will end his days as the Last American (a fictional counterpoint to the real-life Ishi, the last Yahi Indian).

The community is nonetheless capable of reacting decisively when their survival is threatened.

One day a newcomer enters the scene. Charlie is talkative, forceful, charismatic. The kids adore him. It looks like he might even take over as leader of the little group. But it becomes clear that there is something off about him, even sociopathic. He can turn on the charm, but when thwarted he is menacing. He always carries a gun, which he keeps hidden. He is sexually abandoned. And, in a world without antibiotics, he is infected with a slew of venereal diseases.

Something has to be done about Charlie, and the elders of the group meet to decide what. Their options are limited. Keeping him locked up is not a practical possibility for this tiny community. They could banish him. But who is to say he won’t find a gun, and come back, looking for revenge? They could execute him. But what actual harm has he done, so far? They decide to settle the matter with a vote.

Em located four pencils. Ish tore a sheet of paper into four small ballots.

…

This we do, not hastily; this we do, not in passion; this we do, without hatred. …

This is the one who killed his fellow unprovoked; this is the one who stole the child away; this is the one who spat upon the image of our God; this is the one who leagued himself with the Devil to be a witch; this is the one who corrupted our youth; this is the one who told the enemy of our secret places.

We are afraid but we do not talk of fear. … We say, “Justice”; we say, “The Law”; we say “We, the people”; we say, “The State.”

…

Ish sat with his pencil poised … He could not be sure. Yet, at the same time, he knew that The Tribe faced something real and dangerous and even dreadful, in the long run threatening its very existence. … In that final realization, he knew that he could write only the one word there, out of love and responsibility for his children and grandchildren. …

“Give me your slips,” he said.

They passed them in, and he laid them face up before him on the desk. Four times he looked, and he read: “Death … death … death … death.”

Keith Otterbein is an anthropologist who did a study of capital punishment across cultures. He expected to find that capital punishment is limited to complex societies, used to enforce social hierarchy. Instead he found that capital punishment is a universal, present in societies from the simplest to the most complex. It is an option that even the smallest, most easy-going communities – like The Tribe of Earth Abides – may find themselves resorting to. We can infer that for tens or even hundreds of thousands of years, our ancestors have been carrying out group-sanctioned executions of individuals deemed anti-social and a threat to group harmony and survival. This is long enough to have had evolutionary consequences. Long before we domesticated the wolf, the wild sheep and goat, the aurochs, we may have been domesticating ourselves, weeding out the wildest and most dangerous from our midst, replacing the old tyranny of the alpha male with the new tyranny of Custom and The Law.

The idea that human beings are in some ways like domesticated animals is an old one. It has recently returned to the spotlight. The extraordinary long-term experiment in artificial selection for tameness in foxes carried out by Nikolai Belyaev, Lyudmila Trut, and their coworkers in Russia has demonstrated that selection for tameness ends up selecting for a whole suite of anatomical characteristics as byproducts. Strikingly, many of the features that differentiate Homo sapiens hundreds of thousands of years ago from Homo sapiens today are also features that distinguish tame from wild foxes, and dogs from wolves.

Richard Wrangham’s recent book, The Goodness Paradox: The Strange Relationship Between Virtue and Violence in Human Evolution connects the dots, setting out one long argument that an evolutionary history of capital punishment has reduced our disposition for reactive aggression (the hot-blooded, spur-of-the-moment, volatile, antisocial kind), while leaving intact our capacity for calculated, cold-blooded, proactive killing (“not hastily, … not in passion, … without hatred”).

Perhaps this explains a very recent finding in human evolution. Apparently 200,000 years ago, we were about evenly matched with Neanderthals, sometimes replacing them, sometimes being replaced by them. By 40,000 years ago however, Neanderthals lose out decisively to modern humans. It may be that what changed in the interim to give us the edge is that we improved our ability to get along peaceably with insiders (including distant insiders we don’t know personally) without losing our ability to apply lethal aggression to outsiders.

African geneses

303 – 2.88 thousand years ago

Our picture of human evolution in Africa around 300 thousand years ago has changed dramatically in just the last few years.

Here’s something we already knew. This skull was found at Broken Hill, Zambia, in 1921, He (yes, “he,” he’s probably male) is sometimes known as Rhodesian Man. He looks like he’s a step away from Homo erectus, but not quite Homo sapiens. He’s heavily built, with massive brow ridges. (He looks like he could pass the “pencil test” for erectus: you could rest a pencil on those ridges. Of course, seriously, this isn’t enough to define a species.)  But he’s got a flat face and relatively large brain. He could be significantly younger than 300,000 years ago.

But now Rhodesian Man is bracketed both geographically and evolutionarily by some new finds. From Jebel Irhoud, Morocco, around 315 thousand years ago, come these skulls, which are more unequivocally Homo sapiens. pushing the fossil record of our species back 100 thousand years. The skull is still archaic – elongated rather than globular like a modern human – but the face is now tucked under the skull, as it is with us. The brow ridges are not as pronounced as with Rhodesian man, although still heavy for modern Homo sapiens.

And we now have dates for Homo naledi, from South Africa, of 335-236 thousand years ago. This recently discovered species had a tiny brain, and may have been adapted for climbing trees, but still makes it into genus Homo based on other features (teeth and jaws, lower skeleton). The initial guess from a lot of folks was that this was a very early member of our genus, somewhere around early Homo erectus or earlier. But instead, Homo naledi looks to have been around at the same time as early Homo sapiens.

In other words, Africa 300,000 years ago was home to an impressive variety of humans – archaic Homo sapiens in Morocco, near relations in Zambia, and barely-humans in South Africa.

The 700 Club

We’re getting to a time on the blog when Homo erectus (and Homo ergaster, if we accept that erectus-like African specimens are another species) give way to the very earliest ancestors of later species – modern humans, Neanderthals, and Denisovans. (Denisovans – known mainly from DNA rather than bones – are the contemporaries in East and Southeast Asia of Neanderthals in West Eurasia, and early sapiens in Africa.)

And what should we call the whole post-erectus gang of modern humans / Neanderthals / Denisovans / modern humans? Maybe we could call them all Homo sapiens, and use subspecies names for the three branches; then we modern humans would be Homo sapiens sapiens. Or maybe we should reserve the label Homo sapiens just for our branch. In that case, we could call the larger clade “The 700 Club,” (see below), although apparently someone else already has already taken that name.

A recent article from Alan Rogers (a colleague of mine in Anthropology at the University of Utah) and Ryan Bohlender and Chad Huff (Utah Anthropology PhDs) sheds light on this period. The authors look at the distribution of shared derived mutations in two modern human genomes (African and Eurasian) and two ancient genomes (Neanderthal and Denisovan). They fit a model involving past divergence times and population sizes to the data. The model says that about 700,000 years ago. a small population split from the rest of humanity and then quickly split again to give rise to the ancestors of Neanderthals and Denisovans. In other words, it looks like there was an Out Of Africa event in the Middle Pleistocene, well before the better known Out Of Africa event that gave rise to modern human populations around the world. The ancestors of Neanderthals and Denisovans then replaced Homo erectus in Eurasia, although the authors find signs that some erectus genes may have made it into the Denisovan gene pool. This also implies that Homo antecessor in Europe was a dead-end branch of Homo erectus, not a Neanderthal ancestor.

As paleoanthropologist John Hawks notes, in a commentary on the article, “Humans stand out among our close primate relatives as effective biological invaders. Our recent history has included range expansions into remote and harsh geographic regions, and invasions by some populations into areas long occupied by others.” We’ll be seeing more instances of this in days to come on the blog.

And here’s me on what a later history of population replacement might mean for the evolution of ethnicity and ethnocentrism.

Take my mother-in-law

32.1 – 28.8 thousand years ago

I just posted a tweet about population structure in people thirty four thousand years ago. Like modern hunter-gatherers, people back then apparently managed to distribute their marriage alliances broadly and so keep their coefficients of inbreeding down. 

Unlike the Habsburgs. 

And also, apparently, unlike Neanderthals. It looks like Neanderthals frequently had high levels of inbreeding, evidenced by many and extensive Runs Of Homozygosity, big stretches of DNA in one individual that look the same because they trace back to the same recent ancestor showing up multiple times through several genealogical lines (e.g. a great grandma on Mother’s side is also a great grandma on Father’s side) before recombination could shuffle her genes.

In an earlier post I wrote about the evolution of pair bonds in human ancestors, associated maybe with the evolution of a sexual division of labor. (Not everyone buys this story. Some of my colleagues here at the University of Utah think that “male provisioning” in humans is more like the peacock showing off his tail than like Daddy Bird and Mommy Bird feeding the various baby birds.) But human mating is more than pair-bonding; it enlists some distinctively human social aptitudes. Previous posts have covered the human gift for sharing intentions, getting on the same page as the other person. But getting this intimate with another person is scary. It can get you in trouble, even get you killed, if you get off on the wrong foot. So we have another mode of interaction, especially with people we don’t know very well and with our social superiors, where we don’t bare our hearts, but instead follow a safe script. We treat the other person as the occupant of a social role, rather than an individual: Sir, Your Excellency, Your Majesty, Your Holiness, Professor – not Jimmy or Bill. They may wear special regalia or a uniform, and (if you’re in the army) you’re told to salute the uniform, not the man.

Building large scale societies depends on treating other people according to their social roles even when we don’t know them personally. But we were doing the whole roles-norms-and-scripts thing long before the Rise of Civilization. One of the classic topics in anthropology is the Mother-in-Law taboo, which shows up in one form or another in one society after another. You show respect to your Mother-in-Law. You don’t make ribald jokes in her presence. Maybe you don’t address her directly, but through someone else. Or maybe you avoid her company entirely. Maybe when you see her footprints around the campfire you (discretely) brush them away so you’re not looking at them. 

Long before human beings had armies, and bureaucracies, and aristocrats and commoners, they were crafting complicated marriage rules, and expanding their social universe beyond the circle of intimates, to those scary outsiders, The In-Laws. Maybe this is partly what gave our ancestors an edge over Neanderthals.