Here is an excellent video walkthrough of the cartoon, discussing its value as a communication tool.

But do ignore the details of the prehistory because the cartoonist has fallen into the same trap so many others have, well meaning in intention but simply a) not an expert on key things and b) unaware of the real consequences of getting certain things wrong.

When we represent prehistory, we represent humanity both past and present. It is not difficult to do so in a way that leads to serious and meaningful, even impactful, misconceptions.

So, here, I’m going to complain not just about this cartoon, but about the general phenomenon of people who are not paleontologists or archaeologists (or some other appropriate expert) using human prehistory to make a point, but at the same time, throwing accuracy about that prehistory under the bus.

Right way, I want to point out the consequences: Westerners, for sure, but this is more widespread than that, tend to have a view of humans that involve concepts of civilized and primitive, and hierarchical concepts mixed with evolutionary ones. And there are other problems in the conceptualization of prehistory and the diversity of humanity. These problems make it very easy to maintain a racist perspective despite overwhelming evidence against the validity of biological race. These problems make it very easy to lessen the pain and suffering of certain people, which, often, we are busy causing in our own self interest. These problems in conceptualizing the nature of humanity across time and space lead to all sorts of misunderstandings with all sort of consequences including, but not limited to, simply getting it all wrong.

XKCD is a comic written in and fully appreciated by the context of modern skepticism and science cheerleading. Let us please not throw the important social and natural sciences of archaeology, prehistory, paleoanthropology, etc. under the bus in service of making a point in some other area of study. A smart man whom I respect quipped, “but this comic is not about archaeology.” My answer to that: This comic makes one point about climate change and dozens of points about archaeology. It is about archaeology.

Why this is a great cartoon.

Look at the cartoon. Go from top to bottom.

It tells us that over a very long period of time, as humans did all sorts of different things, and conditions on the earth changed dramatically, the global surface temperature a) remained within a fairly narrow range and b) didn’t vary that quickly even when it did vary.

Then, all of the sudden, temperatures shoot way up and are expected to shoot way up even more. Holy crap. Point well made.

Missed opportunities

The climate change science is not bad but a bit off. The baseline of temperatures (pre industrial) vs. now should be somewhat different in relation to the current temperature. If you take the last few thousand years as basline, which is the proper thing to do, we are closer to 1.5, and not 1.0, degrees C above it. But that may be a nitpick since the time scale of this cartoon is larger. But, once you get past that level of time scale, the question of baseline becomes untethered from pragmatics and you can justify anything.

Also, there are probably times in the past, within the time range of this cartoon, where more abrupt and dramatic climate change did indeed occur. And, at those times, major effects happens with humans.

This is where not getting the archaeology right causes the cartoon to both miss some key points and become inadvertantly somewhat less than straight forward.

Here’s the thing. Climate change can have a very negative effect on humans. How do we know? Because it apparently has happened over and over again. For example (and there are many examples), within the time range of this graphic, climate changed caused a significant increase in aridity in a huge area of southern Africa. The place was pretty well populated by hunter-gatherers before that, and after that, and for thousands of years, no one could live there. Climate change had made the region uninhabitable for humans.

Similarly, climate change probably caused depopulations, evacuations, and migrations in many other parts of the world at several points in time represented here.

Critics from the denier side of things would point out that climate change has always caused problems, so this new change is no big deal, and XKCD ignore this. But the cartoon, had it mentioned more of these earlier changes, would instead represent a different fact: Natural variation in climate can be catastrophic to humans. The level of change happening now, and expected in the near future, still caused by humans, is much larger than what happened during this time period, or faster. So look out!!!

But that’s not the point I want to make.

Simple facts and big concepts

NOTE: Since I wrote this post, at least one change was made in the original carton, pertaining to the flooding of the scablands in Washington State. Perhaps other changes will be made over time!

There are a number of simple facts that the time line either gets wrong or represents in a way that we would not like for a basic intro class in archaeology or paleontology. Some of these facts were pointed out to me by John McKay or Helga Ingeborg Vierich. This is not comprehensive, but gets the point across:

• Impressive prehsitoric art appears on the cartoon at 15K. Art and adornmnent appear well before the time line begins, and jot just in Europe. The super impressive cave wall art dates well before the time line, and somewhat less impressive works occur very much earlier. This is a decades old conception overturned many years ago.
• The Clovis First model of the peopling of the Americas is on its last legs and should not be used as assumed knowledge.
• The Missoula mega-flods affected eastern Washington, not Oregon.
• The glaciers weren’t just in New York and Boston, they covered many other places. If the idea is to connect glacial geography to people’s lives, references to other areas might be helpful.
• Wrangle Island is not tiny. He may have confused Wrangle Island with Ts. Paul in the Privilovs.
• Abu Hureyra is one of several sites with early year round settlement. More important may be the more southerly Natufian, where foraging peoples, for a very long time, took up permanent settlement, and the first commensal organisms (which would become very important to humans, like plague carrying rats and domestic dogs, etc.) came on the scene.
• Agriculture has multiple origins, but a single origin is implied here.
• The origin of copper metal working happens in multiple places (two with smelting in the old world, plus it was worked in the new world).
• Similarly, other metal working has multiple origins.
• People will fight about the date for “proto-indo-european” languages or even is fuch a proto-thing existed or could be dates. The majority of historical linguists don’t accept this at all. But if that is right or not, again, Indo-European languages are not particularly important in overall human history. The cartoon centralizes a relatively rare language group and ignores thousands of other language groups, as though the mostly post hoc Western lineage of human civilization is assumed to be the most important.
• “Permanent settlement in the fertile crescent” is out of the blue, and contradicted earlier on the time line. Permanent settlements in the region predate this by 6,000 years.
• All of the early steps in civilization rising are focused on a very limited area, represent only a small (and very Western oriented) portion of civilization, ignoring most of human prehistory, and privilege “civilization” over what the fast majority of people were doing at the time.
• Same problem with writing. Writing was invented many times over many areas, but it looks here like it may have a single origin, the origin that is part of the Western Civilization story.
• Missed opportunity: “Invasion of the sea peoples” may very well have been an example of climate change messing up a population and causing a mass migration.
• For later civilizations, I appreciate the reference to the New World. But again, it is only part of the story, mentioning a small part of the record. Isn’t it a much more interesting story to note that between 10K and 2K (or so) dozens of independent highly organized hierarchical societies, often referred to as “this or that civilization” arose all over the world, while at the same time, the vast majority of people lived off the land as foragers?
• The Industrial Revolution starts in the 18th, not 19th,century, in Europe.

Larger scale things you might learn from this graphic that are wrong.

That agriculture was invented once, as part of Western Civilization, and the same for metal working, marginalizes the new world, many regions of Asia, many regions of Africa. These are misconceptions that those of us who teach intro to world prehistory or similar courses have to spend a large amount of our time refuting.

The idea seems to be represented that humans made the transition from hunter-gatherers at one point in time and thereafter were mostly agriculturalists. The opposite is true. Most humans were living in small groups as hunter gatherers for the entire time represented by this cartoon, except at the end. Half the humans or more at the time of Christ, for example. It is likely that in many regions, at various points in time, an early stab at horticulture was abandoned, and people returned to agriculture.

Is this important?

Well, getting facts right is important. In the case of prehistory, this mainly means not overstating the facts. One might argue that in a simplified version of reality (like in a cartoon) it is ok to overstate things as facts where we really don’t know. No, it isn’t. There are ways to speak briefly, and in an interesting way, of a past that we understand more vaguely than some DK book for five year olds. So let’s do that.

The oversimplification of prehistory contributes to the co-opting of intelligence, innovation, rights over various things like landscapes and cultural phenomena, by the dominant cultures who have condensed the relevant prehistories to centralize and privilege themselves. The prehistory presented here mostly privilages what we sometimes refer to as “Western Civilization” with its middle eastern roots and its simple, linear, one way, always improving, progressive history. A very inaccurate history.

As Helga Vierlich wrote on my Facebook timeline, “In short, this reflects a preoccupation with “progress” whereas what it really shows is a progressive ecosystem and social clusterfuck that brings us to the present situation – characterized by continuing destruction of the last ecologically sustainable (“indigenous”) economies… and also characterized by deforestation, massive climate change, pollution, ecosystem distraction, soil erosion, and species extinction.”

So, in making a point about self destruction by the human species, due to anthropogenic climate change, the oversimplification misses key points in that actual process.

But it is still a good cartoon.

I would like people who pass this cartoon around to make a brief statement, like, “I hear the prehistory is oversimplified a bit, but this makes a great point about climate change” or words to that effect. Many will argue that this statement is not enough. But I’m not a big fan of sacrificing the really cool for the sake of the perfectly pedantical. Usually.

The nomenclature for the US accents is wildly incorrect, but these are good renditions of something.

So here we go.

The tail does not wag the dog

The primary finding of the Pagel et al. study is this: When comparing lexicons from different languages, meanings that shared a common word in an ancestral language change over time more slowly if the word in question is used more often in day to day speech. This finding was found to be consistent enough that the authors call this a “law-like” property of language.
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Greek speakers say ”oura”, Germans ”schwanz” and the French ”queue” to describe what English speakers call a ‘tail’, but all of these languages use a related form of ‘two’ to describe the number after one.

You can do this yourself. Here is the English “horse” translated into two closely related and one more distantly related Indo European languages:

Dutch: paard
German: Pferd
French: cheval

Not a lot of overlap, though a linguist would see the Dutch and German as similar, I suspect. Here, in contrast, is the English word “hand”

Dutch: hand
German: hand
French: main

The three Germanic languages are identical, and maybe that French word is not so different. Now let’s try for some more anatomy, with the English word “penis.”

Dutch: penis
German: penis
French: penis

Wow. According the purported law like properties of language change … oh never mind, no way to draw any hard and fast conclusions at this point I suspect. (I’ve left off the accents and the pronunciations are more different than they look here.)

(Above results all obtained using Google Translate.)

Pagel et al. estimated the rates of change among vocabulary words for 200 different meanings across 87 Indo-European languages. The number of different cognates (words that are linguistically the same) ranged from one to 46. From this analysis they calculated that the half life of a word, on average, was probably a bit over five thousand years, with a very skewed distribution.

Our findings, based on a sample of fundamental vocabulary items, identify a general mechanism of linguistic evolution, which is expected to operate across all languages and timescales and makes predictions about rates associated with specific meanings. To the extent that the structure and everyday functions of human verbal communication mean that some words will tend to be used more frequently in all languages, we expect these words to evolve slowly, and vice versa for infrequently used words. Combined with parts of speech, this simple factor allows us to account for about 50% of the variance in rates of lexical replacement throughout the 6,000- to 10,000-year history of Indo-European languages. Given the many social, cultural and cognitive factors that can influence language, it is striking that word-use frequency alone can explain such a large proportion of the historical variation in rates of evolution. The generality of this influence is suggested in the finding that estimates of the rate of lexical replacement in Indo-European languages are correlated with rate estimates in Bantu10, Cushitic and Malayo- Polynesian.

A Tale of Two Disciplines

This research is partly based on, and partly demonstrates the validity of, the assumption that language change over time can be modeled as a tree-like pattern, much like genetic change over time is modeled to create species (or population) trees. (I hasten to add: I will be using terminology here that may annoy hard core cladists. I love annoying hard core cladists.) However, linguists have come to believe in recent decades that such research, beyond relatively simplistic grouping of very closely related languages that have diverged recently, is not worthwhile. Most linguists active today simply believe that the idea that time-deep language phylogenies can be built with any degree of reliability is utterly discredited.

The work by Pagel et al. seems to prove these linguists wrong, but the culture of incredulity is strong and seemingly unshakable. But I’d like to ask you to imagine what it might be like if things were just a little different in recent history.

( … harp music as everything becomes blurry, and the scene changes to a 1960s era lab with the large and furry figure of Charles Sibley holding four liquid filled test tubes in one hand, up to the light, gazing at them… Nearby, Jon Ahlquist is re-ordering a series of IBM punch cards that just got scrambled when they fell out of the box on the way back from the Batch Window at the computer center … )

“This is never going to work,” says Sibley. “This whole idea of using DNA to make a family tree of living species has too many problems. True, we came up with a number of plausible phylogenies, but the quick work of our colleagues in the fields of biogeography and morphology sure made quick work of our quick work!”

“I wish you would stop with the stupid puns,” intoned Ahlquist. “But as usual you’re right. This hybridization stuff kinda works but the results are not sufficiently resolved to sort out either really closely related species or very distant relationships. As for this in between scale of relationships, we can SEE those. We don’t need this extra expense. What are you doing with those colored liquids in those test tubes, anyway?”

“New martini. I call it “The Sarich,” replied Sibley.

“Meh.”

( …. scene becomes blurry again, with harp music, and refocuses on a group of graduate students and a junior prof type sitting around a table in Nick’s Beef and Brew on Mass Avenue in Cambridge. These researchers are attached to Harvard’s Phylolinguistic Research Center, a new facility just built on the foundation of the recently torn down Peabody Museum…)

“So what if they don’t think it works!” said the one named Merritt. “We’ve been using Pagel’s phylogenetic method on languages for decades, and no one has questioned our ability to make deep phylogenies going back more than half way to the origin of human speech! All we’re trying to do here is to apply the same exact methods to the phylogeny of the mammals, using genes instead of words. Of course it will work!”

The group was interrupted as the waiter, Irv, came by with a large tray and efficaciously dealt out a half dozen Double Cheeseburger Specials as though they were mere playing cards. “Which one of you gets double tops….” he said as he glanced around. Then he noticed Big Tim, and remembered ….. right, double tops…. “Here you go. Enjoy.”

After a few minutes of passing around of the ketchup and adjusting the French fries, the conversation resumed. Just then, the door opened and in came Mark, the group’s statistician. Whenever the door opens in this place, a mighty wind blows across all the tables in the general direction of cook’s grill, where a 93,000 BTU open flame is constantly in use making more and more hamburgers, converting several cubic meters of oxygen into oxidized beef per minute.

(One day, a few years after this conversation, it just happened to occur that no one went in or out of Nick’s for a full hour and ten minutes. All of the oxygen was burned up at the grill and the entire retinue of diners, employees, and Nick himself suffocated, in what would later become known as the Great Snuffing Out on Mass Ave.” But I digress…..)

Pagel sat down with the group and they started to talk again about the application of proven phylolinguistic methods to genetics.

“The problem with genetics,” someone said, “is that the are under selection, unlike words.”

“Another problem,” someone else said, “is that we’re looking at genetic change across vastly different animals, with different metabolic rates and generation times.”

“… and in some cases” someone else jumped in, “Different systems of reproduction…”

“… right, and not even the same number of chromosomes across species, so linkage effects may be different….”

“Don’t worry.” Pagel spoke those words and took a bite of his meal. “Oh, did someone order beer by the way?”

Someone handed Pagel a beer to wash down his cheeseburger.

“Cheers,” Pagel said, “You don’t have to worry about most of that stuff. Most genes are highly conserved across organisms. The plurality, anyway. And other bits of DNA seem to change fairly quickly. You couldn’t find a better system than genetics to try the phylogenetic methods on. It will work better than with language, and it works pretty well with language.”

“Why didn’t they … the biologists … why didn’t they, I mean, shouldn’t they have… um, how come…” sputtered the one called Greg, just starting on his second cheeseburger and not quite sure if he was ready to speak up yet.

“Why don’t they get it? Why did they give up on this sort of thing fourty years ago?” Pagel clarified. “Because their first few attempts used a technique that sucks, and because they had no idea how the numbers worked statistically. Now, with genetic sequencing we have excellent data, and we understand the numbers. This will be easy. You guys go collect the data and bring it back here. I’ll run it on my Android and we’ll have he paper out by dinner time…”

( … scene goes blurry, ad all six of the scholars crowded into the high-backed wooden booth in Nicks simultaneously chomp on the last bit of their cheeseburgers …. )

Well, I doubt it would have happened quite that way, but my point should be clear. Linguists gave up the ghost on phylogentics when they ran into a number of problems. The method became “discredited” and no further work has been done with it. Meanwhile, in another discipline in which this sort of method can be used (genetics, in the real world) the approach continued to be developed. And now, practitioners of this method will be happy to apply these ideas to language, and teach the old boys a thing or two.

(Clarifications: 1) In “real life” the “phylogenetic method” was invented by Pagel and Harvey, but this is not the method being used to do language phylogenies. It is a wholly different thing. 2) No one ever really died of suffocation in Nick’s. 3) Irv would not have been that good of a waiter.)

Mark Pagel, Quentin D. Atkinson, Andrew Meade (2007). Frequency of word-use predicts rates of lexical evolution throughout Indo-European history Nature, 449 (7163), 717-720 DOI: 10.1038/nature06176

It’s like an elephant and a mammoth meeting up in the Twilight Zone. Close enough to know there is a similarity, yet different enough to be a bit freaky.

This is from the work of Mark Pagel, of Reading (England) and his team. And it isn’t quite as simple as I’ve characterized it above. As Pagel told me in a recent interview, “… when I say ‘I’ or ‘two’ are very old, I mean that they derive from cognate (homologous) sounds . Every speaker of every Indo European language uses a homologous form of ‘two’ such as ‘dos,’ ‘due,’ ‘dou,’ ‘do,’ etc. It is an amazing thought because there are billions of Indo European speakers and hundreds of thousands of ‘language-years’ of speaking across all the unique branches of the phylogeny of these languages. In all that time ‘two’ has remained cognate. Cognate does not mean identical … it is a bit like my hand being homologous but not identical to that of a gorilla.”

Pagel acknowledges that may linguists are ‘upset’ with the assertion that there are numerous cognates that share a common ancestor …. which is also a cognate … that must be over 10,000 years old. But he indicates that this dislike for the proposed reconstruction is more of a misunderstanding of this concept of homology than anything else.

Indeed, most linguists reject the idea of even being able to begin to think about maybe planning in the most preliminary way to even maybe consider doing something like what Pagel and his team have done. And these days, the main reason that linguists give for not being able to reconstruct either individual words or linkages between languages and language groups is something like “… You can’t do that because it is long discredited.” But in fact, this is alchemy. Most modern linguists, in my experience, can not provide an actual coherent reason for this discreditation.

Linguists long ago rejected the very methods that were used in the old days (back when linguists thought they could and should reconstruct language phylogenies). There are almost no living linguists trained in this area. The previous generation, which did engage in this activity, were using methods that at the time were cutting edge but today are outdated. So, Pagel is using updated methods for working with words in a similar way that we work with genes, and getting results that are statistically valid.

As with a genetic study, the reconstructed phylogeny is complex. There are meaning-sound links that go back to a certain time period, but not before, because of a change at that node. There are some that are perhaps 40,000 years old (based on an estimate of cultural divergence, which in turn becomes less certain as one goes farther back in time) and others that are only a few thousand years old. As has been demonstrated in other research projects, words that are used frequently are more likely to stay relatively unchanged than are rarely used words. Also, according to Pagel, nouns change more slowly than verbs, and verbs more slowly than adjectives.

So, the phrase “colorless green ideas sleep furiously” uttered in the far distant future might be “blifnork orgonst idears sloop firooslnitch.” According to me, not Pagel. (Pagel refused to comment on that question.)

But seriously, I’m glad to see the linguistic phylogeny challenge taken up again, despite the naysayers, and I’m especially glad that Pagel is doing it because he’s got the methodologies necessary to make this work.

Background.