Ian Tattersall is a world-renowned paleoanthropologist and a fantastic science communicator. His awe-inspiring 2012 book Masters of the Planet changed the way that I think about humanity—and about myself too. It’s wonderful to be able to interview a first-rate paleoanthropologist who really knows how to make science come alive.
Make sure to also read my 25 April 2021 interview with Tattersall “Is Race Biologically Real?”—Tattersall gives a highly informed view on a controversial topic.
I was honored/thrilled to interview Tattersall. See below my interview with Tattersall that I edited for flow, organized by topic, and added hyperlinks to.
Please make sure to subscribe if you like my pieces because that means a lot to me and helps me to thrive on Substack! Enter your email and click this button—that way you’ll get an email whenever I publish a piece:
Before we plunge into the interview, let’s appreciate some beautiful cave paintings. In France, there are Paleolithic cave paintings in the Lascaux cave network and in the Chauvet Cave—these cave paintings are over 12,000 years old! Click on each of these links, zoom in on the images, and really appreciate the images:
a Lascaux cave painting (it’s a replica; image source here)
a different Lascaux cave painting (it’s a replica; image source here)
a Chauvet Cave cave painting (it’s a replica; image source here)
a different Chauvet Cave cave painting (it’s a replica; image source here)
And then click on this cave painting here, zoom in on it, and try to guess which animal the painting depicts:
Can you guess which animal it is?
Once you’ve guessed, check here and here to see the answer (and click here for the image source).
I hope that these cave paintings from Lascaux inspire you and make you wonder deeply about human nature, about human creativity, and about ancient people’s lives.
I also urge all readers to watch Werner Herzog’s 2010 documentary Cave of Forgotten Dreams—that film absolutely captivated me and made me wonder about what it was like to be those people who made these cave paintings all those 1000s of years ago. Herzog masterfully stimulates viewers to wonder the following about the people who painted these things: What were their minds and their imaginations and their worlds like?
General Questions
1) What are the most exciting projects that you’re currently working on?
The most exciting project is always the one you’re currently working on.
During the Covid crisis I was cut off from my lab and other research resources for over a year and a half. That meant I had to suspend my normal research activities in favor of writing books, which could more easily be done at home.
The most fun was a volume called Distilled: A Natural History of Spirits, which completed a trilogy on alcoholic beverages I’ve done with my colleague Rob DeSalle (the others were on Wine and Beer).
The most gratifying was Understanding Human Evolution, which gave me the opportunity to synthesize my work over the last couple of decades on how our extraordinary human species emerged.
2) What are the most exciting projects that you know of that others are working on?
There’s always a lot going on in paleoanthropology, and what you think most important depends on what questions currently occupy you.
For me, that means the amazing work on ancient and modern genomes, which provides so much knowledge that we wouldn’t otherwise have about the history of Homo sapiens on the planet—and about putative interactions between extinct hominin lineages.
We always knew that species were rather leaky vessels, but I think most of us have been surprised to learn just how leaky they’ve been in the human case. And I also think that this knowledge will bring about a long-overdue reappraisal of just how many lineages have existed (and interacted) in the human past.
3) What do you love most about your field?
Its unpredictability—it’s impossible to know what new technology or perspective will pop up next to inform us about some aspect of ancient humanity that we’d thought inaccessible. Who would’ve imagined a few years ago that we’d be learning about the diets of extinct hominins from the DNA preserved in the calculus on their teeth?
4) What are the main ideas in your 2012 book Masters of the Planet?
That book was my attempt to explain—to myself as much as to the reader—how a relatively run-of-the-mill arboreal hominoid living in the late Miocene transformed in an amazingly short span of time into the entirely unprecedented organism that Homo sapiens is today.
Not only are we upright bipeds, but we process information in an emergently unique way, and I devote special attention to how that astonishing cognitive transformation could’ve occurred.
5) What would you add/change in a new version of your 2012 book?
I don’t think I’d change much.
But I’d expand it considerably. For example, I’d look at such conundrums as why the modern human brain—after a steady history of volume increase over the last two million years or so—has actually significantly declined in volume since the peak of the last ice age.
6) What are the biggest mysteries in your field that you’d like to get answers to?
Since I’m currently most interested in the emergence of humans as a cognitive entity, I would of course like to know how the brain generates the unusual modern human form of consciousness—basically, how a mass of electrochemical discharges in the brain resolves into what we humans individually experience of the world and ourselves.
7) What evidence might be discovered that could solve these biggest mysteries?
We know a lot about which parts of the brain are active during a vast range of mental activities.
But we still have no idea how the brain synthesizes everything in terms of individual experience.
And on reflection, I’m not sure I want to be around when (or if) this is finally figured out. Human experience—love, exhilaration, empathy—is simply too precious to be reduced to mere mechanism. There’s a ghost in the machine, and I think we’ll be better off if it remains there.
8) How likely is it that that evidence (that could solve these biggest mysteries) will actually be discovered?
Not in my lifetime. But then, I’m pretty ancient.
9) Is there any more remarkable story in the history of your field than the discovery of the Homo naledi skeletons in the Rising Star Cave? You really couldn’t make this up if you tried.
Paleoanthropology is full of remarkable stories. That actually includes most major discoveries ever made, because what you discover (if you discover anything at all) can’t ever be predicted. Nobody could’ve foreseen what a bunch of laborers would find in a cave in the Neander Valley in 1856. Eugene Dubois’s voyage to the Dutch East Indies in 1887 would’ve looked like a wild goose chase. And who could’ve predicted finding an amazingly complete Homo ergaster skeleton west of Kenya’s Lake Turkana in 1984?
But yes, the amazing Rising Star discovery—in which spelunkers discovered a wealth of fossils of a diminutive hominin deep in an almost inaccessible South African cave complex—has to rank right up there!
10) Do you personally think that the Homo naledi remains were put there deliberately?
I assume you mean: Do the fossils that we found in that remote recess come from cadavers that other members of naledi deliberately placed there?
I’m agnostic on this one. The only comparable paleoanthropological occurrence is at Spain’s Sima de los Huesos—a pile of Neanderthal-relative bones was found at the bottom of a vertical shaft in a cave, and investigators concluded by eliminating all possible alternatives that the cadavers had been thrown down the shaft. But that’s a diagnosis of exclusion, and I think that in both cases everyone would be happier with a more positive demonstration of cause.
11) What are your thoughts about Homo naledi? If we could go back in time and see this creature, what would this creature be like?
The Rising Star hominin was a diminutive biped with a very small brain—analogous in some ways to (though not closely related to) the “Hobbit” from Flores. There’s no archaeological evidence in the cave, so we have no way of knowing how naledi behaved, or what they would have made of us.
Investigators classified naledi in our genus (Homo) despite the small brain that suggested that it was very old, and before it was known how young it was (~300 kyr). As far as I can tell, they did this mainly because they’d concluded that it wasn’t Australopithecus—it seems that when you classify fossil hominins nowadays the algorithm is “If it’s not Australopithecus, it’s Homo” (or vice versa).
12) Is there any way that we can estimate what percentage of each of these categories existed but haven’t yet been discovered in the fossil record? Human ancestors, humanity’s hominid competitors, non-human hominids, and primates.
There’s no way to know for sure—or even to estimate—how many species in each of these categories were once out there, or how many have fossils still in the rocks waiting to be exposed by erosion and discovered. But as we come to know more of the fossil record it’s becoming clear that the hominins are a very diverse group, and that we’re just seeing the tip of the iceberg.
Someone once estimated that some 3% of extinct species are known through the fossil record, but that always sounded much too high to me.
13) What’s the oldest human fossil that we have?
Depends what you mean by “human”. The term has—remarkably enough—never been definitively characterized, and it almost certainly never will be to everyone’s satisfaction. There was no practical need for a definition as long as the apes were our closest known relatives, but the term is becoming problematic now that we know about much closer extinct relatives.
Most paleoanthropologists would probably be reasonably content with the idea of describing all members of genus Homo as “human”—although only Homo sapiens is “fully human”—but then you’d probably have to exclude small-brained forms such as naledi and floresiensis. The oldest fossil attributable to Homo in the sense that it’s reasonably closely related to Homo sapiens is around 2 million years old.
14) What kind of new human ancestor can you anticipate being found that would really shake up the field and cause a revolution in how the field thinks about human origins?
You could always fantasize and dream up a hominin with a big brain and gigantic canine teeth, but so much is known about the hominin record today that finding anything too way-out is extremely improbable.
Still, I’m sure that there are entire branches of the subfamily out there that haven’t yet been discovered.
15) When we say that we’re the product of a “great leap”, is that physiological leap or a cognitive leap or both?
I guess that depends on what “leap” you mean. It was certainly a “leap” to adopt upright bipedality on the ground, another “leap” to shed our body hair once there, and yet another “leap” to start to eat other carnivores.
But I think that most people would use the term to indicate our adoption of the unique way in which we process information, and that “leap” would fall in the cognitive category.
16) What were the factors (the pressures) that spurred the “great leap”? Did it have to do with population density? With climatic changes?
Climate change probably spurred bipedality—drying and increasing seasonality of rainfall caused woodlands, bushlands, and eventually savanna to replace forests.
But the cognitive shift was probably an emergent one where a small—or even adventitious—acquisition produced a radical change.
17) Would further “great leaps” have been possible if the factors that drove the first leap had not been taken away?
Nothing in our evolution would’ve ever happened without the accumulation of everything that had transpired before the development in question.
18) What might those further “great leaps” have been?
We’re dabbling here in the entirely hypothetical—who knows?
19) Has human evolution stopped? If so, when did it stop?
Human evolution on the scale we’ve been looking at stopped when the agricultural revolution happened some 10,000 years ago—at that point, the demographic conditions that made human evolution possible began to disappear. We evolved (i.e., accumulated significant heritable novelties) back when hominin populations were small and thinly scattered across the landscape—ideal conditions to foster the incorporation and fixation of significant new heritable variations. Now we’re sedentary and jam-packed across the planet, and the effective breeding population is vastly too large for any spontaneously-arising new variations to make a significant dent. That could of course change, but really only in the context of some disaster scenario.
20) What do you think about “dragon man”? Is there anything interesting/controversial/mysterious about this discovery?
I haven’t seen it, but as far as I can tell this is a wonderfully-preserved specimen of the species Homo heidelbergensis—the world’s first cosmopolitan hominin because it’s found not only in China but also in Europe and Africa.
Human Physiology
1) Compared to all the primates throughout history, is there anything special about humanity physiologically?
We sweat to shed heat—this made it possible for our slow-moving forebears to become endurance hunters out on the shadeless savanna.
2) What physiological changes has the human species undergone from its emergence through to today?
Strictly within our species Homo sapiens, the major physiological variations have to do with the ability to live at high altitudes.
3) At what point did humans reach a psychological point where a nonscientist today would not be able to notice anything different from a 21st-century person?
Around 100,000 years ago, or maybe rather longer ago than that if some very recently announced discoveries of ancient beads hold up.
4) At what point did humans reach a psychological point where a scientist today would not be able to notice anything different from a 21st-century person?
See above.
5) There were language-less humans that look exactly like you and I do. Does this mean that they could walk about NYC and nobody would see anything remotely unusual about them? If you gave them a haircut and took them to the spa or whatever, then would they be so normal-looking that nobody would notice anything at all unusual? And would they have to do any unusual routines (hair-removal routines, or any other routines) on a regular basis in order to blend in?
They’d look exactly like us.
But in the absence of language they wouldn’t have processed information in the same way and thus would’ve behaved significantly differently.
Neurology
1) What makes humanity special neurologically?
We process information symbolically—which is to say that we mentally deconstruct our environment into a vocabulary of discrete mental symbols that we can recombine to imagine new versions of the world we live in.
2) What are your thoughts on Friederici’s Language in Our Brain, a book that traces the “neurobiological basis of language across brain regions in humans and other primate species”?
I’ll have to read it before I comment.
3) People who study human evolution pay a lot of attention to brain size. Why? I hear a lot about the brain size that each skull indicates.
I think far too much fuss has been made about brain size—or maybe it’s better to say that brain size has inordinately influenced people’s judgment about what fossils are. Brain sizes got larger on average over the Pleistocene, so people have been encouraged to think that human evolution was steady and progressive and linear as people gradually and inexorably got smarter. But that wasn’t the case, and evidently there was a lot of trial and error going on.
4) A bigger brain isn’t necessarily better, is it? Aren’t there many organisms with tiny brains that do remarkable things that humans can’t dream of doing?
Many organisms with relatively small brains can do remarkable things with them, but they usually excel only in one or two behavioral domains. What’s remarkable about humans’ big brain is how all-purpose it is—it can be brought to bear on any problem, and that’s not self-evidently the case with other “smart” organisms.
5) I heard that Homo naledi had a brain the size of an orange. But couldn’t Homo naledi still have had remarkable capacities, a rich inner life, and extraordinary culture?
We really don’t know what naledi could do—so far, we have no archaeological record for it.
Cognition
1) What exactly is symbolic thought?
In my construal, symbolic thought involves reorganizing in the mind of the thinker discrete and arbitrary mental symbols that represent aspects of the world. In the human brain, there are pathways among multiple modalities that allow this reorganization to occur.
2) What do you make of this article’s use of the term “symbol”? The article contains the term “symbol” 30 times, but I think that it’s referring to something that every animal has (ferrets, mosquitos, anything).
Sadly, “symbolic” seems to mean different things to different people—and perhaps this is inevitable because symbols are arbitrary by nature.
3) Is this article referring to something human-specific when it states that the “mind must possess (unconscious) symbols and (equally unconscious) rules for manipulating them”?
See above.
4) What do you think about Noam Chomsky’s argument that the “representationalist doctrine” holds for monkeys but doesn’t hold for humans? Most people probably assume that words like “river” and “house” and “tree” refer to things that are out there in the world. But the fascinating “Internalist Semantics” section in this SEP article mentions literature from “McGilvray (1998), Chomsky (2000), and Pietroski (2003, 2005, 2018)” that challenges the idea of representation in human language. Internalist ideas apparently go back to pre-Socratic philosophy. Paul Pietroski puts forward fascinating internalist arguments.
Other primates can certainly recognize “symbols” in the broadest sense, but they don’t mentally reorganize those symbols—like we do—to not simply describe the world as it is but to actually imagine new configurations.
Cognition’s Emergence
1) When did we gain the power of symbolic thought?
Around 100,000 years ago, or possibly somewhat earlier.
2) What allows us to put a date on that?
The appearance in Africa of putatively symbolic “beads” at about that date—and of explicitly symbolic geometrical images not long thereafter.
3) What is an “exaptation”?
It’s a feature that’s acquired before later recruitment into its familiar context. For example, ancestral birds had feathers long before they used them for flight. All spontaneously arising evolutionary novelties are potentially exaptations.
4) What prompts you to think that humanity’s special capacity is an “exaptation”?
It evidently arose spontaneously, suddenly, and recently. It clearly wasn’t driven into existence by gradual natural selection.
5) What do you think about Chomsky’s “snowflake” idea? In Language and Mind, Chomsky writes that biological systems with a “long and complex evolutionary history” will be messy/imperfect/nonoptimal, but that language was a “relatively sudden emergence” and therefore you can expect an “optimal solution to conditions” that language “must satisfy”. Chomsky analogizes language to “snowflakes, or phyllotaxis, or cell division into spheres rather than cubes, or polyhedra as construction materials, or much else that is found in the natural world”.
Biology is a messy place, I agree—to succeed in evolution you just need to be good enough to get by in whatever circumstances present themselves, so biology isn’t about optimization in an engineering sense. And biology is always limited by what was there before.
And what’s optimal in Chomsky’s sense is always relative—language can be used to deceive as well as to communicate honestly.
6) What do you think about Berwick’s/Chomsky’s account of the nature/evolution of language in Why Only Us?, a book that you endorsed and that quotes your own work?
I like the book.
I only part company with the authors on whether there was purely internalized language that pre-existed speech. In my view, language and speech are reciprocally interconnected—language emerged when an attachment between meaning and verbal symbols spurred a symbolic feedback in the brain.
7) Is there anywhere where you differ at all from Berwick/Chomsky regarding the nature/evolution of language?
Not on the major points that they make about language as a system.
But see above—in contrast to Berwick/Chomsky, I view the spontaneous invention of verbal language as the cultural stimulus that drove symbolic thought into existence.
8) Language emerged within the tenure of anatomically modern humans. That means that if you could go back in time then you would’ve seen humans who look precisely like you and me, except who lacked language. What was the inner life (of these language-less) humans like?
Good question.
I don’t know—like you, I’m a prisoner of the modern human style of cognition, so I find it impossible to imagine being exactly like me except lacking one essential cognitive ingredient.
The Neanderthals’ remarkable achievements are clear evidence of just how far the ancestral intuitive but non-symbolic cognitive style can take a hominin—but those relatives obviously lacked the imaginative spark that has allowed modern humans in a very short time to ruin the surface of the planet on which they live. None of this means that Neanderthals lacked complex interior existences—but they were probably not consciously aware of them in the modern manner.
9) What were these language-less humans capable of functionally/behaviorally?
They were capable of amazing things, as the Neanderthal record shows—but they couldn’t consciously re-imagine the world.
10) In what sense would these language-less humans be truly “human”?
In everything but the symbolic capacity.
11) Do you agree with Chomsky’s account that language first emerged in a single person, then spread to this person’s descendants, and then became useful to externalize only after a bunch of people had language?
Not exactly—internalized language may be valuable to its possessor, but spoken language is a social thing. So if spoken language was the stimulus to symbolic thinking, then it would’ve arisen in a social context—most likely among children at play.
12) What exact functional/reproductive advantages did language confer on the first language possessors?
Because of the intimate connection between language and symbolic reasoning, it conferred an unparalleled (and insuperable) planning ability.
13) Is it likely that language emerged multiple times, and got snuffed out at least once (maybe more than once) before it took hold?
Not impossible.
14) Would the first language possessor have been extraordinarily lonely? Would that not have been a very odd situation for him/her to be in?
No—I’m sure those kids had a blast.
15) How many people needed to have language before it was useful to externalize language?
At least two, I guess.
16) Prior to the externalization of language, wasn’t every language possessor in a very lonely state?
As you know, I don’t think there ever was one single language possessor.
17) What are the fundamental puzzles about how a trait (whether it’s language, or language externalization, or whatever) goes from being the sole possession of a single individual organism to being a trait that every member of the species possesses? What do we know about that process at the genetics level? How do the mechanics of that process work? Do traits need to be advantageous in order to pervade a species? And do all traits really originate in a single individual?
Really good question.
And it’s one that’s been ignored for too long, since the population genetics that should’ve been devoted to answering this question developed at the same time as the “Evolutionary Synthesis” that saw gradual changes in gene frequencies as inevitable within lineages. (These gradual changes were seen as crucial in order to allow lineages to adapt to changing environments and also to better adapt to existing environments.)
It’s clear that new genomic variants necessarily arise within individuals (though genetically similar individuals may be more likely to independently have the same mutations). And it’s also clear that new variants are much more likely to become fixed (by “drift”) in small populations than in large ones. The likelihood of fixation in large populations is vastly smaller.
18) You’ve described human nature as “murky”. Why?
To borrow from Linnaeus: “Nosce te ipsum” (“Know thyself”). Just look around.
Competitors
1) What were humanity’s hominid competitors?
Homo sapiens originated around 200,000 years ago in Africa. We know that at the time there were other species of Homo in Africa (though how many hasn’t been sorted out). There was Homo neanderthalensis in Europe; Homo erectus and Homo heidelbergensis in Asia; the “hobbits” in Flores; and, of course, those mysterious Denisovans. But all of these were gone shortly after Homo sapiens left Africa.
2) What happened to each of the hominid competitors? How many of them did humans wipe out, and by what exact mechanism?
Homo sapiens is clearly implicated in the disappearances, but exactly how is unclear—there was some interbreeding, but evidently not enough to “genetically swamp” the competition.
3) How many of these hominid competitors would modern humans have been able to wipe out without the help of symbolic thought?
Quite possibly none.
4) How would you compare [1] the gap between a linguistic vs. a non-linguistic human with [2] the gap between a non-linguistic human and X/Y/Z hominid competitor?
The first gap would be symbolic vs. non-symbolic, whereas the second gap would be between algorithmically similar brains.
5) If even a non-linguistic human was able to wipe out a given hominid competitor, then wouldn’t a linguistic human make very short work of that competitor?
This is very hypothetical, but the symbolic way of thinking and planning seems to have allowed behaviorally modern Homo sapiens to take over the world and displace other hominins in a remarkably short time.
6) Is it sad that humans wiped out their hominid competitors?
Humans are very good at shedding crocodile tears.
It’s sad when any species disappears, but evidently not sad enough to make us stop wiping species out.
7) What was lost when humans wiped out their hominid competitors?
Our perspective on our place in the world—we no longer had anything to measure ourselves against, or anything to connect us to the world.
8) Did humans commit genocide against their hominid competitors?
This is a modern concept, and I was taught to avoid Whiggish history. But Homo sapiens was evidently just as thuggish then as now.
Cave Paintings
1) How would you describe the beauty/wonder/significance of cave paintings?
Unique and ethereal—an entirely fresh eye on the world, often of surpassing beauty, and clearly crammed with meaning.
2) What strikes you the most about cave paintings?
The best of them display extraordinary mastery of form, and the genre includes some of the most powerful visual statements ever made.
3) Which cave paintings have you seen for yourself, and what did you think about each site that you visited?
I’ve seen too many to list, but every site is unique and has its own particular presence.
4) Do you have a favorite cave painting site?
The one I happen to be at.
5) Do you have a favorite cave painting?
The ensemble of deer paintings at Covalanas has a lightness and elegance that always has a profound effect on me.
6) Covalanas looks wonderful! Let me now ask about a different site: Lascaux. What do you think about this painting at Lascaux? It really grabbed me, for some reason.
This complex composition at Lascaux defies proper analysis and poses a whole host of questions.
This particular composition is in Lascaux’s Lateral Gallery, and I’ve never been in that particular chamber.
But I’ll say about Lascaux’s ensemble of images that I’ve never had a more powerful experience of any kind than visiting that cave for the first time.
7) How significant an artistic sensibility do cave paintings indicate? Picasso’s supposed comments (about cave paintings) are apparently apocryphal.
If they’re apocryphal, they’re nonetheless true—artistically, we haven’t learned much in 40,000 years.
8) To what extent does the sophistication vary from site to site?
There’s a lot of variation from site to site—places like Lascaux exhibit immense mastery on a huge scale and so I’m convinced that accomplished professionals did them. But in contrast, most decorated caves are much more modest in scope and achievement and less accomplished artisans did them. Then as now, there were good and bad painters, so it wasn’t too different from today really.
9) What do you think about the 2010 documentary Cave of Forgotten Dreams? I found it absolutely captivating.
I did too—Herzog did a wonderful job, although I had my doubts about the albino crocodiles.
10) If we could go back in time and visit the people who made these paintings, then to what extent would we find these people to be absolutely our equals in every respect, except lacking the culture/technology/education that we have?
We’d find them to be every bit our equals cognitively.
But they lived in a very different world than the one we inhabit, and their cultural referents would doubtless prove very different from ours.
11) How can we try to put ourselves in the minds of the people who made these cave paintings? It’s very interesting to try to imagine what it was actually like to be them.
It’s a very interesting mind experiment.
But beware of kidding yourself that you’ll ever understand exactly what the art meant to those who made it.
12) How rich were their lives, and their minds, and their worlds? In Cave of Forgotten Dreams, Herzog does a great job stimulating one’s imagination to wonder about what their world was like.
Their lives and their minds and their worlds may well have been a whole lot richer than ours are.
We simply consume our culture, whereas they made theirs.
And we’ve insulated ourselves from Nature, whereas they were part of it.