Welcome back to the Deep Dive. Today we're tackling a really huge question, maybe the biggest one, about what makes us human. Yeah. How did language evolve? It's definitely up there. I mean, it sets us apart so dramatically from, well, everything else. And the clues are scattered everywhere, aren't they? Fossils, genes, animal behavior, linguistics. Exactly. And that's why today we're really emphasizing this interdisciplinary approach. Our sources stress you just can't crack this looking through one single lens. No way. You try just genetics, you hit a wall, just archaeology, same thing. You really have to bring it all together, look for the overlaps, and importantly, accept that there isn't going to be one neat, simple answer. Right. And the core puzzle, the thing that starts this whole quest, is actually pretty simple on the surface, but deep down it's profound. Which is? Why can basically any human child... Learn language, this incredibly complex system, from what seems like pretty limited examples, linguists call it sparse data. Right. While even the smartest chimp, you know, give it all the human interaction in the world, it just can't get there. Yeah, that difference is stark. It really points towards some kind of unique, built -in biological capacity we have. Understanding how that capacity arose, that's the goal. Okay, so before we really dive in, there's a framework we need. You mentioned it before we started, the multi -component approach. Ah, yes. Absolutely crucial. We have to ditch the idea of language as this single solid block. You know, like it's one thing you either have or you don't. That old view makes it impossible to study evolutionarily, doesn't it? Totally. Because how does half a language evolve? But if you break it down, think of it more like a complex machine. It's got different parts, different subsystems doing different jobs. Like what kind of parts? Well, you've got semantics. That's the meaning side, the concepts. You've got vocal control. The physical ability to make and control speech sounds. And then there's syntax, the rules, the grammar, how we put things together. And the key insight is that these different bits probably have different evolutionary stories, different origins in the brain, maybe different genes. Precisely. They didn't all have to pop into existence at the same time. Some parts might be ancient, shared with other animals. Others might be uniquely human and relatively recent. Which leads to that. FLB -FLN distinction, right? Exactly. FLB is the faculty of language in the broad sense. That's kind of the big umbrella, includes everything involved, even things we share like memory or basic conceptual abilities. We cast that net wide first. To see what's not unique. Yeah, to see the shared foundations. Then we narrow down to FLN, the faculty of language in the narrow sense. That's usually where people put the really specific. human -only stuff, often focusing on that computational power, like recursion and syntax. Okay, got it. So starting broad with FLB lets us do comparative work. Yeah. Which brings us neatly, I think, to part one, syntax, semantics, and this big debate about innateness. Right. So that multi -component view, it really opens the door for comparing ourselves to other animals in a meaningful way. Because even if no other species has the whole package, lots of species have some of the parts. Give me an example. Okay, take semantics, the conceptual stuff. A lot of that basic ability to form concepts, understand relationships, maybe even basic event structures. Well, primates clearly have sophisticated versions of that. Dogs, birds, too, to some extent. That's part of FLB, but it's not unique. So the thinking part, the concepts themselves, weren't the big evolutionary leap for language per se. Not necessarily the concepts themselves, no. But then look at vocal learning, the ability to imitate sounds. Pymates, surprisingly, are pretty terrible at it. Our closest relatives can't really learn new calls. But other animals can. Oh, yeah. Songbirds are masters. Seals, dolphins, whales, even elephants show complex vocal imitation. So that piece, the ability to learn and produce complex sounds, evolved independently in other lineages. It's also part of FLB, but again, not uniquely human in its basic form. Evolution's trick was maybe putting these shared components together in a new way. Okay, so we have shared concepts, shared vocal learning ability in some species, but then we hit syntax. That seems to be the real sticking point, the core of FLN, maybe. That's often the argument, yes. Syntax, especially this idea of discrete infinity, is where things get really complex and potentially uniquely human. Discrete infinity. Sounds daunting. Break that down. It basically means we can generate a limitless number of unique sentences, unique meanings, from a finite set of elements, words, and a finite set of rules, grammar. Like Lego bricks. limited brick types infinite structures exactly like lego bricks and crucially it's not just stringing them together it's hierarchical we embed structures within structures think about sentences like the dog that chased the cat that stole the fish ran away your nesting ideas that's recursion right Embedding a phrase or clause inside another of the same type. Yes. Recursion is key to this unbounded generation. And the rules for how we combine things are structure dependent. They care about grammatical roles, noun, phrase, verb, phrase, not just the linear order of words. Which is complex stuff. Yet kids, they just seem to pick it up. Effortlessly, it seems. And that's what fuels the classic argument for innate language constraints the poverty of the stimulus's argument. Right, the idea that the input kids get is too messy, too limited, to logically deduce these incredibly abstract and subtle rules just from listening. Precisely. Take those reflexive pronouns again, himself, herself. The rules governing where they can point back to in a sentence are really quite intricate. Let's use that example because it makes it clear. The sentence, Akbar asked Maria to bathe himself. Why does that sound wrong to... basically any English speaker. Because himself needs to refer back to the subject of the bathing action. Structurally, in that sentence, the one doing the bathing is Maria. But Maria is female, so herself would be needed. Himself tries to jump over Maria to get back to Akbar, but the grammar says no, it has to be bound more locally. But you don't teach a kid that rule explicitly. They don't get examples of sentences like that being wrong. Not usually, no. And yet by four or five, they implicitly know it. Now tweak it slightly. Akbar asked Maria to help him bathe himself. And now it works perfectly fine. Himself refers to him, which refers to Akbar. Right. The child understands without instruction that the binding depends on the hierarchical grammatical structure, not just who's closest in the linear string of words. So the argument is the blueprint for those kinds of abstract rules must be built in somehow, part of our biology. That's the core of the innateness hypothesis. But, and this is a huge but, that innate capacity needs... Input. It's not enough on its own. This is where stories like Kaspar Hauser come in. The idea that if you don't get linguistic input during critical periods, the system doesn't develop properly. Exactly. Kaspar Hauser was tragically deprived of language input for years. When found, despite seeming cognitively normal otherwise, he struggled massively to learn language. He developed some communication, but it was rudimentary, lacking complex grammar. So the biological capacities there, it's necessary. but it needs the environment, the linguistic food, to actually grow and structure itself. Necessary but not sufficient. It's a biological potential that requires environmental triggering and shaping. Okay, so that's syntax and innateness. What about the other big piece, semantics? You mentioned concepts might be older. Yeah, this is a really foundational point in Fitch's work, especially. The evidence suggests that complex conceptual structures, thinking, remembering, planning, categorizing the world evolved well before language as we know it. And they seem to rely on different brain systems. So our ancestors, even before anything like modern language, already had rich mental lives. Absolutely. Think about the last common ancestor. LCA we share with chimpanzees. They likely had sophisticated memory, goal -directed planning, understanding of social hierarchies, maybe even basic causal reasoning, transitive inference. Complex tool use points to this too. And crucially. Crucially, they likely already had the ability to link a mental concept like danger or food source to an arbitrary sign, maybe a specific grunt, maybe a gesture. The basic symbolic capacity seems to be there. So evolution didn't need to invent thought. It needed to invent a communication system powerful enough to express the thoughts that were already possible. That's a really nice way to put it. The internal world was rich. The challenge was building the interface to share it effectively. But that raises a question. If the concepts were there and the basic symbolic link was possible, why didn't complex language just happen much earlier? Why the long delay? Ah, that's a great question. It forces us to maybe question linguistic uniformitarianism a bit. The idea that all languages, past and present, are equally complex. No such thing as a primitive language. Right. Linguists generally hold that view for modern languages. But when thinking about evolution, some researchers, like Neumeier, suggest we might need a more nuanced view. Maybe language or proto -language didn't even start primarily for communication. What else would it be for? Thinking. Possibly. Using linguistic -like structures internally to organize thoughts, plan complex sequences, represent knowledge better, maybe that internal structuring happened first. And only later got co -opted for talking to each other. It's a hypothesis. It suggests the initial evolutionary driver wasn't sharing information, but refining the internal mental toolkit. Communication was a later, secondary benefit. It means accepting that early language might have looked very different and served a different primary purpose than today's languages. That idea of stages leads us right into part two, these proto -language models. What did those intermediate steps look like? Let's start with the lexical proto -language idea. Okay, this is closely associated with Derek Bickerton. It's essentially a syntax final model. The idea is that the first major step towards language was building up a large vocabulary, a lexicon. So lots of words for things. Objects, actions, maybe basic properties. Exactly. Hundreds, maybe thousands of learned words with specific meanings. But critically, without the complex grammatical machinery, the syntax, that glues modern language together. So communication would be kind of like pigeon language. Yeah. Or Tarzan speak. Yeah. Me hungry. Danger water. Find mammoth west. Pretty much. Simple concatenation of words relying heavily on context or shared knowledge to figure out the full meaning. The structure is minimal. What would drive the need for so many distinct words, though? Why not just a few dozen basic calls like other primates? Bakerton's argument focuses on foraging. He argues that early hominids, as omnivorous scavengers and hunters, dealt with resources that were scattered, unpredictable, but potentially very high value, like a large animal carcass. Finding one would be a big deal for the group. A huge deal. And being able to communicate specifics about that find would be incredibly advantageous. Not just food, but big animal killed, two days walk west, many hyenas. The more detail, the better the group can coordinate and benefit. So the pressure is for more content, more specific information transfer. Yes, driven by these high -spakes foraging scenarios. That constant need for better, more precise information pushes the lexicon to expand. Okay, that's a very practical, survival -focused driver. But there's another major idea about the driving force, focusing more on social life, Robin Dunbar's hypothesis. Right, Dunbar comes at it from a different angle. He looks at primate social groups and the role of grooming in maintaining social bonds. Physical grooming, like picking fleas. Exactly. It's crucial for building trust, alliances, managing conflicts in primate groups. But it's very time consuming. You can only groom one individual at a time. And Dunbar noticed that as primate brain size, and presumably group size, increased. They'd eventually hit a time crunch. Hominid groups were likely getting larger, maybe for better defense against predators on the savanna. Dunbar calculated that for a typical estimated early human group size of around 150, they'd need to spend something like 40 % of their day just grooming to keep the social fabric intact. Which is unsustainable. Pretty much. So Dunbar proposes language evolved as a form of vocal grooming. talking, gossiping, sharing social information. You can do that with multiple people at once. Exactly. It's far more efficient. You can groom several individuals simultaneously, reinforcing bonds, sharing crucial social intel, who's trustworthy, who's cheating, who's allied with whom. And this ties into the free writer problem. How does language help there? Well, shared language, especially the development of dialects or accents, can act like a social badge. It helps you quickly identify who belongs to your cooperative group, who shares your norms, who you can likely trust. It helps maintain cooperation in these larger, potentially more anonymous groups. So for Bickerton, it's about the information needed for survival tasks like foraging. For Dunbar... It's about the social bonding needed for group cohesion and cooperation. Yeah, they focus on different primary benefits, though both ultimately tie back to the advantages of cooperation in larger groups. Was the key innovation the ability to share detailed environmental info or the ability to manage complex social relationships efficiently? Or maybe both played a role. Fascinating contrast. Now let's completely shift gears away from what was said or why to how. The gestural proto -language idea. Right. This set of theories, pushed by people like Michael Corbalis, suggests that the first complex symbolic communication system wasn't vocal at all. It was manual gestural. Using hands and bodies, like sign language precursors. Essentially, yes. The argument is that the pathway through gesture is actually much smoother, evolutionarily speaking, than jumping straight to complex vocal control. Why smoother? Several reasons. First, primates already have pretty sophisticated voluntary control over their hands and arms, much more so than their vocalizations. Think about tool use. Okay, makes sense. Second, gestures are inherently visible. This makes learning easier. You can see exactly what someone else is doing and imitate it. And third, gestures can be iconic. Meaning they can look like the thing they represent, like... Mimicking, drinking, or eating. Exactly. That provides a natural bridge from action to symbol. You can pantomime actions, trace shapes, point. It offers a more direct route to establishing shared meanings, perhaps, than arbitrary sounds initially. And wasn't there already a sophisticated gestural system in our ape ancestors? Yes. Chimpanzees and other apes have complex gestural repertoires used intentionally in social communication. The foundation was likely already there in the last common ancestor. We didn't have to invent gesture from scratch. And this connects to the mirror neuron discovery, doesn't it? It does, very strongly. The discovery of mirror neurons, neurons that fire both when an individual performs an action and when they see someone else perform that same action, provides a potential neural basis for understanding and imitation. The brain mechanism for achieving parity, recognizing the equivalence between seeing and doing. Precisely. Arbib and others have argued this mirror system, likely present in the LCA, could be a crucial pre -adaptation for language, especially a gestural one. It helps solve the problem of how meanings become shared through imitation. If my brain simulates your action when I see your gesture, we have a shared understanding almost immediately. It sounds like a really plausible starting point. Hands are controllable. Gestures can be iconic. The mirror system helps. But then you hit the big problem. Ah, yes. The gestural problem. If gestural proto -language was the start, and we know that modern sign languages are fully expressive, complex languages on par with spoken ones, why did we ever switch? Why did speech take over almost universally? That's the million -dollar question for gestural theories. The move to vocal language must have offered some massive advantage to outweigh the benefits of gesture and, crucially, to overcome the significant downsides of speech. Like? Well. As we discussed, speech requires incredibly fine motor control of apparatus not initially designed for it. It takes over the mouth needed for breathing and eating. Remember those tough Pleistocene diets? And perhaps most significantly, the anatomical changes needed, like the lowered larynx. Increase the risk of choking, a potentially lethal tradeoff. A huge risk. So what advantage could be worth that? Gestural proponents struggle to provide a killer argument. Maybe communicating at night. or when your hands are full carrying tools or babies, or over longer distances. But are those advantages big enough to drive such a fundamental risky shift across the entire species? It remains a point of debate. The pressure for switching must have been immense, which leads us nicely into part three, thinking about sound itself and the role music might have played. The musical proto -language hypothesis. This feels different again. It is. These models suggest the intermediate stage was, well, song -like. Not necessarily words set to music, but complex, structured vocalizations that had rhythm, melody, intricate phonology, but maybe lacked precise compositional meaning initially. More about emotion, social bonding, display. Exactly. Think elaborate bird song rather than conversation. And this idea actually goes way back to Darwin himself. Darwin had a theory on this. He did. Quite a detailed one. He proposed three stages. First, general cognitive development in our ancestors, driven by things like tool use and social complexity. That's the foundation. Okay. Second, the evolution of vocal imitation, but used musically. He explicitly talked about true musical cadences, essentially singing, and he thought the main driver was sexual selection. Like birds singing to attract mates or defend territory. Precisely. Early hominids using complex songs in courtship displays or to challenge rivals. It provides a powerful context for honing vocal control and imitation skills. Think of it as practice for the complex motor sequences needed later for speech. And only after that musical vocal capacity was established. Only in Stage 3, according to Darwin, did specific propositional meanings start to infiltrate the system. Words attached themselves to the pre -existing musical structures. Meaning came later. So the ability to make complex sounds came first, driven by social display. And then we figured out how to attach specific meanings to those sounds. That's the core idea. And it highlights the power of phonology, the sound system itself. Which brings us to duality of patterning. Explain that. This is a key design feature of spoken language. We have a small set of meaningless basic sounds, foams. Think K -A -T. Individually, they mean nothing. Right. But we can recombine this small set in different orders to create a vast number of meaningful units, words. Cat, act, tack. This is the first patterning. Then we take these meaningful words and combine them according to grammatical rules to make limitless sentences. That's the second patterning. Our levels of combination. Meaningless sounds make words. Words make sentences. Exactly. And this system is incredibly efficient. A small inventory sounds gives you potentially tens of thousands of distinct words. This generative power is a huge advantage of vocal systems. Arbitrariness, the fact that the word cat doesn't sound like a cat, becomes easy, almost automatic, once you're combining meaningless sounds. And this. intricate, efficient design. This is where Pinker argues natural selection must have been involved. Yes. Pinker's point is that such a complex, well -engineered system is unlikely to arise just by chance or general learning mechanisms. Its efficiency, its rapid acquisition by children, its universal structure, it looks like a biological adaptation shaped by natural selection over time. Selection favored individuals whose brains were better wired for this kind of structured vocal communication. Okay, so selection shapes the brain for sound processing and production. What about the physical apparatus, the vocal tract itself? This brings us to the lowered larynx debate. Ah, the famous descended larynx. It's one of the most obvious anatomical differences between us and apes related to speech potential. Our larynx sits much lower in the throat. Which, as we said, is dangerous. It creates a shared pathway for food and air, low down the pharynx, increasing choking risk. Why take that risk? The classic explanation came from Philip Lieberman. He argued forcefully that the lowered larynx was a specific adaptation for speech production. How so? By lowering the larynx, you create a larger pharyngeal cavity above it. This two -tube shape of the human vocal tract, oral cavity and pharyngeal cavity, allows us to produce a wider range of distinct vowel sounds, particularly the point vowels A, I, and U, which are acoustically very stable and distinct. And Lieberman really emphasized the vowel I, the E sound. He did. He argued it is particularly important because it represents an acoustic extreme. Having these clear, distinct vowel sounds, especially the extremes, makes speech much more robust and easier to understand, especially when dealing with variation between speakers, different vocal tract sizes. It helps listeners normalize the signal. So the benefit for reliable speech perception outweighed the choking risk. It sounds like a neat story. But comparative evidence complicated things. Hugely. Lieberman's initial work was based mostly on humans and chimps. But then researchers started looking more broadly. The killer finding came from studies of red deer. Red deer? What do they do? Male red deer temporarily retract their larynx way down into their chest when they roar during the mating season. Why on earth would they do that? To make themselves sound bigger. Lowering the larynx effectively lengthens the vocal tract tube. which lowers the resonant frequencies, formants of their calls. Lower frequencies typically correlate with larger body size, so they're essentially using laryngeal descent as a form of acoustic bluffing, exaggerating their size to intimidate rivals. Wow, so the anatomical ability to lower the larynx wasn't originally for speech vowels at all. It seems not. It looks like it was an adaptation for size exaggeration, likely driven by sexual selection or competition, perhaps present much earlier in mammals. In humans, this pre -existing ability was then co -opted for speech. We repurposed the size exaggeration machinery to make a wider range of speech sounds. Exactly. The anatomy came first, likely for display, and speech took advantage of it later. This fits better with the musical proto -language idea, too. Display first. referential meaning later this also connects back to the idea of holistic meaning doesn't it if early vocalizations were more like roars or songs there were likely holistic signals allison ray champions this idea a complex vocalization pattern wouldn't be broken down into words the whole chunk of sound would carry a meaning like danger or come here or this is my territory so the big transition then was moving from those holistic chunks to an analytic compositional system where meaning resides in smaller parts, words that get combined. That's the crucial shift needed to get to modeled language. How do you break down those holistic signals into meaningful segments? How does analysis emerge? And this might not be purely biological evolution. This is where cultural evolution likely plays a massive role. The process of language change itself over generations of speakers learning and using the language can drive this analytic structure. How does that work? Can you model it? Yes, researchers like Bart DeBoer have used computer simulations. You can create artificial agents with basic biological predispositions like the ability to imitate sounds and perceptual motor constraints similar to humans and then have them learn from each other over generations. And what happens? What often happens is that structured systems like vowel systems that resemble human languages emerge spontaneously. The pressures of learnability and usability, acting culturally over time, push the system towards becoming more segmented, more structured, more analytic. So the specific structures, like the exact vowel inventory of English or Japanese, might not be directly coded in our genes. Probably not. They might be culturally discovered solutions, stable patterns that emerge from the interaction of our general biological capacities with the demands of communication and learning passed down culturally. The biology provides the canvas and maybe some basic tools, but the specific painting is a result of cultural history. That integration of biology and culture seems key. Okay, let's move to part four. What are the actual physical traces, the neural and genetic footprints? Right. First, let's revisit motor control. We said primates lack complex vocal learning. Speech requires incredibly fast, precise, coordinated movements of the tongue, lips, jaw, larynx. Much more complex than eating or breathing requires. Far more. And neuroanatomically, humans seem to have something unique. Direct neural connections from the motor cortex straight down to the motor neurons controlling the larynx. Bypassing some of the intermediate pathways seen in other primates. Exactly. This direct wiring allows for much finer, more voluntary moment -to -moment control over vocalization. It's thought to be essential for the dexterity needed for speech articulation. Any evolutionary story has to explain when and why these novel circuits evolved. And this brings us to the famous FOXP2 gene. It's often called the language gene, but that's too simple, right? Way too simple. FOXP2 is not the gene for language. It's a regulatory gene, a transcription factor, meaning it affects the expression of many other genes. But it's clearly important for language, specifically the motor aspect. How do we know? From studies of a family known as the KD family, where about half the members had a mutation in FOXP2. They suffered from a severe speech disorder, developmental verbal dyspraxia. They had trouble coordinating the complex sequences of muscle movements for clear speech. They also had some grammatical difficulties, possibly linked to the sequencing problems. So it's crucial for the motor skills underlying fluent speech production. Yeah, that seems to be its core role in humans. And interestingly, FOXT2 shows deep homology. Meaning the gene itself is ancient and found in many animals. Yes, and it often plays analogous roles related to motor control or learning in other species. In songbirds, it's involved in the brain circuits, essential for learning and producing their complex songs. In mice, it's... It's involved in motor learning, like learning complex sequences of movements. Studying FOXP2 in birds or mice can actually tell us something about the fundamental mechanisms relevant to human speech. Absolutely. It justifies that broad comparative approach. The basic molecular tools might be conserved, even if the final output birdsong versus human speech is different. Okay, timing. When did the human version of FOXP2 arise and become fixed? Genetic analyses looking at the differences between the human and chimpanzee FOXP2 genes and the patterns of variation in modern humans suggest the human -specific version underwent strong positive selection. It was highly advantageous. The estimates for when it became fixed in the human lineage cluster somewhere between, say, 200 ,000 years ago and perhaps as recently as 100 ,000 years ago, though there's still debate. That time frame, roughly coinciding with the appearance of anatomically modern humans, seems significant. It does. It suggests that the fine -tuning of the motor control system for articulate speech might be a relatively recent event in human evolution specific to our lineage. How does that square with the fossil evidence? Because that seems to point earlier. Ah, the eternal tension between genes and bones. Yes, the fossil evidence is tricky because language doesn't fossilize. We have to rely on proxies. Like the ipoglossal canal. Right. That's the hole at the base of the skull where the nerve controlling the tongue. the hypoglossal nerve passes through. In humans, it's significantly larger relative to body size than in apes. Suggesting more nerve fibers, finer muscle control of the tongue? That's the inference. More wiring for more dexterous tongue, presumably needed for complex speech articulation. And when does that canal reach modern human size in the fossil record? Well, studies on fossils like those from Sima de los Huesos in Spain, which are ancestors of Neanderthals, and on Neanderthals themselves, suggest the canal size was already in the modern human range by at least 300 ,000 years ago, maybe even earlier. Okay, so that's potentially 100 ,000 years or more before the estimated FOXP2 sweep. The tongue control might have been in place earlier? It creates a puzzle. Maybe the basic anatomy for tongue dexterity was there, but the specific neural programming facilitated by the modern FOXP2 variant came later, allowing for faster learning or more complex sequencing. And we can go back even further, can't we? Brain shape changes. Yes. Looking at endocasts, impressions of the brain's surface on the inside of the skull, there's evidence suggesting that the region around Broca's area, typically associated with language processing and motor control in modern humans, might have started reorganizing or expanding as far back as Homo habilis around two million years ago. Two million years. That's vastly earlier. What could have been driving that change so early? One influential idea links it to toolmaking. The appearance of the first stone tools. Oldowan tradition and later, the more complex Acheulean hand axes require sophisticated planning, sequential action, and fine motor control. often biased towards the right hand. Which is controlled by the left hemisphere, where Broca's area is typically located. Exactly. So the hypothesis is that the neural circuits for complex sequential motor planning, perhaps initially evolved for tool manufacture, were later co -opted or provided a foundation for the sequential processing required in language, both for production, syntax, articulation, and maybe even comprehension. The brain circuits got good at sequencing actions for making tools, and that ability turned out to be useful for sequencing sounds. It's a compelling example of exactation. The ability evolved for one purpose, or maybe multiple purposes related to motor control, and then became available for this new, incredibly powerful function of language. It really paints a picture of language being assembled piece by piece over a vast timescale, doesn't it? Absolutely. It's a mosaic, not one single language organ appearing overnight. So wrapping this up, the overall picture is complex integration. Definitely. It's an integrated mosaic. You have ancient components related to concepts and social intelligence shared widely with other animals. You have intermediate steps like changes in motor control, possibly linked to tool use, maybe... basic vocal control for display and then you have the more recent perhaps human specific innovations like the fine -tuned vocal learning circuits involving foxp2 and potentially the full recursive power of syntax all layered on top of each other over millions of years Exactly. And molecular genetics is becoming incredibly powerful here. Genes like FOXP2 act like genetic fossils, as Fix calls them. They let us start putting dates and sequences on these events. We can see which changes likely came first, which selective pressures were acting when. It helps unravel the timeline in a way fossils alone can't. Right. For example, the evidence seems to lean towards anatomical potential for speech sounds, like the hypoglossal canal, maybe preceding the full refinement scene with FOXP2, which in turn might precede some aspects of complex grammar emerging culturally. Which leads us to that final, really thought -provoking tension you mentioned earlier. If the core biological capacity for language, the ability to acquire a structured system, is innate, how much of the actual language you or I speak is just... cultural happenstance. That's the big question, isn't it? How much is biology? How much is history and culture? Many specific features of languages, why English uses subject -verb -object order, why German has complex case markings, why French has grammatical gender. These might not be direct biological adaptations. They could be. What was the term? Grammaticalization. Yes, grammaticalization. They could be solutions that cultures have stumbled upon and standardized over time to solve the incredibly difficult problem of mapping complex multidimensional thoughts onto a simple linear string of sounds. They're culturally evolved conventions shaped by efficiency, learnability and historical accidents. Our brains are biologically prepared to find and use structure -dependent rules, maybe recursive rules. That's the innate part, the FLN. Arguably, yes. But the specific form those rules take in English versus Japanese versus Swahili, that's largely shaped by cultural transmission. That's a very prominent view. The biology provides the constraints, the potential, the learning biases, but the actual linguistic system is fleshed out and transmitted culturally. Chomsky himself talked about many surface features of language being down to accidental historical and cultural events. Which leaves us with a fascinating final thought for you, the listener, to mull over. Think about the language you speak every day, its specific word order, its quirky idioms, its grammatical rules. How much of that structure reflects a deep biological blueprint for human language, and how much is just the echo of countless historical accidents, innovations, and conventions passed down through generations of speakers? Where does biology end and cultural history begin? It's a blurry line, and exploring it is what makes this field so endlessly fascinating. Thanks for joining us on this deep dive into language evolution.