Webinar – Raising the Dead: How do we know what ancient humans looked like?
Aired May 20, 2021
Briana Pobiner:
Hello, everyone! Welcome to the Human Origins and National Museum of Natural History's HOT Topic program. Today our topic is "Raising the Dead: How Do We Know What Ancient Humans Looked Like?" featuring paleoartist John Gurche. We will get started, I'm so glad to see so many of you here, and my name is Briana Pobiner and I am a paleoanthropologist and educator here at the Smithsonian National Museum of Natural History. Whether this is your first time joining us or whether you've attended a HOT Topic program before, we have these programs every month, we're so glad to have you here. But before we get started with our program, I have a few housekeeping notes. This discussion today offers closed captioning. You can turn them on or off using the CC button, which should be located at the bottom of your Zoom interface.
you have questions during the program, please go ahead and type them into the Q&A box, that two speech bubbles at the bottom or top of your screen so that we can sort through as many of them as possible. The Q&A tends to really fly by, and so the Q&A box is also where we will share any relevant links during the program, so keep an eye out there for answers to questions.
So we're going to start this program with an opening presentation by our speaker, John Gurche, and then after about 25 or 30 minutes of that presentation, I will join him here and I will read questions that come into the Q&A. So now I'd like to go ahead and introduce our speaker. So John, if you'd like, feel free to turn on your camera and microphone now. So John Gurche, thank you for being with us. John is a world-renowned paleoartist, known for his paintings, sculptures, and sketches of prehistoric life, especially dinosaurs and early humans. John fashioned an evolutionary series of heads from clay while in fourth grade, but he studied art only up until middle school when he attempted to create a family tree for all animal life. He then studied anthropology and paleontology at the University of Kansas, and he's currently an artist in residence at the Museum of the Earth in Ithaca, New York.
John's artistic work has been on display at the American Museum of Natural History, the Field Museum of Natural History, and our own museum, the Smithsonian's National Museum of Natural History. John has also created illustrations of hominins, or early humans, and other prehistoric life for National Geographic, and he even designed a set of four dinosaur-themed stamps that were released by the U.S. Postal Service in 1989. Due to his paintings of dinosaurs, John was given a role as a consultant for the movie "Jurassic Park." And in 2000, John received the Lazendorf Paleoart Prize from the Society of Vertebrate Paleontology for his mural of Sue the Tyrannosaurus, a piece which accompanies the dinosaur skeleton at the Field Museum. In 2013, John published a book detailing his work on the 15 hominin reconstructions he created for our own Hall of Human Origins, titled "Shaping Humanity: How Science, Art and Imagination Help Us Understand Our Origins." So now I would like to turn the program over to John, and when you're ready, you can share your screen.
John Gurche:
Well, I'd like to start by thanking you all for joining us today. This is an exciting topic, at least I think so, and I wanted to ... Before I go much further, I wanted to thank Briana and the crew at Natural History Museum at the Smithsonian. And basically the topic today is "Raising the Dead: How Do We Know What Early Humans Looked Like?" And the short answer is we don't, so you can all go home now.
Briana Pobiner:
Our program's not over, just kidding.
John Gurche:
If you'd like to listen to a little bit about how we make the best guesses we can make about what human ancestors looked like, that's what I'm here to talk about. And it basically falls into several categories of increasing degrees of speculation. As I said, we can't know anything at least short of having a time machine, we can't know anything about how our early ancestors looked, but there are some ways of making very good guesses. And the best of those ways involve correlations in bony anatomy, which we can find in the fossils, and soft tissue anatomy, which is our target, which is our goal of reconstructing. So starting with a ... Let me just share a screen here, so ...
Briana Pobiner:
Great, and I'm going to go off-screen while you do that, so I will come back on again when you're done. Thank you!
John Gurche:
All right. All right, so this is an ancestor. This is just a sort of opening shot, but it's an ancestor that lived around 3.8 million years ago. It's Australopithecus anamensis, and the skull was just announced for the first time in 2019. So this was a very exciting project to work on. Okay. All right.
Briana Pobiner:
If you have lost your mouse, it seems to be on the screen that you're sharing, if that helps.
John Gurche:
Say again?
Briana Pobiner:
I said if you've lost your mouse, it's on the screen that you're sharing.
John Gurche:
Okay, let's see. Having a little trouble here pressing the ... There we go. Okay. All right. So if we find a modern human skull and we want to establish an identity for that skull, as in many crime cases, one of the things that police often do is reconstruct the head of that person in an effort to get someone to recognize it and provide further clues about the possible crime. So one of the ways we do that is we use tissue depth or tissue thickness data taken from modern human cadavers and sometimes from living humans if we're using a scanning process, at various points on the face and we can tailor it to gender and ethnicity of a particular skull and get some idea what an individual looked like. So that's all pretty straightforward ... I mean, it's really not, but it's more straightforward than reconstructing an ancient hominin.
What do we do when we have extinct species to work with and we cannot measure cadavers or living members of that species? How do we reconstruct that soft tissue anatomy? Well, in that case, you have to bring in comparative anatomy of living forms, and often there will be relationships between bony anatomy and soft tissue anatomy that can inform a best guess about the extinct hominin in that you are reconstructing. So I'll start with an example of the temporalis muscle, and this is the muscle that you feel on the side of your head pulsing when you chew just above the cheekbone. And you can see it in humans on the left, a chimpanzee in the middle, and a gorilla on the right, on the lower row here. And the skulls of each species are on the upper part of the slide top row.
So I think you can see there's a line marked in the bone that's called the temporal line that marks the origin of that muscle in humans. It's represented by a black line that's been drawn over this skull, and then in the middle you see a chimpanzee skull and you can see the temporal line stand out quite visibly is so, it's very clear the upper extent of that temporalis muscle, which turns out to be more extensive than what you find in modern humans. And in the far right column you see gorillas with a temporalis indicated below and a bony crest on top of the skull in the upper part of that column. And that bony crest develops during the life of an individual as the temporalis muscle. If it grows large enough, it meets its counterpart on the other side and stimulates the growth of this bony crest. And I might stop and say that bone, unlike popular opinion, is not really a static system, it's a dynamic system. So if you apply force to it, it will ripple and flow and basically change in order to accommodate that force.
So in this case, you have the development of this mohawk-like bony crest on top of the skull. Okay, so if we find a fossil ... Oh, before we go any further: I want to say the best of the relationships that we can find between soft tissue anatomy and bony anatomy are numerical relationships that exist in between, let's say, an eyeball and an eye socket. And it turns out these are only usable, really, if they are very similar in at the very least chimpanzees, bonobos, and humans, and gorillas too, if that works out. But the basic idea is that if the extant forms in the entire African ape clade, of which humans are part, if all of the extant members of that clade have a certain numerical relationship between, in this case, the eyeball diameter and the measure of the eye socket, then it's a pretty good guess for extinct members of that same clade.
So in this case, we're very lucky to find that there are dimensions of the eye socket that correlate with eyeball diameter and have a very similar ratio in gorillas, chimps, bonobos, and chimpanzees. Okay, so if we've established this idea of temporalis and the development of this bony crest, then when we find a fossil like this Australopithecus boisei on the right, or Paranthropus boisei is what we now call it, and if we find a fossil that has a bony crest like you see here, it's not a big mystery what that crest is all about. We know what it's for because we can see what its function is in extant forms, especially gorillas and in male orangutans you have that developing also. So in my reconstruction of Paranthropus boisei, I've given it temporalis muscles that are very extensive and meet at the top of the head and stimulate that bony crest.
Before we move on, I'll show you the final reconstruction of that creature, Paranthropus boisei, and you can see this reconstruction at the Natural History Museum at this Smithsonian. One side note, and it gets into a more speculative aspect of reconstructing ancient hominins, look at the top of the head here, and in this next slide, I've made it into sort of a cone head by adding additional soft tissue on top of that bony crest. Now that's an alternative possibility for Paranthropus boisei and the reason I've done that is because in both forms of extant great ape where the males feature such a bony crest for the anchoring of temporalis, they feature also a thick fat pad on top of that crest. And now this may be a matter of sexual selection, it has the effect of exaggerating a male feature so maybe this looks hyper-male to females and attracts females? We don't know. But that would be an alternative possibility for reconstructing Paranthropus boisei, is to add such a fat pad. But it's pretty speculative. I think you'll agree.
All right, so I thought I would take you through a reconstruction and we'll address some specific issues and you'll notice that of these issues, there are varying degrees of certainty that we can apply. Some of them are very good guesses based on modern forms, all the extant forms of the African ape clade, including humans, and some of them are more speculative and even get into adding information from ecology and behavior. All right, so this is the skull of Australopithecus afarensis, it's a big male and it was announced in 1994, found in Ethiopia. It's about 3 million years old and it's basically the first skull that was found for Australopithecus afarensis, which is Lucy's kind. Lucy basically made her debut without her head. There are only a few scraps of skull. So this is the first complete skull known.
This is a slide of the reconstructed skull, some of the missing parts were mirror-imaged from the other side, et cetera. And this is some of the deepest soft tissue. I've discussed how I reconstruct the size of the eyeballs using dimensions of the eye socket. But also you see here the chewing muscles and you see temporalis there almost meeting at the top of the head, but not quite in the back of the head it actually does meet and forms a little crest, but it's not quite like what you get in Paranthropus boisei. You also see the jaw muscles here and there are quite a bit of clues on the skull and mandible as to the reconstruction of this muscle so its position and its development, degree of development, are not so much a mystery.
You also see the nasal cartilages here, and I should say that at this point that the bones carry quite a bit of information about the nose. You often hear that the nose and the ears cannot be reconstructed based on bone morphology. It's true of the ears, you can reconstruct a position but not much about the morphology. But with the nose there's quite a bit of information in a skull and some of the most important applies to the amount of projection of the nose. So I've reconstructed the cartilaginous nasal septum here, and then also the greater cartilages of the nose that kind of ride that septum. The projection of the septum is pretty easy to ... Well, not easy, but it's pretty straightforward to determine that based on extant forms, but the greater cartilages that ride that septum, their position is a little harder to reconstruct.
But I won't get into detail here because if I got into detail about everything, I have to tell you that when I do a reconstruction, it follows a worksheet that's over a hundred pages long and it's all sorts of data from dissections of great apes that I've done and also humans and equations I've worked out from that data. So let's come to the band of muscle that you see here ringing the mouth. That muscle is called orbicularis oris, and the interesting thing about that muscle, or the challenging thing, really, is that it's very different in a modern human, which you see here on the right, and in great apes, which you see a gorilla here on the left. And so it looks like all of the modern great ape species have a well-developed muscle in this area ringing the mouth and humans have a much reduced area by comparison.
So it becomes a matter of trying to decide when is the most likely time for the reduction of this muscle? Well, that gets into what the muscle is used for in extant apes and humans, and extant great apes use the muscle often as they use the lips as a third hand. In fact, orangutans even preferred sometimes to use that when using tools, they prefer to manipulate it with their lips rather than their hands. And so some of the functions included for great apes are procurement and preparation of food items. So for example, a gorilla might put a branch with leaves on it into its mouth and then strip the leaves away by pulling the branch out and closing the front teeth. Well, it turns out that some of the specimens of Australopithecus afarensis have similar wear on their teeth to the gorillas that do this kind of stripping of leaves.
So we don't know exactly what they were doing, but they were obviously using their front teeth in the preparation of food. Another clue that this might be true of this species, which is Lucy's kind, Australopithecus afarensis, is that if you look at the temporalis muscles in the markings in the back, what you're seeing here is the back of two Australopithecus afarensis skulls, and in the midline you see these double ridges. Those are markings for temporalis muscle and basically, the fibers of temporalis in this species, Australopithecus afarensis are emphasized in the back instead of the front. So what do those fibers do? Well, the fibers of temporalis cross before they attach to the mandible so the posterior fibers of this muscle that attach on the back of the skull, back top of the skull, power the front of the mouth. So it's another clue that they were emphasizing force at the front of the mouth as opposed to the back.
And a third clue comes from looking at the bottom of these two skulls, both Australopithecus afarensis, and you can see the markings for neck muscles behind that hole, especially on the one on the left here. That topography, that rugged topography you see is related to attachment of neck muscles and they're strongly marked. And so one of the things that, for example, going back to the example of gorillas stripping a branch of its leaves, they have to stabilize the head or even pull the head back, and it's a clue that possibly Australopithecus afarensis was behaving in a similar way.
So in my reconstruction of this big male Australopithecus afarensis, I gave it large, rather ape-like muscles ringing the mouth. So it's just a little example of if we're lacking something numerical that we can apply to this kind of reconstruction, we can sometimes bring in ecology and behavior and that'll give us clues.
Further down the line of the reconstruction is I've added thinner sheets of muscle that are more superficial in the face. And this slide shows the reconstruction a little further down the line with some of the skin beginning to be added. And then the final reconstruction in clay looks like this. And you can see a lot of the features that are either part of the skull or are indicated, as I've talked about, indicated by some of the guesses that we're making, best guesses. You can see that this has a small brain; Australopithecus afarensis had a brain only marginally larger than a chimpanzee's. The wide cheekbones show up large projecting jaws, but you can also see the reconstructed features like a flat ape-like nose, the large soft tissue area around the mouth and the large chewing muscles.
This is the final reconstruction done from that in that series and a version of this is visible in the Natural History Museum, and several things come into play here. One of them is skin color, although we humans tend to make a big deal of skin color, it's really only a fairly simple adaptation to optimum amounts of sunlight. So your skin, if it receives too much sunlight, there's a danger of skin cancer or other health problems. If it receives too little sunlight, you're unable to synthesize enough vitamin D that your body needs. So there's an optimal amount of sunlight, but of course sunlight varies with latitude. So in higher latitudes, the need is to let more sunlight in; in lower latitudes, the need is to block some of it out. So pigmented skin increases that ability to block out sunlight to the appropriate degree. And so since this was found almost on the equator, I've given it dark skin. Hair patterns we don't know anything about. The best I can do is extrapolate from commonalities in what you see with modern humans and what you see with extant apes.
All right, I'm going to take you through, quickly, I'm going to take you through a reconstruction of Lucy's body. So this is the same species, Australopithecus afarensis, but this is a female and this is Lucy, as she was found, often said to be about 40 percent complete. By the time you mirror image the parts that are missing on one side you have a more complete skeleton and that is often added to with specimens from other members of this same species. And there are quite a few now, fossils of Australopithecus afarensis. This is a collection as of the '70s, we've added to it quite a bit by now.
This is a reconstruction of Lucy's skeleton. This was done by Swiss anthropologist Peter Schmidt, and it gives you an idea of what the whole body looks like. My first step in beginning this reconstruction was to reconstruct a composite female skull because we do not have, or did not at that time, have a more complete female skull. So this is a composite that you see in the background and it's based on Lucy's bits, but also parts of two other females, one of which is the face that you see here in the front.
And the final reconstruction of Lucy's face is something like this. It looks in a way like a delicate version of what we had in the other reconstruction. Okay, reconstructing the hand. One thing I want to do to notice here is what you see on the left is a human hand skeleton. And on the right a Australopithecus afarensis hand skeleton, you can see that both are missing the terminal thumb bone and afarensis is missing a couple more. But the reason I show the slide is just to show that the thumb in the composite is shorter and not as robust as in modern humans. And I will see whether this holds up when a fully complete hand skeleton is found from a single individual but for now, I've reconstructed the hands of Lucy as having thinner and shorter thumbs.
All right, this shows the known foot bones for Australopithecus afarensis and so I based Lucy's foot on that collection of bones. What you see here is a ... You see part of a chimpanzee foot skeleton, and the emphasis here is on the way that the basal bone of the great toe fits with the rest of the tarsal bones. So you have a very diverging basal bone of the big toe in the chimp on the right, in the middle is afarensis and the next one over is a human. And I think you can see in the human that the joint is not as curved and that joint is immobilized. We use our big toes in totally different way than chimpanzees do, we use it as a stiff paddle to push off with when we're walking on two feet. chimpanzees still have a very grasping foot, and so they can make that great toe diverge quite a bit.
Well, there's been a lot of debate about this joint between the basal bone of the great toe and the rest of the tarsal foot bones. Was it capable of some mobility? And there's been a lot of debate, but some of the latest papers have argued that afarensis, Australopithecus afarensis, Lucy's species, did retain some mobility in that joint and it's probably related to climbing. So they were possibly able to diverge that big toe to a small degree.
So based on those bones, I built a fossil foot skeleton reconstruction and then started to reconstruct the muscles on the bottom of the foot. Further down the line. And this is what the final foot ended up looking like. And you can see it's a very unusual-looking foot, it doesn't look much like a modern foot, it doesn't look much like a chimpanzee foot either. It's got a sort of hand-like look. And that's partly due to the lengths of the various toes. The big toe is still short in relation to the long lateral toes, unlike modern humans where the lateral toes have been shortened. And you can see that I've given it a little bit of a gap here to indicate that it was able to diverge that great toe to some degree at least. Here's what the reconstruction looks like from the top.
All right, another thing to look at in reconstructing Lucy's body position is how Lucy might have held her shoulders. So on the right you see a chimpanzee here with its shoulders held in kind of a high hunched position, on the left, a human skeleton with more horizontal collarbones. And this is a fossil called the Dikika Baby, Dikika. And it's the fossil of a skeleton of a child around three years old, and it gives us many clues about locomotion and some of the best of these, this is Australopithecus afarensis also, you might call it Lucy's baby.
One of the things that the shoulder blade of this infant told us, and that's the shoulder blade you see here in the upper left, is a clue relating to the arm muscles and the shoulder muscles. And one of the things I want you to notice is the area above the spine of the scapula, and that spine, in the lower left, which is a human shoulder blade, that spine is almost horizontal and the great apes tend to have it much more angled. You see a gorilla up top here on the right and then a chimpanzee below that.
It turns out that the area for attachment of muscles raising the arm is greater in great apes than it is in humans. Well, of course they practice a lot of locomotive behaviors in climbing and so forth where they use the arm in a raised position. Well, the Dikika Child has a little bit of that going on. It has a larger area for arm-raising muscles than what you see in a modern human of a similar age. So in this skeleton, the skeleton I worked from in recreating my version of the Lucy body, I've given it collarbones that are somewhat raised in relation to the human situation. It's subtle, but it influences the shape of the thing in the end. So the shoulder's a little bit hunched. Addition of some of the shoulder muscles and back muscles and some of the muscles of the trunk and arms and the gluteal muscles of the hip. And excuse the psychedelia here, part of the development process went apparently wrong and this is the only slide I have of this part of the reconstruction. But anyway, this shows you the full muscular reconstruction from the back.
And this is the final clay reconstruction of Lucy before molding and casting was done. And you could see that it's got a very unusual body shape. It's not just like a modern person, and it's also not just like a chimp and it's got a wide trunk as indicated by the pelvis, and some would say the ribcage, it's got long arms relative to its legs, not as long as in chimpanzees, but longer than what you find in modern humans. And so it's a very unique body form. This is the final body form. And you can see this reconstruction in the Smithsonian's Natural History Museum.
I should tell you, if I have time, that the pose chosen here was one ... I wanted to address the issue of locomotion head on. We know that these creatures were walking bipedally when they were on the ground, they were fully upright, but we also have hints that maybe they were still climbing, there's debate about that, as I've said. So I wanted to indicate a position where this creature is just dropping down from a tree, but it's dropping down into a bipedal upright position, not a quadrupedal position. So sort of tackling both locomotion issues at once.
One of the things that this reconstruction says, that doing such a detailed reconstruction says, is that you can't just tuck a little human body underneath those ape-like heads for Australopithecus. These are reconstructions that are at the American Museum in New York, American Museum of Natural History, and you can see they've got the short legs and the long arms, but otherwise their bodies are pretty human-looking and I would beg to differ on that.
All right, just to indicate another issue where we have to take into account physiology to get anywhere with a best guess at reconstructing of faces, What I'm showing you here is that chimpanzee baby on the left and a human baby on the right. And you can see that I think that the major difference here is that there's so much in the human baby's face. So if we look at great ape faces, we find that human faces and bodies have a layer of subcutaneous fat, and that is lacking in the African great apes, especially in the face, there's very little fat unless the ape has been prevented from an active life in some way. But in normal African ape faces, you do not find a great amount of fat. And so the babies are a good illustration of that.
So what is that difference all about? Well, it's important because it's an important factor in how the final face will look, and cartoonists are aware of this. What makes Tweety Bird look so adorable? Well, it's partly those big eyes, but it's also the baby cheeks, the fat baby cheeks. They've given it a human-like look here. So when we look at ... I had to address this issue when I was reconstructing a teenage Homo erectus, this is called the Turkana Boy. And Homo erectus has a ... Well, I'll save that. Let's just say that the first question to ask is why the difference between great apes and humans in that layer of fat?
Well, it turns out that the human subcutaneous fat layer functions, among other things, as a nutritional buffer for a creature developing an outrageously large brain. In human evolution, we have tripled our brain size so that took some developmental and some physiological tricks, and one of them was developing this fat layer that could serve as a nutritional buffer in times of where food was scarce. So it seems to be that among the extant great apes and humans, anyway, looking just at that clade, it seems there's a relationship between brain size and fat content.
And so when you're looking at reconstructing an early hominin, you might ask yourself the question: "Has this thing evolved a large enough brain size yet to have required such a nutritional buffer?" Well, in Lucy's kind, the brain is only marginally different than a chimpanzee's brain size. And so my best guess was no, this acquisition of the fat layer in human evolution had not occurred yet. But by the time you get to Homo erectus, the brain has enlarged quite a bit. It's still not as large as in modern humans, but it's enlarged quite a bit over Australopithecus as in Lucy. And so I've just made the decision that the best guess was to give this creature a degree of subcutaneous fat in its body and face. And so you can see here I've reconstructed a fat layer that's different from what you would get in a great ape. Now this is a guess, but it's a guess that's at least is based on some physiology. This is the final reconstruction of that face. Last I looked, it's equivalent to about a 12-year-old modern human.
Before I open it up to questions, I thought I would just quickly take you through a series of reconstructions and most of these are visible at this Smithsonian's Natural History Museum. This one is not, because it was done after the hall opened, and this Australopithecus anamensis at 3.8 million. This is Australopithecus afarensis, and you can see this at the museum, it's around 3 million years old, plus or minus. This is a reconstruction of Paranthropus boisei, not an ancestor for modern humans but a representative of a side branch that specialized in chewing hard and abrasive foods at least as a fallback food. This is Australopithecus africanus, South African version of Australopithecus.
And I've given it a smile, I've given it this expression because there's some overlap between facial expressions in chimpanzees and modern humans. And one of them is what you might call the human nervous smile. There's a submissive smile that chimpanzees engage in that is very much like a human nervous smile so based on that commonality, I've given a similar expression to this Australopithecus africanus.
Homo erectus. Brain enlarging, and the face becoming more diminutive. Nose is starting to project. I haven't gone over the physiology of projecting noses because there's not really time here, but you can see it in the bones. This is Homo floresiensis, a bizarre side branch, not an ancestor, that was discovered in 2013, I think, on the island of Flores. Very primitive features in some areas of the body and more advanced or evolved features in others. Homo heidelbergensis begins around 600,000 years ago, and the brain for the first time has now enlarged to the point of entering the modern. This is a Neanderthal. And again, you can see these last two, last three, actually ... no, the last four at the Smithsonian's Natural History Museum.
And that is the end. So I will stop it there, but I'm sure you probably have questions and I hope I can answer some of them.
Briana Pobiner:
Thank you so much, John, that was wonderful and I loved seeing our early family, photos of our early family that you can see when our museum opens back up again. We have a lot of questions that have come in already, so I will just go ahead and jump in.
John Gurche:
Okay.
Briana Pobiner:
Barry asks, "How do you determine hair distribution and thickness?" And there was another question, and Nona had asked a similar question, "How do you decide on hair coverage?"
John Gurche:
Yeah. Hair coverage, is a slightly easier question to answer, and if you're talking about a whole body, because we humans have a cooling system that is unique to us, it uses enhanced sweat glands for evaporative cooling. Now that function does not work with a full coat of body hair. And so we know that somewhere along the evolution from great apes to humans, we lost that coat of full body hair. Well, there are indications in the fossil record of when that transition may have occurred because there are indications starting with Homo erectus of when humans started adapting to climate with body proportions. So African versions of Homo erectus have similar body proportions to Africans living at the same latitude today. And it's an indication that humans had started to adapt to climate as we do, and that suggests that they're using such an enhanced sweat gland cooling system. So they probably did not have a full coat of body hair.
Before that, it's a matter of guessing when in our early evolution we lost that coat of body hair. And I've always given Australopithecus a sort of an intermediate coat of body hair where it's lost in some areas, but in areas that would be exposed to direct sunlight it's retained, so top of the head, the shoulders. But it's a guess. As far as the other question about distribution of hair, especially facial hair, we don't know. I can only base it on the commonalities we see in great apes and humans, which there are some. But otherwise, so far we're in the dark. Maybe genetics will eventually inform that decision, but so far we haven't gotten any DNA out of human fossils older than 400,000 years and Australopithecus is quite a bit older.
Briana Pobiner:
Yep, that makes sense. All right, so here's a process question. Cecilia asks, "How long does it take to reconstruct a face?" And Garanch also asks in general, "How long does it take to do your reconstructions?"
John Gurche:
Yup, okay. Reconstructing a head generally takes me, for the whole process, takes me four months. So it's roughly two months on just the anatomy, building in clay over the skull, and then after that two months is over, then taking another two months to make it really lifelike. So that includes painting of silicone into a silicone mold, but the silicone is tinted to be representative of your desired facial skin color and includes installing eyes and implanting hairs, which you have to do one by one in the areas where it's going to really show where you can look and see into the roots, you can't get away with multiple root hair punching, so you better put on some good music and just settle in if you're doing that kind of work.
Briana Pobiner:
Great. And actually, you partially answered this question from Halia: "What kind of materials do you use to reconstruct a face?"
John Gurche:
Yeah. So I use, basically, a kind of clay that does not inhibit silicone mold-making material. And so that lets out plastilina, you can't use that because it'll inhibit the curing of the silicone, you have to use something like clean clay or Protolina's ... No, sorry, Van Aken's product called Protolina Clay. Those clays are formulated not to inhibit silicone curing. And then for the curing, for the mold itself, I use GI-1000 silicone, and then there's another material, another kind of silicone called V-10-68 that I use to make the face out of. And that material has the advantage, you can make it any color, you can make it any luster, so you can make it all the way from matte to shiny, and you can make it any degree of opacity from translucent to totally opaque ... There's quite a bit of control that you have over that material.
Briana Pobiner:
Nice, thank you. We had a couple of questions. We had several sort of career path questions, but these two questions are about your mentors or influences. So Chris asked, "Can you tell us how artist Jay Matternes influenced you?" And Nona asks, "Are you familiar with works of Mikhail"... I don't know if I'll pronounce his last name correctly. "... Gerasimov?"
John Gurche:
Yup.
Briana Pobiner:
"He reconstructed the face of Ivan the Terrible among many others. Who were your mentors in this complex line of work?"
John Gurche:
Well, I guess this is a sad tale. I was expecting when I first got into this that there would be a lot in the literature that would help me with reconstructing ancient faces. And so in particular, I looked up the work of Gerasimov, the Smithsonian's Larry Angel had quite a bit of information about facial reconstruction, not all of it published, but he gave me what he had. And I looked at Matternes's methods also, but I was disappointed because the Smithsonian actually has a collection of death masks and skulls from the same individuals so you can look at that and you can test some of the predictions of facial reconstruction process on these heads. And I found that most of them came up lacking. So some of the predictions about projection of the nose or the widths of the nose did not hold up. For example, predictions about whether the corners of the mouth turned up or down based on muscle markings, I could not verify that.
So I had to sort of branch out on my own to do this kind of stuff and I had to start dissecting, and I spent about 35 years dissecting great apes and humans. So that includes chimpanzees, bonobos, gorillas, orangs, and humans, male and female, young and old. And all of that was done with an eye toward establishing a method of reconstructing ancient humans. The thing I was looking for that was the most important was commonalities in the relationships between soft tissue and bony tissue.
So as far as mentors go, I was inspired by the work of some of those early artists, especially Jay Matternes, I love some of his old drawings, but he didn't get into a lot of detail about the specifics of tissue thickness, soft tissue thickness at various points in the face and that kind of thing. And I wanted to take it further into that realm so that's what the dissection was all about.
As far as inspirations, I have to say Stanley Kubrick. I think that the thing that started me off on this path in the first place was seeing 2001: A Space Odyssey when I was 17, and it brought home what a unique and bizarre and wonderful creature humans are and what a wonderful development in the history of life, the evolution of humans represents.
Briana Pobiner:
Oh, fantastic. I think you just answered, actually, a question from Kabae: "How did you get into the history behind humans?" So.
John Gurche:
Yeah.
Briana Pobiner:
That's nice, yeah. Let's see. So there's a question from Nadjes who asks, "Is there a part of the bone that tells you what size the muscle attaching to that part of the bone is? I suspect that this might vary depending on the bone and the muscle."
John Gurche:
Yeah, you can look at bony ... There are quite a bit of markings on the skull that indicate the attachment sites of various muscles. As I said, muscles tend to exert force on the bone, which causes the bone to basically ripple and flow. So when you have a muscle attaching to the bone and exerting force on it, you often get a rippling in that area, sometimes it's a pit or a roughened area, sometimes it's a bump, a raised bump, and those can be informative for the larger muscles.
As far as the ... Well, definitely the position of the muscle, but also the degree of development of that muscle. It's kind of an intuitive thing. I don't have numbers to back this up for most of the muscles except for the chewing muscles in the head I do. But a lot of the smaller muscles, you get a range of development of the muscle marking and it does not correlate, much to my chagrin, it does not correlate with a range of development or size of that muscle, so you can't use it. I found that to be true with a muscle called levator anguli oris that raises the corner of the mouth. I was very hopeful when seeing that pit marked on some of the fossil skulls, but it's not something I could, in the end, use.
Briana Pobiner:
Interesting, thank you. I love this question, this is a question from Katie: "Which species has been the most challenging to reconstruct and which has been your favorite?"
John Gurche:
Well, I think each one is my favorite at the time I'm doing it, because often I'm working on skulls that no reconstruction has been done before. So that was true of Homo floresiensis and Australopithecus sediba and Paranthropus aethiopicus and also Australopithecus anamensis, so ... and Homo naledi was also in there with the brand new reconstructions.
So those are always very exciting because the reconstruction process is also a discovery process. I don't start with a preconceived idea of what this face should look like. I let it be the cumulative result of all the specific anatomical decisions I make along the way. And then as far as challenging, the most challenging to work on, I'm tempted to say that something that's sort of intermediate in our evolution, in other words, not all the way back to Australopithecus and not all the way forward, not as recent as something like a Neanderthal. They're probably the most debatable, they have the most debatable features. Like for example, with the correlation of the fat content in the face and body with brain size. I've made a guess there, but I think my guesses are probably more accurate earlier and later than that, so.
Briana Pobiner:
Thank you.
John Gurche:
Yeah.
Briana Pobiner:
A couple questions have come in about using modern imaging equipment. So Molly asks: "Have you used modern imaging equipment or studies like MRI or CT to augment the information provided by dissections?"
John Gurche:
Yeah.
Briana Pobiner:
"And if so, how has it influenced your process and the outcomes of your reconstructions?" And Jay asked a similar question: "Has 3D scanning and imaging helped you find in finding contours in cross species comparisons?"
John Gurche:
Yeah. It's helped quite a bit because it's provided additional data on soft tissue thicknesses, and that's been done both for extant humans and extant apes like chimpanzees. And so I get a much larger data set to work from. Now, you have to be careful because not all researchers are measuring the same, ostensibly, the same measurement the same way, so you have to be really careful about how each measurement is taken. You also have to be careful about the data sets and that's a big concern because a lot of the data sets that are currently used in facial reconstruction, if you look at them, they seem great at first until you look at the dataset and it's got an average age of 79 years old. So that's a problem because we know that tissue thickness at various points in the face varies with age, and so if you're reconstructing young adult early hominins or possibly middle-aged early hominins at the oldest, using data from humans that are 79 years old on the average is not going to be very useful.
So you have to eliminate data from elderly individuals, you have to eliminate data from also obese individuals or emaciated individuals because that probably is not a good reference point for relating to the tissue thickness of ancient hominin which would probably pretty physically fit, not allowed to accumulate a lot of fat, but also not allowed to let their musculature atrophy, they were probably pretty fit individuals. So once you tailor the datasets, they can be very useful. And some of those datasets are obtained with various scanning processes of living humans and great apes.
Briana Pobiner:
Thank you. Here is a question from a group, Lily Levy, Anna, Maria, and George ask: "What kind of hair do you use?"
John Gurche:
Ah! Okay. Well, now this may reflect a bias, but with choice of hair that I use, I can use human hair, but only going back so far because human hair has a unique look to it among the animals because we cut our hair so it has a very different look than the cumulative effect of the tapered ends of animal hair, including the great apes. So I use human hair for modern humans. Neanderthals were engaging in body ornamentation, so I'm assuming that may have include cutting the hair. Humans have this sort of ever-growing hair that would've been, I presume, maladaptive if it weren't able to be controlled in some way, that is cut or burnt or tied up in some way. And so that's reasonable behavior for Neanderthals.
But going much further back than that, I get into unsurer territory. And especially when we're talking about something as far back as Australopithecus, I think attributing any sort of hair-modifying behavior to them that would render our ever-growing locks to be adaptive, I think it's probably would be the wrong guess. And so for the really ancient forms I use, something that's a really good stand-in for chimpanzee hair, and that is the hair of black bear.
Briana Pobiner:
Nice. Good to know when thinking about the reconstruction in our exhibit. We have a couple of career path questions. So Piper asks: "What's your advice for an undergrad getting into paleo art?" And Heather asks: "What kind of classes or education does someone need to do this kind of work?"
John Gurche:
Right. Well, obviously you need both scientific skills and you need artistic skills. So the easiest way I think by far is to go the scientific route and find a way to keep your artistic skills developing on the side much easier than trying to do it the other way around where you go to school taking art classes and you somehow try to keep up with scientific literature without any training. That would be a challenge. So I would suggest going the paleo route, taking paleontology and anthropology, and find a way to keep your art skills alive on the side. It may not involve classes, it may be something you can do on your own. That was my path. But it's important probably to do the science first and the art stuff on the side.
Briana Pobiner:
Okay, thank you.
John Gurche:
Yeah.
Briana Pobiner:
Another sort of career question from Rebecca: "You are the only paleoartist I've heard of. Is this a growing field and how are you and your colleagues working to make it more diverse and accessible?"
John Gurche:
Oh, okay. Well, I'm not the only one. There are a number of paleoartists work working today. We're all in competition with each other. We all use different datasets.
Briana Pobiner:
Hm.
John Gurche:
And that's a problem because reconstructions of the same fossil often come out to look quite differently. And as far as how I'm working to keep it diverse, I would say, other than mentoring people who cross my path that come from all sorts of different backgrounds ...
Briana Pobiner:
Great, that was a question about if you're mentoring new artists or scientists as well. So thank you, yeah.
John Gurche:
Yeah. And I don't do a lot of that because, basically, I don't have time. I mean, trying to teach someone the 100+ pages of what I do in my work would be a years' long process. And if I was part of some university or something that sponsored that kind of thing, I would love to do it. But I'm kind of functioning out here alone on my own out here. And so it comes to just giving my own time when I can. And so that can be a diverse crew, but there's not a huge amount of it going on. And part of that reason for that is I haven't really shared specific data with anyone because I haven't published it yet, and that publication is waiting on getting my sample sizes up to respectable levels.
Right now, I would call everything I do hypothetical. I mean really, it's all hypothetical anyway, even with larger datasets. But I would call my process hypothetical, and I wouldn't publish it at this point because I think I can strengthen it by far by increasing the datasets. But that includes, unless I'm somehow getting a grant for this, which is hard to get for a person doing the kind of stuff I do, it'll probably take years. So I have to be honest in saying that my sharing of specific data with people has been limited because it's not published yet.
Briana Pobiner:
It sounds like a scientific process, basically, in some ways.
John Gurche:
Yeah, it's kind of a problem because I don't fit in into the granting profiles.
Briana Pobiner:
Yeah.
John Gurche:
I'm not on university staff somewhere where I'm paid a salary-
Briana Pobiner:
Right.
John Gurche:
... and nobody wants to pay for anyone's time. So I'm just kind of doing it on my own, but as well as I can.
Briana Pobiner:
Yeah, we have time for about a few more questions, maybe two or three. So I particularly like this one from Jessica: "Seeing a face has such a profound effect on us as humans. Do you ever feel like you're meeting these individuals when you reconstruct them?"
John Gurche:
I do, I do. And it's eerie, and usually I meet them before they have their skin fully on. I'll be working late at night, let's say, pouring over my notes and making some calculations and reconstructing some of the muscles or glands, and I'll look up and suddenly I see this thing watching me. I have this startling awareness suddenly of their, they're being a presence behind those eyes. And that's an indication that you're doing things right, I think, that you're on the right track, at least on the right track of trying to make something that looks like a presence, because I try to build that into my reconstructions. Not that you're just looking at a mannequin face, but that there's actually someone home. There's actually a presence behind those eyes.
So at some point during the reconstruction, when I'm working on it, I get a jolt usually, and I feel like I'm meeting that ... Or starting to, it doesn't even have skin yet ... meeting that individual for the first time. Because as I said, the reconstruction process is also a discovery process for me. I'm not reconstructing it according to a preconceived idea of what it should look like.
Briana Pobiner:
Nice. All right. One more question, and I apologize for all the questions we didn't have a chance to answer before we close but here's the question from Debbie: "Are you working on anything now, perhaps from recently discovered new species?"
John Gurche:
Yes, is the first answer. But can I talk about it? I'm currently under a non-disclosure agreement with ... I don't even know if I can say who, working on something that's pretty new, and I can't say much more about it than that, but except stay tuned. And the other new thing, I can actually talk about this one, is there's a new skull of Paranthropus robustus, it's the most complete skull of that species ever found, and it's also the oldest ever found. And it's been important in the literature because it's thought to indicate ... Well, it's 200,000 years older than the oldest Paranthropus robustus skull we knew about previously and it's also quite a bit more primitive. So they think they're seeing microevolution across the space of 200,000 years and they're correlating with climate change, so that's really interesting little elucidation that that new skull provides. And I am working on a new reconstruction of that new skull.
Briana Pobiner:
Oh, and this is the skull from Drimolen in South Africa, right?
John Gurche:
That's right. Yup.
Briana Pobiner:
Fantastic. All right, well, we will stay tuned.
John Gurche:
Okay.
Briana Pobiner:
So we're going to wrap up our program. Please join me in thanking John for sharing his work with us. I'd also like to give special thanks to those who made this program possible to our behind the scenes team who helped sort through your questions, to our donors, volunteers, and viewers like you, and finally, to all our partners who help us reach, educate, and empower millions of people around the world today and every day. Thank you.
So I hope that those of you who joined us today will join us for other programs over the summer. We will have online HOT Topic events in June and July, we will take a hiatus in August and resume in September. We've put a link in the Q&A where you can find information about our upcoming programs and about how to sign up for the museum's weekly e-newsletter, and that's really the best way to stay informed on upcoming programs and learn more about the museum's research and exhibitions.
After this webinar ends, you'll see a survey pop up asking for some feedback about the program. Please take a moment to respond, we're very curious to know what topics you might be interested in seeing for future programs, and we appreciate your input.
Again, thank you to everyone who was in attendance today and the audience. Thank you so much to John for sharing your insights in your process. That was really fun. And hopefully we'll see many of you next month at our next HOT Topic.
John Gurche:
Thank you all.
Briana Pobiner:
Take care!
