- Hi everyone. Welcome to today's program: Tools, Hippos and Early Humans at the Dawn of Technology featuring biological anthropologist Tom Plummer, part of our ongoing Hot Topic series, our Human Origins Today series. My name is Briana Pobiner and I'm a paleoanthropologist and educator at the Smithsonian's National Museum of Natural History. I'm a brown and gray-haired woman wearing a pink shirt in front of a Zoom screen with an African Savannah photo with grass and an acacia tree behind me. Whether this is your first time joining us for a hot topic or you've attended before, we're so glad to have you here. Before our program gets started, a few housekeeping notes.
This discussion offers closed captioning. You can turn the captions on or off via the CC button, (clears throat) which should be located at the bottom of your Zoom interface. We're in a webinar format so we can't see or hear you. As you have questions, please go ahead and submit them to the Q&A box which is at the top or bottom of your screen. It has two speech bubbles so we can sort through as many questions as possible. The Q&A time really flies by.
The Q&A box is also where we, excuse me, is also where we will share any relevant links during the program so keep an eye out there. We'll start with an opening presentation by our speaker, Tom Plummer, and then I'll join him here to take your questions. During the presentation, I'll also write answers to some of your questions, at least any that I can answer, as will another member of our behind the scenes team. So now I'd like to go ahead and introduce our speaker. Dr. Tom Plummer is a professor in the Anthropology Department at Queens College, City University of New York and he's a member of the CUNY Graduate Faculty and the New York Consortium in Evolutionary Primatology.
His research focuses broadly on late Pliocene and early Pleistocene hominin behavior and ecology with a special interest in exploring the adaptive significance of Oldowan stone tools. His research includes a strong paleo-ecological component because paleo environmental information is integral to issues ranging from the origin of major morphological complexes like bipedalism, understanding adaptive shifts within and between hominin lineages like between hominins with gracile and robust chewing morphology and understanding the context of novel behaviors such as the production of stone tools in the formation of the first archeological sites at least 2.6 million years ago. His fieldwork focuses on investigating archeological and paleontological occurrences in late Pliocene and Pleistocene sediments on the Homa Peninsula in southwestern Kenya. His ongoing excavations at the two million year old Oldowan site of Kanjera, South Kenya have uncovered one of the largest assemblages of artifacts and archeological faunas from any Oldowan site. Today though, he'll be telling us about a new site he's been excavating from the same region called Nyayanga and what he and his team have found there. So Tom, I'm excited to welcome you and take it away.
- Thanks very much, Briana. That's probably more than anyone's ever said about me so I appreciate it. And I'm going to share my screen now and we'll start the presentation. So first of all, you know first off, I'd like to just mention that this is a really big interdisciplinary project that there are major institutions involved you know in addition to the City University of New York.
This project was started with Rick Potts, who's the director of the Human Origins Program and then we are also partnered with the National Museums of Kenya and there's a lot of research collaboration with people there and then a wide variety of institutions around the world in the US, the UK, Italy, et cetera. So you can see the list of people that are involved. This isn't just me. This is a lot of people. And you know, one of the things to start off with thinking about is that humans are really a technologically dependent species. So, you know, humans have been able to adapt to a wide array of environments in the planet because of technology. They create their own ecosystems in places like New York and they're even able to leave the atmosphere and go into the space because of technology, right? So we're dependent on technology and this dependence on technology is really brought home in kind of entertaining ways by shows like "Naked and Afraid" where you just drop a couple of people into the wilderness with nothing and they have to survive.
And what do they do to survive? They make shelter. They produce fire. They get, they make some simple fishing or hunting or gathering tech. They create the technology they need to survive. So we are a technologically dependent species. Also, our gut is adapted to eating nutrient dense foods.
So foods that give you a lot of nutrition per unit volume. And this, there's a link between extracting nutrient dense foods from the environment and using technology. Technology is done for that. And you can look at, you know, humans today, how much technology is used in processing, preparing, cooking foods.
Or you can look at human groups who are living in more natural settings, like the few foraging peoples that are still out collecting foods in the wild. And it's the same deal. Technology allows humans to extract food from the environment. Here we've got some foods that are eaten by Hadza, foragers, you know honey, antelope, tubers, baobab root, you know fires used for cooking.
And with this extractive foraging of high quality foods goes food sharing hand in hand with that because that lowers the risk of relying on these high quality foods. If you're food sharing, then individuals that didn't make a kill say on a particular day, can share with individuals, get food from individuals who did make the kill. And it's almost certain that body size and brain size expansion that you see in the hominin lineage when you go from Australopithecus to early forms of Homo, Homo erectus to Homo sapiens, that this body size increase, brain size increase. This is being fueled by changing dietary quality over time.
And again, technology is an important part of that. So, I'm interested in the Oldowan. The Oldowan is an early, you know the earliest sort of widespread, persistent expression of technology in the geological record.
And in the Oldowan, you've got basically, you know, two-handed percussion of rocks. You can see in the upper left panel, you've got a hammerstone in your dominant hand. You've got a rock that you're driving sharp, sharp shards off of called flakes in your non-dominant hand. So in my case, I'd be holding a hammerstone in my right hand and holding the core that we're knocking flakes off of on the left hand. And this technology, you know, it's it may look simple but it actually takes a little bit of effort and practice to master it. But this technology is really, really important, we think and that's one of the things that I'm really interested in in looking at is what is the adaptive significance of hominins driving off the sharp shards of rock, essentially giving them both a cutting technology, the shards, the flakes can be used like knives with sharp edges to cut things as well as a pounding technology.
So the Oldowan's, the best documented early technology, it's known from roughly 2.6 to 1.7 million years ago so about a million year period. It might be an expression of some sort of major adaptive shift.
So for example, I'm interested, we were just talking about how humans are reliant on technology for survival. Is this true for the Oldowan? I mean is the Oldowan technology really something that's integral into the life ways of early hominins? Does this technology actually signal a dietary shift away from foods that Australopithecines may have been eating? Also, are there any socio-ecological chains that might be as changes that might be associated with this like food sharing between, you know within, within related between related individuals or even unrelated individuals? And one of the things you see with the Oldowan is clear expressions of the restructuring of hominin activities across the landscapes. You start having the accumulation of materials, of stone tools and fossils that at particular points in the landscape that we recognize as archeological sites. So if you look at technological milestones and during the interval that we have the Oldowan, you know one of the things we have is that you've got the first persistent tool technology. You'll see the Oldowan's not the oldest technology, that's the Lomekwian at about 3.3 million,
but that's only known from a couple of sites in the west side of Lake Turkana. At this point, we don't know it's if it's more widely distributed, but it hasn't been documented as being more widely distributed. You can see that toolmaker's expanding out of Africa occur during the Oldowan interval. Persistent butchery and megafauna butchery, megafauna being very large animals like hippos, rhinos, elephants, that all occurs during the Oldowan. You'll also notice that, you know, in terms of where we have, where we know things are happening, it's mostly situated in the two million year and younger Oldowan sites. We don't really know much about the the oldest Oldowan sites which is why the site I'm talking about today is of interest.
One of the reasons why is it's an early Oldowan site and these sites aren't that well understood. Everyone wants to know who made the these early stone tools and these are just a sample of the hominins that were alive during the time span of the Oldowan. So people have always assumed that the genus Homo was making stone tools. This is an unnamed species of Homo from Ledi-Geraru in Ethiopia that goes back to 2.8 million years ago. You know, Homo habilis, Homo rudolfensis, early Homo erectus.
Everyone is comfortable with saying that Homo ergaster or Homo erectus, early Homo erectus, was making stone tools. I'd say many people would, you know, be you know, willing to believe that Homo habilis was making stone tools as well. But there are other hominins around on the landscape including another genus of hominin called Paranthropus and also late Australopithecus. And these are just the East African hominins.
So if we're gonna throw in South African hominins there'd be even more. So you've got the potential that multiple hominins are making Oldowan tools and possibly even multiple genre if you throw in Paranthropus and Australopithecus in there. So it's an interesting but difficult problem to think about. I would say that it's almost certain that you've got more than one species making them and yet, you know, it may be that you've got different species making them through time. I'm working on the Homa Peninsula in southwestern Kenya, right on Lake Victoria and I've been working there since the late 80's with Rick Potts.
So Rick Potts is the curator and director of the Human Origins Program. And he and I have been working on the Homa Peninsula since the late 80's. So here's a shot for Rick if he's around. Just an old shot of us from the 1980s with our field crew when we were first starting field work on the Homa Peninsula.
I was much hairier then. And a lot of my time has been spent at a site called Kanjera South where there is a large Oldowan occurrence. It's about two million years old. And it was one of the, one of the field workers who was working with us at Kanjera South who actually showed us that there were artifacts and fossils eroding out at Nyayanga, Peter Onyango. And Peter took us over there, said you know, "They these look similar to what you see at Kanjera.
"What do you think?" And we went there and it ended up being a really interesting site. One aside about dating is that many, there are many localities around the Homa Peninsula. In fact, the localities are actually draped in sediments on the flanks of this mountain. This mountain is the Homa Mountain Carbonatite Complex and you've got sediments that ranged in age from about 3000 years ago to about six million years ago around this mountain. But unfortunately, because it's a carbonatite volcano, it doesn't produce crystals that are amenable to the dating method that you would want to use if you had to pick a dating method which is argon-argon dating. So unfortunately, the Homa Mountain doesn't produce feldspars so we have to look at a variety of different dating methods to try to age our sites.
Here's an aerial view of Nyayanga. You know, you see some of the excavations we've put in. You can see that there's a gully running along here and then it opens up into an amphitheater.
So the gully starts out actually pretty shallow, about half a kilometer away from the amphitheater. So when you look at this gully, you know you can actually just hop into it and walk along. Some of the same sediments that are exposed here are exposed in the amphitheater. So this is a sequence you can look at as you're walking up the gully. And you know, here you've actually got some fossils eroding out of one of the ancient beds.
These are hippo fossils. As you continue down, walking down this gully, it gets deeper and deeper until it's a pretty deep ravine. And here near the mouth of the ravine, close to where this amphitheater are, is where we'll talk about these excavations, excavation three and excavation five. You've got a clear channel cut. You can see the outline of a channel. And this channel's really important.
This was the channel that was actually depositing the sediments that we were, that we're excavating through that preserved the fossils and stone tools that we're finding. So if you're looking at, at that site in the background, you can see that ravine and that channel cuts in the ravine and where all the people were standing are the overbank deposits that were laid down when the channel was flooding during wet seasons and that would bury artifacts and fossils that were on the grounds that had been left by hominins. So it was preserving the record of hominin behavior. And what had come out of those overbank deposits? Well, you know, we were happy to see Oldowan tools when we first surveyed this site. And you know, you could see in the you can see the core with, in the, on the upper panel with the facet of a flake knocked off. You can see a flake in the lower central panel and you can see a tool with pounding damage in the right panel as well.
So these are all the hallmarks of an Oldowan toolkit. There are also lots of fossils there. So hippos are very, very common. This was a 'hippotastic' place to be in the past. And you know, everywhere we go, you know, you find hippos and there are multiple partial hippo skeletons eroding out.
Antelopes are also pretty common as is true at most Oldowan sites or or paleontological sites. Pigs are reasonably common as well and this is very useful cuz we have a pig expert on the project named Laura Bishop. And when she first saw the pigs that were coming out of the collections, she was impressed because they were clearly more archaic, much older than the pigs we had at Kanjera and Kanjera's two million years old. So for example, the Metridiochoerus andrewsi fossils we found, these pigs are around for a long period of time, from 3.4 million years ago to about 1.7 million years ago.
But they start off as having really short teeth that are not very tall. And we had these primitive sort of short, not very high andrewsi teeth at the site. And that suggested to her that the sediments were probably older than 2.5 million. The other pigs as well, like Notochoerus were are much more common in the older sediments than in sediments like Ken, what we have at Kanjera. So the pigs were the first clue that this was probably a pretty old site. Then we have Equids as well, so horse relatives and we don't have any of the modern genus Equus.
What we have are Euygnathohippus which were three toed equid and Equus doesn't appear in Africa till 2.3 million years ago. So the fact that we don't have any Equus, even though we have a lot of Equids is suggestive that this site is in fact old. Again old, older than 2.3 million. Lots of Proboscideans, you know, this this one giving us the eye and the left is a Deinotherium. It's got kind of an attitude cuz it's got tusks coming out of its lower jaw instead of its upper jaw like you see in modern elephants today like the Loxodonta that's next to it.
Deinotherium was a huge proboscidean and probably would have been something you would have steer cleared of if you were walking around the landscape back then. Other things you'd wanna steer clear of were sabertooth cats. So we've got a sabertooth cat fossil, that bendable on the lower panel, a Megantereon. On the right, on the lower right panel, you see it actually being excavated that was found in situ. So there are big cats around.
That up canine in the upper right panel is a canine from a non-sabertooth cat. So you both have lion, probably lion ancestors as well as sabertooths. There are hyenas as well.
So this was a pretty carnivore rich environment too. And we don't have many crocodile teeth but we do have one enormous tooth that we've dubbed Croczilla just because this was from a really, really big crocodile like the one shown on the inset where, you know, that would've had me as a snack on a Sunday afternoon. And we have a good, very diverse primate fauna that include things like bushbabies in the upper left panel, baboon-like creatures papio or parapapio, leaf feeding monkey relatives like the lower left panel and also things that are vervet sized like the like the lower right. So a diverse primate fauna which is suggestive that along this stream channel, you probably had trees and that this was supporting this primate fauna. And we found the first hominin on the Homa Peninsula. The Homa Peninsula's had research going on there since the early 1900s but there had never been a demonstrably old hominin.
And on the surfaces of Nyayanga we found an upper molar, the largest hominin tooth ever found. It's an upper M2 from Paranthropus, one of this this cousin of humanity that I mentioned earlier. So we'll talk about Paranthropus a little bit later. And their indications of damage on bones, hominid damage to bones. So stone tool cutmarks, so sharp, sharp shards were used like knives to cut meat off of this bone and that left these incisions in the bone.
And this bone was also broken open for marrow. So they were eating the fat out of out of the bone as well. When you flip it over, you can see flake scars from where the bone was struck and little bits of of bone exploded from it when it was being hammered to open it up so the hominids could eat the fatty marrow inside. So, you know, 50% of any paleoanthropological project are more than 50% is geology. So one of the first things we did was work out the geological section, the stratographic section.
I'm gonna focus on NY1 today cuz that's where the finds are that I'm talking about. And these were overbank deposits, silts and clays from and occasionally sands from from that channel that I talked about, that stream flowing alongst lateral to the site. And you know, once we worked out the stratographic record, you know, we were also interested in dating.
So we already had a hint that the date that this site was old from the pigs and we can't do argon-argon dating but we did another radiometric dating method called apatite crystal dating and got dates of about 2.9 million years ago. And that allowed us then to look at the magnetostratigraphy through the sequence. So the Earth's magnetic field changes through time. The Earth's like a giant magnet.
During intervals that are shown in black here, the magnetic field is oriented like it is today. So if you walked outside with a compass, your compass needle would point towards the north. But in the white bands, the Earth's magnetic field was actually reversed. It was the opposite of today. So your compass needle would actually point to the south rather than the north. And you can tell by doing careful sampling of sediments what the magnetic fields' orientation was during the time that your deposits were laid down.
And you can compare this to the history of the Earth's magnetic field reversals through time called the global polarity timescale. And you know, we, we ended up having an on a largely normal sequence in the interval that we're looking at. So it was transitional normal at the base, which suggests that it's near the cut, you know, it's near the point of switch from reversed to normal and then it goes to normal. And if you look at 2.9, that would put you, you know,
the apatite dates would put you right into this normal band here, the C2an.1n subprime which is dated between 2.59 and 3.05 million years ago. (clears throat) So that, that gave us the an age interval that we're working with. We think that, you know, I'm pretty confident we're falling in this interval. The fauna that I've mentioned before makes perfect sense for falling in this interval.
And you know, it may be that we're actually in the earlier end of this interval based on the apatite dates and this transitional normal at the base. But you know, conservatively, I would say we're definitely between 2.6 and three. And my hunch is that we're probably closer to like 2.9 or three. So if you look at where Oldowan tools have been found in the past, early Oldowan tools, they've all been from Ethiopia.
They've all been from this region called the Afar Triangle. Sites like Gona and Ledi-Geraru are sites that are within 50 kilometers of each other. So the question always was is this where this innovation first occurred and did it spread from this area? Or are we just not getting the full distribution of archeology at this time interval because there just aren't that many because of sampling error, because they're not that many sites. Now if you add Nyayanga in the mix, that's a 1300 kilometer range expansion for this, the oldest Oldowan that puts it across much of Eastern Africa. And that suggests that the earliest Oldowan in fact is probably more widely distributed than we had realized, more widely distributed at an earlier date than we realized.
And that makes sense given what Mohamed Sahnouni has found in Algeria with sites at Ain Boucherit at 2.4 million years ago and with Oldowan dates creeping backwards in South Africa as well. I think the Oldowan is probably more widely distributed at an earlier date than we realized. And as I said, when you look at the artifacts, we're focusing just on the NY-1 artifacts. We've got artifacts from other beds but I'm just talking about NY-1 here today.
You know, we've got Oldowan artifacts that would hae fit comfortably in any Oldowan assemblage, you know in terms of their cornflake size and other technological attributes. They look just like Oldowan tools. We've got the cores.
We've got the pound, you know, pounding tools and we've got the shards, the flakes that are used for cutting things. What's unusual about Nyayanga though is how much percussions going on. The a lot of tools are being used for pounding and a lot of them are just cobbles that were brought to the site and were only used for pounding. So pounding seems to be, you know, an important, a really important activity at Nyayanga.
And, you know, some of these tools even looked like they may have had objects put on them and the objects were actually pound, they were like being used as anvils essentially. And some of them are clearly showing a lot of pounding damage here like this. And this pounding damage is really well developed. It would have taken hours to to have developed pounding damage to this degree on a hard rock like a quartz site.
So we have a high frequency of pounding tools, 7% of the assemblage, you know, relative to most Oldowan assemblages. The means around half, half a percent, right? So pounding is clearly something that's going, that's in the behavioral repertoire and it's being represented, expressed more commonly here. Now I'm gonna show you the results of a couple of our excavations. Excavation three is the larger excavation. It was a five by five meter square excavation. And then I'll talk about excavation five up on top here.
These are both in NY-1. This is sort of lower mid NY-1 and this is upper NY-1. Excavation five's upper NY-1. So if you look at the fauna that's found in excavation three, you can see it's dominated by hippos, by that like green hippo or bluegreen Hippopotamidae. And that's because we've got a hippopotamus skeleton here.
And this is clearly at the place where the hippo died. It's got its ribs are there, it's vertebra are there, it's long bones are there. It's got cranial bits, teeth and bits, bits of its skull there. So this, this was a place where a hippo died. And you know, 42 artifacts were actually associated directly with these hippo bones.
So sometimes lying right, right on top of them. So there's a very tight spatial association between artifacts and these hippo bones. And if you look at this hippo skeleton, I mean hippos are big, impressive animals. You look at the excavation though, you can see that there's a line that beyond which you don't have any hippo bones and the color is a color change.
You go from a light brown to a reddish brown sediment. And that's because there's a volcanic fault that runs I mean sorry there's a fault that runs right through the excavation and it downfaulted part of the site. So a big portion of the hippopotamus is actually dropped down two meters that and we had to then dig down to get to it which we did eventually. So here you've got the downfaulted sediment in the upper patch. You can see that line where the fault was. On the lower panel, you've got a site plan.
Each one of those, these one meter bars, you know, each one of these represent the scales, one meter on this and the blue dots were the hippo's bones. And you can see the hippo bones dragged down two meters. And then you've got the down where you've got the arrow. You can see the downfault to the hippo with artifacts. We actually dug down there and actually found the hippopotamus and we're able to, after 2.8 million years, you know, re-associate the bones and bring it some peace.
Also down at this level, we found a Paranthropus tooth right at the same level as the hippos and the artifacts. So here's a hippo shoulder blade, a scapula in close association with an artifact like I mentioned. You often find the artifact just lying right next to the hippo bones. And here's this Paranthropus tooth. Again, this cousin of humans that had giant jaws and teeth. So this was found at the same level as the artifacts and the hippo fossils.
There were a number of marks on the hippo bones that we thought were related to hominin butchery. Unfortunately, the surfaces of the bones aren't fantastically preserved but if you look at this, this linear mark here, there's a blob in the middle of it. That's actually calcium carbonate.
This linear mark was filled with calcium carbonate which actually protected the internal morphology. And when you look at the internal morphology, it was protected by the calcium carbonate. You can see these little lines, these striations where the orange arrow is showing.
Those lines are typical of what you find when a when a flake, a stone flake is dragged across the bone. It leaves a bunch of little parallel lines inside it called linear striations. So, you know, this even though the bone wasn't really well preserved, the fact that we actually have the nice micro striations in this linear feature, we think is an indication that this was a butchered hippo.
And then up above, we've got better preserved bone, again still in bed NY-1. In a smaller excavation, only six meter squares, we've gotta continue this. But again, a lot of hippo bones, well a lot of the bones are hippo bones. This is an interesting jumble of bones. You've got part of an innominate.
You've got a scapula, so them, innominates pelvis, part a shoulder blade, the heel bone and a shin bone of a hippopotamus. And the stream wouldn't have dropped them together like this. I think probably, hominin, maybe hominin activity actually dropped them this. They're associated with stone tools. When we looked at the shin bone, the tibia, number 170 and you know, the knee is oriented to the left. This is the anterior crust.
This is where you've got major muscles attaching and human quadriceps, you know, quadriceps muscle would attach there. And you can see the blowup where of that box you can that you've got stone tool cutmarks in this spot. The hominins were actually cutting at the muscle that was attaching at that spot.
So this is another butchered hippopotamus in bed NY-1. We are also interested in looking at how, what, what the stone, what was being done with the stone artifacts by looking at the edge damage, the artifacts, the chipping and polish that you get on artifacts that are being used to process different materials. And here we had a couple of specialists, Cristina Lemorini from the University of Rome and Isabella Cericola, specialists who look at flakes and and percussion tool, tools beat that are percussed. They made replicas of using the same raw materials the hominids were using at Nyayanga and carried out experiments working a wide variety of materials to create a reference library that could then be used to assess the archeological materials and interpret what they were used for.
And once this reference library was produced, they studied the the chipping and damage and polish on the actual archeological specimens. And their interpretation was with that the artifacts were used to cut and pound soft and hard plant tissues. So there was a lot of plant processing going on. You know you've got these hippos that are being butchered. So you're thinking butchery, butchery, butchery.
But the use-wear is actually saying there's a lot of plant processing going on (clears throat) and that includes underground storage organs. So, you know, roots and tubers, woods being worked possibly to make other tools out of wood. Perish, perishable material, you wouldn't find that preserved after all this time.
And soft food, plant foods like fruit. And also they found evidence for meat, for butchery, for cutting meat and also breaking bone opens and their experiments confirmed that these pounding tools at Nyayanga were being used for hours. So, they weren't just bringing a pounding tool there and just using it a few minutes and then dropping it. You know pounding was really an important component of the behavioral repertoire of the hominins.
In terms of the paleoenvironmental setting, there are a number of different ways of looking at this, looking at the fauna, looking at the isotopes of the soils. So pedogenic carbonate isotopes. You can look at I'm not gonna go into detail about this but if you just look at the pedogenic carbonate chemistry that relates the the carbonized isotopic signature gives you an indication that you've probably got some grassy and shrubby and woody vegetation as well as some wooded grasslands all along this stream, which makes sense. We've got, you know, some trees along the stream like we thought before and also there's a lot of grass. And actually, the fact that you've got a lot of, a lot of grass represented is from is also indicated by the fauna and the isotopic signal of the fauna. So whoops.
So you've got a C4 dominated fauna, right? If you've got a browse dominated fauna, animals are eating from trees or from shrubs, they have a C3 photosynthetic pathway that you can tell from the chemistry of the of the enamel or the pathogenic carbonates. If the an, if in this case animals have a C4 dominated diet, they have a strong signal of grasses from that that's shown based on the way that the C4 photosynthetic pathway works. So we're talking about chemical signals of different photosynthetic pathways, more arboreal tree sort of photosynthetic pathways versus grass, you know, the photosynthetic pathway used by by more arid adapted grasses. And the diet here at Nyayanga, where that blue arrow is, is showing that it's a grazer dominated ecosystem that the mammals are by and large eating a lot of grass which suggests there's a lot of grass in the vicinity.
So it looks like hominid activities were in a wooded grassland to grassy woodland. There's a seasonal flowing stream, there's an abundance of C4 grasses, there are probably some trees along the the stream channel. So this is a figure that equated all used to for the Gona archeological sites but I think it works for Nyayanga as well.
You've got a seasonally flowing stream during the dry season. There may not be a lot of water on the channel. During wet seasons, the channel would fill up and even overflow and would bury materials here on the landscape in the edge of the stream. You had hominins, happy hominins, sort of enjoying the water and the shade and the fruits and avoiding the sabertooth cats and the giant crocodiles.
You got hippos sort of moving in and out of the stream, you know, happily grazing and making their hippo noises. Occasionally, a hippo dies and the hominins use their stone tools and butcher it. So that's sort of the scenario we're working at with this, with this site. And you know, people often ask, did were the hippos hunted? I don't think the hippos were hunted. Hippos die naturally and you know, can float downstream as giant dead bags of gas or hippos are killed by by cats when they come out of the water, especially young hippos can be killed when they're feeding at night.
And then those are available to be scavenged. So I think the hippos that these hominins were eating were likely scavenged. I just think they're a lot there in the environment and they're just getting opportunities to scavenge them periodically. All right, the Hominin, there's no doubt in terms of named Hominin taxa that the two teeth we've got: the surface collected tooth in the top and the the more fragmentary tooth we've got below from the excavation are Paranthropus.
The fissure patterns, the cusp proportions, the size are all indicative of Paranthropus and not Homo or Australopithecus. (clears throat) And like I mentioned before with with photosynthetic pathways and the plants. You know, you've got, you've got a C3 photosynthetic pathways and C4s photosynthetic pathways.
You know, animals that eat a lot of materials from trees and shrubs will have a certain isotopic chemistry. They're less enriched in carbon 13. Animals that are eating a lot of grasses and sedges in tropical Africa are enriched in Delta C13.
And you can see this, these are the two Paranthropus teeth. They're really enriched in Delta C13. They have a diet that's dominated by foods from the more grassy end of the spectrum. And you can see for Paranthropus, these diamonds are Paranthropus through time.
So here we've got millions of years ago that Paranthropus starts off with having a lot of variability and then this is East African Paranthropus. So in this case, what I'm circling now is Boise eye. And then later on in time, they really specialize in C4 foods. And you know, people have wondered, does does the really big jaws and teeth, does that reflect a specialization on C4 foods in the diet? And you know the fact that we've got probably the oldest Paranthropus and they're showing a really strong C4 signal may be an indication that in fact there is a relationship between these C4 foods, whatever they're eating, grass seeds, grass, underground storage organs, you know, sedge, sedges, you know that these C4 foods are actually what's selecting for or driving the evolution of the giant masticatory apparatus, at least the big teeth, cheek teeth that you see in Paranthropus. So again, who made the Oldowan tools? We have hominins and we have tools, really old tools but we don't have Homo. So, you know, if we had found Homo, probably we would've just said, okay, you know, this is what we would have expected.
We've got Homo. We've got these Oldowan tools. Homo's making the Oldowan tools but we've got Paranthropus.
And a lot of people have suggested well, you know, we don't think Paranthropus could make or were likely tool users just because they show this extreme dietary adaptation. You know, they've got these giant jaws, these giant cheekbones, these really big cheek teeth. If you look at Paranthropus cheek teeth, so we're looking at upper molars from a Paranthropus compared to a human.
Each Paranthropus molar is four times the size of a human molar in terms of surface area. These are really big cheek teeth. So why, why evolve these really enormous cheek teeth if you're, you know, gonna be processing things outside of the mouth? Well I, you know, and I've often said that as well, I've said that in print as well. But this, this association with Paranthropus at Nyayanga got me thinking of that, about that a little bit. And if you've got enormous jaws and teeth, but you're a smart hominin, cuz there's every indication that Paranthropus was a you know had a brain size larger than chimpanzees and chimpanzees are very smart.
That, you know, they could be, you know, making tools as well. And you know, given that their teeth are really flat and have very little shearing capacity, a cutting and pounding technology, even for processing tubers, fibrous tubers, would be really useful. And if they were eating meat at all, then they would really need the cutting and pounding technology.
Cuz remember, everything's being eaten raw at this point. There's no cooking, no fire at this point. So you would have to cut meat into pieces and pound it probably to make it tender enough. Even early Homo would to eat.
So our results are thus. You know the early Oldowan is widely distributed. You know, this Nyayanga has a 1300 kilometer range expansion. We've got hominid activity and woodlands along a stream channel in a grazer dominated ecosystem. I think this the fact that you've got hominids using tools for such a wide variety of purposes, tasks says something about the adaptability and how hominins are relying on stone tools to allow them to process and extract foods from a wide variety of sources.
Some of that food is coming in packages big enough that could have been shared. There's a lot of pounding activity going on. So we gotta think about that more as early Stone Age archeologists. You've got Paranthropus associated with these Oldowan tools and it's got a C4 diet early on. Is Paranthropus a hominid making early Oldowan tools? We'll have to keep looking at associations between tools and hominins as more sites are found.
And I think probably these sites are not the oldest sites, you never find the oldest site. So it could be that the Oldowan actually goes back even farther in time, maybe maybe even older than three million years ago. So that's it.
I'd like to acknowledge the National Museums of Kenya, the Human Origins Program, all my collaborators, the Kenyan field crew. Funding sources: the Leakey Foundation, the National Science Foundation, the Wenner-Gren Foundation, PSC CUNY, the William H Donner Foundation and the Peter Buck Fund. And thank you very much for giving me the opportunity to speak and I will now take questions. - Awesome. Fantastic.
That it's very exciting research to potentially push back some of the earliest dates for things like the origin of Paranthropus and the origin of the Oldowan. I'm gonna jump right in with questions. So we have a really interesting question from Mark.
Does the Y-geographic distribution of Oldowan technology imply that there was travel and dissemination of knowledge throughout Africa about two and a half million years ago or does it speak to multiple origins of this technology? - Yeah, it's a good question. Why don't, you know, I don't know. So, like is what's happening at 2.4 million years ago
in North Africa is that, is that just an independent evolution of of this pounding and flaking technology? I think overall, given that the Oldowan does spread over a really big geographic area and seems pretty persistent, I think at some point there is cultural transmission going on and that's part of the geographic expansion. But at the very beginning, I wouldn't be surprised if you had multiple points of origin like that's a possibility. So I think it's probably a common, it's possibly a combination of both. - Hmm. Yeah, I think that makes good sense. All right, I'm gonna jump in and ask a question now.
So you showed pictures of and talked about pounding tools that have all this damage on them. So I'm wondering how can you tell that those, you know, they're rounded rocks, how can you tell that those were tools used for pounding as opposed to like rocks that gold got rolled around in a river and got damaged? Is there, how do you tell the difference? - Well, right. (coughs) - Well the pounding damage is localized, so it's not all around the rock.
And also these rocks are coming out of silts, so so they're coming out - Ah, Okay. so they're coming out of very fine sediments. So pretty much where we find them is where we think the hominins dropped them. We don't think they moved far from where they were dropped.
- Okay, cool. - But they have really localized patches. So, so you know and some of it, it's cupped so it looks like it may have actually been used as an Some of them look like they may have been used as anvils even, like things are being pounded on top of them. - Ah, okay.
Here's a sort of basic question from Sebastian who just wants a reminder. What year or years does this take place in? So I think like how old are the sediments and maybe like what years have, were you doing the excavations? - Well, Peter brought us to the site in 2000. That was the first time we went there but I was deeply involved in excavations at Kanjera South and we had a big, big excavation there and Brianna's worked on material from Kanjera South so she's seen some of that. And we ended up digging one big site in Kanjera South for 20 years.
So from 1995 to 2015, we were basically making something that would be comparable to what Mary Leakey had had at FOK in terms of, you know size in terms of the lithic assemblage as well as the fossil assemblage. So it was hard, you know, the sites are far enough apart that it's, it was hard to coordinate excavations at both places and I was just mainly finishing Kanjera. Though we started digging at Nyayanga around 2015 as things were winding down at Kanjera.
Actually we started in 2014, but we, but the excavations that actually produced anything were in 2015. And then in 2016 and 2017, we had really nice material coming out. So a lot of what you saw today were from 26, those slides were from 2016 and 2017. And we were back again last summer and there's more material there. We were we excavating at excavation three still.
I was hoping to finish that site. We got below the hippo level and I was thinking great, we can just backfill this and forget about it. But then we found an elephant bone and a hippo scapula and a flake just as we were finishing. So it's like, ugh, if you got an elephant bone, that's probably not traveled far from the death site either. We we're gonna have to dig that level. It was in a little place.
We're gonna have to probably dig that level and expand the site and you know, if we have an elephant butchery site, that would be awesome, so. - So. - So anyway, we're gonna keep digging that site and excavation five needs a lot more work.
I think the hippo bones we're going into the wall, so I think we'll actually find more of that hippo and maybe more evidence of butchery then from that hippo, of that hippo as we excavate into the wall. Unfortunately we had a datum for a transit in that hillock, so I'll have to move the transit date on before we take the hill out. - Thank you. Yeah. Yeah. - So we're still working there.
- Yeah, that's exciting. I can't wait to hear about what else you find. - Well should come visit sometime. - That, I will take you up on that.
That'd be great. And actually Sebastian typed another question. He said no, he actually meant like what BCE so like how many years ago are is all this. - Oh, so 2.6, 2.6 to 3 million, that time interval based on that - Excellent. - That C2an.1n sub chron.
- Okay, thank you. So here's a question from Walter. Have any fossils of hand bones been found in these sites? This might be helpful in understanding the evolution of hand anatomy and how this might have contributed to stone tool and other tool evolution. - Yes, that's true and not, not in where we're working. Hand bones are not super common, but people are looking at hand bones and looking at the association. I mean, there are sites where we've got hand bones.
There may be some hand bones associated with Homo habilis at Olduvai Gorge. Homo naledi has hand bones in South Africa. There's some hand bones from Homo erectus, Australopithecus, different Australopithecus species actually have hand bones. So I, I would think that, you know, from what we've seen in terms of digit proportions that most likely, you know, any of these hominins I would think would probably be able to make Oldowan tools. I mean some of them, they're the Homo erectus seems to have more stability in the palm that would allow it to percuss more effectively with more finesse.
But I think probably the older hominins with their hand proportions, even ones that had kind of long, long curved fingers would probably be able to make Oldowan tools. But that is an active area of research. There are people working on that. It's just not something we're working on. - No, and I think we have, we have our behind the scenes team has a question. Outside of this is sort of a good follow-up on this so I'll just interject with it.
Outside of finding a fossil holding, a fossil hand holding a stone tool, like is there any way we can identify which hominin species or multiple species were using these tools? Is there way to like, and I think like you said, maybe hand morphology is a good one. Are there any other ways that we can maybe exclude species or anything like that? - I think it's I think it's always hard to say when you've got so many hominins in the landscape who's doing what. And I think, you know, the basic level of information is is just associations of different species with artifacts.
So... - Yeah. Hmm. - If you've got an archeological site that's got good context, then you've got some hominin finds from that, then you've got at least a spatial association. And you know, at this point, I think the spatial association between the Oldowan and early Homo. I think you probably have about the same number with Paranthropus as you do with early Homo. And you know, everybody thinks Homo erectus is making stone tools.
I mean there are places where they're only Homo erectus in the record and they're stone tools. So, there's no doubt about that. And I would say that if we had a, you know, if Homo habilis is the likely ancestor, something closely related to Homo habilis is the likely ancestor to Homo erectus, then you probably have it in that lineage. So I would think the erectus lineage, so whatever early homos, you know, evolving into erectus, I would think would probably be you know you could say with some confidence who's making stone tools. Other than that, I think we're gonna have to look at associations and maybe I said, maybe maybe as we get more and better data from isotopes, maybe that would help as well in terms of thinking about how broad or narrow the dietary specialization was. So if Paranthropus ends up having a really specialized diet and you know, that might actually rule out Paranthropus from, you know, butchering a lot of animals.
I don't know but they could still be using the stone tools for plant processing. I don't know, - Yeah. - It could be that it's a combination of like isotopes of the teeth, associations with the archeology. I think it need, we need a bigger sample though. Like the sampling's not good enough really at this point.
- And multiple lines of evidence. Exactly. - Yeah. Yeah. - So here's a, speaking of lithics, here's a question about the lithics from Rosemary who said you mentioned quartz site. Any idea if it was locally sourced or imported from a distance? - We think it's probably coming from from it's like coming from the local conglomerates.
- Okay. So we've got - the local con, we've got conglomerates right on site. They are almost all carbonatite rocks. It is really crappy for making stone tools.
It weathers really badly. It's really soft. So we think the quartz site is coming from kilometers away. - Okay. - So that's a separate story.
That's why I didn't talk about it. That's actually a separate, a separate publication we're working on. - Oh, exciting. - Yeah. - Here's another tool related question from Mark who says if we think that there may be multiple geographic origins of Oldowan technology, do we see stylistic differences in region to region comparison which might support that multiple origin hypothesis? - I think there are a lot of conflating variables.
So the thing about the Oldowan is that, you know, hominin, a lot of, a lot of what like Mary Leakey was interested in the cores and she thought the cores were what were being used as tools. And that the hominins actually had a mental template that they were working towards like, like cores that were flaked along one edge on both sides. She was calling choppers and you could use those for chopping things. (clears throat) We now think that in fact it's the flakes that are really driving the the technology at flaking and you know, hominins could flake for a while and have a chopper or they could keep flaking and have something that's flaked all the way around its perimeter and if you look like a discus.
So you know, or or they could keep flaking and you'd have multiple angles that are being flaked, multiple possible platforms. And the different raw materials actually differ in their, in their their ease of flaking and their hardness. So, hominins may flake some raw materials more than others. So what you see a lot with the variabilities has to do with class size, like how big the rocks are and what the rocks are like what the quality is.
Are they hard? Are they soft? And how far away they are from different raw material sources. So a lot of variability just explained in those, in sort of those terms. - Hmm. - So, so I mean people are interested in looking for cultural variation in the Oldowan and there are people who are sort of looking at that.
But at a place like Kanjera, we've got cores that you, you know, would find at a variety of different Oldowan sites all in one assemblage from little quartz like tiny, like inch and a half long quartz cords like you would find in the Omo. Two cores that you would find at Olduvai and different, different degrees of flaking. So there is a lot of variability that just has to do with raw material and class size and the physical properties of the rock. - Okay, rather than maybe potentially sort of regional specialization or... - People, people are looking, people are looking for that. So it's, it's not like people aren't interested in it, but they're all of these con confounding variables.
And like for me, for me, like I can't see anything on the peninsula that I would say is "Like this is a like a peninsula, sort of regional .Hmm. cultural variance. But it may be that people will come up with it. We just, you know, there aren't that many Oldowan assemblages. so it's, - Yeah. - it's just a matter of like working, working up the databases.
- Yeah, I know. That's a good question. Here's, here's an interesting, another question from Sebastian. Did they eat sabertooth tigers? So do we have any evidence of that? - Ahh. - I don't know. I've never seen a cutmarked large felid.
Do you know of any, Brianna? - I don't. - Have any in sites? Yeah. No. Hmm. - That'd be cool. - It would be cool. - I mean people have, people have thought about hominids eating.
There's an argument that a Homo erectus that had a pathology that was interpreted as being hypervitaminosis A that that Homo erectus had gotten sick from eating carnivore livers cuz carnivores accumulate vitamin A at very high concentrations in their liver. - Hmm. - Herbivores don't, so you could happily eat a wildebeest liver, but then if you ate the lion liver, you could get sick.
- Hmm. - So that might be indirect evidence of hominins eating carnivore, you know, eating carnivores. - Yep. And this particular hominid - actually possibly dying from it. But we, I haven't seen any cutmarked felid bones. - No, I haven't either.
And I think there's also an alternative explanation that I have heard for that hypervitaminosis A for that particular skeleton. That maybe also be brewed has a lot of vitamin A. So maybe it was - Yeah. - carnivore liver.
Maybe it was, you know, something else. - There was - There was a follow-up paper to that and they were testing African B brood and they didn't find high vitamin A. - Oh, that's good to know.
Excellent. Okay. - But, but yeah, - you're right. I mean, I'm not sure the universe of possible sources of vitamin A has been depleted. It could be something other than carnivore liver but that is a cool thing to think about - And it is. and it - and it does have a lot of vitamin A.
So that, - Yeah, and - that's a possibility. - And you might not necessarily even find cutmarks on any particular bones if you're eating liver. Anyway, this is yeah, fun conversation. - Yeah. Yeah. - All right, I'm gonna take the prerogative of asking the last question, and this is also a behind the scenes team question. So is there any more indication that Paranthropus was using tools and the possibility that they were the victims of tools? How might you sort of... Yeah, evaluate that alternative hypothesis? - Well, I - It would be very cool to find a Paranthropus bones with cutmarks on it and you know, Paranthropus at Olduvai Gorge, the zinged skull.
You know, you've got a beautiful specimen. No cutmarks on it unfortunately but it's, it is found. It's a cranium found at an Oldowan site. So is that something that died nearby or is that something that was, you know, a victim or did it just get associated by happenstance with the artifacts? Yeah, I think, I think finding cutmarked hominin bones would be really, really interesting. That was the question right? - That was it.
Well it was basic - Before I lost track of it. - The question was basically how can you rule out whether Paranthropus was using the tools or had the tools used on them. So, yeah. - Right, right. - Yeah, I think that is a valid question and I think if you find enough sites where you only have Paranthropus and and not other hominins, maybe that would sort of tip you towards that the Paranthropus is using tools. It is thought that South African Paranthropus is using tools. Not, they're found also associated with Oldowan tools spatially in South Africa, but they're also bone tools that many people think are being used by Paranthropus.
So that would not be something that was necessarily shaped by Paranthropus, but it was, unless they knocked it up, they broke the bone to do it. - Hmm. But they showed the - the tool ends show a lot of polish, showing that Paranthropus was using them for digging into things, either termite bounds or digging into soil to get underground storage organs, that sort of thing. - Hmm.
- So the idea that Paranthropus is using tools I don't think is controversial. I think the question is whether they were making Oldowan tools. - Yeah, exactly. And hopefully, more research might shed some light on that. - Yep. Hopefully.
- Exactly. All right, so... thank you so much. This is gonna, I'm gonna wrap up today's virtual program, so please join me in thanking Tom for sharing his work with us.
I'd also like to give special thanks to those who made this program possible. Our behind the scenes team who helped sort through your questions including Ryan McRae from George Washington University, 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, we thank you. Next month's Hot Topic program will be on May 18th, also at 11:30 AM Eastern Time and it will be Chasing Tails: Humans, Dogs and Evolution with Angela Perry from Texas A&M University.
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2023-05-10