Homo popularis: From Bipedalism to Fire

In Through the Lens of Anthropology we read the second of three parts of chapter 4, “Human Biological Evolution” for Intro to Anthro 2022. This class concentrates on the genus Homo. The previous class speculated on walking and bipedalism and at the end we set up the next class on how Race is not a valid biological concept.

Homo popularis: rough transcript

[In the last class] we ended up with some very bipedal creatures: the Australopiths. The ones that have definitive evidence, skeletal evidence, and those volcanic ash prints for being bipedal. We’re not completely sure how creatures became bipedal, but they sure are bipedal by about two and a half to three million years ago. We have habitual bipedalism going on there with the Australopithecines in Africa. As we ended the last class, the idea of being mobile is enormously important. It’s at the heart of human evolution. It’s one of the key aspects that makes us into the human beings we are is being able to be bipedal and walk around like that.

In this class we get up to some different creatures that are mostly part of the genus that we label Homo. Starting with, well we’re going to start with Homo erectus.
So in terms of the body stuff we have a couple things going on. We have as we talked about with the Australopiths, we saw ape-like cranial structure or ape-like brain capacity, but bipedal. But by the time you get to Homo erectus you definitely have some cranium expansion going on. So around two million years ago the heads, the brains, are getting bigger and we’re getting some taller specimens as well, averaging around five feet and some of them even over six feet tall. You know, getting pretty big there.

They also are starting to use fire. We see the evidence of stone tools coming in about three million years ago, maybe, or two and a half million years ago. But they’re pretty rudimentary. Whereas with Homo erectus we have a more sophisticated tool-making tradition developing including the very famous hand axes and evidence for hunting. Some people have speculated that the first form of hunting or one of the primary forms of hunting was using that bipedalism to not only be able to endurance walk over terrain, but to endurance run. Humans are the only primate who can do things like run a marathon and keep running, because of our ability to sweat and to control our body temperature. In that way you can actually, if you are a fit human, you can take one of those deer that you see in the morning and just start running after it and the deer will be faster than you at first, but if you can keep going you can run that deer down and you can get it. You don’t even need to have that much weaponry on you, you can just get it.

Actually when I grew up in Montana, one person, you have to be pretty fit and it helped that it was once the snow fell, you could get on the deer tracks and actually run a deer down. So people got really excited about this. You may see on the web sometimes, people are like “ah endurance running, that’s what all humans should be doing all the time.” We’re all selling sneakers and stuff. There is some contradictory evidence to this as well. I don’t want to (some people get really into this), but there may be other forms of, as we’ll talk about, hunting than simply endurance hunting. But it is an interesting fact about the Homo species . . . Some people get really excited also about the cooking part. Some people are like “oh no they maybe they were able to kind of use fire, but they didn’t have control over fire. I put a little bit of a question mark there. There is pretty good evidence that they start using fire. Extremely important for us is that this is the first time that we have a bipedal expansion from Africa. You have an expansion of the range of bipedal creatures out of Africa for the first time. Again almost all the good stuff in human evolution happens in Africa. But at this time Homo erectus is actually found in different places from about 1.9 to 2 million years ago. We again see the emergence of Homo erectus in Africa . . . But we see some of the first specimens were actually found in what is now China and down here and what is now Indonesia and in Eurasia as well. You have this expansion out of the range of the bipedal creatures and especially with Homo erectus, and there’s been a pretty huge question is: what happens to the lineages, how does Homo erectus interact with these various lineages? How does Homo erectus get to be Homo sapiens? this has been a huge question and up for a lot of debate and in the last 20 years there has been a lot of speculation. So that’s why I asked you to kind of look into your favorite species that is represented in science or pop culture and compare it to what our text finds. We have Homo erectus spreading out. Then we have some confusing stuff that happens, but for our purposes we’ll first say that again remember: being able to migrate and being able to adapt and learn and change in response to a changing environment are crucial to the spread of the bipedal creatures Homo erectus into different areas.

The reason I was not into Homo heidelbergensis and I don’t think your book is either is that there’s a lot of confusion over what exactly this is. Because here’s a jaw found in Heidelberg and it’s sort of an over-representation of the European content. Then they’re like, “aha, Homo Heidelberg did all these great things like is living in here,” then somebody finds a skull in Africa and calls it what they call Homo rhodesiensis, which has to do with Rhodesia and was named after a colony. So some people were like “ah that’s Homo Heidelberg over there too, look they’re everywhere.” So some people want to expand out the Homo Heidelberg thing. Some people want to just lump Heidelberg together with Homo erectus. As Wikipedia says, and I think this is still true, that this middle period there’s a lot going on, but there’s a lot of muddle as well. So whether you’re going to call this Heidelberg and go and use that to indicate a whole range of creatures from Africa to Asia to Europe, or whether you’re going to call each of them different species or whether you’re going to like me want to just say: “ah it’s basically Homo erectus.”

So you have to realize that when I say something, I am an extreme lumper. Remember we talked about the lumpers and the splitters. The splitters hold up a jaw and they’re like “a new species, I found it.” I am on the opposite extreme where I feel like yes there was a lot of variation here, but I’m not going to tell you about that much about Homo habilis, which some people want to put before Homo erectus. Then I’m not going to tell you that much about Homo heidelbergensis, which some people say comes after Homo erectus because for me they’re all kind of in the range of Homo erectus. I totally agree that they’re doing cool new things, but I don’t know that they’re that different from what Homo erectus is doing. I’m not going to take off points if you’re a splitter, if you like to be a splitter that’s fine, but for the purposes of your exam you should be happy that I’m a lumper. Why? Don’t have to remember it! Don’t worry, no Homo Heidelberg is going to be on your exam, no Homo habilis is going to be on your exam, because I’m an extreme lumper you don’t have to worry about that. Exams are about concepts and ideas not about memorizing things, at least in my class. So that doesn’t mean it won’t be hard, it just means you don’t have to remember that.
I think the science is part of this, I will admit it is personal preference. I feel like there have been too many splitters in human history. I feel like we’re in an age of people who are trying to divide us and tell us how different we are. I prefer to be a lumper. But I also think the science has told us that over the past 20 years, which we’ll talk about, is that a lot of these things that people were trying to demarcate and claiming to be separate species turn out to be not only not separate species, but very much involved in the genetic mixture of what makes contemporary human beings. I agree that we should have something more on the creatures that were around the age of Homo heidelbergensis, but until they change that name around I’m not listening to that . . . The Neandertals, which is when we have much more skeletal and other information about. Again in part because a lot of them were first found in Europe. The reason they get their name is because of the Neander valley in which they were first found. Now you may notice that they are sometimes spelled t-h-a-l-s, which is the original spelling, but that comes to us from the old German spelling or the old way in which “thal” was represented in English. It simply means valley, t-h-a-l or t-a-l, the Neander valley, but it’s been spelled in two different ways. In the updated spelling of this we have Neandertals, but it’s the same stuff that was found in the Neander valley. They were a very successful species of Homo that were originally found in Europe, but had a wider range. So have been found in parts of what is now the Middle East as well, dating back to as far back as 400,000 years ago probably emerged, but maybe we have better evidence of them around 130,000 years ago and coexisting with Homo sapiens up to around 35-30,000 years ago, which is more than we used to think. They are usually more robust than Homo sapiens. So usually larger, maybe a little bit stronger have sometimes very developed one arm or the other, which indicates that they were doing a lot of scraping of hides and stuff like that.

They actually had cranial capacity that was larger than Homo sapiens. Now we have to be careful with this, what it is telling us. I’m not sure that it doesn’t completely translate into “aha, they’re smarter.” A lot of this is that their brain organization and complexity may be different, or are definitely different, and also when we’re talking about cranial capacity we have to remember that’s as a percentage of body size. Since they’re more robust they might just have had larger heads, and in general there is evidence for that. They carried out burials and people are finding things like jewelry. There’s evidence that they cared for the members of their population that were sick or old and some of them that show evidence of deterioration in various ways were cared for into older than they would have lived. Again, evidence for forms of hunting. A pretty sophisticated and successful species that had quite a large geographical range as well. We have the Neandertals emerging in the Middle East and in Europe. Then about 200 to 300,000 years ago we have the emergence of Homo sapiens in Africa. The oldest Homo sapien fossils have actually recently been discovered in Morocco, which was not a place where people were expecting them to be, at about 300,000 years ago. We used to say about 200,000 years ago, but we’ve recently been pushing this date back a little bit in terms of Homo sapien evolution. So Homo sapiens first emerge within Africa. Then there’s an extremely successful spread of Homo sapiens. They are the first and the only bipedal creatures to migrate and get all the way into Australia. Then, as we’ll talk about in the next section, into the Americas. As the Homo sapiens go around, there’s first coexisting with some of the other bipedal species, but eventually the other bipedal species disappear. The Neandertals go away and other species and other stuff that was going on that may have been descended from some of those Homo erectus populations or Homo heidelbergensis or whatever they were, they all go away. So when the first Neandertal skeletons were found in the Neander valley, people are like, “aha, we have the ancestor of Homo sapiens,” but we quickly found out, relatively quickly, about a hundred years ago, that the Neandertals were not directly ancestral to Homo sapiens. It’s not that there is no evidence that Neandertals kind of evolved into Homo sapiens, but ever since the Neandertals were found there has been this question of “well what was the interaction there? Did they interact? Are they the same species? Did they interbreed?” There were two main models proposed for how Homo sapiens arose and how they interacted with the other Homo erectus species.

One of the models that was at first favored in anthropology was called the Multi-regional Evolution or the Regional Continuity Model. This model actually comes to us from Franz Weidenreich. It was first proposed in 1946. It is actually an old and complex and sophisticated model of human evolution. Some of the names here, incorporating Gigantopithecus and some of these names here are not the names that we want to use in today’s world, but the model is interesting because what it posits is a continuous interflow of genes and genetic interflow across an entire geographical range that evolve as a single interbreeding species into the groups of humans that we have today. There is always continuous gene flow across the range, but the reason they call it the Regional Continuity Model is the idea that in all in these different parts of the world their features are continuous with some of the Homo erectus features of those populations.

In 1987, and I still remember when my dad showed me the copy of Newsweek with these highly stylized people that were said to be Adam and Eve there was another model proposed. It was some of the first work that had been done with mitochondrial DNA where Rebecca Cann and colleagues took mitochondrial DNA from different populations, different contemporary populations, and figured out that by their estimation that all humans, all contemporary humans, had a common African mother at about 75,000 years ago and that these populations had replaced all of the Homo erectus or Neandertal populations in other parts of the world. This model went by several names: African Eve; Out of Africa 2, because it was a second migration from Africa, or Mitochondrial Eve or the Replacement Model, because what it posited was that there was no DNA continuity between the Homo sapiens that emerged from Africa and the others that were the Homo erectus derived populations are already there. From 1987 to 2010 the Replacement Model seemed to be winning the field. We were getting more and more genetic evidence that there was no mixture between Neandertals or any other of the Homo erectus lineages that had gone into what is now China or Asia. It seemed like the Replacement Model was the way to go and. In fact, although some prominent people were defending the Regional Continuity Model, but it was being misrepresented it was being said that the Regional Continuity Model was saying that there were separate populations evolving into Homo sapiens and in general [the Regional Continuity Model] was going away from the textbooks and I stopped teaching it for a little bit.

It was perhaps the triumph of the splitters at that point, because Homo sapiens seem to have nothing to do with the Neandertals. Now I want to be clear that from the beginning, in both of these models, the Regional Continuity Model and the Replacement Model always said that Homo sapiens, from the beginning and throughout our history, were always one interbreeding species. There was never an idea in either of these models that there had been separate evolutions of Homo sapiens from separate Homo erectus populations. Both of them always said that Homo sapiens evolved as and continue to be one inter-breeding species. For a long time the Replacement Model seemed to have won. But then in 2010 we got what I call the one to four percent admixture surprise, when people started doing even more sophisticated genetic analysis and taking more than mitochondrial DNA and we find what happens with those Neandertals.

We found out that there’s genetic evidence for Neandertal interbreeding and admixture across Eurasia. It looks like what happens is that there were interbreeding populations or some degree of intermixture as the Homo sapiens were in probably that Middle Eastern region. Originally of course most people thought that the Neandertal DNA would be among the European population because that’s where we found a lot of the Neandertals, but it turns out it’s actually distributed across Asia and Europe and some of the latest stuff I’ve been reading suggests that there might be more in contemporary Asian populations than in contemporary European populations. At the very beginning of this there was, actually the researcher John Hawks calls a myth that there was no evidence of genetic admixture in African populations. That’s actually not true. There’s less perhaps Neandertal DNA in African populations, but there is some and it’s not very much in all of us, but there’s some. The other thing that happened around then, is that they had a pinky bone and some other little stuff and they found evidence of a new subspecies that they call the Denisovans who are kind of like cousins to the Neandertals, except in the eastern part of the range, over in Siberia. They’re named because found in Denisova cave. There’s not a lot of fossil or archaeological evidence from the Denisovans, but the genetic evidence is pretty good and we can see that in some contemporary populations, especially in the area of Australia and in Asia there is some also some evidence for Denisovan DNA showing up. Not a lot, again, we are talking about a little bit, maxing out at maybe four percent, which is not a lot, but some. This has made things very confusing for everybody.

There’s a lot of crazy stuff going around like, “Neandertals gave us asthma,” or Neandertals did this, or Neandertals make us depressed. So just be careful with that. There’s a lot here to sort out and just because we have one percent Neandertal DNA does not mean that they completely changed our lives. We’ll see what this all means and whenever we see a headline just be careful with it. What it seems to confirm is a model that John Relethford of SUNY Oneonta proposed long before any of the genetic stuff came out, and was rather prescient, able to see things ahead of time. He talked about the “mostly out of Africa model,” that most of the human genome and human evolution occurs within Africa, but not all. There have been various migrations into and out of Africa. Those migrations are potentially genetically and ancestrally important. It’s “mostly” out of Africa.

For me I want to emphasize that humans have been moving around, mating, and mixing together from a long long long time ago. A lot of times we’re sitting around and people talk about, “aha, people are coming together for the first time and now people are seeing others from around the world.” No, that’s been going on for millions of years or hundreds of thousands of years or however many you want. This is not just something that happened recently, it’s not just something that happens occasionally, it happens all the time throughout human history, and there have never been any human populations that have gotten so isolated that they form anything like even what we might call a subspecies. In terms of Homo sapiens, the most isolated you might be able to say are people who migrate into Australia from about maybe as early as 75,000 years ago, but as soon as soon as there was re-contact there was plenty of moving, mating, and mixing. There are no species separations within Homo sapiens.

Now that’s some of the stuff that’s happened in terms of populations that we know now are related to contemporary Homo sapiens, there are a couple of other creatures, populations, that have been found that are very exciting interesting such as Homo floresiensis because discovered on the island of Flores in Indonesia. They’re the most liked. In fact, I was looking for them on Google, how you type in on Google, and you find out. Then what other people want to know about them, they want to know how tall they are, that’s the first thing, and they’re short. Then they want to know if they’re still alive, because it’d be cool to have them be still alive. Then they want to know if they’re hobbits or not.

So they’re very fun, little Flores people. There was so much debate about are they a separate species? Are they simply humans with microcephalia, and are they Homo erectus with small heads. Is this island dwarfism, which is the idea they got to this island and everything shrinks down on islands, or grows big, because when you’re on an island weird things happen. It’s really hard to tell. I think that the current consensus is a separate species, not some sort of sickness, or not a kind of deformity, but it’s hard to say. They’re still kind of in their own thing. The other finding is that of Homo naledi, which nobody wanted to write about, but it has been pretty exciting to people in part because a lot of the finds that we talk about are like a jaw or a tooth, and here they have like all kinds of bones, and all these individuals and a really interesting story how they had to spelunk into this cave, and it took some very daring female spelunkers and anthropologists to get these things out. But it’s still unclear where exactly they fall in the lineage. They definitely seem to coexist with some of the Homo sapiens in Africa.

So what did these two finds give us? I think what the biggest thing for me about Homo floresiensis and Homo naledi is that they help us to have, what some have called the second cranial revolution. The first cranial revolution was that we found out that big brains were not what separated the eventual ancestors of Homo sapiens from the other apes, but it was habitual bipedalism. So that we were bipedal for a long time before there was any cranium expansion. That [first cranial revolution] happened in the 1960s and 1970s. The second revolution, which I think is happening with the Homo floresiensis and Homo naledi is that you can have tool use and maybe even things like burying and hunting and all these things without necessarily having to have a big head. So Homo naledi and Homo floresiensis seem to be doing things with tools and thinking through things that people just assumed that you had to have more than 400 cc’s to do. I mean there’s still a lot of debate about what exactly they were doing, and are we reading too much into the evidence, but it seems to be that you can do a decent amount of stuff, more than we thought, without necessarily having any expansion in brain size. We’ll see how this goes in the coming years.

It also testifies I think to what we call mosaic evolution and the ideas of punctuated equilibrium, where you have these different combinations of traits that seem to be evolving at different rates in different populations, combining and recombining together to give us what we are now.

So we have Homo erectus spreading out all over the place. Then you have in Africa, you have all kinds of populations like Homo naledi and probably more, you have Homo heidelbergensis. Then the Neandertals emerging in the Middle East and in Europe. You have then the Denisovans or actually probably around the same time emerging in what is now Asia. Then you have the Homo sapiens, oh Homo erectus goes away, right, then you have these other populations and you have Homo sapiens emerging first in Africa and being in Africa. Then a pretty early migration all the way into Australia and probably some inter-crossing here with the Denisovans and Neandertals. Then going into Eurasia and basically then all the other populations have disappeared. You have Homo sapiens all throughout Eurasia, Australia, and Africa. Then from some of the north Asian populations coming into the Americas . . . Homo sapiens spread out to all the areas of the habitable world and there are no other bipedal creatures around except one population of interbreeding Homo sapiens by about 30,000 years ago.

I want to summarize evolution, the big points.

Always remember that when it comes to the mechanism of evolution, natural selection, that you need diversity or variation. You need to have that. You don’t have it, you don’t have evolution. It’s essential that we have diversity and variation. It’s the basis, the ground for the evolutionary process. That was the big find of Darwin and Wallace.
We know now that evolution is not about survival of the fittest, but that there are trade-offs in evolution and that fitness can only be measured, the traits that are good or bad, in ever-changing environments.

We also know if we use the extended evolutionary synthesis, that as organisms are being alive and doing things and we see this more and more with the evolution of our own kind, of Homo erectus with all those tools, and Neandertals, they’re changing their environments. They change the conditions for selection for the next generation and are both adapting to and adapting and contributing to the construction, the actual building of different niches.

We also know that in evolution there’s a lot of stuff that you can’t predict, and it’s just random, and it’s going to make huge changes. Let’s rewind back to a few episodes in evolution, let’s say you could go back to the age of the dinosaurs and there’s these huge creatures that have evolved going around and doing all those cool dinosaur things Jurassic Park style, and there’s these little tiny mammals running around, and they’re little tiny mammals that are hiding out and getting stomped on every so often. No one would say that the mammals were going to make it, be the big thing. Then an asteroid or something happened. It’s random. Or if you went back to say the time of the great apes and looked at Gigantopithecus, that sculpture that we have out at Hartwick, and said, “aha, Gigantopithecus, that’s going to be the big one, I know it.” Gigantopithecus has gone away. Or if you went back to the Neandertals and you talked about their big heads and their neurons and their robust bodies and how they’re going to really adapt and change everything. I would have put my money definitely on the Neandertals, not on those puny Homo sapiens that were coming out, Neandertals looked much cooler. You can’t rewind. I mean you can rewind, and you can make predictions, the thing is a lot of random stuff happens. You don’t know which traits are going to be good and which traits are going to be bad.

The other thing we know is that although it’s debatable how many species there were or if it’s like variation within a species, we know that up until about 30,000 years ago our own ancestors the Homo sapiens, there was a pretty wide range of bipedals that they were interacting with. Creatures that probably had forms of language and could use tools. There was quite a range. The range now, I guess I would say, the range now is less. As Homo sapiens emerge as one single interbreeding species, we Homo sapiens are actually a subset of this earlier variation. Some have called us a “relict species” in the sense that we are all that remains of a much wider range of variation. The reason that Homo sapiens are able to go all these different places is because of a sophisticated tool kit that was flexible, and the kind of learning that Homo sapiens were able to do in different environments. Now what I hope this all adds up to: A lot of people have tried to use evolution to support their ideas about racial traits and superiority and inferiority, but in fact what evolution tells us is that given this situation we should be pretty suspicious of those who want to draw lines within the Homo sapien population of today and say, “aha, here’s a race and this race has these characteristics and they are more superior or more inferior to this other group that we’re going to call a race.”

Evolutionary theory very much would cause us to be suspicious of, or very careful of, making these kinds of assumptions around groups.

In Through the Lens of Anthropology we read the second of three parts of chapter 4, “Human Biological Evolution” for Intro to Anthro 2022. This class was after speculating on walking and bipedalism and set up the next class on how Race is not a valid biological concept.