Host Eric Garza invites listeners on a deep time walk that explores the energetics of human evolution and human development. He begins this journey as our lineage parts ways with ancestors of today's chimpanzees (Pan troglodytes), taking us through the development of stone tools, the harnessing of fire for warmth and cooking, the crafting of spears, clothing, and bows and arrows, and lastly more modern technologies designed to harness exosomatic energy sources often derived from fossil fuels.
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Eric Garza: Welcome to episode 9 of the Quillwood Podcast, a show dedicated to helping people just like you learn to navigate today's changing world. I am your host, Eric Garza.
Last episode introduced the idea of deep time. Cliff Berrien and I talked about it, but I realized neither of us defined it specifically. Thinking back to episode 1 of this podcast, I framed Quillwood Podcast as a journey, and what I wanted to do with this episode is to explore the journey of our human species from a deep time perspective. That way folks have a better sense for what deep time might offer us in terms of a pedagogical approach. And also, maybe it'll give folks some perspective, and people can find value in that as well.
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Before I dive into today's journey, know that the Quillwood Podcast is brought to you by Quillwood Academy. Through Quillwood Academy I offer a range of different events to help people just like you learn to navigate today's rapidly changing world. I just opened registration for a reading and discussion group on the broad issue of overshoot. We will read the book Overshoot, by William Catton Jr., and I'll add some other commentary and perhaps resources on top of that to supplement what is in that book. The book was published in 1982. It is, as far as I'm concerned, a classic. And it was written in 1982, which was 40 years ago, so plenty of room to update that topic. You can head over to quillwood.org to learn more about this reading group and to register for it. You can also sign up for Quillwood Academy's newsletter there, as well. I'll send a newsletter out once or maybe twice a month, so not a huge amount of email in your inbox if you sign up for that newsletter.
So with my plug for Quillwood Academy out of the way, I hope you enjoy today's episode on deep time.
One of the benefits that deep time studies offer us is the benefit of perspective. It helps us wrap our heads around long stretches of time, and also helps us appreciate how impermanent many facets of our reality are. My first introduction to deep time was through a deep time walk that I took when I attended a workshop that was facilitated by someone who was familiar with the Work that Reconnects, a body of work created by Joanna Macy. That deep time walk led us through stretch of time equivalent to the length of time that the Earth has existed, and it did that in a way where we looked at different milestones over the course of a hike through the woods. The person who was leading the walk had walked the route ahead of time, put signs in the route we were walking, and then we would stop at each of the signs and talk about what milestone that represented. The walk was a few, couple miles long, is what I would guess, and so it was a little bit of a time investment. But it was representing 4.5 billion years of Earth's history, so there were a lot of different milestones that we stopped to talk about along the way.
I want to lead you through something similar. Obviously, we will not do this in exactly the same way. I'm not leading you on a tour through the woods. But my goal for this episode is to lead you through a deep time walk of human development. So this walk will start when our lineage splits off from that of chimpanzees about 5.5 million years ago. I am not trying to cover quite as much distance, quite as much time, as the deep time walk I went on did.
Of course, a lot happens in that time span of 5.5 million years. Some of the events that I want to focus on are key developments in our procurement of bioavailable energy. I am very interested in energy, energy return on invested, that kind of stuff. That's what this particular walk will focus on. And in order to make it something that is relatable, I'm going to squish our 5.5 million years of history into a walk that is about a mile long, 1.6 kilometers for those who don't speak the Imperial system of measure. So we will squish all of that 5.5 million years of human history into a walk that will last for about a mile. And I'll mention a few milestones along the way, and how far we are from the finish line, which represents our present day.
So again, we begin this walk 5.5 million years ago, around the time our lineage split from chimpanzees. This is when our last common ancestor with chimpanzees lived, and groups of that ancestor started moving in different directions. The Latin name of chimpanzees is Pan troglodytes. You saw the reference to that genus name in the title of this podcast episode.
It's important for our journey to see our ancestors through the lens of energy acquisition. Our goal as animals is to harvest bioavailable energy from the landscapes that we inhabit, while minimizing our energy expenditures, the calorie burn that we use to get that bioavailable energy. This is not a goal unique to us, or even unique to animals. It's a goal that is common to all living organisms, including fungi and bacteria and plants. Because we are heterotrophs, we acquire our bioavailable energy in the food that we eat, unlike plants, for example, that can manufacture their energy by absorbing sunlight from the sun and using that sunlight to turn carbon into simple sugars. We measure the energy that we acquire in units of calories. We also measure the energy expenditures that we make to get it as calories also, calories burned.
All organisms need to generate an energy surplus with their foraging strategies. Their goal, and I alluded to this already, is to acquire more energy in edible calories than they expend to acquire that energy by doing whatever work they do in their foraging activities. By generating that surplus it gives them the ability to grow, to mature as individual organisms, but also to reproduce and continue their lineage on, adapting to the changing world that they live in, and passing on their genes. And their capacity to generate a surplus is one of the many factors that natural selection acts on in the natural world. You and I are alive today because our ancestors' foraging strategies managed to generate a surplus and allowed us, as a genetic lineage, to continue.
With that background, know that our one mile journey starts in Africa. Exactly where it starts is really not all that important. 5.5 million years ago we did not look all that different from our last common ancestor with chimpanzees. We didn't have any fancy accoutrements back then. We didn't have smartphones, we didn't have cars. All the other technologies that we associate with modernity were not part of our experience. At the time, we ate a plant based diet that included fruits, nuts, insects, and occasionally meat that we were able to scavenge. We lacked sharp teeth, or nails. We also couldn't run particularly fast, so we were not very adept hunters. And we also didn't have any tools at that time that might have allowed us to make up for those deficiencies in terms of our hunting prowess.
I say all of this because, let's be honest, we are, as a species, largely defined by our tool use. Many of the milestones that I want to point out on the one mile journey that is going to represent our history are milestones that are defined by tools that we invented, and that proliferated throughout the human species, or the progenitors of our modern humans species. And those tools allowed us to acquire more bioavailable energy at a lower metabolic cost. In other words, they allowed us to generate greater energy surpluses, and to be more successful as species, as a lineage, that would eventually lead to our modern species, and the present day.
I point these milestones out so that we can gain a visceral sense of how new many of our most momentous innovations are, and also perhaps how impermanent they might end up being. We start our one mile journey just as we diverge from our chimpanzee cousins, or the genus Pan. From there, we travel just over halfway to our modern finish line before we reach our first innovation. Over half a mile along our journey, we invent stone tools. This is 2.6 million years ago, as best we can discern so far. And at this 2.6 million year mark, we see the first crude stone tools show up in the fossil record. Stone tools are important, because what a piece of chipped stone provides us is a cutting edge, something that allows us to cut into animal carcasses in a way that we couldn't do that before. And that innovation of stone tools and a cutting edge gives us access to more meat and more fat from animals, than we had ever had access to your prior to this point. If we found meat prior to this point, we had no way of opening up an animal carcass on our own. If we came across a dead animal, we relied on other, more efficient predators to open up that carcass, to get through its thick skin. And of course, those animals would eat a lot of the meat and the fat themselves. So all we had access to is whatever scraps were left on a carcass when we found it. Once we had stone tools, though, those allowed us to open the carcass ourselves, and get first pick from the meat and the fat rather than the leftovers. Many anthropologists think that it is access, greater access to meat and fat in our diet that changed our metabolism and allowed us to support a larger and a more metabolically active brain. So it was access to meat, particularly access to fat, that paved the way for our ancient ancestors to start down a path that would lead us to become what we think of today as anatomically modern humans.
The next big milestone is a controversial one, when our ancestors learned to tame and to use fire, especially for cooking. Some put this date back as far as our first stone tools. There is some circumstantial evidence to suggest we might have been using fire back then, although whether or not we actually were able to control it is a different story. There is solid evidence, though, to suggest that we were using fire about a million years ago. That already is more than 4/5ths of the way to our finish line of the modern day on this mile long walk. So if we imagine standing on this mile long path, looking towards the finish line, by the time we are able to use fire, by the time we've tamed fire, we're about 960 feet away from the finish line, well more than halfway there. We're about 960 feet away from that finish line.
Now fire is an innovation because it does many things for us. An obvious one is that allowed us to burn fewer calories when it was cooler because we can make fire, and that fire could help us stay warm. Another thing is that fire allows us to cook food. And being able to cook our food allowed certain types of food to be more digestible, so we could extract more calories from them. It also made more animals and plants useful as sources of bioavailable calories. Although we can eat meat, certain types of animals might have parasites that would make us sick, so we would probably learn not to eat those particular animals. But if we can cook meat, that cooking, cooking over a fire, kills parasites, and makes meat that might not otherwise be safe to eat, safe. So that expands the calories that we can get from a landscape by making more animal foods safe for us to eat. Cooking also makes more plants available to eat because cooking degrades a lot of toxins, and it breaks down certain complex starches so that we can digest them in our digestive tracts. So again, by learning how to use fire, we gained access to a wider array of plant foods from our landscapes, and expanded the amount of calories that we could get from any given place. So cooking was really important, and our use of fire, taming fire, learning how to use fire is what allowed us to learn how to start cooking food. So that was about a million years ago, 960 feet away from the finish line on this mile long route.
The next big advancement is part of what I would call the Great Escalation in our innovative capacity. Here, we see innovations coming faster and faster. This next innovation is the use of spears about 400,000 years ago. So this is about 380 feet from the finish line on our mile long journey. The first spears had stone points lashed to long sticks, or maybe they just had sharpened wooden points. Nonetheless, we were able to use those as thrusting weapons, and sometimes even throwing weapons, to bring down large game. So again, it gave us access to a wider array of animals and also allowed us to become more hunters than just scavengers. Really important milestone there 400,000 years ago.
Our first use of clothing is 170,000 years ago. This is about 160 feet from the finish line of our journey. Wearing clothes allowed us to stay warm and allowed us to expand our range into more temperate climates. And then another, also related to weapons like spears were, the development of bows and arrows. About 65,000 years ago is when they start showing up. And this is only 62 feet from the finish line on our mile-long journey. We used spears as projectile weapons for time, but they were not incredibly accurate. They were also not particularly long distance weapons. But bows and arrows definitely were long distance weapons. They were a projectile weapon that really expanded our access to different types of game animals. So spears 400,000 years ago, clothing 170,000, and bows and arrows about 65,000 years ago.
The next big advancement came with agriculture. This happened around 12,000 years ago. And to put this in perspective on our mile long walk—you know a mile is 5280 feet—the development of agriculture 12,000 years ago was only about 12 feet from our finish line on this mile-long journey. Now agriculture was never a homogenous thing adopted everywhere by everyone. It emerged in different parts of the world more or less independently, as best we can tell. It took different forms in different places. Some places relied more on domesticated animals. Some relied more on domesticated plants, some use both. In many regions agriculture was adopted, and then it was abandoned, and then it was maybe readopted in a different form.
What agriculture allowed us to do is to get more calories from a piece of land by commandeering a larger share of that land's primary productivity. So we could get rid of plants or animals that were not useful to us, and we could plant or we could raise animals or plants that were. So more of the sunlight that hit the leaves of plants and was turned into simple sugars and that would go on to feed animals, more of that stream of bioavailable calories were available to us than might otherwise be. And that sounds great, but when we commandeer larger and larger shares of a landscape's primary productivity, the benefits that we accrue from that come at a cost.
Agriculture is probably the single greatest contributor to the onset of overshoot of the human species. Agriculture allowed people to draw down soil carbon and to degrade soil quality. It also allowed people to diminish local and regional biodiversity and really represents the first application of what people in the overshoot literature call an ecological debt. Effectively, when groups of people start using agriculture because it does draw down soil carbon, because it does degrade soil quality and contribute to desertification, effectively what those people are doing is they are borrowing bioavailable calories from the future, using those calories in the present to increase their population. But at some point that debt is going to come due. And we see this in many regions of the world, where early agricultural civilizations eventually gave way to deserts, they gave way to desertification, soil degradation. Many of those agricultural societies ended up collapsing under the weight of the ecological debt that they incurred. Other agricultural societies like the one that I'm part of right now, and you might be part of one of those as well, they're able to kick that ecological debt can down the road. But of course, the more they do that, the further down the road they kick that can and the more they draw out agriculture as a system for procuring calories, the larger that debt grows, and the cost of servicing that debt also grows.
There's a lot of other innovations that I can name, and I want to spend time on those that are specifically related to modern energy sources. The first use of coal for heat started about 6500 years ago, that's a scant six feet from our finish line, near the end of our journey here. The use of wind for locomotion in the form of sailing started around 5500 years ago, that's only about five feet from the finish line. Using wind for kinetic energy in windmills started 1100 years ago. That is one foot from our finish line. So we're standing here, and the finish line is right there. That is when we started using windmills for kinetic energy. The steam engine that uses coal to create kinetic energy was invented about 325 years ago. So when we inch forwards to that milestone, there's only about four inches separating our toes from the finish line. Commercial oil extraction started about 165 years ago, back in the mid-late 1800s. When we get to that point, we're only two inches from the finish line. Commercial electricity use began about 152 years ago. So we're about 1.6 inches from the finish line. The internal combustion engine was invented 137 years ago, so we're just under an inch from the finish. And of course, since the invention of the internal combustion engine there have been a bunch of other innovations in our energy use technologies. All of those, however, in this mile long journey, are so close to the finish line that it's hard to discern them in the grass beneath my feet.
I bring up these innovations not because they directly relate to getting food. We don't eat coal, we don't eat oil. But what all of these innovations did, in various ways, is they allowed us to begin using exosomatic energy on a larger scale—exosomatic, meaning that the energy comes from outside of our bodies. But it began allowing us to use more concentrated forms of exosomatic energy to accomplish tasks that we otherwise would have had to have done with our own labor. Now, of course, we've been using exosomatic energy for a long time. We started using it back when we began burning wood in fires. But the quantity of exosomatic energy that we have access to as users of coal, for example, as users of oil, as users of wind power, of solar power, and other such things, is on a completely different magnitude than it has ever been, while we were using wood.
And we can use those exosomatic energy sources to do a lot of things. We can use it to procure food, and of course we do, we use a lot of these technologies in the service of agriculture. We use it in the service of food processing. We can also use it to do other things as well, though, so it's not just about food. It's not just about our procurement of bioavailable calories. Nowadays, it's about a lot of other services that we expect from our energy sources, too. But I just want to point out that all of these innovations that I mentioned from agriculture on, even if they did not directly relate to the procurement of food, they are innovations that paved the way for us to acquire more bioavailable calories, even if indirectly.
Looking back at this journey, it's fascinating to me how we develop relatively slowly moving out until we first see our invention of the spear about 400,000 years ago. And after we hit that point, things started happening a lot faster. We gained access to more meat in our diet, and more fat in particular, and that allowed our brains to develop and it created kind of a feedback loop, where we become more and more dependent on all the fancy tools that we make, in order to generate the energy surplus that allows us to become—and remain—a successful species.
I value deep time exercises like the one that I lead us through for a lot of different reasons. One of them is the perspective they offer. I can read numbers on a page, and when I do that, that 400,000 year threshold doesn't really jump out at me as anything particularly special. But when I think about it in terms of distance traveled over the course of a mile long walk, and I see how long it took to get to spears and then how quickly things progressed after that, that changes my perspective in a useful way.
Most of our lineages history after our split from chimpanzees is characterized by pretty much a stone age existence, and not much change every 1000 years. Certainly new species of hominid evolved, and maybe some of them supplanted older species, some species went extinct. But our change, our rate of change, was very, very slow for a very, very long time, millions of years. And then that rate of change quickened. It's useful, I think, for us to recognize that the modern world that we live in today, that is built on and from energy from fossil fuels, which are finite resources, that world is new. And it's hard for a lot of people, including oftentimes me, to really wrap my head around exactly how new and how novel that is.
Marion King Hubbert taught us that energy from the fossil fuels, the production of which is going to go up and then eventually it will go down, these fossil fuels are finite and they are a temporary part of our existence. Much of our human history took place before we had access to fossil fuels, and there will be a substantial part of our human history that will take place after our use of fossil fuels. So that energy subsidy that we get from fossil fuels is going to be impermanent. That realization, which is not part of our journey because it's not happened yet, leaves me wondering what our future will look like, in particular what our future after fossil fuels will look like. And I'm curious what this deep time exploration inspires you to wonder about? Maybe if we cross paths at a Quillwood event sometime soon, you can let me know what it inspired you to wonder about. I'm very curious to find out.
So thanks for listening to this episode of the Quillwood Podcast. Again, this podcast is brought to you by Quillwood Academy. You can find it on the web at quillwood.org. Check out, while you're there, the Overshoot Reading Group that I just opened for registration. Maybe it will intrigue you enough that you sign up. I'll also be opening other events in the near future, so check back in the Quillwood website for those events even if Overshoot is not your thing. Also consider signing up for the Quillwood Academy newsletter while you're there.
Until next episode, this is Eric Garza signing off. Walk softly, and take good care.