HEALTHY BITE | Work: A History of How We Spend Our Time

The average working adult will spend one-third of their life at work. But what is the history of work and how do we spend our time? Tune in as I talk about James Sussman fascinating new book.

How We Spend Our Time

I want to share with you this book that I have been reading. I’m actually only a third of the way through, but it’s so interesting that I have to share some of the insights in it with you.

The book is about work, and if you get a hard copy, this one is A Deep History from Stone Age to the Age of Robots by James Sussman. James Sussman is an anthropologist specializing in Caucasian people of South Africa. He’s based in Cambridge, England. He’s the author of Affluence Without Abundance. The Disappearing World of the Bushmen is quite an interesting title, Affluence Without Abundance. I’m looking forward to reading that. 

His most recent book, Work: A Deep History, from Stone Age to the Age of Robotics or in the Kindle version, the byline is A History of How We Spend Our Time. He explores particularly in the first third of the book, which is what I’m up to and what I wanted to share. 

The Ju/’Hoansi people in Namibia who up until 50 years ago still hunted and gathered for a living, just as their ancestors had done since the first expansion of modern Homo sapiens across southern Africa around 200000 years ago. This is a very interesting group and it’s interesting to explore how they live and also in the process to explore the development of Homo sapiens. One of the three on which we are said to see it goes something like it starts with Australopithecus, which is what split up from the primates, chimpanzees, and gorillas, some, I think, five million years ago. 

About under two million years ago. Homo habilis, then Homo erectus, then Homo Neanderthalensis or Neanderthals, and then Homo sapiens. The most interesting about that development is to explore how brain size and how cranial capacity developed. There’s a host of different theories proposed to explain surges in brain size growth. 

I wanted to read some of the extracts from the book, but only one accounts for the outsized energy demands associated with building and maintaining big brains with big neocortices. The neocortex is where we do most of our refined thinking, and Australopithecus had a brain size of somewhere between 400 and 600 cubic centimeters under the average of around 500 cubic centimeters. Now our brains only constitute two percent of our total body weight. This is Homo sapiens, which if you think Australopithecus has a brain size of 500 cubic centimeters, Homo sapiens and Neanderthals had to have a brain size of around 1500 cubic centimeters. 

It went down a bit in the last few hundred years or thousands of years but Neanderthals and Homo sapiens, up until the agricultural revolution, had a brain capacity three times that of Australopithecus. It’s interesting to consider how did that happen. And he makes the point here. Homo sapiens brain size only constitutes two percent of our total body weight, but they consume around 20 percent of our energy resources. 

The book about work is a book about energy

One would argue, why do we work, where we work to survive, to gather enough food, to provide us with energy so that our bodies and brains can function optimally. For chimpanzees whose brains are roughly one-third the size of ours, similar to Australopithecus, it is between the chimpanzees whose brains are roughly one-third the size of our own. 

The energy used is closer to 12 percent compared to the 20 percent of Homo sapiens. For most other animals, it’s between five and 10 percent of their total energy needs. You can see that we as Homo sapiens, our brains consume a lot of energy, 20 percent compared to 12 percent from chimpanzees and between five and 10 percent for other mammals. 

It’s building and maintaining such big brains on the basis that this is where it gets really interesting, particularly in our world of raw vegan food, the basis of a foraged raw food, a vegetarian diet would have been impossible. Building brains bigger on that diet would have been impossible even if we were to eat constantly every waking minute of every day, similar to what gorillas and orangutans would not be able to meet the outsized energy requirements of running a brain, the same size as ours based on a diet of wild fruits, leaves and tubers alone. 

To do this requires eating more nutrient-dense foods. The word nutrient-dense keeps cropping up in on so many levels, nutrient-dense and we’ve talked about that in many podcasts. He is saying that on an evolutionary scale, this is what I find so interesting about history lessons from the past. We have so much to learn from how we got to where we are now. The point he’s making is that our brains just wouldn’t get that energy requirement for meeting a diet based on wild fruits, leaves, and tubers alone. To do this requires more nutritionally dense food.

The transition from Homo habilis to Homo erectus is marked by good archeological evidence for the more frequent consumption of just such a food source. So we went chimpanzees, primates, those chimpanzees and gorillas to Australopithecus, similar brain size 500 cubic centimeters. Homo habilis to Homo erectus. There was an increase in brain size. Homo erectus was around 800 cubic centimeters. So things started really moving. The transition from Homo habilis to Homo erectus is marked by good archeological evidence for more frequent consumption of just such a food source. 

Based on the scant evolutionary evidence for five years until half a million years ago, it seems likely that cooking spurred the next big period of brain growth, let’s explore that. Let’s just go back and see what was going on.

About two million years ago

Australopithecus could only extract energy from the world by proxy. Like many other species, they did this by eating plants that had captured, stored, and repackaged mainly solar energy in more conveniently edible forms like leaves, fruits, tubers using photosynthesis. Then, around one and a half million years ago, Homo habilis extended the energy by proxy model by developing a taste for more complex organisms that had already gone to the trouble of concentrating nutrients and energy in plants by converting them into flesh, organs, fat, and bone. This was our lineages’ first energy revolution because additional nutrition and energy that flesh, fat, and bone provided Homo habilis to grow much bigger brains. 

The first energy revolution that transformed us from primates and Australopithecus and small-brained people to larger, enlarged brains, as in Homo erectus, was our decision to start eating a more omnivorous diet. It also reduced the extent of their dependency on less energy-dense gathering foods. They reduced the total hours they needed to dedicate to the task of finding food, work, this was work, but raw flesh, fat, and bone was not enough on their own to grow and maintain brains as big and energy-hungry as ours Homo sapiens. 

This is where it gets interesting to do that, they needed to cook their food. To cook their food, they needed to master fire a process that kicked off the second and arguably the greatest energy revolution in our history. This is what I found so interesting about James Sussman’s, well, as I said, I’m a third of the way into this book. The focus in the first section is so much on the gathering of energy and the impact that that increased energy has on our human development and on our need to work. If we have to sit and eat vegetables all day to gain the nutrient density that we need, then on an evolutionary level, we wouldn’t have got to where we are today. 

The second big thing was, the ability to cook the food because it makes not just meat more available and digestible for us, but it also makes many vegetables as well. I’m not sure where that leaves the raw vegan diet. Anyway, the interesting thing further is that the Ju/’Hoansi, those hunter-gatherers that were doing what they were doing up until 50 years ago, as their ancestors had done for 200000 or 300000 years before that, these foragers considered fat marrow, meat, and offal to be the strongest of all the foods rich in energy, vitamins, proteins, and minerals.

They were in short supply in nuts, tubers, and fruits they gathered, but meat and its absence were one of the few things that could even cause the calmest among them to lose their cool. When somebody had a kill, they were excited, but it was really the fat, marrow, and offal that was the prized possession. What relevance does that have to us today?


The Homo sapiens and the Neanderthals had brain capacity actually bigger than ours has been in the last 10000 or so years. The agricultural revolution has certainly challenged us from a nutrient-dense perspective and this is the work of western price and why we’ve referenced that many times and the way that manifests itself here and now is this. We have evolved to have not just a brain capacity of 1500 cubic centimeters, which is smaller now, but our jaws are smaller, too. 

Our entire head is smaller because we do not consume the nutrient-dense foods we should from before conception to the moment of conception through pregnancy and childhood and beyond. I could ask every one of you, how many people listening to this have all 32 of the teeth that we have evolved as a species to have in our mouths and our jaws? 16 teeth on top, 16 teeth on the bottom. And the answer is, well, if you’re one of the lucky ones to have all of those all 32 teeth through and in perfect alignment, that means your wisdom teeth are not impacted. 

That means you haven’t had your wisdom teeth out. That means your teeth aren’t a little bit crowded. If you’ve got all 32 of your teeth through an imperfect alignment, you would be less than five percent of the population. 95 percent of the population do not have enough room for their teeth, all their teeth. What’s the significance of that? Size, you have heard this before on my podcast, the size and shape of your mouth determines the size and shape of your upper airway, and that determines your predisposition for sleep, disordered breathing, and other dysfunctional breathing issues and it is affecting us all. 

This whole human journey is an interesting one. When I saw this about the two great revolutions was one, our choice to start consuming meat with meat which made nutrients denser, and then to cook that meat which made meat and vegetables more accessible to us. I thought that’s a really interesting observation, which fits into a lot of the themes I explore in this blog. 

I know the raw vegan diet is a very popular one at the moment and when we come to a look at industrial meat production, I totally agree. If you’ve been a listener of this podcast, you will know that that is why I am so passionate about regenerative agriculture. What is good for the animal is good for the planet and it’s good for us. It’s a win-win-win all around but animals have been part of our journey from the moment we split from primates, gorillas, orangutans and into their lineage via the Australopithecus, the Homo habilis, the Homo erectus. 

As our brain size has continued to grow and our neocortex has continued to grow, we developed into the species we are today. As I often ask people who are on a raw vegan diet, I may have missed this and I may be wrong, but is there any other society in all of human history, homo sapien human history, which has survived and thrived generation after generation on a raw vegan diet, over on a vegan diet, for that matter? And I think the answer is no. 

The reason is that nutrient-dense foods, we’ve had a relationship with nutrient-dense foods, foods on our evolutionary journey. I just wanted to share that with you. It’s a great book. It’s a great read. I’m only a third of the way through it. I’m really looking forward to exploring how the age of robots will impact our human journey.

I’m very optimistic that it will be a positive one, particularly when we combine that with the work of another book that I’ve reviewed by Rutger Bregman, the Dutch historian, where he explored Utopia for Realists and the Universal Basic Income. When we explore the impact of AI and robots giving us a lot more free time, then I’m rather optimistic about the future of humanity, but I wanted to share that with you. 

I hope this finds you well. That’s the book, Work: A History of How We Spend Our Time, which is what the byline is on the Kindle version or this version. The hard copy, A Deep History from Stone Age to the Age of Robots.


This podcast provides general information and discussion about medicine, health, and related subjects. Content is not intended and should not be construed as medical advice or as a substitute for care by a qualified medical practitioner. If you or any other person has a medical concern, he or she should consult with an appropriately qualified medical practitioner. Guests who speak in this podcast express their own opinions, experiences, and conclusions.