Every so often, I read a book that is a breath of fresh air. Something that isn’t a rehash of old ideas and yet isn’t complete nonesense either. Richard Wrangham’s excellent book, Catching Fire (affiliate links: UK, US) is one such book.
Don’t let him loose in your kitchen
Why is it so great?
Ultimately, this book is great because it is built around a great new thesis. Frankly, Richard could have scrawled this book in summary bullet points on the back of a cigarette packet and it would still have been amazing.
But the book is also incredibly well-written. It’s short, pithy, informative without being bogged down in detail, and it draws strong, defensible conclusions that leave you feeling content and knowledgeable.
Richard is a great writer and an exceptional communicator with a sense of humour and the ability to conjure vivid images. Describing an ape’s mouth size relative to a human’s, he comments that “Mick Jagger’s biggest yawn is nothing compared to a chimpanzee’s”. But, I am getting ahead of myself. Let me tell you what the book is about.
What it’s all about
The central thesis of the book is that cooking food caused a change in the evolutionary development of what ultimately became homo sapiens. Here is a short summary of what you can find in a few of the key chapters:
#1: The cooking hypothesis
Richard explains the background to the prevailing theories of human evolution before presenting his own case briefly. He notes that Homo errectus is the first step on the evolutionary ladder (around 1.8m years ago) where much smaller teeth and jaws are seen. What accounted for these small mouths?
As we noted above, even our largest-mouthed representatives have small mouths compared with other apes. In fact, Richard comments that while it is common to call ourselves “the naked ape”, we could just as easily differentiate ourselves with the phrase “the small-mouthed ape”. Even Mick Jagger.
#2: Raw foodists
Richard looks at a number of studies in which people ate raw food. He concludes that a diet comprising exclusively raw foods is not satisfactory for humans in that it often causes extreme weight loss. By the end of the chapter, I agreed with him but I was uncomfortable with the confounding factors in the studies he cited.
The study that irritated me most involved the observation that certain Western subjects lost weight when eating a raw food diet. Given that most Western people are overweight from eating calorifically dense unatural foods, I imagine you could have got similar results feeding them nothing but boiled potatoes. But I digress, because this chapter is only really there to pre-empt the counter-arguments from the raw food camp.
#3: The cook’s body
This is the really fascinating chapter. Richard explores the changes in our bodies that occurred once we started cooking our food. Cooking food releases more energy because it requires much less work by the body to digest.
We developed small mouths and lips, weak jaws, small teeth, small stomachs, small colons and small guts overall. I had not appreciated that chimpanzees, for example, have very large and muscular lips for eating juicy fruits and squeezing them hard against their teeth.
I did not know that gorillas have jaw muscles that are so large that they reach all the way up to the sagittal crest on the top of their heads. Ours only come up to our ears. Our guts are much smaller than all other apes because our food arrives partly digested by cooking.
#4: The energy theory of cooking
This fun chapter dives further into the science behind why cooking releases more energy from food. Some fascinating studies have been done, particularly on snakes, as Richard describes. Apparently, there are certain snake species that are so relaxed that they will allow you to feed them. At the same time, you can measure their heat loss as they digest the food.
The snakes were fed different meals, including minced meat, whole meat and whole rats (their normal diet). The heat loss was least from the minced meat, suggesting that the snakes received more calorific benefit as less energy was used in digestion.
#5: When cooking began
Richard looks into how our behaviour changed in line with our physical form. As Homo errectus, we became more upright and less able to climb. This meant that we must have adapted in some way to sleeping on the ground. But the ground was a dangerous place, compared to up in the trees where our ancestors slept.
Richard concludes that Homo errectus must have been in possession of fire for them to be safe on the ground. This then ties in with the title of Homo errectus as the ape who began cooking.
#6: Brain foods
Richard notes that Homo errectus had a significantly larger brain than their predecessors. They also had smaller guts. This is in line with what is called the “expensive tissue hypothesis”, which suggests that there is only so much energy to go around. If the gut needs less energy to digest food, this can be used to expand other organs, including the brain.
One interesting point is that fire also created a tendancy for communal eating. Previously, eating could be done anywhere but once the food was being cooked, it was fixed in one place and Homo errectus had to be more sociable. This could be linked to our increase in brain size, as brain size tends to be linked to the size of our social groups.
#7: How cooking frees men and #8: the married cook
Richard explores the interdependance of a man and his wife over two chapters. Essentially, observation of hunter-gatherer societies reveals that in the vast majority of cases, men hunt and women gather.
In most cases, the man is dependent upon the woman for having a warm hearth and food awaiting him when he returns. The woman is dependent upon the man for food, as his hunting often generates more calories than her gathering. However, he risks returning with nothing so her less risky, but lower calorie food is essential to their joint survival.
I found these chapters fascinating. I recalled Ray Mears talking about the Northern Wilderness and his learning about the ancient cultures there. He notes that a man could not survive without a wife in those places, as he needed someone back home mending his clothes and equipment and cooking while he hunted, often for long days.
I also began to think about what I have read on the subject of human mating (steady on there!). Previously, without much contemplation on the subject, I had thought of hunter-gatherer societies as more open and promiscuous, with the advent of agriculture being the catalyst for monogamy (see this amusing riff on the same topic).
However, this would suggest that the monogamous relationship goes back further than this to the time of Homo errectus, which is fascinating.
If you have any interest in the ideal human diet, nutrition or our evolutionary origins, then you absolutely have to read this book.
Without this book, you are significantly behind the curve in terms of where our thought on the subjects has reached. What’s more, you’ll enjoy reading it because it’s beautifully put together.