Weapon of Choice: The Story of the Human Body: Evolution, Health and Disease
Daniel E. Lieberman (Edwin M. Lerner II Professor of Biological Sciences, Harvard University)
Dear Daniel E. Lieberman: You slayed the universe with your tale of Stone Age bodies living futuristic lives. You covered such a wide array of solutions to human health problems, I’m still stunned that it’s all contained in one book. The Story of the Human Body: Evolution, Health and Disease is a masterpiece of popular science that combines the authority of empirical research with the allure of popular writing. Required reading for everyone. No exceptions.
Getting Bounced from the Garden of Eden
For 6 million years, natural selection, cultural evolution, and climate change sculpted hominims into elite, finely tuned hunter-gather machines, able to survive and thrive in even the most hostile environments. We evolved to withstand constant running, walking, grinding, communicating, carrying, climbing, smashing, lifting, playing, thinking, baby-making, remembering, tracking, digging, scraping, creating, starving, sweating, chewing, innovating, cooperating, throwing. We evolved to use the shit out of our bodies and minds, and stimuli like these very literally shaped the kind of creatures we are. In fact, our bodies need these stresses to develop normally. “Use it or lose it” is a profound truth about human bodies.
AND THEN [dramatic pause], in the blink of an evolutionary eye [dramatic pause again], BAM–we’re living in cities, voluntary tethered to desks and chairs and soft beds, staring into glowing rectangles all day and night, cosseted within small, sanitized, climate controlled rooms within concrete jungles within vast industrial-agricultural zones that produce enough cheap calories to drown us all. Our current situation vs. the conditions in which we evolved in the African savannah could not possibly be more opposite.
“The Ascent of Man” [read in a boomy, 50’s newscaster voice]
Let’s take it from the top: About 6 million years ago, a branch developed in the evolutionary tree of ape life. One side of the branch led to chimpanzees and bonobos. The other branch led to humans.
The development of modern humans has many twists and turns and dead ends, but we can identify five major turning points:
1) Bipedalism: Around 4-6 million years ago our ancestors ditched knuckle-walking on four arms and started to “walk” (waddle, actually) on two legs. This change was spurred by climate change: low hanging fruit was getting harder to find, and the ability to forage for food on two feet conferred huge advantages (e.g, carrying food with hands and travelling farther using less energy). In an environment where our ancestors had to battle for every calorie, the importance of this modest adaptation can’t be understated.
2) Enter the gatherer: Next came the “australopiths” about 3-5 million years ago. Think: human/ape hybrid. Australopiths’ foraged in open landscapes for all kinds of plant foods AND climbed trees for fruit and sleepy-times. They had chewing muscles the size of steaks; molars double the size of ours, and massive jaws and faces to withstand constant forceful chewing. They needed it: Imagine constantly eating raw sweet potatoes ALL DAY, EVERY DAY. It would be a serious grind, especially having to dig them up with a stick. Naked. In the baking sun. With lions stalking you. #FML
3) Enter the hunter-gatherer (Homo sapiens): About 2.6 million years ago, evolution put the “hunter” into “hunter-gatherer”. The ability to run after animals over long distances and then club them to death when they got tired was a radical development that gave our ancestors a tremendous survival advantage. This “persistence-hunting” adaptation is why humans became the best long distance runners in the mammalian world. Also around this time, our digestive systems and faces began to shrink because we began outsourcing chewing and digestion to fire and pounding.
4) Big hangry brains: As archaic human hunter gatherers flourished and spread across much of the Old World, they evolved even bigger brains, made possible by the additional, high quality calories now available from hunting/gathering and food processing technologies. We also started developing larger, fatter, slower growing bodies.
5) Bringing it all together: About 200,000 years ago, our ancestors had developed special capacities for language, culture, and cooperation. We were now modern in body and behavior. We also expanded our dietary diversity hugely to include basically everything that crept on the earth. This collection of traits allowed us to disperse rapidly across the globe (starting about 60,000 years ago) and to become the sole surviving species of hominid on the planet.
Every single human alive today is still a highly evolved, super-sophisticated Paleolithic hunter gatherer geared toward survival in tough environments (yes, everyone). In evolutionary time, the agricultural and industrial revolution happened so recently that we have only just begun to evolve away from our hunter-gatherer DNA. Unfortunately, this means that our hunter-gatherer bodies often lethally malfunction when subjected to modern lifestyles.
Paleolithic bodies living futuristic lives
So: What sorts of troubles arise from the mismatch between our Paleolithic bodies and our lazy, gluttonous urban ways? Here are some examples of the non-infectious ones (nasty, infectious “herd diseases” like diphtheria and the Black Plague are a whole other story):
- Heart disease, sleep apnea, constipation, metabolic syndrome, cavities, asthma, allergies, anxiety, depression, flat feet, misshapen bodies, osteoporosis, reproductive cancers, muscle atrophy, low back pain, chronic stress, impacted teeth, auto-immune disorders, plantar fasciitis, myopia, dementia, insomnia, obesity, and so on.
You get the point: an absolutely HUGE cross section of human health problems in the developed world are a result of the mismatch between our modern environments and our Stone Age bodies and brains. Solving the mismatch enigma would alleviate a tremendous amount of human misery and would save trillions of dollars in health costs over a generation (Lieberman provides some off-the-cuff calculations in the book that demonstrate this). Very literally, Western societies cannot afford to ignore the root causes of mismatch diseases forever.
Where did things go so wrong?
There are two main culprits behind the mismatch between city lives and hunter-gatherers bodies: The agricultural revolution (about 10,000-ish years ago) and the industrial revolution (about 250 years ago – present). These two historical transformations threw our Paleolithic bodies for a loop that we’re only now starting to untangle.
The agricultural revolution caused people to stay put and farm a patch of land rather than travel large distances in search of food sources. This way of life increased the amount of carbohydrates we were consuming relative to protein, and reduced the amount of physical activity required to live (for some).
These trends were hugely amplified by the industrial revolution which “increased exponentially the amount of calories available to us, and slowly allowed countless devices to reduce, calorie by calorie, the amount of energy we expend to exist”. (think about it: cars, computers, can openers, suitcases on wheels, escalators, electric razors, electric knives, snowblowers, elevators, public transit etc, etc). As Lieberman puts it “Nothing over the last few million years of human history has changed human energetics as much as the low cost of working at a desk using machines run by electric power”. Unfortunately for us, “years of unnecessarily relying on labor-saving devices can contribute to decrepitude”.
At the same time, food producers have figured out how to cheaply and efficiently grow and manufacture exactly what people have desired for millions of years: fat, starch, sugar, and salt. Especially since the invention of corn syrup in the 1970s, we now have a super-abundance of blood-sugar-spiking, cheap, garbage food. The situation has become so insane that people now actually pay MORE for foods that have less sugar and calories.
Evolution never prepared us for a situation where we’d get exactly what we craved. We crave fat, starch, sugar and salt because throughout almost the entire time that humans have existed on this earth, these things have been EXTREMELY difficult to get. Being hungry was normal for our ancestors. But now, we’ve been so successful at producing (and marketing) the things we crave that, that we’re collectively hanging ourselves by our own noose. We’re the victims of our own success as a species. How rockstar.
Adding fat to the fire
A big part of the problem is that we’re really good at passing our shitty behaviours and practices down to our children who pass them on to their children. In this way, the root causes of mismatch diseases transmit themselves from generation to generation.
Another contributing factor is that we’re really clever at relieving the symptoms of mismatch diseases. Temporarily masking the presence of a disease lulls us into a complacency that prevents us from addressing the root causes of the disease (which is admittedly more difficult than taking a pill).
Yet another exascerbating factor is that people are highly vulnerable to the charms of garbage food manufacturers and marketers. Experiments have repeatedly shown that we instinctively prefer sweets, starches, salts and fats – that’s the way we’re hard-wired and behavioural overrides are challenging. Understanding the nature of the beast is part of the solution, “but many of us also need skills, motivation and reinforcement to overcome basic urges in order to make healthier choices”.
The one-two punch of longer life spans and lifestyle induced diseases is going to dominate government finances as the baby boomers work their way through the system. Unless something changes, society is going to be bankrupted by easily preventable health problems.
Cultural innovations got us into this mess; they can get us out too
I won’t describe Lieberman’s proposed solutions (cough, cough, buy the book), but I will say that it has a lot to do with prevention, which really is the most powerful medicine. Moving around more and eating less cheap, crappy carbs (e.g., corn syrup) are a big part of the solution. Unfortunately for us, prevention is not a profitable form of medicine. Private commercial interests avoid it, and the medical establishment and all levels of government neglect it to the point of negligence. Moreover, the money we allocate to treating diseases once people are sick comes at the expense of money to prevent them in the first place. But things don’t necessarily need to be that way. Awareness is coming. Slowly.
Buy the book. Read it. Internalize it. Let it spur you and everyone you know to action.