Caveman Syndrome: Today’s Killer Diseases Stem From Evolutionary Mismatch

 

By Karen Weintraub
CommonHealth Contributor

Cavemen didn’t have flat feet or type 2 diabetes. They didn’t need orthodontia or get impacted wisdom teeth. The ones who couldn’t see their prey – or predators – from far away didn’t live long enough to pass their nearsightedness on to their children.

Indeed, the vast majority of what ails us today — from leading killers like heart disease and cancer, to smaller health woes such as back pain — is the result of a mismatch between the environments we evolved in and the ones we now inhabit, argues Harvard evolutionary biologist Dan Lieberman in his sweeping new book, “The Story of the Human Body: Evolution, Health, And Disease.”

Lord Jim/flickr

Lord Jim/flickr

Lieberman, perhaps best known for his energetic advocacy of barefoot running (which he sometimes does), convincingly makes the case for a wholesale rethinking of how we live our modern lives based on overcoming these evolutionary “mismatches.”

“Most of us in this room are probably going to die of a mismatch disease,” Lieberman told a capacity crowd Thursday night at the Harvard Museum of Natural History.

Our bodies evolved as hunter-gatherers to walk 5-10 miles a day, eat a varied diet loaded with fiber and pack on fat in times of plenty to get us through the leaner times, he said. But instead, we live in an environment where we can drive to the mall, park close to the door and take the escalator up to the food court for a dinner that barely needs chewing.

This mismatch has led, he suggests, to a proliferation of heart disease, cancer and diabetes – which were nearly unknown to our prehistoric ancestors, as well as disabling conditions like low back pain and autoimmune problems. (Full disclosure, Lieberman is a long time acquaintance.)

Looking at health from an evolutionary point of view suggests new approaches to prevention and treatment.

Through this lens, it becomes clear that low back pain is the result of muscles weakened by spending most of every day relaxing in a comfy chair, Lieberman says.

Instead of the extra lumbar support that some would suggest to allow the back muscles to rest, this evolutionary approach would advocate a standing desk and more exercise.

We might have more luck fighting cancer, he suggests, if we view it as a disease of evolution, where certain cells win out by reproducing faster than others. Treating cancers with poisonous chemicals like chemotherapy might encourage the evolution of even more dangerous cells, just as some antibiotics and hand sanitizers can encourage the growth of more dangerous bacteria.

“Perhaps evolutionary logic may help us find a way to better combat this scary disease,” Lieberman writes in the book. “One idea is to promote benign cells to outcompete harmful cancerous ones; another is to trap cancer cells by first promoting those that are sensitive to a particular chemical and then attacking them when they are in a vulnerable state.”

Lieberman bases his arguments on his more than 20 years of studying and teaching evolutionary biology.

When he first started teaching about our evolutionary ancestry, he ended his lectures roughly 12,000 years ago with the emergence of modern humans and their spread across the globe. His students always wanted to know what happened next, how people continued to evolve; and he grew dissatisfied with the stock answer that we weren’t changing much.

Instead of evolving through natural selection – the process laid out by Darwin – human bodies have been mostly changing through cultural evolution, Lieberman now says. The biggest change early on was the movement to farming, which provided some survival advantage because there was more food available most of the time allowing women to have more babies – but which also led to new diseases and a harsher lifestyle.

It’s only within the last 200 years — thanks to sanitation and antibiotics — that humans have regained ground our ancestors lost when they traded hunting for farming.

Hunter-gatherers who survived childhood lived on average into their 60s, 70s and 80s, Lieberman said, while during the agricultural period, only a few were lucky enough to make it past their mid-50s.

Similarly, humans lost height when their diet narrowed from hunting to farming. Paleolithic men in Europe averaged about 5’8” research shows. Heights shrunk to 5’4” during the farming era, before rebounding recently to 5’10”, he said.

Lieberman does not advocate a return to the Paleolithic way of life. Food was crunchier and more fibrous, which helped our digestive systems and teeth, but infant mortality rates probably neared 50%. Humans, he notes, didn’t adapt over millions of years to be healthy in old age – but, rather, to reproduce more efficiently. So going back to this mythical past isn’t going to solve every health problem.

Instead, he says, we need to figure out how to keep the best of today’s lifestyle without reducing our quality of life through poor habits.

“We could be doing a lot better,” he says. “About 70 percent of all medical care in the United States is for preventable illness.”

Like many others, Lieberman, who has run 10 marathons and has seemingly boundless energy, focuses on diet and exercise.

“If there’s one evil ingredient out there it’s sugar,” he says, noting that Paleolithic diets relied heavily on fruit. But that was before fruit was bred for sweetness – back then, an apple was no sweeter than a carrot, he says. And people ate the equivalent of about 4-6 lbs of sugar a year — or about what we’d buy in one large bag from the grocery store. Americans now consume about 100 lbs of sugar per person per year.

Lieberman says the most urgent thing to do is require more physical exercise in schools — at least an hour a day.

For adults, he supports the kinds of higher taxes on junk foods and smaller sizes of drinks that recently got New York’s Mayor Michael Bloomberg into trouble.

The changes we’ve undergone in the past show that we’re capable of changing again, under the right circumstances.

“We’re not going to get out of [today’s medical] problems without understanding why they occur,” Lieberman says. “The way in which our bodies evolved is relevant to the way we live today.”

Screen shot 2013-09-27 at 2.17.45 PMHere are some mismatch diseases and Lieberman’s suggestions (some backed by research, others more speculative) for preventing them:

Heart disease, cancer, diabetes: More exercise, less sugar

Osteoporosis: More exercise, particularly in late childhood and early adulthood

Myopia (poor distance vision): Spending more time outdoors as a child

Crooked teeth and impacted wisdom teeth: Chew more fibrous food and perhaps sugarless gum in childhood

Allergies and autoimmune diseases (such as Multiple Sclerosis and Lupus and even some autism): Allow kids to be more exposed to dirt and germs; prescribe probiotics along with antibiotics.

Foot pain and fallen arches: Avoid shoes with arch support; Let kids go barefoot more often

Back pain: Sit less, exercise more

Karen Weintraub is a health/science journalist based in Cambridge, Mass. Find her on Twitter @kweintraub.

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  • dave birney

    thats interesting about the autoimmune disease, i have one and ive always had a hunch that i got it because i was hardly never that sick when i was younger, compared to all the other kids i knew anyway, so maybe i wasnt exposed to as much germs.

  • Susan Briody

    So it’s alright for my husband to hate doing yard work, he just should not pay someone else to do it! And when he says, “Yeah, but I have to keep doing it every week!” I should just say, “Yeah, and that’s what’s so good about it! keeps you out of trouble and in better shape!”

  • Mango Momma

    Whatever happened to real physical education in school? I was in high school back in the 70′s and we had to actually get outside and do stuff. We even got a grade. When my kids were in high school in the late nineties, they didn’t even need to bring a change of clothes in because physical education had been replaced by “health ed” which was apparently lectures on (how ironic) how to live a healthier life.

  • Dave Holzman

    Great article, on what sounds like a great book. My only criticism is with the notion that human evolution is not happening anymore. Researchers who look directly at this issue say that it’s happening much faster than it used to. The reason: the population has skyrocketed in the last 10,000 years, from perhaps a few million or so that existed prior to the invention of farming to tens and then hundreds of millions, and now more than 7 billion. That means there are far more new genes that get into the population, and they spread pretty quickly. The iconic example is the lactase gene, that digests milk sugar. That gene has been around a mere 6,000 years, and it’s spread from northern Europe into Asia and Africa. Genes with a wide variety of functions have similarly spread.

  • Ralfine

    i dont think antibiotics encourage the growth of bacteria. they just kill off the benign ones, so that tye competition has less to worry about. same with fungi. kill bacteria and fungi will grow.
    same with insecticides. kill all insects, but the pests will grow faster thanvtheir predators thats why it is so profitable to sell insecticides. after killing off all the predatore, farmers willcrely on insecticides to kill off pests.

  • alexafleckensteinmd

    There is not only a physical mismatch – there’s also a mental/emotional mismatch. We used to live in tribes and multi-generation families. Now we live in small apartment (more people now live singly than in family situations). We used to get hugged more often, and get slapped more often when we tried to eat more than our share. We slapped in bear-hide piles with relatives around us, with no electricity. Add to this our modern “non-food” foods, and we can see why 40 percent of Americans are depressed.

    Yes, cavemen lived to their eighties – if they avoided fatal accidents and homicides early on; infectious diseases were not such a great threat then because the tribes were too small to give rise to epidemics. That only happened when cities developed.

    We can reclaim our birthrights, and take some “cavemanhood” back by moving more outdoors, eating fresh foods, get enough sleep and cultivate friends and small communities of like-minded people.

    Alexa Fleckenstein M.D., physician, author.

    • Allison

      I completely agree, and the same goes for anxiety. We evolved to feel anxious because we needed anxiety to survive—awareness of our surroundings, possible predators, possible food sources—and we don’t need it now. But it’s still there, and people are wondering why they are so excitable. Add on top of that our new habitat of concrete…

  • birthdance

    Great suggestions. Feels kind of overwhelming to try to make these kind of changes as an individual (and a mom with a mainstream pediatrician), in a society that is truly not set up for them. I like the standing desk idea — will see if I can at least do that one!

  • Isobel Clinton

    Most of what Mr. Lieberman says I’ve heard often before from biologists: my ex was one, so I spent a lot of time with them. I’m intrigued by the pooh-poohing among these comments. Of course going barefoot from early on doesn’t solve congenital problems with your anatomy–but my flat-foot pain (it’s in the family) didn’t show up till I stopped! As for antibiotics, natural antibiotics have been used for far longer than 200 years. Maybe they mean synthetic antibiotics? Anyway, the proposals aren’t new or shocking, so it’s interesting to see the kind of response they get. Apparently there’s a real need for a book like this!

  • Vandermeer

    interesting article… I don’t buy it all, but the evidence against sugar keeps showing up in so many scientific journals… that I’m cutting back big time.

  • Rebecca N.

    Antibiotics are about 70 years old, not 200. Sanitation is a relative term, but 200 years sounds long to me. Also when was the “farming era” when men were only 5′ 4″ and when is the “recently” that includes regained height? That sounds historically fuzzy to me. Lieberman’s fuzziness, presumably, not the article writer’s. (I’m a college professor who teaches medical history.)

    • Dave Holzman

      Farming has been adopted at different times in different parts of the world beginning probably a bit more than 10,000 years ago in the Fertile Crescent and in China. The recently also varies around the world, depending on sanitation, affluence, better nutrition (the transition from hunting and gathering to farming involved replacing as many as 80 different plant species with a few starchy staples) and a few other factors. In other words, Lieberman is fuzzy because these changes happened at different times in different places. Note that there are still some tribes of hunter-gatherers in the world.

      And while penicillin goes back little more than 70 years, vaccination for smallpox goes back 200 years (google Edward Jenner).

    • Mary Anne

      one thing sanitation means is “modern” plumbing to deliver safe water and assure human waste is properly handled, first world has had this for more than 70 years, 200 isn’t too long although check the history of germ theory

  • Jake P

    cavemen lived to their 80′s? heh, where the evidence of that. this guy’s just trying to get in the news
    Poor eyesight is caused by not playing outside enough? heh, please…

    • KOVAINANBAN

      Well think what happens to the eyes when you look at close and distant objects. Suppose if you don’t lift your arms above shoulder much, what will happen to your arm muscles?

      • cuvtixo

        But by the same logic shouldn’t some of us get super close eyesight from reading so much? That’s something “cavemen” certainly didn’t do. Is our reading distance eyesight so much better than the hunter-gatherers? Maybe but I’m doubtful

        • fun bobby

          have you noticed the nerds wearing glasses?

    • birthdance

      I believe the science says that kids who spend more time outdoors have less near-sightedness because of the brightness and contrast of objects in sunlight and how that affects eye development.

    • Dave Holzman

      Bones. Archeologists dig up bones. They can determine when the various people lived, how long they lived, often what they died of, etc. Also, there are still hunter-gatherers today. Ethnobotanist Wade Davis recounts in some tribe where he lived for a while, of a hunter-gatherer in his 80s who died by falling out of a tree. Yes, the guy in his 80s was climbing a tree.

      As for the question of eyesight, when your eyes are developing as you grow, if you are doing nothing but looking close up all the time(reading, screens, etc.) they develop wrongly. There was documentation in some tribe of Alaskan eskimos that while there had been no nearsightedness, as soon as kids were sent to school, there were kids who needed glasses.

      • Jake P

        Some documentation eh? But you of course can’t produce it…

        • Dave Holzman

          You could read Guns Germs & Steel, by UCLA professor Jared Diamond. It’s in there, along with a slew of other fascinating information. I wrote about this stuff so long ago–1997–that I don’t have my notes anymore, but George Armelagos of Emory University is one of a number of researchers in this area.

          The logic is compelling. When people lived nomadically in small bands, there weren’t epidemics, partly because diseases had nowhere to easily spread (which is why HIV didn’t appear until recently–it was sequestered somewhere in Africa where there weren’t many people), partly because sanitation isn’t a problem among small nomadic bands, and partly because nutrition was good among hunter-gatherers as they ate 10s of different types of plants, while once people started farming, they ended up eating mostly a couple of types of starches, and starches have calories, but very little nutrition (one can’t live on cereal alone). The ravages of that lifestyle shows up in the teeth and bones of neolithic farmers.

  • lesleyca

    Under allergies it says “prescribe antibiotics”. Shouldn’t that be “proscribe (restrict) the use of antibiotics”?

    • Jake P

      if you’re looking for A+ material, you’re gonna have to go somewhere else :)

    • careyg

      Thanks so much for pointing that out — now fixed — it was meant to say, ‘prescribe probiotics’ along with antibiotics –