You’re Not Lazy, You Just Quickly Minimize Exertion, Study Suggests

A new study finds we quickly change our gait for greater efficiency. (Peter Mooney/Flickr)

A new study finds we quickly change our gait for greater efficiency. (Peter Mooney/Flickr)

By Josh Eibelman
CommonHealth intern

If you’re feeling guilty and blaming yourself for being lazy, take heart: We evolved to minimize how much we move, and new research suggests we adjust our bodies quickly to expend the least possible energy.

In a new study, “Humans Can Continuously Optimize Energetic Cost During Walking,” published in the journal Current Biology, researchers found that people optimize their gaits — the manner in which they walk — in real time in order to expend less energy.

Subjects in the study were fitted with exoskeletons that forced them to walk in abnormal ways. The scientists found that participants automatically fine-tuned their manners of walking to more energetically efficient ones in response to the exoskeletons.

I spoke with Jessica Selinger, lead author of the study and a doctoral candidate at Simon Fraser University, to learn more.

How would you sum up your results?

What we found was that people quite readily will tune or change really fundamental characteristics of their gait — characteristics that have been established over millions of steps over the course of their lifetime — in order to move in a way that uses the least amount of energy.

That’s probably intuitive for a lot of us. We know that we like to do things that require the least effort and do them in the least effortful way. I might prefer to take a bus to work when I could walk or I might prefer to sit when I could stand. But what’s really interesting is that even when you make a conscious choice to exercise or spend energy, what our study shows is that your nervous system is optimizing and tuning behind-the-scenes your movements so that you’re burning the fewest calories possible.

What message do you want people to take away from these findings?

For one, it’s really remarkable that the body can do this. There are countless ways that someone could walk from point A to point B. We can choose different speeds, step rates and even muscle activity patterns, yet we have very strong preferences for particular gaits — the energetically optimal gait. It’s really amazing that our body is able to home in on what is the most energetically optimal way to move. It’s a complex problem and an impressive feat. You have to be smart to be that lazy!

And the other really interesting thing was that that people would adapt their gait even in response to very small savings in energetic cost. We’re talking about just a few percent of the body’s total energy use. It seems that the body is really sensitive to this measure. Energetic cost is not just an outcome of our movement, it is continuously shaping the way me move.

Can people do anything to counteract this laziness? Continue reading

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. Continue reading

Opinion: Why Evolution Politics Favor The Democrats

Here’s a pro-Obama (or at least pro-Democrats) argument you probably haven’t heard: evolution favors mutual support and group efforts over fierce individualism and autonomy. At least that’s the case being made in a piece today on “evolution politics” by Walter C. Clemens, Jr., political science professor emeritus at Boston University and an associate at Harvard University’s Davis Center for Russian and Eurasian Studies, and Stuart A. Kauffman, professor emeritus at the University of Pennsylvania, currently teaching at the University of Vermont.


In their piece for WBUR’s Cognescenti, the authors ask the question: “Which works better — rugged individualism or mutual aid?” Here’s their response:

Republicans champion self-reliance. Most Democrats also extol hard work — but agree with former President Bill Clinton that “we’re all in this together.” This view, Clinton told the Democratic National Convention in Sept., “is a better philosophy than, ‘you’re on your own.’”

The science of evolution supports the notion that self-centered autonomy generally leads to dead ends. Survival requires mutual aid. Today’s life scientists see that evolution is not the Jack London-social Darwinist version of nature that many Republicans embrace. To be sure, individuals and entire species compete for scarce resources, but all of life — from the biosphere to the econosphere — is filled with mutualisms that facilitate a diverse abundance. Continue reading

Daily Rounds: Lyme On The Rise; Why We Cry; Tubes Misused

Summer’s nearly over, you’re back from the Cape vacation and you probably thought your nightly ritual of full-body tick examinations could stop. Think again. The Boston Globe’s Stephen Smith reports that Lyme disease is on the rise — in non-beachy places like Framingham and Natick, communities that rarely had to contend with the tick-born disease.

NPR analyzes the evolutionary underpinnings of crying and reports that natural selection likely favored babies who wailed loudest — an efficient way to get what you want. (The piece also explores the related concept of ‘theory of mind,’ understanding another person’s emotional state. For more on this, see the work of of MIT’s Rebecca Saxe, who has done groundbreaking research on the part of the brain that governs this phenomenon.)

And if you missed it, read Gardiner Harris’ hard-hitting story in The New York Times on mixed-up medical tubes inadvertently killing or hurting patients — all due to lax federal oversight and resistance from the medical device industry.