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Our Feet Are Fallible, But They Beat A Chimp's

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Our Feet Are Fallible, But They Beat A Chimp's

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Our Feet Are Fallible, But They Beat A Chimp's

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  • <iframe src="https://www.npr.org/player/embed/128573578/128614368" width="100%" height="290" frameborder="0" scrolling="no" title="NPR embedded audio player">
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RENEE MONTAGNE, host:

It took a few million years for our ancestors to evolve into the walking, talking, texting and blogging creatures we've become. Along the way, the human body and brain have changed a lot. In our series on evolution, The Human Edge, NPR is taking is a look at those changes - in particular, the ones that made us the dominant species. As NPR's Christopher Joyce explains, we couldn't have done it without our feet.

Mr. BRIAN RICHMOND (Soccer Coach, Physical Anthropologist): Oh, nice shot. Oh, beautiful shot.

BOY: I got (unintelligible).

CHRISTOPHER JOYCE: Brian Richmond is a kid's soccer coach. He's also a physical anthropologist. As far as he's concerned, soccer is not just the world's most popular sport, it's the one that might just be best suited to argue uniquely human strength.

Mr. RICHMOND: It would be difficult to play soccer without a foot that's constructed like ours. I suppose, if we had a foot of a chimpanzee you could pick up the ball, you know, and you could throw it.

(Soundbite of kids yelling)

JOYCE: But we don't have a chimp's foot. A chimp's foot is flexible, built for grasping branches and climbing trees, like our own earliest ancestors. Our foot is stiff, taut and springy, built for walking and running. And Richmond wants to know, how did we go from a climber's foot to this amazing human appendage?

At his office at George Washington University in Washington, D.C., Richmond shows me a photograph.

Mr. RICHMOND: These footprints are the earliest footprints of early humans.

JOYCE: A million and a half years ago, one of our ancestors left those prints in the African mud. The feet were about size nine. Richmond discovered a whole trackway(ph) of these prints. They looked like the diagrams of feet that dance instructors use to show how to do the salsa or the tango.

For me, and I suspect for Richmond, the prints are even more exciting to behold than a bone or a skull that old, because you can just imagine...

(Soundbite of footsteps)

JOYCE: ...an ancient action...

(Soundbite of footsteps)

JOYCE: ...a living moment - captured.

(Soundbite of footsteps)

Mr. RICHMOND: A fossilized footprint is basically fossilized behavior. Shows you what the individual did one and a half million years ago at that instant in time.

JOYCE: And what do those prints tell Richmond?

Mr. RICHMOND: Sure enough, they were walking with a long stride, they had an arch in the foot the way we have.

JOYCE: Long legs and an arch in our foot. Our primate cousins - gorillas, chimps, bonobos - and they're flat-footed, no arch. The arch is actually the manifestation of a very complex apparatus inside our foot - an apparatus for walking - like no other in the world.

(Soundbite of door opening)

Mr. RICHMOND: We're heading into the gross anatomy lab where we have human cadavers for dissection.

JOYCE: Blue gloved and white coated, Richmond leads the way into a brightly lit room at the George Washington University Medical School. Metal gurneys are lined up in neat rows, each covered with a steel lid.

Mr. RICHMOND: I look at the human body and see how it's put together from a functional perspective and an evolutionary perspective; see how it's different from other primates.

JOYCE: Richmond lifts a steel cover. Underneath, a cadaver lies pale and heavy, the head shrouded in gauze. In death, these donated bodies are instruments of learning. Richmond lifts a flap of skin, the sole of the foot, with a metal probe.

Mr. RICHMOND: So, here I've just pulled the skin back, and here you can see one of those characteristics that's really uniquely human. And that is the long tendon that runs from the heel, forward, underneath the skin, all the way to the base of the toes.

JOYCE: It's called the plantar aponeurosis. It's a flat broad tendon, whitish and taut. Along with spring ligaments, it gives the foot its arch and its stiffness. Imagine thick rubber bands stretching from your toes to your heel. Step down and...

Mr. RICHMOND: They absorb energy going into your step.

JOYCE: Then at the end of your step...

Mr. RICHMOND: They actually recoil, bounce back and help propel your foot.

JOYCE: We've also got short toes and a big toe that's in line with the other toes. These all make for better walking and running, and surviving on the ground rather, than in the trees.

Now, the Kenyan prints did seem to show an arched foot, but Richmond also wants to know how the owners of these feet walked - their posture, their stride, even the angle of their leg bones. He wants to figure out what kind of movement makes that kind of footprint.

Mr. RICHMOND: So that when we have a footprint, we can work backwards and reconstruct what the steps were like in that individual, even at one-and-a-half million years ago.

(Soundbite of laughter)

Ms. CALLISTA BEARNALL: Hi.

JOYCE: This is where graduate student Callista Bearnall comes in. Richmond is filming her walking in sand and comparing her footprints to the Kenyan ones.

Ms. BEARNALL: I'm standing here while they're trying to put these reflective markers on my joints.

JOYCE: She's in a GW lab getting ready to walk the walk.

Ms. BEARNALL: Can I wear a toe ring?

JOYCE: No toe rings; just tights and a dozen or so reflective markers stuck to her hips, her legs and her bare feet. She's going to walk through a sandbox. As she walks, cameras focused on those markers will produce a sort of stick figure computer animation of her gait - the turn of her ankles, the angle of her thighs, even the curl of her toes.

Ms. BEARNALL: Each footprint that I make, we're going to do 3-D scans and try and figure out, based upon how I move and in what type of sediment I step in, how my footprints change. Pretty much as soon as he hits the start button, I start walking.

Mr. RICHMOND: Yep. Let's do our experiment. Of course, when you're ready.

(Soundbite of footsteps)

JOYCE: Bearnall strolls through the sand as casually as she can under the watchful eyes of several researchers and a row of cameras.

Mr. RICHMOND: Good. Actually, we got the full left and right. It's better coverage than I thought it was.

JOYCE: She leaves a nice set of prints in the sand. Richmond measures them with a laser and photographs them.

This work is painstaking and a bit seat-of-the-pants. Richmond's not sure what to look for. He's got a snapshot - the footprints. He hopes they'll provide clues to how walking evolved over millions of years, from primitive ancestors to us.

The prints he found in Kenya were probably made by homo erectus. Erectus emerged about 1.8 million years ago. They made tools, hunted, used fire, were taller and had a bigger brain than their predecessors.

Mr. RICHMOND: They were starting to change their way of life, where they would go much farther, and a lot of people think it's mainly in terms of finding meat. And meat became a new important part of the diet. That also led, eventually, to us populating the world more.

JOYCE: The foot, ultimately, is the thing that connects us to our planet. It gave early humans an advantage in an unforgiving world. They didn't have to swing to the next tree. They could just walk. They could run and hunt better. When the climate changed, they could migrate - and eventually they did, laying down their footprints everywhere.

Christopher Joyce, NPR News.

(Soundbite of song, "The Hokey Pokey")

Unidentified Woman: (Singing) You put your right foot in, you put your right foot out, you put your right foot in and you shake it all about. You do the hokey pokey and you turn yourself around, that's what it's all about.

MONTAGNE: Not only did our ancestors walk; they also ran. And on ALL THINGS CONSIDERED this afternoon, you can hear why some scientists think that running gave us the human edge.

(Soundbite of song, "The Hokey Pokey")

Unidentified Woman: (Singing) ...you put your left foot in and you shake it all about. You do the hokey pokey and you turn yourself around, that's what it's all about.

MONTAGNE: It's NPR News.

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