Monday, January 28, 2013

Born to run?

Could the millions of readers and followers of Christopher McDougall’s book "Born to run" have been led astray? An Australian anthropologist thinks so and has an alternative theory that could change the way you look at running forever. 

If you read Christopher McDougall’s best-selling book Born to Run, or listened to his erudite TED talks you will have heard a theory on human evolution that goes something like this:
About two million years ago our ancestors’ brain size exploded – going from “pea brained” Australopithecines to “melon head” Homo erectus. However, to support that big brain, you need a source of condensed caloric energy – meat – and the first edged weapons didn’t arrive until about 200,000 years ago. So he says “Somehow our ancestors were killing animals without any weapons.”

To explain this quandary, McDougall says we evolved as “hunting pack animals”, using our efficient running gait and cooling adaptations to chase quadruped prey, which have neither, until they collapsed from heat exhaustion providing us with plenty of brain fuel – with no claws or fangs required.

The implication is that modern humans are built to run - and if you think otherwise then you’re not only denying history. You’re denying who you are.
This “endurance running hypothesis” as that’s commonly known is an amazing and compelling idea: man the elite athlete and great hunter, taking on the African savannah with only his bare hands like a pre-historic Bear Grylls; so it’s no surprise it’s commonly accepted by both anthropologists and the mainstream media.

But there’s one problem – it’s wrong. At least that’s the opinion of Stephen Munro, a former anthropology professor at Australian National University and current curator of the National Museum, Australia.

Munro is part of a growing faction of the scientific community, including Elaine Morgan and Sir David Attenborough, who say that the endurance running hypothesis is unlikely at best.

“The endurance running model from two million years ago – I struggle with that,” Munro says. “As far as I’m concerned endurance running came later with Homo sapiens [about 200,000 years ago].”

Why we’re not born to run

Munro says the idea that early hominids chased their prey to heat exhaustion on the savannah presents some serious logistical challenges.

“Our children aren’t endurance runners – certainly babies aren’t – pregnant women wouldn’t have been and likewise for the old folk,” he says. “Supposing they were actually doing this, it would have been only the healthiest males – and maybe females – running for many kilometres at a time to hunt. But at the end they have to somehow take that meat back to the people who couldn’t run.”

Of course this would have all taken place under the watchful eye of every other predator and scavenger on the savannah, many of whom would no doubt view a pack of exhausted apes carrying a dismembered animal the same way we see a super-supreme pizza.

The idea that we evolved on the hot dry savannah, Munro states, is flatly wrong. Munro says the fossils of butchered animals point to an aquatic setting. “One of the most common animals they find is hippopotamus; there are also records of whales being butchered and crocodiles. The [fossils] that are bovid, are animals like waterbuck that spent most of their time feeding in wetland grasses.”

In addition, Munro says there are a host of problems with the way our ancestors were built that would hinder their long-distance running ambitions. Homo erectus, the first human ancestors said to have used endurance running for survival, had a heavier skeleton than any primate in history, making it even less suited to running than its evolutionary predecessors.

“As a runner, there’s no real advantage in having heavy bones”, Munro says. “Good long distance runners don’t carry much fat and they’re slightly built – they’re not big hulking guys. Homo erectus had big muscles – big muscle attachments – and we assume they would have had subcutaneous fat like modern humans do. In my opinion, they were totally unsuited anatomically for long distance running.”

Furthermore, modern humans’ sweat glands, conventionally proposed as cooling adaptations for endurance running, combined with our dilute urine make us vulnerable to dehydration and salt depletion. Without trace elements like iodine, which are relatively scarce in a savannah environment, we fall victim to hypothyroidism and mental retardation.

Right now you’re probably asking yourself: ‘Dead hippopotamuses and retarded primates? What’s all this got to do with trail running?’ In a word: everything.

Running is a primal activity, so doing it well requires understanding your origins. How can you develop a good running style when you can't even say for sure why you stand on two feet rather than four? If you don't know what environment you came from, how do you expect to make good decisions about your water and salt intake? And if you don't know what food your digestive system spent a few million years evolving to process, then how do you expect to put together an effective training diet?

More likely: born to wade

So if running wasn’t the shaping force in our evolution, what was? According to Munro and his colleagues the driving force was water.

A model that explains our evolution in terms of foraging in and around oceans, lakes and rivers, answers many questions that savannah-based models (like the endurance running hypothesis) leave dangling: our hairlessness, our ability to consciously control our breathing and the wetsuit like layer of fat under our skin.

“If you’re swimming in water…then it’s an advantage to be naked and have subcutaneous fat but also to be linear – to have the legs spine and head all in one line,” Munro Says. “People often will assume we’re linear because we’re bipedal… in some respects we might be bipedal because we have a linear body that’s good for foraging in water.”

He says spending time around water would have provided the impetus for our breath control, which is one of the pre-conditions for speech.

However, he says it’s important to note we weren’t mermaids. “I don’t think humans were ever aquatic in that they were spending all their time in the water. They weren’t fast swimmers. They were foraging beneath the water, collecting things like shellfish; things that didn’t run or swim away.”

Munro says a waterside diet – eating coconuts and shellfish and scavenging the high water mark – explains our omnivorous tendencies and also the high docosahexaenoic acid (DHA) diet needed to grow the large brain necessary for tool use.

“You can survive on that. You don’t need to be running after anything, but you need tools, because you need to be able to open the shells. Tool use is very important.”

A shoreline lifestyle would have given us the perfect conditions to evolve our problem solving and tool making skills – the successful waterside ape would need to open mussel shells one day, carve up a beached whale the next and pilfer birds’ eggs in between. Eventually, basic tool use would have led to fishing spears and other projectile weapons.

In Munro’s opinion, it was only after we’d mastered these skills and evolved into our final Homo sapiens format 200,000 years ago that we began to hunt larger land-based prey, eventually dominating the planet and learning to endurance run.

So what does that mean for runners?

If Munro’s beliefs are true then we’re not the highly evolved endurance running specialists that many experts think. Instead, running, like language, art and science, is something that we learned to do much more recently.

While Born to Run fans might be feeling a bit down right now, for the rest of us Munro’s theory answers a whole stack of questions that have probably been nagging at you since you first laced up a pair of running shoes.

It explains why getting off the couch and running an ultra-marathon isn’t as straightforward as some people would have you think. It tells us why perfect running technique doesn’t come to us all as easily as we’d like and why you need to train carefully, scientifically.

It says that if you get injured, that’s okay, you’re not earmarked for natural selection – it just means you need to use that big old Homo sapiens brain of yours to figure out what’s going wrong with your running and fix it.

At the end of the day, Munro’s theory tells us that although we’re not natural born runners, we are born to adapt, improvise and persist – and when we do that, anything is possible.