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The Blond Beast
Thursday, November 18th, 2004, 09:23 AM
http://www.nature.com/news/2004/041115/full/041115-9.html

Long-distance running was crucial in creating our current upright body form, according to a new theory. Researchers have suggested that our early ancestors were good endurance runners, and that their habit has left its evolutionary mark on our bodies, from our leg joints right up to our heads.

Early humans may have taken up running around 2 million years ago, after our ancestors began standing upright on the African savannah, suggest Dennis Bramble of the University of Utah, Salt Lake City, and Daniel Lieberman of Harvard University in Cambridge, Massachusetts. As a result, evolution would have favoured certain body characteristics, such as wide, sturdy knee-joints.

The theory may explain why, thousands of years later, so many people are able to cover the full 42 kilometres of a marathon, the researchers add. And it may provide an answer to the question of why other primates do not share this ability.

Our poor sprinting prowess has given rise to the idea that our bodies are adapted for walking, not running, says Lieberman. Even the fastest sprinters reach speeds of only about 10 metres per second, compared with the 30 metres per second of a cheetah. But over longer distances our performance is much more respectable: horses galloping long distances average about 6 metres per second, which is slower than a top-class human runner.

"Everyone says humans are bad runners, because when you think of running you tend to think of sprinting," he adds. "There's no question we're appalling sprinters, but we're quite good at endurance running."

Race training

How did we get so good at running? Scavenging is the best answer, Lieberman suggests. Our savannah ancestors would have been in competition with hyenas, who are also good long-distance runners, to get to the site of a big kill and pick over the remains. "You could see a flock of vultures on the horizon and just take off towards them," he says. Or perhaps early humans used their endurance simply to chase prey to exhaustion.

The theory makes sense of a raft of human characteristics, Bramble and Lieberman write in this week's Nature1. Not only do we have springy Achilles tendons and stout leg-joints, our hairlessness and tendency to sweat make us very good at dissipating heat.

Running may even have improved our balance, says Fred Spoor, who studies human evolution at University College London. "Running requires a lot of delicate coordination: your legs are off the ground and you need to coordinate your eyes to see where your foot will land," he says.

Many animals keep their balance with the aid of semicircular canals in the inner ear, which are filled with fluid that acts as an acceleration detector. These structures are unusually large in both modern humans and our evolutionary cousin Homo erectus and this shows, says Spoor, that they might have helped primitive runners stay on their feet.

In fact, running seems to be the only reason that we have prominent buttocks, says Lieberman. He has measured the activity of the gluteus maximus muscle in volunteers during a walk and a jog. "When they walk their glutes barely fire up," he says. "But when they run it goes like billy-o."

It remains to be seen how the theory will be received, says Spoor. If correct, it means that the genus Homo is unique among primates in its running ability. But some experts maintain that there is nothing special about human locomotion, and what separates us from other apes is simply our outsized brains.

morfrain_encilgar
Thursday, November 18th, 2004, 10:52 AM
"Everyone says humans are bad runners, because when you think of running you tend to think of sprinting," he adds. "There's no question we're appalling sprinters, but we're quite good at endurance running."

Bramble and Lieberman make it clear that they aren't comparing human long distance running to galloping, but to trotting, which the short raticle doesn't make clear.

"Quadrupedal cursors easily sprint faster than humans over short distances, but sustainable ER speeds of humans are surprisingly comparable to specialized mammalian cursors such as dogs and horses in two respects. The first comparison to make is with trotting, because bipeds are incapable of galloping, but also because human bipedal running and quadrupedal trotting are biomechanically most comparable. Both gaits synchronize contralateral foreand hindlimbs, effectively restricting each stride cycle to just two steps, and both are inherently ‘bouncy’ gaits with substantial vertical displacements of the centre of mass. When compared to quadrupedal trotting, human ER speeds are relatively high when adjusted for body mass. The predicted preferred trotting speed for a human-sized (65 kg) quadruped is approximately 2.8ms-1, and the trot–gallop transition is 3.8ms-1.
more extreme comparison of performance that is not adjusted for body size is between humans and large mammals such as ponies and horses. Human ER speeds exceed the preferred trotting 3.1ms-1) and the trot–gallop transition (4.4ms-1) speeds ponies (110–170 kg), and even the preferred trotting speed predicted for a 500-kg quadruped.

Most cursorial quadrupeds such as zebra, antelopes, and African hunting dogs trot when running long distances, but a few such hyenas and wildebeest are known to run long distances using a lowspeed gallop (typically a canter). When galloping, species with high sustainable speeds such as dogs or horses can usually outrun humans. The maximum sustainable (~10–15 min) galloping speed predicted for a 65-kg quadruped is 7.7ms-1, and elite racing horses can gallop 10 km at 8.9ms-1. However, human ER speeds are quite comparable to the preferred galloping speeds that cursors use over longer distances and times. Minetti has shown that sustainable galloping speeds in horses decline considerably for runs longer than 10–15 min, accounting for the average daytime speed of 5.8ms-1 at which long-distance postal horses were consistently run for millennia. Wildebeests (~100 kg) prefer
canter at 5.1ms-1. Well-conditioned human runners exceed the predicted preferred galloping speed for a 65-kg quadruped and can occasionally outrun horses over the extremely long distances that constrain these animals to optimal galloping speeds, typically a canter."

Dr. Solar Wolff
Friday, November 19th, 2004, 03:48 AM
Reasons Humans are not runners, jogger, trotters, etc.

1. Think your a runner, try keeping up with any old dog. Most old dogs, untrained, can run most humans into the ground.

2. Humans try to lose weight be running. This is because they expend so much more energy running than they do walking. The average person could walk a marathon if they had to. But, the average person cannot run half that distance.

3. Anatomy. Humans as compared to other primates, have large, high gluteal muscles (butt muscles). In gorillas, for instance, these gluteal muscles act more like human leg biceps. But in humans, they draw the femur backward and at the same time exert tension on the pelvis and spine, keeping the body erect. Jogging hardly activates the gluteal muscles at all. On the other hand, walking activates this very large, very human muscle completely. In fact, walking uphill is about as good as it gets besides deadlifts. If the basic human movement were jogging, we would not need such gluteal muscles as we have. The ablility to long-distance walk, untrained, and with a minium of energy expendature, is the basic human form of motion.

Tuor
Friday, November 19th, 2004, 04:11 AM
This whole article is flawed by the assuptions riddled throughout. The Lamarkian theory that exterior conditions or actions form the human species is untrue. The correct assumption would be under a Darwinian model where humans with specific genes to become upright survive and are long distance runners. The humans with genes that do not prove adequate to survive are killed, simple as that.

morfrain_encilgar
Friday, November 19th, 2004, 09:21 AM
Reasons Humans are not runners, jogger, trotters, etc.

1. Think your a runner, try keeping up with any old dog. Most old dogs, untrained, can run most humans into the ground.

2. Humans try to lose weight be running. This is because they expend so much more energy running than they do walking. The average person could walk a marathon if they had to. But, the average person cannot run half that distance.

3. Anatomy. Humans as compared to other primates, have large, high gluteal muscles (butt muscles). In gorillas, for instance, these gluteal muscles act more like human leg biceps. But in humans, they draw the femur backward and at the same time exert tension on the pelvis and spine, keeping the body erect. Jogging hardly activates the gluteal muscles at all. On the other hand, walking activates this very large, very human muscle completely. In fact, walking uphill is about as good as it gets besides deadlifts. If the basic human movement were jogging, we would not need such gluteal muscles as we have. The ablility to long-distance walk, untrained, and with a minium of energy expendature, is the basic human form of motion.

Bramble and Lieberman point out that when galloping, dogs can outrun humans, but in endurance running, dogs (or at least African hunting dogs) trot, not gallop. They also discuss the energetics of endurance runing in Homo. "The one category in which humans perform poorly compared to many quadrupeds is the energetic cost of running. The massadjusted COT of human running is about 50% higher than a typical mammal, including other primates. Compared to the only value measured for a chimpanzee (a 17.5-kg juvenile), human running is 25% less costly in absolute terms, but about 10% more costly when adjusted for body mass. Interestingly, other endurance cursors such as wolves and African hunting dogs also have high massadjusted COT relative to the average mammal. One important characteristic of human ER may be its range of accessible economical speeds. Horses have U-shaped COT curves with narrow ranges of preferred speeds for trotting and galloping and gait transitions that minimize cost, thereby achieving an effectively flat COT curve that excludes many speeds within the aerobic range. It is not known whether other quadrupedal cursors such as dogs have U-shaped COT curves, but human runners differ from horses in employing a single gait, with a flat COT curve at all but the fastest endurance speeds. Like another group of cursorial bipeds, kangaroos and wallabies, humans are thus able to adjust running speed continuously without change of gait or metabolic penalty over a wide range of speeds. Further research is necessary to determine whether other cursors are capable of such a broad range of economic speeds."

The gluteus maximus is mentioned here as an adaptation to endurance running and they claim it isn't an adaptation to long distance walking.
"Yet walking alone cannot account for many of the other derived features in Table 1 because the mass-spring mechanics of running, which differ fundamentally from the pendular mechanics of walking, require structural specializations for energy storage and stabilization that have little role in walking. Such specialized structures include: an extensive system of springs in the leg and foot that effectively store and release significant elastic energy during running; hypertrophied gluteus maximus and spinal extensor muscles that contract strongly to stabilize the trunk in running but not walking; and an elongate, narrow waist in combination with a low, wide, decoupled shoulder girdle that have an essential stabilizing function only in running."

I hope this is interesting.