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inside reading 4, 1- were humans born to run?

1- were humans born to run?

Compared to cheetahs, whose bursts of speed reach 70 miles per hour, or migrating wildebeests that roam over 2,000 miles a year, we humans must seem lead-footed homebodies. As big as we are, we cannot seem to catch a cat or a mouse or even a chicken unless we can corner it or trick it.

But has our natural envy of a few fleet- footed species or our clumsiness in catching nimble escape artists caused us to underestimate ourselves? University of Utah biologist Dennis Bramble and Harvard University paleoanthropologist1 Daniel Lieberman think so. In fact, they maintain that decades of research indicates that humans are very good runners indeed—perhaps the best in the world—when the distance gets long and the weather gets hot.

A: HOT TO TROT

To understand how they can make this claim, let's consider what humans can do. The very best long-distance runners can run five-minute miles for several hours. These efforts are amazing achievements, but even the casual jogger can often keep up an eight to ten minute a mile pace for several miles. Only a few animals of similar weight—large dogs, hyenas, wolves, and wildebeests—are capable of maintaining such speeds, and actually prefer to trot a bit slower. Even a thousand-pound horse will not cover long distances any faster than a good recreational jogger.

And in hot weather, humans may hold a decided advantage. One of the most incredible feats of human endurance is the annual Badwater-to-Mt. Whitney run in the United States. The race begins in Death Valley, California, at an elevation 285 feet below sea level, in July, the hottest month of the summer. The runners run 135 miles, crossing several mountain ranges with a cumulative elevation gain of 13,000 feet, and finish at an elevation of 8,360 feet at the Whitney Portal trailhead, about halfway up the 14,440-foot mountain. Each year approximately 75 men and women enter the race with 60-80% finishing within 60 hours and with the winning time usually well under 30 hours. Despite temperatures reaching

130°F, there have been no fatalities so far. These men and women can probably outrun any animal on the planet.

What makes it possible for these people to undergo such an ordeal? It turns out that humans are beautifully designed to run long distances in hot weather. Long-distance running requires the ability to keep from overheating, and we humans have several advantages in this regard. First, we release heat by sweating through millions of sweat glands rather than through panting. And because we have no fur, our sweat evaporates quickly. Our upright posture also helps immensely by exposing less area to direct sunlight and more surface area to the cooling effect of the wind we create as we run. We excel at keeping cool, while most other animals simply cannot shed heat fast enough to run long distances.

But cooling is not enough to explain our speed over long distances. A second advantage is our long stride. When Professor Bramble filmed his student David Carrier running alongside a horse moving at an easy gallop, he noticed that Carrier took fewer strides than the horse, indicating that Carrier's strides covered more distance than the horse's. Bramble was surprised by this and began considering what elements of human biomechanics make this possible. Working with Daniel Lieberman at Harvard, he realized that humans, like horses and rabbits, can run without their heads bobbing up and down due to a piece of anatomy, the nuchal ligament, which links the head to the spine. This tendon-like band is not involved in walking, suggesting that it is an important anatomical feature for a species that at one time needed to run. not walk, to find its dinner.

B: A SPRING IN OUR STEP

In fact, walking, it turns out, is a distinctively different motion than running. When walking, the heel hits the ground first, the leg straightens, and the body lurches forward a bit. As the weight transfers to the ball of the foot, the arch stiffens and then pushes the body forward, with the other foot moving forward to keep the stride going. With running, the legs become large springs. You land more heavily on the arch of the foot and bend your knee, which causes the body's center of gravity to lower. The force from this hard landing is captured by the tendons of the foot and leg, particularly the calf muscles, and you spring forward as the tendons recoil. According to Bramble, these huge, springy tendons are not necessary for walking.

Huge, springy tendons explain where the energy comes from, but how do humans maintain their balance and keep from falling over? All other two-legged animals that run fast, such as kangaroos and roadrunners, have large tails that serve as a counterweight to keep the animal balanced. Humans are obviously tailless, so how do they do it? Motion studies of runners on treadmills offer clues. Instead of a tail. we have a very large muscle, the glutew maximus, that connects our hips to our lower back. This muscle does not do much when we walk, but it works very hard when we run. Its role. it seems, is to act like a brake on our torso to keep it from lurching too far forward when our foot hits the ground. Other anatomical features that facilitate running are our long necks and our shoulders. We are able to twist our shoulders without moving our head, allowing us to pump our arms as another steadying mechanism that helps counterbalance our head and keep it upright.

There is no doubt, then, that humans are able to run, but why? Today most people are sedentary and run solely for pleasure or sport. Could it be that in our prehistoric past long- distance running was necessary for survival? Sprinting fast allows an animal to drag down prey or escape a predator, but why would an ability to sustain a long run through hot weather be necessary? To hunt, perhaps? But didn't prehistoric humans hunt by sneaking up on animals and spearing or clubbing them? That certainly seems more efficient than chasing an animal for miles until it drops from heat exhaustion. Or is our ability to run a byproduct6 of some other ability? It seems running muscles also help us stand up quickly and climb things, and certainly our springiness helps us fight more effectively.

Any conclusions we draw at this point are preliminary. But knowing that we can run long distances may point us in the right direction for further study. It gives us clues as to how prehistoric humans lived. Perhaps adult hunters needed to travel long distances to track a herd and return before dark. Humans do not see well at night and by running could extend their hunting range without constantly breaking camp and uprooting a family or village. Perhaps they needed to move quickly in order to reach prey killed by other animals and join in on the feast. Getting quickly to distant food sources before animal rivals could reach them is one clear advantage of our running ability.

The debate undoubtedly will continue, with those who dislike sweaty activity naturally skeptical of any prehistory that forced us to move out of the shade. But those eighty or so people who attempt the Badwater-to-Mt. Whitney run and the hundreds of thousands who run 26.2-mile marathons each year make it difficult to deny the obvious—some humans, if not all, are definitely born to run.


1- were humans born to run? 1- ¿los humanos nacieron para correr? 1- les humains sont-ils nés pour courir ? 1- 人間は走るために生まれてきたのか？ 1- Os seres humanos nasceram para correr? Люди рождены для того, чтобы бегать?

Compared to cheetahs, whose bursts of speed reach 70 miles per hour, or migrating wildebeests that roam over 2,000 miles a year, we humans must seem lead-footed homebodies. Comparados con los guepardos, cuya velocidad alcanza los 110 kilómetros por hora, o con los ñus migratorios, que recorren más de 3.000 kilómetros al año, los humanos parecemos unos pies de plomo. As big as we are, we cannot seem to catch a cat or a mouse or even a chicken unless we can corner it or trick it. Por grandes que seamos, parece que no podemos atrapar a un gato o a un ratón, ni siquiera a una gallina, a menos que podamos acorralarlos o engañarlos.

But has our natural envy of a few fleet- footed species or our clumsiness in catching nimble escape artists caused us to underestimate ourselves? Pero, ¿acaso nuestra envidia natural de algunas especies de pies ligeros o nuestra torpeza para atrapar a ágiles artistas de la evasión nos ha llevado a subestimarnos? University of Utah biologist Dennis Bramble and Harvard University paleoanthropologist1 Daniel Lieberman think so. Así lo creen el biólogo de la Universidad de Utah Dennis Bramble y el paleoantropólogo de la Universidad de Harvard1 Daniel Lieberman. In fact, they maintain that decades of research indicates that humans are very good runners indeed—perhaps the best in the world—when the distance gets long and the weather gets hot. De hecho, afirman que décadas de investigación indican que los humanos son muy buenos corredores -quizá los mejores del mundo- cuando la distancia se alarga y el tiempo se calienta.

A: HOT TO TROT A: HOT TO TROT

To understand how they can make this claim, let's consider what humans can do. Para entender cómo pueden hacer esta afirmación, consideremos lo que pueden hacer los humanos. The very best long-distance runners can run five-minute miles for several hours. Los mejores corredores de fondo pueden correr kilómetros de cinco minutos durante varias horas. These efforts are amazing achievements, but even the casual jogger can often keep up an eight to ten minute a mile pace for several miles. Estos esfuerzos son logros asombrosos, pero incluso el corredor ocasional puede mantener a menudo un ritmo de ocho a diez minutos por milla durante varios kilómetros. Only a few animals of similar weight—large dogs, hyenas, wolves, and wildebeests—are capable of maintaining such speeds, and actually prefer to trot a bit slower. Sólo unos pocos animales de peso similar -perros grandes, hienas, lobos y ñus- son capaces de mantener esas velocidades y, de hecho, prefieren trotar un poco más despacio. Even a thousand-pound horse will not cover long distances any faster than a good recreational jogger. Ni siquiera un caballo de mil libras recorrerá largas distancias más rápido que un buen corredor de recreo.

And in hot weather, humans may hold a decided advantage. Y en climas cálidos, los humanos pueden tener una ventaja decisiva. One of the most incredible feats of human endurance is the annual Badwater-to-Mt. Una de las hazañas más increíbles de la resistencia humana es la carrera anual Badwater-to-Mt. Whitney run in the United States. Whitney en Estados Unidos. The race begins in Death Valley, California, at an elevation 285 feet below sea level, in July, the hottest month of the summer. La carrera comienza en el Valle de la Muerte, California, a una altitud de 285 pies por debajo del nivel del mar, en julio, el mes más caluroso del verano. The runners run 135 miles, crossing several mountain ranges with a cumulative elevation gain of 13,000 feet, and finish at an elevation of 8,360 feet at the Whitney Portal trailhead, about halfway up the 14,440-foot mountain. Los corredores recorren 135 millas, cruzando varias cadenas montañosas con un desnivel acumulado de 13.000 pies, y terminan a una altitud de 8.360 pies en el Whitney Portal trailhead, aproximadamente a mitad de camino de la montaña de 14.440 pies. Each year approximately 75 men and women enter the race with 60-80% finishing within 60 hours and with the winning time usually well under 30 hours. Cada año se inscriben en la carrera unos 75 hombres y mujeres, de los cuales entre el 60 y el 80% la terminan en menos de 60 horas, y el tiempo del vencedor suele estar muy por debajo de las 30 horas. Despite temperatures reaching A pesar de las temperaturas

130°F, there have been no fatalities so far. 130°F, no ha habido víctimas mortales hasta ahora. These men and women can probably outrun any animal on the planet. Estos hombres y mujeres probablemente puedan correr más que cualquier animal del planeta.

What makes it possible for these people to undergo such an ordeal? ¿Qué hace posible que estas personas pasen por semejante calvario? It turns out that humans are beautifully designed to run long distances in hot weather. Resulta que los humanos están magníficamente diseñados para correr largas distancias cuando hace calor. Long-distance running requires the ability to keep from overheating, and we humans have several advantages in this regard. Las carreras de larga distancia requieren la capacidad de evitar el sobrecalentamiento, y los seres humanos tenemos varias ventajas en este sentido. First, we release heat by sweating through millions of sweat glands rather than through panting. En primer lugar, liberamos calor sudando a través de millones de glándulas sudoríparas en lugar de jadear. And because we have no fur, our sweat evaporates quickly. Y como no tenemos pelo, nuestro sudor se evapora rápidamente. Our upright posture also helps immensely by exposing less area to direct sunlight and more surface area to the cooling effect of the wind we create as we run. Nuestra postura erguida también ayuda enormemente al exponer menos superficie a la luz solar directa y más superficie al efecto refrigerante del viento que creamos al correr. We excel at keeping cool, while most other animals simply cannot shed heat fast enough to run long distances. Somos excelentes para mantenernos frescos, mientras que la mayoría de los demás animales simplemente no pueden deshacerse del calor lo suficientemente rápido como para correr largas distancias.

But cooling is not enough to explain our speed over long distances. Pero el enfriamiento no basta para explicar nuestra velocidad a grandes distancias. A second advantage is our long stride. Una segunda ventaja es nuestra larga zancada. When Professor Bramble filmed his student David Carrier running alongside a horse moving at an easy gallop, he noticed that Carrier took fewer strides than the horse, indicating that Carrier's strides covered more distance than the horse's. Cuando el profesor Bramble filmó a su alumno David Carrier corriendo junto a un caballo que se desplazaba a galope fácil, observó que Carrier daba menos zancadas que el caballo, lo que indicaba que las zancadas de Carrier cubrían más distancia que las del caballo. Bramble was surprised by this and began considering what elements of human biomechanics make this possible. Bramble se sorprendió por ello y empezó a considerar qué elementos de la biomecánica humana lo hacen posible. Working with Daniel Lieberman at Harvard, he realized that humans, like horses and rabbits, can run without their heads bobbing up and down due to a piece of anatomy, the nuchal ligament, which links the head to the spine. Trabajando con Daniel Lieberman en Harvard, se dio cuenta de que los humanos, como los caballos y los conejos, pueden correr sin que su cabeza se balancee arriba y abajo gracias a un trozo de anatomía, el ligamento nucal, que une la cabeza a la columna vertebral. This tendon-like band is not involved in walking, suggesting that it is an important anatomical feature for a species that at one time needed to run. Esta banda tendinosa no interviene en la marcha, lo que sugiere que se trata de una característica anatómica importante para una especie que en un tiempo necesitó correr. not walk, to find its dinner. no caminar, para encontrar su cena.

B: A SPRING IN OUR STEP B: UN RESORTE EN NUESTRO PASO

In fact, walking, it turns out, is a distinctively different motion than running. De hecho, resulta que caminar es un movimiento claramente diferente al de correr. When walking, the heel hits the ground first, the leg straightens, and the body lurches forward a bit. Al caminar, el talón golpea primero el suelo, la pierna se estira y el cuerpo se inclina un poco hacia delante. As the weight transfers to the ball of the foot, the arch stiffens and then pushes the body forward, with the other foot moving forward to keep the stride going. A medida que el peso se transfiere a la bola del pie, el arco se endurece y empuja el cuerpo hacia delante, con el otro pie moviéndose hacia delante para mantener la zancada. With running, the legs become large springs. Al correr, las piernas se convierten en grandes muelles. You land more heavily on the arch of the foot and bend your knee, which causes the body's center of gravity to lower. Se apoya más en el arco del pie y se dobla la rodilla, lo que hace bajar el centro de gravedad del cuerpo. The force from this hard landing is captured by the tendons of the foot and leg, particularly the calf muscles, and you spring forward as the tendons recoil. La fuerza de este duro aterrizaje es captada por los tendones del pie y la pierna, en particular los músculos de la pantorrilla, y usted salta hacia delante a medida que los tendones retroceden. According to Bramble, these huge, springy tendons are not necessary for walking. Según Bramble, estos tendones enormes y elásticos no son necesarios para caminar.

Huge, springy tendons explain where the energy comes from, but how do humans maintain their balance and keep from falling over? Los enormes y elásticos tendones explican de dónde procede la energía, pero ¿cómo mantienen el equilibrio los seres humanos y evitan caerse? All other two-legged animals that run fast, such as kangaroos and roadrunners, have large tails that serve as a counterweight to keep the animal balanced. Todos los demás animales de dos patas que corren rápido, como los canguros y los correcaminos, tienen grandes colas que sirven de contrapeso para mantener el equilibrio del animal. Humans are obviously tailless, so how do they do it? Los humanos no tienen cola, ¿cómo lo hacen? Motion studies of runners on treadmills offer clues. Los estudios sobre el movimiento de los corredores en cintas de correr ofrecen pistas. Instead of a tail. En lugar de una cola. we have a very large muscle, the glutew maximus, that connects our hips to our lower back. tenemos un músculo muy grande, el glúteo mayor, que conecta nuestras caderas con la parte baja de la espalda. This muscle does not do much when we walk, but it works very hard when we run. Este músculo no hace mucho cuando caminamos, pero trabaja mucho cuando corremos. Its role. Su papel. it seems, is to act like a brake on our torso to keep it from lurching too far forward when our foot hits the ground. parece, es actuar como un freno en nuestro torso para evitar que se tambalee demasiado hacia delante cuando nuestro pie toca el suelo. Other anatomical features that facilitate running are our long necks and our shoulders. Otras características anatómicas que facilitan la carrera son nuestros cuellos largos y nuestros hombros. We are able to twist our shoulders without moving our head, allowing us to pump our arms as another steadying mechanism that helps counterbalance our head and keep it upright. Somos capaces de girar los hombros sin mover la cabeza, lo que nos permite bombear los brazos como otro mecanismo de estabilización que ayuda a contrapesar la cabeza y mantenerla erguida.

There is no doubt, then, that humans are able to run, but why? No cabe duda, pues, de que los humanos son capaces de correr, pero ¿por qué? Today most people are sedentary and run solely for pleasure or sport. Hoy en día, la mayoría de las personas son sedentarias y corren únicamente por placer o por deporte. Could it be that in our prehistoric past long- distance running was necessary for survival? ¿Podría ser que en nuestro pasado prehistórico correr largas distancias fuera necesario para sobrevivir? Sprinting fast allows an animal to drag down prey or escape a predator, but why would an ability to sustain a long run through hot weather be necessary? Esprintar rápido permite a un animal arrastrar a una presa o escapar de un depredador, pero ¿por qué sería necesaria la capacidad de mantener una carrera larga cuando hace calor? To hunt, perhaps? ¿A cazar, quizás? But didn't prehistoric humans hunt by sneaking up on animals and spearing or clubbing them? Pero, ¿no cazaban los humanos prehistóricos acercándose sigilosamente a los animales y alanceándolos o apaleándolos? That certainly seems more efficient than chasing an animal for miles until it drops from heat exhaustion. Desde luego, parece más eficaz que perseguir a un animal durante kilómetros hasta que caiga exhausto por el calor. Or is our ability to run a byproduct6 of some other ability? ¿O nuestra capacidad de correr es un subproducto6 de alguna otra capacidad? It seems running muscles also help us stand up quickly and climb things, and certainly our springiness helps us fight more effectively. Parece que los músculos de la carrera también nos ayudan a ponernos de pie rápidamente y a trepar, y sin duda nuestra elasticidad nos ayuda a luchar con más eficacia.

Any conclusions we draw at this point are preliminary. Cualquier conclusión que saquemos en este punto es preliminar. But knowing that we can run long distances may point us in the right direction for further study. Pero saber que podemos correr largas distancias puede apuntarnos en la dirección correcta para seguir estudiando. It gives us clues as to how prehistoric humans lived. Nos da pistas sobre cómo vivían los humanos prehistóricos. Perhaps adult hunters needed to travel long distances to track a herd and return before dark. Quizá los cazadores adultos necesitaban recorrer largas distancias para rastrear una manada y regresar antes del anochecer. Humans do not see well at night and by running could extend their hunting range without constantly breaking camp and uprooting a family or village. Los humanos no ven bien de noche y corriendo podían ampliar su radio de caza sin levantar constantemente el campamento y desarraigar a una familia o una aldea. Perhaps they needed to move quickly in order to reach prey killed by other animals and join in on the feast. Tal vez necesitaban moverse con rapidez para alcanzar presas matadas por otros animales y unirse al festín. Getting quickly to distant food sources before animal rivals could reach them is one clear advantage of our running ability. Llegar rápidamente a fuentes de alimento distantes antes de que los animales rivales pudieran alcanzarlas es una clara ventaja de nuestra capacidad para correr.

The debate undoubtedly will continue, with those who dislike sweaty activity naturally skeptical of any prehistory that forced us to move out of the shade. No cabe duda de que el debate continuará, ya que a quienes no les gusta la actividad sudorosa son naturalmente escépticos ante cualquier prehistoria que nos obligara a salir de la sombra. But those eighty or so people who attempt the Badwater-to-Mt. Pero esas ochenta personas que intentan el Badwater-to-Mt. Whitney run and the hundreds of thousands who run 26.2-mile marathons each year make it difficult to deny the obvious—some humans, if not all, are definitely born to run. Whitney Run y los cientos de miles de personas que corren maratones de 26,2 millas cada año hacen difícil negar lo obvio: algunos seres humanos, si no todos, han nacido definitivamente para correr.