Google+ Badge

Monday, December 2, 2013

Why Does Man War? The Shoulder Bone Connection to the Warrior Mentality

I have become a huge fan of "Big History," a current series on Channel H2 of the A&E Television Network. Watching each episode opens new horizons of interest for an old codger like me. Historian David Christian says the series takes its title from a coinage to describe an approach to history that draws on many disciplines and is less interested in wars and monarchs than it is in the way events are connected thematically and even molecularly, all the way back to the Big Bang.

I have always loved history, but this study teaches history in connections not evident on the traditional timeline. Christian explains, "By weaving science into the core of the human story, Big History takes familiar subjects and gives them a twist that will have you rethinking everything from the Big Bang to today’s headlines. The series creates an interconnected panorama of patterns and themes that links history to dozens of fields including astronomy, biology, chemistry, and geology."

Big History crisscrosses through time and space to examine these surprising connections and unexpected twists that have resulted in our world today. By exploring popular items such as cell phones and airplanes and natural phenomena such as mountains and salt, each episode of the series looks at a topic from a “Big History” perspective. I think the episodes are fascinating and novel.

Click on this site for the "Big History" homepage and be sure to watch each episode:

 "Big History" of the Human Shoulder

One interesting study is the human shoulder. It is widely held by anthropologists, anatomists, and archaeologists that the unique structure of the shoulder altered the course of human evolution by giving us survival skills we never could have imagined without it.

"Because it's pointing straight out," says David Green, an anthropologist at George Washington University who studies the evolution of the shoulder, "our arms are allowed to just kind of hang freely, and then we can flex our arms at the elbow and have our hands out front, and that's useful for manipulation. In apes, the joint actually points almost toward the ceiling."

The shoulder of the ape is great for hanging from a tree, but not so good for a creature that walks on two legs.

Enter human evolution.

Humans became unique among living primates by walking bipedally -- on two feet. This is humans' chief mode of locomotion. An upright posture also freed their hands up for using tools, one of the key factors behind humans' domination of the planet.

Evolution created many changes in the shoulder. Early on, the joint descended lower on the human chest. For a while, the shoulder-blade was more on the side, over the rib cage. Then, it moved onto the back.

Anatomists contend even after early humans left the trees altogether -- a little over 2 million years ago -- the shoulder wasn't settled. The next stage involved a change with limited range of motion more suited for making tools than for throwing objects.

In another 2 million years or so, the collar bone lengthened and the joint moved to the horizontal position we have now. When these changes occurred, the shoulder gave us a critical novel ability -- the ability to throw.

Over time and with much practice, throwing with speed and accuracy became monumental achievements for early humans. That set us apart. Yes, other species like chimpanzees can throw objects, but at a maximum speed of about 20 miles per hour -- one-third the speed of a 12-year-old Little League pitcher.

This image shows differences in the position of the shoulder between chimpanzees (left) 
and humans (right). These differences can be seen in both the muscular anatomy
 and in the bony anatomy of the scapula (shoulder blade).

Neil Roach, a postdoctoral scientist at George Washington University's Center for the Advanced Study of Hominid Paleobiology in Washington, D.C., confirms from study that humans are the only species that can throw with great speed and precision. The anatomical changes to the shoulder, arm and torso likely bolstered the hunting prowess and defense capabilities of our extinct human ancestors.

(Neil T. Roach, Madhusudhan Venkadesan, Michael J. Rainbow, Daniel E. Lieberman. "Elastic Energy Storage in the Shoulder and the Evolution of High-Speed 
Throwing in Homo." Nature, 2013; 498)

Roach's study is the first to suggest a link between a human's incredible throwing ability and the critical evolutionary shifts made possible by our ancestors' increased hunting. It is also the first to demonstrate the use of elastic energy in the human arm.

"When humans throw, we first rotate our arms backwards away from the target," Roach explains. "It is during this 'arm-cocking' phase that humans stretch the tendons and ligaments crossing their shoulder and store elastic energy. When this energy is released, it accelerates the arm forward, generating the fastest motion the human body produces, resulting in a very fast throw."

(Denise Chow. Throwing Ability, Human Evolution Linked In New Research Involving College Baseball Players. LiveScience in The Huffington Post. June 27, 2013)

The secret of the modern shoulder is its ability to move the arm in almost any direction, even behind the back. That, combined with other early human traits, enabled us to gain great powers. Co-author of the "Elastic Energy" study and Harvard professor of biological sciences Daniel Lieberman says:

"The ability to throw was one of a handful of changes that enabled us to become carnivores, which then triggered a host of changes that occurred later in our evolution. If we were not good at throwing and running and a few other things, we would not have been able to evolve our large brains, and all the cognitive abilities such as language that come with it. If it were not for our ability to throw, we would not be who we are today."

And the Shoulder "Bone" Is Connected to the War "Bone"

Combine the extraordinary shoulder with powerful human wrist and legs, and the ability to war becomes possible. John Shea, an archaeologist at Stony Brook University in New York who specializes in the history of weaponry, explains, "We have a wrist that can move like a whip, that can accelerate through throwing." "And your gluteus muscles — you know, your rear end, your thighs, your calves — these are things that make for good running, but they also make for good throwing."

What did man first throw? Probably rocks. But rocks weren't good weapons, especially against fast-moving prey. Shea says, "Best-case scenario, you've annoyed it," he says. "Worst-case scenario, this is one of these animals that deals with annoying primates by trying to stomp them into paste."

So humans invented wooden spears good for a maximum distance of about 30 yards. The oldest we've found were discovered in Germany. They are about 9 feet long, date back 400,000 years and were probably made by Neanderthals. Shea thinks these earliest spears were not much good for throwing, and instead were used more as lances.

But humans eventually discovered physics. If we could make our arms even longer, our throwing speed would increase. This discovery led to something called an atlatl that became a catapult for the arm. It's a slender, 2-foot length of wood, really a long, flexible dart that attaches to the end of a rod, which is strapped to the hand. The name comes from the Aztecs, who were very proficient with this spear-thrower.

Humans threw the atlatl by stepping forward and basically flinging the dart forward with the arm and a flick of the wrist.  By throwing your arm forward and flicking your wrist -- much in the same way a pitcher throws a baseball -- the dart shoots forward. The atlatl's flexibility allows energy from the throw to be stored in the dart to extend its range and lethality.
Even a throw of 150 feet is easy. One of Shea's students threw a dart the length of a football field.

(Christopher Joyce. "Armed And Deadly: Shoulder, Weapons Key To Hunt."
National Public Radio. August 02, 2010)

Weapons have destroyed civilizations and created new ones. All of these early weapons were extensions of shoulder-powered arms that kept enemies at greater distances. Early people used clubs, axes and spears In Australia, Aborigines hurled large boomerangs at their enemies.

By 3,500 BC, the Sumerians had created a highly civilised society that fought with chariots pulled by donkeys carrying archers who used bows and arrows.

Ancient Egyptian soldiers went into battle with spears, swords, axes, daggers and clubs or maces. They also used slings and bows and arrows. And, while the Greek warrior also carried swords and daggers, the Roman soldier carried a throwing spear known as the pilum and a short sword, the gladius. 

Then, of course, man learned to modify weapons and use mechanical "shoulders" to catapult various types of missiles. The Macedonians are believed to have been among the first to employ the catapult.

Then, the ancient propellant gunpowder, a Chinese invention, was introduced to the battlefields of Europe in the Middle Ages, thereby revolutionizing military strategy and introducing a whole new range of propellent-based ordnance. Gunpowder birthed even more deadly weapons as superior extensions of the shoulder-propelled, elementary rock -- cannons, rifles, machine-guns, tanks, battleships, war planes, rockets -- and eventually nuclear weapons.

"Big History" allows us to see the origins and the development of killing one another in war. By breaking down beginnings to a unique aspect of human anatomy -- the shoulder -- the series allows us to personalize a historical study in a manner that relates to the core of our own aggression and strength.

Who hasn't attempted to hurled an object at top speed? Even if you have never wielded a sword or shot a bullet in battle, you can understand how hitting flesh with the aid of a weapon can injure an enemy and prolong a war. Without a unique structure, humans would be forced to battle each other with primitive means.

Like so many things, man has learned to employ a tool for his advantage but also he has learned to use it in anger that could spell his potential annihilation. Perhaps our bodies have evolved greatly while our brain has stagnated. We may never learn before it is too late. All thanks to the amazing anatomy of the human shoulder, we have security and anxiety.

Post a Comment