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Archive for May 18th, 2014

The ability to throw accurately and at high velocity is a uniquely human trait. Other primates don’t even come close to our range, speed and aim. The chimpanzee, despite being immensely strong physically, can only throw at around 20 miles per hour and is not especially accurate. A twelve-year-old human child, on the other hand, can achieve more than three times that speed and a far sharper aim.

bushman-throwing-his-spear-at-a-winded-gemsbok

Deadly ranged attack – Bushman throwing a spear

The ability to kill from a distance wrought changes in the lifestyle and diet of early humans by revolutionising their capacity to hunt and to defend themselves. This not only had significant physical and developmental impacts, it also had social, psychological and moral implications as well. The capacity for a weaker individual to slay a stronger one without engaging in physical contact must have transformed early human social relations.

To be able to kill at a distance in the first place, early humans had to learn how to throw effectively, and this is something they did to a quite astonishing degree. The adaptations that enabled such fast and accurate throwing began to develop around two million years ago in Homo Erectus. The key changes, as identified recently in a study by Dr Neil Roach of George Washington University, were a wider waist, the lower position of the shoulders on the torso, and the capacity to twist the upper arm bone.

Humans vs chimps, throwing

Competitive advantage – Rotating arm, low shoulder, wide waist

Studies tracking the movement of American baseball players clearly illustrate how the human shoulder works like a slingshot by storing and releasing energy in its tendons and ligaments, allowing humans to hurl projectiles with incredible and deadly speed.

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Slingshot action – Baseball Pitcher

The action of throwing begins by first rotating the arm backwards, during which movement elastic energy is stored in the shoulder. When the arm rotates forward, that energy is released in a lightning motion and transferred through the arm to the missile.

Throwing diagram

The Art of Javelin Throwing

It is hardly surprising that this throwing action became so greatly refined and specialised, considering the enormous advantages that it offered. Indeed, one could argue that learning to throw quickly and accurately drove human evolution more powerfully than any single factor outside of upright walking and language. The morphology of organisms is determined by a number of environmental factors, and one of the most key is how they acquire their food and defend themselves. Hence long beaks and tongues for dipping into flowers; huge teeth for grinding bone; incredible speed for chasing or fleeing; sharp claws for climbing or rending flesh, venomous bites for attack or defence – the diet and the nature of external threats drives the design.

chimpanzee with machine gun

This never happened…

If you studied the morphology of hominids over the last two million years and asked, how do these creatures acquire food and how do they defend themselves? – the most obvious answers would be by running, climbing and throwing. Focussing on diet, we then might ask – which of these techniques provide the most protein? – and throwing is the obvious answer. Those more capable of throwing not only made considerably better hunters and had a wider variety of meat available to them, they were also better adapted to seeing off rivals in a dispute. Once humans began to rely on throwing as a key hunting technique, natural selection ensured that those better adapted to throwing passed on their genes.

Consider how natural the inclination is for people to practise throwing and to gain pleasure from it. Just as other animals chase, spar and wrestle in play as a kind of innate training program for skills they will need in adulthood, so almost all human children practise throwing from a young age and derive immense pleasure and satisfaction from their accuracy and skill. We are designed to throw – it is the only explanation as to why we are so good at it. Once early humans began to hurl rocks and spears, there was no looking back – it was, quite simply, the best means by which to acquire rich sources of protein.

Grass Silhouette

Designed to Throw – It’s a human thing

Being able to take down prey at longer range meant access to a great deal more meat, providing more fuel for growing brains and supporting larger social groups. The skill itself must have driven brain development through the complex calculations required to judge a throw – distance, angle, height, wind-speed, tracking the prey’s movement and knowing exactly when to release. The ability to make aerodynamic spears, or choose the most effective stones must also have called upon significant brain power and encouraged manual dexterity.

The range and variety of habitats available to early humans would also have changed dramatically. No longer required to stay near rich sources of fruit and vegetables, or to use the cover of the woods to surround and ambush prey, early humans were free to enter new habitats, acquiring their food through long-ranged attacks on the herds grazing the savannahs.

The point at which early humans first began to rely on missile weapons has long been debated by archaeologists. Whereas the evolutionary adaptations begin to appear almost two million years ago, archaeology can only provide much more recent evidence for the use of throwing spears, with dates ranging from less than 100,000 years ago, to half a million years. Indirect evidence derived from impact fractures on spear tips suggest people were throwing spears at least as far as 500,000 years ago, but this interpretation is widely disputed and it is difficult to determine conclusively whether spears were thrust or thrown. The failure of wood to preserve well means we lack sufficient evidence and, as the dictum goes, absence of evidence is not evidence of absence.

Chimpanzees are well known for using a variety of simple tools. Poking sticks into ant and termite nests to collect insects, breaking nuts with rocks, and, it seems, even attempting to spear smaller primates with sharp sticks.

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Chimpanzee fishing for termites

This latter behaviour is, evidentially, rare, and chimpanzees are not known for throwing spears or using them in combat or hunting. Yet it doesn’t take much imagination to consider that if an ancestor with whom we parted ways some seven and a half million years ago uses such technology, then early humans might have taken the sharp stick a few steps further and started throwing them at creatures. On these grounds some anthropologists have suggested that hominids may have been using spears as weapons as early as five million years ago.

Whatever questions may hang over the archaeological evidence, it seems the only place we need look to determine when early humans began to use throwing as a principal means of hunting is the biology. If the adaptations were there two million years ago, then surely this is because early humans were increasingly throwing things two million years ago – it’s the only logical explanation. It is hardly likely to have just been for play, or courtship – the most logical driver is the benefits it offered in food acquisition and self-defence. As to what those early humans were throwing, it is hard to be sure. They likely began with rocks, possibly for dislodging things from trees, before graduating to more refined and aerodynamic missiles.

chimp with rock tool

Chimp with simple stone tool

The huge competitive advantage offered by this skill ensured that humans were able to dominate their environment. It may also have played a significant role in developing the codes of ethics and morality which kept inter and intra-clan strife to a minimum. Dominant males could no longer rely on brute strength and intimidation alone to see off rivals. The knowledge that a weaker, less dominant individual – male or female – could, through a carefully aimed spear, assassinate them, would have transformed the social landscape. More tact, more consideration, more rigid rules might well have emerged in the wake of developing such deadly capability.

chimp with stick

I wonder what will happen if I throw this…

From the humble rock and primitive throwing spear, humans later took their ranged attacks to new heights through the development of better spears, then spear-throwers – Atlatls and Woomeras – and ultimately, bows and arrows, for which the earliest archaeological evidence dates to roughly 13,000 years ago. Some have suggested that these technological advances might in part explain how Homo sapiens outcompeted Neanderthals, but, like so many theories on that front, it is based on a number of assumptions and guesses. Even without the use of spear-throwing implements, which have been shown in tests to have an effective, accurate range of between 45-55 metres, with a maximum range considerably longer, it is possible to hurl a spear a significant distance.

aboriginal spear

The Woomera and Atlatl (spear throwers) dramatically increase velocity

The Olympic javelin record is just under a hundred metres, and whilst no one would suggest such ranges were achievable or desirable with prehistoric weapons, light, wooden spears can be deadly at tens of metres, allowing the hunter to keep a very significant gap between prey – or predator for that matter – especially when the prey failed to perceive that such a distant human could be a threat.

Whatever the case, the development of throwing is one of the main reasons we are here today. It is one of our most refined skills, and for millennia, likely for millions of years, it remained our species’ preferred means of hunting and acquiring food. That we are so good at throwing is no accident – it is simply natural selection favouring the genes of the better hunters. The preying mantis uses lightning speed, the snake has deadly venom, the honeybee favours a suicidal sting and we humans have missiles – that’s just how we roll.

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