Veronica Waweru shares some of her recreated arrows with Alan as Larry Engel and Peter Miller capture the video and audio and Producer Graham Chedd looks on. Credit: Maggie Villiger

By Veronica Waweru

Ancient human inventions always engender debate among paleoanthropologists. Models are developed to explain the appearance and timing of new “novel” technologies or behavior. I am no different from these researchers and harbor a fascination with the origin of the bow and arrow. This technology is central to discussions on the hunting abilities of ancients. Were they not-too-smart creatures that scavenged leftovers from big cats, did they only hunt docile animals or were they proficient hunters who brought down dangerous animals? These debates often also include comparisons of Homo sapiens of the last 200,000 years to their Neanderthal contemporaries. Often, the discussion pivots on whether early Homo sapiens were better hunters than Neanderthals. The evidence cited by most researchers suggests that our cold-adapted relatives in Eurasia were not such adept hunters – what with their rodeo-rider-type injuries and their large spears that would force them to engage prey face to face. The most damning evidence for Neanderthals’ technological ineptitude is their extinction – at least for those who do not believe that they interbred with Homo sapiens. But that is a different debate altogether!

Veronica holds a stone point that dates to 100,000 years ago.

Stone armatures or points are amongst the most durable artifacts found in the archaeological record. These were used to arm the business end of knives, javelins, stabbing spears, atlatls and the bow and arrow. All of the organic elements of these implements dating back to 200,000 years ago have decomposed, of course. We are left with the stone tips to determine what weaponry system they were part of. Here we apply laws of physics and ballistics, take copious measurements of the stone tips and attempt to extract ancient blood serum and fats from their edges to make our cases. Then we cite evidence of indigenous people who still use spears and arrows to hunt.

My work focuses on finding evidence of the bow and arrow using stone points from Cartwright’s site, located on the Kinangop plateau in Kenya. I have used most methods employed by researchers in the field but also went ahead and had replicas of the prehistoric tips made and hafted onto arrow shafts. We then shot them at sides of pork and a complete goat carcass (very humanely dispatched and used for food afterward). The results indicated that in terms of distance traveled and penetration, some of the points worked well as “arrowheads.”

Veronica examines the arrows of a modern hunter in Kenya while the Human Spark camera captures their exchange. Credit: Maggie Villiger

To any hunter, putting distance between yourself and prey that might potentially fight back is important. Here, arrows have an advantage over spears. Weapons also need to deliver lethal blows, induce massive bleeding or cause damage to internal organs. Penetration depth is therefore important. In a nutshell, we have a lightweight projectile weapon dating to approximately 100,000 years ago in east Africa! One that can be transported for long distances, the head easily replaced, and the arrow shot from a variety of positions and potentially by a group of hunters, without alerting prey. Modern hunters often add a cocktail of poisons to the shafts of their arrows. These are derived from plants (such as the arrow poison tree) that have wide distribution in Africa. Did prehistoric hunters use arrows to deliver poisons to quarry? We may never know because poisons are unlikely to survive that long.

If arrows could be used effectively against large dangerous prey, why not against our enemies? Here the gore starts – coalitionary violence against members of our own species. What might prehistoric people fight over? Perhaps not oil or ideology but scarce food resources during dry climatic conditions brought on by glacial cycles. Would such a weapon, when used in tandem with poisons, not threaten the very survival of a group if people took to shooting each other over resources?

After showing that prehistoric stone tools were likely used with the bow and arrow, I am now investigating the implications of this invention. Many researchers have argued that human aggression has a genetic substrate. I suspect that cultural mechanisms would have evolved to protect members of a social group from each other. I am presently studying poison-tipped arrow use in interethnic violence in Kenya. This will give insights into lethal violence between members of an ethnic group and non-members. 100,000 years ago, long before Hammurabi’s law or the Ten Commandants were in place, ancients may have had an unwritten — albeit tempered — Second Amendment. Thou shall posses and use poison tipped projectiles, but only on outsiders.

Veronica became the center of attention at the Kariokor Market in Nairobi when she showed up with our film crew. Here a vendor exhibits the modern arrows he sells there. Caption: Maggie Villiger

My fascination with the gore and science of ancient projectiles and poisons, led me to join the Human Spark film crew in Kenya last summer. I did some background work to find people to interview about bows and arrows and poisons. Metal-tipped arrows for sale were easy to find. The poison sources and makers were more elusive. Do you want to kill a stray dog? A person? Why not try bewitching them? The best answer I got was that only very old men made poisons, but they lived “very far away” and may not to want talk to women or strangers. So when the Human Spark crew arrived, I had but one contact who made bows and arrows for sale and who failed to persuade his great uncle to speak about poisons. Our first shooting site was a local market in downtown Nairobi. The crew appeared very much at ease among the throngs of curious crowds and open sewers. My favorite part of the whole event was getting pulled over by local policemen on our way out of Nairobi. They are notorious for taking bribes, but one look at the huge camera and they let us go. I almost dared them to ask for a bribe.

Next summer, I will get a big dummy camera to scare away corrupt traffic police, and endure more rides through potholed dirt roads to coax recipes of poison cocktails from unwilling old men of the Kamba ethnic group. The curiosity is intense and unrelenting. I blame it on a primordial curse – The Human Spark!

“Becoming Us” premieres January 6 on PBS.

A Spark or an Ember?

By John J. Shea, Anthropology Department, Stony Brook University

John Shea with some of his stone age technology. Photo: Larry Engel

Filming The Human Spark with Alan Alda led me to question some of the assumptions we make about the evolution of human uniqueness – the metaphorical “spark” in the title of this series.  Most anthropologists assume that the qualities that made humans unique evolved recently and only among members of our species, Homo sapiens.  But what if this assumption is an accident of history?  Might the things we think make us unique actually be characteristics we share with other hominins who are now extinct?  A spark can be the beginning of a fire, but it can also be the last ember of a conflagration.  What if our spark is not the start of something new, but rather the culmination of a long-running evolutionary trend?

In evolution, only differences matter.  The differences between humans and our nearest primate relatives, the chimpanzees, are not subtle.  We differ in locomotion, in how we use tools, in our diets, in how we get along with one another.  In virtually every way anthropologists care to make comparisons, we differ more from chimpanzees than chimpanzees differ from other apes.  Genetic studies suggest these differences accumulated over nearly 6 million years.  If all one had to work with were comparisons of the morphology, genetics and behavior of living species, one could not help but conclude that we are special, that we humans have a “spark” that chimpanzees and other apes do not.

But we know there is a fossil record for human evolution, and it tells a very different story.  Humans evolved in the Pleistocene Epoch (2.5 Million to 12,500 years ago).  This was a momentous period in the evolution of life on Earth.  It was a great time to be a hominin.  The term hominin refers to the group of bipedal primates that includes humans.  Two million years ago there were at least three major groups of hominins, Australopithecus, Paranthropus, and Homo, all living in Africa.  Each of these groups comprised at least two and almost certainly more distinct species.  For much of the Pleistocene, there was more than one human-like species walking the Earth at any one point in time.  As recently as 40,000 years ago, there were at least three, Neandertals in Europe, Homo sapiens in Africa and Asia, and Homo floresiensis in Indonesia.  Today there is only one hominin species, us.

Being the sole remaining contestant of “Survivor: Pleistocene” influences our ideas about our “human spark” and about the nature of human uniqueness.  Our “human spark” looks special to us because we cannot compare it directly to those of our extinct hominin relatives.  The evolutionary gulf between living apes and us is a recent evolutionary condition.  If one takes extinct hominins into account, the gulf between humans and apes will appear not so wide, because it would be populated by countless ape and hominin species.  Each species would have had its own “spark,” its own uniquely evolved characteristics, and those characteristics would differ with evolutionary distance.  Species with a recent common ancestor would be more similar to one another.  Our “human spark” would be very similar to that of the Neandertals, less similar to that of Homo floresiensis, and very different from that of Australopithecus.  Our “human spark” would still differ from those of living apes, but along a complex continuum of ape and hominin variation.

What caused the reduction of species in the Genus Homo?  The simple answer is that we do not know, but we can venture some well-founded hypotheses.  Climate change and habitat loss almost certainly played a role, as they do in recent animal extinctions.  Many early hominin fossils (particularly australopithecus and paranthropus) are found in woodland habitats.  Such woodlands have been losing ground to grasslands for the last two million years.  Predators may have played a role.  The carnivores that preyed on australopithecines and paranthropines were mostly solitary felids (large cats like leopards).  The Pleistocene witnessed the evolution of large social carnivores, like lions and wolves.  These carnivores may have caused problems for some hominin species, either preying on them directly or out-competing them for access to meat and fat from large animal carcasses.  Bad luck may have played a role, as well.  Neandertals lived in some of the coldest habitats ever occupied by primates during a period of rapid, near chaotic climate change.  Their extinction, though tragic, is not particularly surprising.

Paleoanthropologists have been strangely reluctant to consider the role of competition among hominin species in the evolution of the Genus Homo.  Yet, competition is the engine that drives evolution.  In evolutionary competition, your most formidable rivals are those to whom you are most closely related.  Homo sapiens’ evolutionary success must have come at the expense of other hominin species, most likely those closely related to us.  One can see proof of this in a pattern that occurs in the fossil record.  In region after region, the first appearance date of Homo sapiens fossils is closely correlated with the last appearance dates of other hominin species.  There appear to have been some places where other species “held their ground:” Neandertals in southern Spain, Homo floresiensis in the forests of Indonesia, but these are exceptions, and in neither case is there clear and convincing evidence for long-term, face-to-face encounters between our species and other hominins.

This is why I am skeptical about arguments that early Homo sapiens killed off the Neandertals and other hominins.  It is not that I think they were necessarily good-natured.  Their moral sentiments probably varied widely, just as ours do.  Rather, I think they just did not encounter other hominin species often enough for the benefits of sustained conflict to exceed the risks and costs.

So, why did Homo sapiens survive and other hominins become extinct?  One key to our “human spark” is our uniquely broad ecological niche.  An ecological niche is the network of predator-prey relationships between one species and other species.  In evolutionary competition, generalists (species with a complex niche) always beat specialists (species with a simple one).  Homo sapiens is the ultimate generalist.  We sustain ourselves on animal prey ranging from snails to elephants, on birds, fish, and countless plant foods.  Much of this niche breadth reflects recent innovations, such as agriculture and pastoralism.  I am increasingly convinced that there was an earlier “revolution” in our ancestral human niche, one underwritten by the use of projectile weaponry.  Projectile weapons, such as the bow and arrow are niche-broadening tools.  The same bow that can launch an arrow at a fish or rodent can bring down an elephant, when it is tipped with poison.  Projectile weaponry is uniquely human and culturally universal.   We are the only species that uses projectile weaponry, and no human society has ever abandoned its use.

In seeking the origins of human uniqueness, I think it is absolutely crucial for archaeologists to work out when and where humans began using projectile weaponry to broaden their ecological niche.  Right now, evidence in the form of stone points similar to recent arrowheads is strongest in equatorial Africa, the region in which Homo sapiens first evolved.  The strongest such evidence dates to between 50,000 to 100,000 years ago, but as noted in the Human Spark, new discoveries will almost certainly push these dates back further.  I do not think that projectile technology alone explains human uniqueness.  Nothing in evolution is that simple.  Yet, projectile weaponry is an interesting piece of our human evolutionary puzzle that has not received the scientific attention it deserves.

Some academics look down at television programming as “merely” entertainment.  I disagree.  If you take public money for your education (as I did), and expend such funds in your research (as I do), you have a moral obligation share the fruits of your studies as broadly and effectively as possible.  Far more people will view the Human Spark than will ever listen to my academic lectures or read any of my scientific papers.  The most effective way to show how scientific research about human evolution matters is by working with people like Alan and his colleagues to create a thought-provoking program like the Human Spark.

Photo by Aaron Logan

One of the ways The Human Spark investigates what makes us uniquely human is by looking at our closest living relatives, the other great apes. Scientists are attacking the question of how we became human from a number of new directions – in addition to analyzing the more traditional hard evidence of ancient fossils. This article in New Scientist magazine explains several ways researchers are gathering data from primate groups alive today to gain insights into early hominid evolution. Tune in to The Human Spark’s second episode to learn more. What do you think these kinds of inferences can add to our understanding of where we came from and how we became who we are?

• New Scientist: “Ape behavior reveals secrets of human evolution“

When Amanda Henry went through airport security in Washington on her way to Boston she made the inspector nervous when her bag revealed dental instruments – apparently the security officer hates going to the dentist. The officer may have been even more freaked out if she knew the teeth Amanda was on her way to clean with her dental picks belonged to a 100,000-year-old.

A very famous 100,000-year-old at that – at least in archeological circles. The teeth are still all neatly in place in a skull now at the Peabody Museum of Harvard University [tons of images here], where it has resided in secure climate-controlled storage since it was unearthed in the 1930s from a cave in Mount Carmel, in present-day Israel. We had met the skull the day before, when Dan Lieberman had arranged for it to be brought out of storage and introduced to Alan.

Known as Skhul 5, the skull is the oldest known human with almost modern features, and so plays a pivotal role in our story. He poses the central puzzle we’re trying to get to the bottom of: people looked like us apparently long before they started behaving like us – at least according to the commonly accepted view that the modern human mind – with what we are calling the Human Spark – didn’t evolve until tens of thousands of years after the owner of the Skhul skull and his like lived in the Middle East – most likely alongside, or at least at the same time as, their cousins the Neanderthals.

The Human Spark camera rolls while Amanda demonstrates her dental scraping techniques to Alan. Photo: Maggie Villiger

As we’d just been learning from Alison Brooks, it’s now looking increasingly likely that the Human Spark in fact started to glimmer much earlier in Africa, perhaps even before the ancestors of Skhul 5 made their way north. So archeologists would love to know as much as possible about how Skhul 5 lived. It was Alison who told us about Amanda, a student of hers at George Washington University, who – armed with her dental picks – was going to demonstrate to Alan how she’s figuring out what Skhul 5 ate.

After carefully removing the skull from its padded box, Amanda showed us how she very, very gently scrapes dental plaque from the skull’s molars (much more gently than your oral hygienist cleans yours).  Plaque, she explained, is the perfect material to preserve microfossils from the plants Skhul 5 ate – starch grains and tiny silica bodies called phytoliths that Amanda will be able to identify under the microscope and tell what plants they came from.

Amanda’s care in her scraping wasn’t only because, as she reminded us, the skull is priceless, but also because, “I have to leave some plaque behind in case somebody comes up with a different way for studying it in the future.”

Alan wanted to know if she poked around in his teeth, could she find out what he’s eaten.

Amanda: Well it depends, how good are you at brushing and flossing?

Alan: Oh just great, yes.

Amanda: I’ve actually done some experiments where you eat whatever you normally eat for breakfast, lunch and dinner. At the end of the day , you take one of these dental picks…

Alan: And you could say what the person had eaten?

Amanda: Some of it, sure.

Alan: No kidding.

Amanda: It’s quite easy. It’s not just in the plaque. It’s in any of the pellical, basically the scum that builds up on your teeth. As that hardens into plaque then it’s more permanently kept on your teeth. I don’t know, actually, how far back I’d be able to tell what you ate, whether I could just tell this morning what you had for breakfast, or what you had three weeks ago.

Fortunately for Amanda, and despite the astonishingly good shape of Skhul 5’s teeth, he lived a good long time before the invention of dental floss, so she has high hopes of discovering what he ate 100,000 years ago.

Alan summed up the reaction of all of us: “Astonishing.”

- Graham Chedd