The conflict between the need for food and becoming food has made predation one of the most pervasive and influential ecological mechanisms in the animal kingdom—the sharpest instrument in natural selection’s toolbox.67,68,69 Predation generates competition, not only between individuals, but also between species. And competition, as we know from Darwin, is the fuel that drives the natural selection engine.
Predation has been fundamental to the evolution of major adaptations like the cobra’s venom, the leopard’s stealth and the eagle’s aerial agility. It created insects that look like leaves, frogs with poisonous skin and fish that can change colour to match their background. It transformed massive terrestrial dinosaurs into petite flying birds and dog-sized mammals into blue whales. Predation gave sharks their optimum aerodynamic shape, porcupines their spines and skunks their terrible smell. It bestowed phenomenal sprint speed on cheetahs, equipped bees with their stings and rhinos with their thick skin.
Nowhere in nature do we see natural selection resulting in so much unbridled creativity as in predator and anti-predator adaptations. It goes beyond the ingenious techniques of camouflage mimicry we see in the insect world. The special colours and markings that warn off predators are equally ingenious. Predation produced complex strategies, elaborate traps and the sweetest perfumes to lure unsuspecting victims to their deaths. What could be more inventive than the Angler Fish dangling a tiny fishing rod from its head, complete with wriggling bait in its mouth to catch unsuspecting prey?
Given that selection pressure generated by predation has been indispensable to the evolution of a wide range of animals, from snails to whales, it is not unreasonable to suggest that—given the right ecological conditions—predation could result in archaic stone-age hominids transforming into fully modern humans.
But here’s the rub. There are two sides to predation dynamics— predator and prey—and although the idea of ‘man the hunter’70,71,72 is deeply embedded in anthropological thinking,73 the general view of most researchers is that evolutionary scenarios based on humans as predators do not adequately explain our unique evolutionary trajectory.74,75,76
While we’re accustomed to seeing ourselves as the pre-eminent predator on the planet—residing at the top of the food chain—this view has seriously compromised our ability to think impartially about our lowly origins. My interpretation of the evidence suggests the abrupt transition from Middle Palaeolithic to Upper Palaeolithic, our unique physical appearance and our distinctive behaviour are consistent only with the view that humans evolved—for a period of time at least—as a species of prey.
In other words, the defining physiological, behavioural and emotional characteristics of Homo sapiens may be the adaptations of a prey species exposed to systemic long-term predation by a single predator.
My hypothesis argues that, although we are currently one of the few species on Earth to have no natural dietary predator, this was not always the case. It suggests that, like almost all the other 1.5 million animal species on the planet, we too were shaped by the ecological consequences of predation.
The next step in the hypothesis is to identify the significant predators in our evolutionary history. A number of suspects immediately spring to mind—lions and leopards would probably top the list. During our African sojourn these feline predators undoubtedly took their toll on an- cestral hominid populations. So too did snakes, rhinos, elephants, bears, buffalo and any one of the 400 other species known to kill humans.77 And although arachnophobia is one of the most common human phobias (and we certainly have evolved instinctive ‘brush away’ reflexes to deal with spiders and other creepy crawlies), spiders did not fundamentally reshape us as a species. Nor did lions, although they probably played a part in chasing our ancestors out of Africa.
My examination of the archaeological evidence from the Levant, plus the latest genetic data from both ancient DNA (extracted from fossilised bones) and from the human genome, lends itself to only one plausible interpretation—that the principal predators of archaic humans were Neanderthals (Homo neanderthalensis).
Neanderthal predation theory (NP theory) argues that Neanderthal pre- dation was the single macroevolutionary factor that transformed archaic hominids into modern humans and that, without it, we would still be a docile stone-age hominid. Everything that defines what humans are today is due directly or indirectly to Neanderthal predation. Just as we have in- herited a fear of spiders from our prehistoric ancestors, modern humans have also inherited a primordial dread of Neanderthals—and this daily affects all our lives.
The core hypothesis of Neanderthal predation theory proposes that from at least 100,000 years ago until around 48,000 years ago, in the East Mediterranean Levant, Neanderthals systematically abducted, raped, hunted and devoured archaic humans to the edge of extinction— generating selection pressure for defensive changes in human physiology and behaviour. The resulting strategic adaptations created modern humans. All the major biosystems that make us human—high intelligence, spoken language, art, hairlessness, our distinctive faces—are derived from Neanderthal predation.
Obviously, for predation to have occurred, Neanderthals and Middle Palaeolithic humans must have been living in the same place at the same time, long enough for Neanderthals to have altered the trajectory of hu- man evolution. So the first tenet of NP theory, and the first of its pre- dictions, is that archaic humans and Neanderthals lived within the same geographical and chronological context for at least a few thousand years. This prediction can also be used as the first test of the hypothesis.
The Mediterranean Levant during the Late Pleistocene provides the earliest and best evidence of contemporaneous cohabitation. The long stretch of land on the eastern edge of the Mediterranean Sea called the Levant has often been described as a biogeographical ‘corridor’ between western Eurasia and Africa through which African migrations transited for millions of years.78
LATE PLEISTOCENE
The Late Pleistocene stage of the Pleistocene epoch dates from around 126,000 years ago to around 10,000 years ago. That stage is followed by the Holocene which continues to the present.
Flint artefacts retrieved from Yiron, in northern Israel, provide the earliest evidence of hominids living in the Levant. At 2,400,000 years old, Yiron is the earliest hominid site outside Africa.79 The earliest actual skeletal remains from the area are represented by a fragmentary 200,000 year old hominid excavated at the Mugharet-el-Zuttiyeh cave, in Israel. The paucity of the remains makes identification problematical, but they are thought to be that of an early Neanderthal.80,81
Based on recent dating of Middle Palaeolithic shell beads from the Skhul cave on the slopes of Mt Carmel, in Israel, anatomically modern humans were living in the Levant from between 135,000 to 100,000 years ago82,83,84 and possibly much earlier.
Fossils from the nearby Qafzeh cave tell us they were still there 85,000 years ago.85
While their skeletons were much the same as ours, behaviourally the Skhul and Qafzeh people were still Middle Palaeolithic stone-age hominids, although the shell artefacts found in the Skhul cave suggest they were at least on the cusp of a transition to a more advanced culture—even if their tools were still primitive. As to what they looked like: although their skeletons were relatively modern, it’s impossible to say if they outwardly resembled modern humans or some other primate—in all likelihood, they were something in between.
The supposed migration route for the Skhul-Qafzeh humans was through the Great Rift Valley in eastern Africa, along the Nile corridor (between the Red Sea and the Nile) and into the Levant (below).86,87
At the time, the Levant was part of a major migration route for animal species from northeast Africa and southwest Asia.88,89 For early humans living in the Levant this provided an abundance of prey species, including boar, mountain gazelle, red deer, ibex and aurochs.90
Today, that area of the Middle East has a typical Mediterranean climate, with long dry summers and cool humid winters.91 Judging from pollen records obtained from marine cores, the climate in the Late Pleistocene was cooler, more humid, and punctuated by periods of drought.92 With the climate relatively stable and food plentiful, the African migrants appear to have adapted well to their new environment. The coastal regions of the Levant had permanent supplies of fresh water and its mountains were riddled with limestone caves (including the Skhul and Qafzeh caves) which the humans occupied as permanent sites. Also, its woodlands were among the richest habitats in western Eurasia,93,94 and the Mediterranean Sea was close enough to harvest shellfish to supplement their diet.
In these favourable conditions, their Middle Palaeolithic technology—although rudimentary by our standards—was sufficient for the Skhul- Qafzeh humans to prosper for thousands of years.
All good things must come to an end, and one day a group of these archaic humans came face-to-face with a strange and very different group of hominids they had never seen before—Eurasian Neanderthals who had moved into the Levant from Europe.
This encounter may be the most important single event in human history.
Ostensibly, it was simply two sibling species meeting for the first time. But from a broader evolutionary perspective, that encounter represents the introduction of a major new environmental stressor that would fundamentally impact on early human ecology. On that day, what was to become an interminable selection pressure was exerted for the first time—a pressure that has continued to reshape and redefine humankind up to the present.
It is thought that some Neanderthals had been forced out of Eastern Europe by one of the periodic ice ages that engulfed the region. What- ever the circumstances of their migration, the Neanderthals from Europe that occupied the Levant gradually developed a few physical variations. To distinguish this sub-species from the parental European population (often called classic Neanderthals) the Levantine Neanderthals are usually referred to as Eurasian Neanderthals, or Near Eastern Neanderthals. In this book, I use the former.
Eurasian Neanderthals are represented principally by fossil material found at a number of caves in the Levant—Amud, Kebara and Tabun— all in Israel. On the basis of dates from both early modern human and Neanderthal sites at Mt Carmel, there is an overwhelming weight of evidence that Skhul-Qafzeh humans and Eurasian Neanderthals occupied the same area of the Levant at the same time.95,96,97,98,99,100,101,102,103
As to the important question of how long this coexistence lasted, the imprecision of dates derived from thermoluminescence dating technology and uncertainties relating to provenance make it difficult to say for certain.104
One particular problem is the possible interstratification of stratigraphic levels relating to one of the Levant hominids (known as Tabun C1). Normally in an archaeological dig, the lower down you go, the older the material is. But sometimes, because of earthquakes, floods, landslides and other natural phenomena, the levels (and the archaeological material in them) get jumbled and, occasionally, even reversed. This interstratification can make dating difficult.
If the famous Tabun C1 Neanderthal (which was dated at 171,000 years old) comes from Level C, as suggested by archaeologist Nira Alperson and her team,105 it would indicate Skhul-Qafzeh humans and Neanderthals shared the Levant for at least 70,000 years.
Based on excavations at Geula Cave, Israel, plus the Skhul and Qafzeh fossils, Chilean physical anthropologist Baruch Arensburg suggests a 100,000-year geographic overlap between humans and Eurasian Neanderthals from Tabun, Kebara and Amud.106 Other scholars date the Levantine overlap at 90,000 years,107 while several other teams argue the two species coexisted on the eastern shores of the Mediterranean for 65,000 years.108, 109, 110
In all likelihood, throughout this period, there were multiple ‘trickle’ migrations into the area by both Neanderthals and early humans, driven by climatic variability and parallel migrations of fauna into the region from Africa.111 Ofer Bar-Yosef argues at least one migration of European Neanderthals into the Levant was precipitated by the rapid onset of glacial conditions in eastern Europe and western Asia 75,000 years ago.112
While estimates for the length of time both species shared the Levant vary, everyone agrees they did so for many thousands of years. I conservatively estimate Neanderthal cohabitation with the Skhul-Qafzeh people in the Levant occurred between 100,000 to 50,000 years ago, providing a 50,000-year period of potential Neanderthal predation.
On the basis of 20 years per generation, 50,000 years represents 2500 generations. At 25 years per generation, that’s still 2000 generations.
However, I will later argue that the indirect impact of Neanderthal predation continued right up to the Late Neolithic Period (a mere 2000 years ago) and even beyond, which would add another 45,000 years of evolutionary pressure. At 20 years per generation, that’s 4750 generations of humans that were subject to selective pressures generated directly or indirectly by Neanderthal predation. Considering that only 100 generations have lived since the time of the Romans and ancient Greeks,4750 generations is more than enough time for a macroevolutionary event to occur.
When it first became evident that humans and Neanderthals had lived in the same region for over 50,000 years, there was a great deal of heated debate as researchers struggled to understand the implications of such a lengthy cohabitation.
Erik Trinkaus and Pat Shipman describe it in The Neanderthals:
This new twist pointed up a fundamental problem that had been there all along, overshadowed by the problems of chronology and phylogeny. It was awkward, if not downright contorted, to try to explain how two groups of humans [sapiens and Neanderthals] occupied the same region—either alternately or simultaneously—using the same set of tools to exploit the same plants and animals over a period of fifty thousand years and yet remained anatomically and genetically separate.113
But cohabitation of the same ecological niche also has another consequence-it generates competition-that great driving force of evolution. Without it, evolution grinds to a snail’s pace.
Competition from Neanderthals provides another vital clue— motive. NP theory draws on this maxim to argue that the competition Neanderthals introduced with their colonisation of the Levant kick- started a burst of evolutionary activity among the Skhul-Qafzeh humans that would eventually transform them into a new species. In effect, competition with Eurasian Neanderthals became the catalyst that created modern humans.
Here, though, the competition wasn’t between two physiologically different species. It was between sibling species—species that were similar in general appearance and occupied the same ecological niche. This upped the ante, and also complicated things.
There is general agreement among palaeontologists that, because both species had similar needs for food and shelter, from the day Neanderthals arrived in the Levant they would be competing against the local humans for the same resources,114,115,116 the same cave sites, fresh water, fruit trees, ochre and flint. But the fossil evidence also tells us they were rivals for something much more basic—they were hunting many of the same prey species.117,118
From the perspective of the Skhul-Qafzeh humans, the interloping Neanderthals suddenly disrupted the ecological homeostasis humans had enjoyed for at least 40,000 years—and probably considerably longer. From the Neanderthal perspective, the new Skhul-Qafzeh neighbours presented both a direct challenge—and an opportunity.
In The Origin of Species, Darwin observes that “competition will generally be most severe between those forms which are most nearly related to each other in habits, constitution, and structure.”119 He goes on to say that, in the struggle for existence:
...it is the most closely-allied forms,- varieties of the same species, and species of the same genus or of related genera,- which, from having nearly the same structure, constitution, and habits, generally come into the severest competition with each other; consequently, each new variety or species, during the progress of its formation, will generally press hardest on its nearest kindred, and tend to exterminate them.
The case for lethal inter-species competition is also suggested by Gause’s law of competitive exclusion,120 which states that two species with similar diet and ecological requirements cannot both indefinitely occupy the same environment. Something’s got to give. Applied to the Levant, it predicts that Neanderthal encroachment into the Skhul-Qafzeh’s habitat would cause ecological instability within the hominid niche.
This elemental evolutionary imperative to out-compete, exterminate or expel a competitor from a common territory pitted Neanderthals and humans against each other. And, clearly, the stakes were high. It was a struggle for survival, and the loser faced extinction.
This raises the most fundamental question: if both hominid species were trying to out-compete each other, who would win? This question encapsulates the most fundamental truths about our species and takes us to the second major tenet of NP theory.
NP theory is extrapolated from a simple premise—Neanderthals weren’t the harmless hominids that many anthropologists have presumed them to be—but something else entirely. They were the pre-eminent European-Eurasian predator—what biologists call an apex predator—one with no rivals within their ecological niche. As such, they resided at the summit of the food chain.
This predicts that as the more powerfully-built hominid—who had evolved the predatory instincts, strength, ferocity and lethality to pursue and subdue a wide variety of large and dangerous prey over hundreds of thousands of years in the most demanding environments—Neanderthals would quickly assert a strategic dominance over the Levantine early humans.
It also argues that Neanderthal competition acted as an ecological catalyst that generated enormous selection pressure on the Skhul-Qafzeh humans which, in turn, drove evolutionary change.
These hypotheses claim that practically everything we know about Neanderthal evolutionary history (phylogeny), habitat, diet, hunting strategies, tool use, sexuality, territoriality and a host of other core factors—and how they affect behaviour (what scientists call behavioural ecology)—needs to be reassessed. Importantly, a fundamental reassessment of Eurasian Neanderthal and early human behaviour, physiology and ecology is also the best way to test these hypotheses.