Just how easy was it for predators to serve up hominid du jour? The fossil history tells us little, if anything, about behavior and virtually nothing specific about defensive behavior against predators. We may find the fossilized remains of the losers in a predator—prey encounter, but we do not have enough fossils to draw any conclusions about the predation rate on hominids or their successful strategies to outwit predators. Obviously if we had been passive victims we would not have survived as a species. True, rabbits and other small mammals are examples of prey that are on the menu of every carnivore, snake, and raptor—and they still survive as species—but animals such as rabbits depend on strategies of quick escape and quick "littering" (short gestation periods combined with large numbers of young born simultaneously). Hominids, on the other hand, are not overly quick at escape: bipedal individuals simply cannot outrun swift four-legged predators, nor was fast and furious reproduction in the hominid plan.
We've put a lot of emphasis so far on the success predators had in making a meal of ancient hominids. But our ancestors weren't just standing around waiting to be eaten. Staying alive is the goal of all creatures, and those individuals who do things that facilitate staying alive are the ones who pass on their genes to the next generation. We have only to look at our primate relatives to see strategies that have emerged to foil predation.
In his classic 1967 field experiment, Adriaan Kortlandt of the University of Amsterdam presented wild chimpanzees with a stuffed leopard. What did the chimpanzees do? They obviously were aware that the leopard was not in the act of hunting, since it was neither hidden nor moving. They may even have sensed that an immobile, staring leopard is certainly not normal, and they should take advantage of the situation. They vocalized to each other and communicated about this bizarre situation. Then one of them picked up a stick and rushed in to whack the leopard. Another one uprooted a small tree and used it as a weapon. One by one they all attacked the leopard with sticks and small trees, screaming and hooting to keep up their collective adrenaline rush.1
Such staged experiments have been validated repeatedly in field and laboratory conditions with many different primate species. Given a situation where the predator can be vanquished, many primates will attack preemp-tively.2 For example, baboons have thrown stones at human observers in conjunction with other typical fear-and-escape behaviors. Captive capuchins, the wily little "organ-grinder" monkeys of South America, were found to be capable of throwing rocks with pretty good aim.
What about non-staged encounters with predators—the real thing? The ultimate act of defense, killing the predator, is atypical but not unknown. A wild white-faced capuchin actually clubbed a venomous snake to death, a daring event witnessed by field researcher Sue Boinski in Parque Nacional Manuel Antonio, Costa Rica. Baboons and chimpanzees have both been known to put up a struggle and win against carnivores. Chimpanzees in the Mahale Mountains of western Tanzania were seen on several different occasions harassing a female leopard and finally succeeding in killing her cub. (Although these attacks occurred during the day, researchers maintain that at night the tables would have been turned in favor of the leopard.)
A single male baboon is a powerful adversary. With nearly 2-inch-long canines and a weight of up to 70 pounds, a male baboon with an attitude is formidable. Lukas Stoltz and G. S. Saayman, two zoologists working in the Transvaal section of South Africa, observed one dominant male baboon maim or kill three large dogs when they attacked his troop. When we looked at scientific papers and compiled just the instances of aggressive retaliation by baboons against leopards, we found that out of eleven such battles, the leopard was killed in four of them. This, of course, is a small sample but it serves to show that when baboons feel it is in their capacity to use aggression, they will not only thwart the predator but permanently eliminate it nearly one-third of the time.
For primates undergoing severe predator pressure, a combination of many anti-predator defenses may be necessary.3 One example of a species that employs a veritable multitude of anti-predation strategies is the savanna-dwelling patas monkey. Sometimes called the military monkey because of the male's white moustache, colorful red coat, and martial posture, patas monkeys are a ground-dwelling primate of the African grasslands. They are renowned for:
1. Their speed during flight from predators: over 30 miles per hour
2. Their bipedal stance to scan the dry savanna for predators
3. A silent, furtive life in small, highly dispersed groups
4. A conspicuous male who stays on the periphery of the group to distract any potential predator's attention—sort of an altruistic decoy to draw predators away from the core of the social group, the females and young
5. The camouflage coloration of female and infant patas—they are practically invisible in the dry grasses
6. Altering the primate norm of nocturnal birthing by giving birth during the day.
On this last point patas give birth in the daytime because their small-group composition and open-savanna habitat make them particularly vulnerable at night. Nine species of carnivores are potential nocturnal predators of patas: lions, leopards, two small African wild cats (caracals and servals), golden jackals, blackbacked jackals, side striped jackals, spotted hyenas, and striped hyenas. To counter this array of nocturnal
Because they live in the open grassland habitat with very few trees, patas monkeys employ a multitude of anti-predation strategies. (H. Kummer)
predators, patas have adapted by emphasizing unpredictable behavior, wide dispersal, and concealment in their sleeping patterns. Nocturnal births of baby patas might provide legions of hungry night-stalking predators with odorous cues to the location of female patas in the darkness and thus undermine the other defense strategies. So, daytime birth evolved as a defense strategy.4
While primates can be multi-faceted and even fierce in their own defense, we can't deny they also can be caught in a hopeless, hapless state of shock. In the late 1940s Colonel J. Stevenson-Hamilton, a warden at Kruger National Park in South Africa, recorded what he deemed a "massacre" of baboons by two lionesses. In his own words, "A pride of lions was taking its midday siesta close to a drinking-pool when a troop of baboons was heard approaching." Most of the lions just woke up and lay still, except for two females who placed themselves in a patch of vegetation close to the trail. The baboons were unaware of the big cats and walked into the "trap" set by the two lionesses. When the lions rushed out, the baboons were panic-stricken and ran straight toward the main part of the resting pride. "A complete massacre ensued. The baboons were apparently too terrified even to try to escape up any of the surrounding trees, and hid their faces in their hands while the lions simply struck them down right and left with blows of their paws."5
What can we glean about early hominids from the observations of living non-human primates? Here is a rundown on how primates were offsetting predation at the time the first hominids arrived on the scene: Generally body size had dramatically enlarged from the first small proto-primates, social grouping was the norm, alarm calls allowed communication between group members, primates had been spurred to greater cognitive development in order to outsmart predators, and attack as a last resort was a fallback position. These behaviors and changes were already in place as generic primate adaptations by the time hominids appeared.
All of these strategies—size, society, vocalizations, intelligence, threat behavior—have broad implications in their own right, but they all function as extremely competent defensive adaptations. Hominids came equipped with the hardwiring for these defenses and continued using and refining them.
If you are a smallish primate itching to get out of the trees and forge a new evolutionary path, what in the world do you do to defend yourself? We propose that two uniquely human traits—bipedalism and speech—
were also just extensions of inherent primate-ism. Stimulated by prédation and helpful in coping with it, these human attributes of upright walking and language evolved from the generic primate-defense system. You could say that the early hominid "package" of body size, group living with multiple males, communication, bipedality, complex threat behaviors, and cognitive skills were in a sense born of caution and honed by predation. Some parts of the package were much more effective than others; some were uniquely embraced by human ancestors and not by other primates (walking upright); many package items were evolving concurrently and none were mutually exclusive; and many were redefined completely by humans (speech from alarm vocalizations). Let's consider the effectiveness of the strategies included in the human anti-predator package one at a time.
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