Anthropology For Dummies. Cameron M. Smith

Anthropology For Dummies

ago, in the evolution of the Hominoidea. Remember, we’re not the only member of the group, and our neighbor species, such as the chimpanzees and gorillas, have also survived all this time. (Note: This classification is a bit of a gray area. Only recently have some anthropologists included chimps and gorillas in the same family as humans, as I do here; previously, Hominidae was reserved only for the bipedal primates.) The main anatomical characteristics of the Hominoidea are

Dental formula of 2.1.2.3

Lack of a tail

Both arboreal and terrestrial lifestyles

Relatively long arms (even with a terrestrial lifestyle) due to origins as tree-swingers

Simple molars for crushing, rather than the Old World Monkey’s shear-like molars

Relatively large body size, averaging more than 10 kilograms (30 pounds)

The Hominoidea is easily divisible into two main families, which mainly separate the Hominoidea into the somewhat monkey-like gibbons of Southeast Asia and the African apes.

The Hylobatidae contain the gibbons of Southeast Asia, who tear through the forest canopy like Tarzan and have complex vocalizations (also like Tarzan). They’re the lightest of the Hominoidea and the least like humans: They spend a lot of time in the trees, they have relatively small brains, and they survive on a diet that, although somewhat varied, is predominantly fruit.

Much more like humans are members of the Hominidae, the group containing the chimpanzee and gorilla (according to the DNA and skeletal evidence), and humans themselves. Generally speaking, these primates are large (averaging over 40 kilograms or 80 pounds), may live much of their lives on the ground, and have a generalized rather than specialized diet. They include Homo sapiens sapiens, a relatively large primate (averaging 70 kilograms or 140 pounds) that possesses a very large brain compared to body size and uses extremely complex behavior and tools to adapt and survive. That should sound familiar because you’re one of them.

When you think about the past, and the fossil record, and the many individual primates that lie in your own past (right back to the first primates more than 60 million years ago), remember that a lot of speciations and extinctions have occurred. Generally speaking, most species (defined in the “Biological classification” sidebar earlier in the chapter) survive only about 4 million years; most genera survive for about 20 million years. Our species, Homo sapiens sapiens, has been around for about 100,000 years. But, as I discuss throughout this book, humanity is so different from most other life forms — for an array of reasons — that this natural timescale doesn’t necessarily apply to it. Humanity has invented many ways to prevent itself from falling prey to the circumstances that cause other species to become extinct (and at the same time has invented many means of committing suicide, such as nuclear and biological weapons).

Yes, We Have No Bananas: Primate Subsistence

The previous sections give you a good idea of the origins and main groups of the primates; now take a look at some details or characteristics that can help to clarify where humanity fits in as one of many primate species. I begin with subsistence in this section; later sections cover locomotion, social groups, and behavior.

Subsistence refers to how an organism fulfills its need for food, water, and nutrients. All kinds of subsistence have evolved in nature, including carnivory (eating prey animals) and herbivory (eating plant matter). Most primates basically practice omnivory, meaning that they eat wide variety of foods.

Many anthropologists today believe that the most important factor driving the diversity of subsistence behavior in primates is food availability and distribution; that is, what’s the distribution of food in space, and how does that distribution vary with time? Because, like any species, primates have to eat, the extent to which their foods are available from season to season has important effects on their behavior and anatomy. Some common primate responses to seasonal changes in diet include switching to different food sources, increasing the time spent in search of food, and splitting the social group to spread out the resource demand. For example, studies show that in lean times, spectral tarsiers (tiny, giant-eyed, super-cute Southeast Asian primates) spend more time traveling in search of food than they do in better times. This change affects all kinds of behavior, including conflict resulting from territorial disputes.

The following sections take a closer look at the actual diets processed by primates.

The indiscriminate-eaters: Omnivores

Although the following sections show some exceptions, most primates are rather omnivorous, eating a variety of foods from bird eggs to leaves to seeds and even grasses, insects, tree gum, and flowers. This is in pretty stark contrast to, say crocodiles, who eat meat (fish and any vertebrate that falls into the water), or zebras, who eat only vegetation (grass and shrubs). Those animals are dietary specialists; primates, generally speaking, are generalists. Chimpanzees, for example, eat lots of fruit, snack on termites, and occasionally hunt down small monkeys; some monkeys savor bird eggs; and gorillas live in a giant salad bowl, eating just about whatever vegetation is in reach. This dietary diversity is reflected in the nature of our versatile mouth.

The average primate mouth reflects the order’s tendency toward omnivory in the teeth. We have several kinds of teeth:

Incisors are the thin, blade-like teeth at the front of the mouth for snipping and clipping.

Canines are the pointed, conical teeth used for puncturing and light crushing; many primate species use these teeth to defend and threaten, so they’re much larger than in our species.

Premolars are the somewhat-pointed-but-somewhat-jagged teeth immediately before the molars, and they do the light crushing.

Molars are the heavy, flattish teeth in the back of the mouth that do the heavy crushing.

You can see that this multitalented mouth can process just about any food, so primates generally fall into the category of heterodont (different-teeth) rather than homodont (same-teeth). Your dog and cat are homodont — both are carnivores (at least evolutionarily) — and omnivores, such as people and pigs, are heterodont.

Technically speaking, homodonty really means that all the teeth have the same form, as in crocodiles. Because dogs and cats (mentioned in the preceding paragraph) do have differences between their incisors and molars, for example, they’re technically heterodont. However, relatively speaking, all their teeth are for processing a meat diet, so compared to primates (who eat a more varied diet), they’re considered homodont.

A trained anthropologist can learn an enormous amount from a single fossil tooth. Under a microscope, scratches and polishing, called dental microwear, can reveal how the jaws worked and even whether the diet was moist or dry. Knowing that it was moist or dry, in turn, can tell you something about the general conditions in which the animal survived. Extrapolations like these are used to reconstruct the lives of ancient species.

The bug-eaters: Insectivores

Insectivores eat a diet heavy in insects; this is where the primates began: as small early mammals eating small insects. Today, many primates eat a few insects — like the chimpanzees who fish termites out of their mounds by using twigs — but few focus their diet on insects, and even those who do still eat other foods such as tree gum and leaves. But for mouse lemurs and some other prosimians, insects may compose close to half

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