Humans are not among these primates, mainly because of changes in the foot that took place when our prehuman ancestors shifted from a quadrupedal locomotion to bipedalism Figure 6. Humans lack this feature due to their adaptation to life on the ground. Cervical The body trunk of primates is also distinctive.
The backbone has ive function- ally distinct types of vertebra—from top to bottom, the cervical, thoracic, lumbar, sacral forming the sacrum of the pelvis , and coccyx vertebrae—which give it a greater range of movements than other animals have Figure 6. The body trunk Thoracic also tends to be vertically oriented, such as when the primate climbs, swings from tree limb to tree limb, or sits.
This enhancment helps inform primates about texture and other physical properties of objects, such as potential food items. On the inside surfaces of the i ngers and toes and on the palms and soles, respectively, Sacrum of the hands and feet, the skin surface is covered with series of i ne ridges called dermal ridges ingerprints and toe prints.
These ridges further enhance the tac- tile sense, and they increase the amount of friction, or resistance to slipping, when Coccyx grasping an object, such as a tree branch.
On the backs of the ends of the i ngers Lemur Human and toes, most primates have nails instead of claws Figure 6. Made of keratin, spine spine the strong protein also found in hair, these nails may protect the ends of the ingers and toes. They may aid in picking up small objects. First, very early in vertebrae, responsible for bending, twisting, and stretching. The sacral vertebrae are much less movable, as they form part of the pelvis. Notice, too, the s-shaped spine in humans versus the c-shaped spine in other primates, such as the lemur.
Consider what would happen if a primate attempted to leap from one branch to another without being able to determine the distance between the two branches.
Now imagine a human leaping over a relatively narrow chasm without knowing how far to leap. In animals such as the lemur, a postorbital bar lines the back of the eye orbit but does not fully enclose it. In other animals, such as the raccoon, the eye orbit is open, with no bone enclosing it at the rear. As a result, the two ields of vision overlap, providing the primate with depth perception. Second, color vision evolved.
Crucial for spotting insects and other prey within the surrounding vegetation, color vision likely evolved as early primates shifted from a nocturnal adaptation to a diurnal adaptation. Most higher primates have lost the rhinarium the external wet nose, which most mammals have and the long snout.
Some of the prosimians—the more primitive primates, such as lemurs and lorises—have retained the rhinarium, and they continue to rely on a well-developed sense of smell. But some primates, such as baboons, have Baboons do not rely on olfaction. Their snout retained a large snout to accommodate massive canine roots, especially in adult remains large because of oversized canines.
See also Figure 6. As indicated in Table 6. Some primates, such as tarsiers, have different numbers of teeth in the upper and lower jaws. Primates show a series of behavioral and anatomical tendencies that make them especially good at living in trees.
Notice that humans thoracic, lumbar, sacral, coccygeal do not have the large projecting canines evident in the other four dentitions. Each time the jaws are closed, the upper canines are Enhanced sense of vision Convergence of eyes; color vision sharpened against the lower third premolars.
This evolutionary conservatism relects the continued purpose of these teeth, especially of the molars: grinding and crushing food. For example, some primates have high, pointed cusps on the occlusal, or chewing, surfaces of their molars, for puncturing and crushing insects. Others have crests on their molars, for shearing leaves. The many primates that eat fruit and seeds tend to have low, round cusps on their molars, for crush- ing and pulping.
The molars of monkeys, apes, and humans have distinctive occlusal surfaces Figure 6. Like the dental formula, molar morphology can be used to determine whether fossilized remains of a primate represent an ancestor of Old World monkeys or of apes and humans.
Each pair of cusps, front and back, is connected by an enamel loph An enamel ridge connecting cusps on ridge, or loph.
Apes and humans have a lower molar with ive separate cusps that are separated bilophodont Refers to lower molars, in by grooves. This is called a Y-5 molar. This specialized feature, a tooth comb, is especially useful for extracting resins from trees Figure 6.
The horizontally oriented canine is one of three different kinds of canines in primates. The vertical, incisor-shaped canine appears only in humans. The project- ing, pointed canine appears in all monkeys and all apes. In Old World monkeys canine-premolar honing complex The and apes, the canines are part of a canine-premolar honing complex, in which the dental form in which the upper canines upper canine its in a space, or diastema, between the lower canine and lower i rst are sharpened against the lower third premolar.
This coniguration slices food, especially leaves and other plants. When premolars when the jaws are closed. The upper canine tends to be large, especially in males. In addition to its masticatory function, the large upper canine provides a strong social signal for establishing and maintaining dominance among male members of the primate society, such as in baboons, and as a warning signal to potential predators Figure 6.
Primates display a broad range of dietary adaptations. Orangutans and hu- mans have thick enamel, whereas chimpanzees and gorillas have thin enamel. Thick enamel relects an adaptation to eating tough, hard foods. Although humans today rarely eat hard foods, they have retained this primitive characteristic. Female primates give birth to fewer offspring than do other female mammals. Primate mothers invest a lot of time and energy in caring What Is a Primate? Here, a chimpanzee mother holds her baby.
Primates require longer development periods than do other mammals in part because they are more intelligent. The back portion of the brain where visual signals are pro- cessed is expanded in primates, whereas areas of the brain associated with smell olfactory bulb The portion of the anterior olfactory bulb and hearing are considerably smaller than in other mammals. Frontal Parietal lobe Occipital The drawings are out of scale to show differences in anatomy.
The Homo sapiens dot is way off the line because humans have a much bigger brain relative to body mass. This combination of greater mass and complexity provides humans with greater intel- ligence compared with other primates and has led humans to develop language and advanced culture. Today, more than taxa—number of species—of primates live in various parts of the world. If we count subspecies, there are more than kinds of primates, from the mouse lemur, which weighs less than a pound.
Each group includes hierarchically arranged subdivi- sions, culminating at the bottom with genus and species Figure 6. The order Primates has two suborders, prosimians Prosimii and anthropoids Anthropoi- dea. Prosimians—sometimes called lower, or lesser, primates—are the most primi- tive primates, having undergone relatively little evolutionary change. In general, they retain a number of primitive characteristics, such as the rhinarium, and they tend to have more specialized diets and behaviors than anthropoids do.
The different kinds of prosimians are lorises, galagos, tarsiers, and lemurs. Anthropoids—the higher primates—are the monkeys cercopithecoids, or Old World monkeys, and ceboids, or New World monkeys , apes hylobatids, or lesser apes, and pongids, or great apes , and humans hominids.
The higher primates fall into two infraorders, platyrrhines New World higher primates and catarrhines Old World higher primates. The major primate groups and the various taxa included in them are distin- guished by their anatomical and adaptive characteristics. These differences—for example, the differences between an ape and a monkey—matter, i rst, because they are a means of understanding the variation among primates.
Second, the key characteristics of the different primate taxa appear at speciic points in the evolu- tionary record. Paleontologists look for these characteristics in their study of the origins and evolution of the different primate groups. For example, when did the Y-5 molar, a dei ning characteristic of apes, i rst appear? When did bipedalism i rst occur? When did monkeys living in the New World irst differ noticeably from those living in the Old World?
Such questions are central to the study of primates and of their evolution. They can be answered only by knowing the attributes unique to different primate taxa. In addition, it is important to know about the physical differences between primate taxa because the variation in the living primates provides models for un- derstanding the morphology, the behavior, and the adaptation in the evolutionary past. For example, the Y-5 lower molar pattern seen today in apes and humans irst appeared in anthropoids 20—30 mya.
This morphology indicates that apes origi- nated at that time. Humans have the pattern, but evolved after apes. Similarly, characteristics that deine bipedality in humans—long lower limbs and short upper limbs—i rst appeared 5 mya or so. When they ind these anatomical characteristics in fossilized remains fossils are the subject of chapter 7 , anthropologists are able to identify the origins of humanlike ancestors.
And knowing how those ancestors walked helps complete a timeline of adaptation. Add Hominin? How a primate is classiied is important and not just a simple exercise.
In the last several decades, taxonomists have focused increasingly on genetic relationships as a means of classifying primates. In addition, DNA comparisons reveal that chimpanzees and humans are more closely related than either is to gorillas. Therefore, anatomical and genetic classiications produce somewhat different results Table 6. The anatomical classiication includes three families: hylobatids gibbons , pongids great apes , and hominids humans.
By contrast, the genetic classiication includes two families: hylobatids gibbons and hominids great apes, including humans. It includes three subfamilies: pongines orangutans , gorillines gorillas , and hominines chimpanzees, bonobos, and hu- mans. And it divides the hominines into tribes: panins chimpanzees, bonobos and hominins humans.
In fact, the basic difference between the two classiica- tions is that in the genetic system humans and their ancestors are called hominin hominin Humans and human ancestors instead of hominid. Many anthropologists are shifting to based on genetics.
For identifying genetic i. For understanding the adaptation of anatomical variations, however, anatomical classiication is bet- ter. As is emphasized throughout this book, humans have taken a very different adaptive trajectory than apes, and so humans are unique in some key ways, such as in how they walk, think, and communicate.
Therefore, because this book focuses on adaptation, it uses anatomical classiication. With these terms in mind, we can look at the major features of the different primate taxa, starting with the prosimians.
TABLE 6. Shared adaptive physical features help determine the degree of relatedness among primate species. What Are the Kinds of Primates? As a result, they have enlarged nasal passages, a rhinarium, scent glands, and a large and distinctive olfactory bulb in the front of the brain. Ring-tailed lemurs, among the most fascinating and adaptable prosimians, spend considerable time on the ground, and their hands are humanlike in key respects Figure 6.
In evolutionary terms, lemurs, lorises, and galagos are among the oldest pri- mates primate evolution is the subject of chapter 8. Many of the primitive char- acteristics they retain have been around for many millions of years.
Until humans i rst occupied the island, about a thousand years ago, very large species of lemurs lived on Madagascar, including some that were the size of a cow Figure 6.
Lorises live in Africa and South- east Asia, and galagos live in Africa. Their most distinctive physical characteristics, very large eyes and very Not all primates are completely arboreal. Lemurs Ring-tailed lemurs, for example, are terrestrial and lorises have primitive dentitions—some have 36 teeth, having retained three during the considerable periods of time in premolars in their dental formula.
They also have the specialized tooth comb which they forage for food. Although native see Figure 6. Catherines Island, Georgia, as part of Tarsiers, which live in Southeast Asia, are primitive overall. Rather than having four lower inci- sors, two on the left and two on the right, tarsiers have only two. Like some of the other prosimians, they have retained three premolars on each side of the upper and lower jaws, giving them 34 teeth. The sizes of living and extinct lemurs overlap somewhat, but Megaladapis, the largest extinct lemur, was substantially larger than any living lemur.
These long bones give extra leverage for leap- ing in search of prey, such as small birds. Anthropoids: The Higher Primates Anthropoids differ from prosimians in a number of ways. In general, anthro- poids have larger brains, they are more dimorphic sexually in body size and other anatomical characteristics, they have fewer teeth premolars, in particular , their eyes are convergent and enclosed by a continuous ring of bone, and they see in FIGURE 6.
Unlike the anthropoids, many species of prosimians such as the red-bellied lemur, pictured here are The two infraorders of anthropoids—platyrrhines, or New World monkeys, and nocturnal. The largeness of their eyes improves catarrhines—are named for the morphologies of their noses Figure 6.
Darkness protects nocturnal prosimians from a wide nasal septum, the area of soft tissue that separates the nostrils. To understand with other members of the same species. As a result, nostril orientation, look at your own nostrils in a mirror.
They should be directed many nocturnal prosimians vocalize during the night. Sound travels easily in humid night air, so members downward since you are a catarrhine. The two ceboid families, see each other. This trait is unusual in nocturnal animals, because dim light typically prevents them from seeing things that clearly.
Calcaneus b What Are the Kinds of Primates? Opossums and kinkajous are among the other mammals with a fully prehensile tail. Ceboids are arboreal, spending nearly all their time in trees. They use sus- pensory locomotion, in which all four limbs grasp onto branches and help move the body from one tree or branch to another. Within the atelids are two subfami- lies, one of which, the atelines, is distinctive in that each of its four types howler monkeys, spider monkeys, woolly monkeys, and woolly spider monkeys have a prehensile tail Figure 6.
In addition to locomotion functions in the trees, the prehensile tail can be used to suspend the body from a branch so the hands and feet can be used to feed. Ceboids have a diverse diet, ranging from insects i. Smaller ceboids Catarrhines obtain protein from insects, whereas larger ones obtain it from leaves. They inhabit a wide range of habitats throughout Af- Catarrhines rica and Asia, but mostly live in the tropics or subtropics.
Some are arboreal and In addition to their differently shaped noses, some are terrestrial. Cercopithecoids have bilophodont upper and lower molars, a these two groups differ in their numbers of narrow face, a sitting pad on the rear, and a long body trunk that terminates with premolars; platyrrhines have six upper and six lower premolars, while catarrhines have four a nonprehensile tail.
Cercopithecoids are divided into two subfamilies, colobines and cercopithecines Figure 6. Each chapter then ends with an expanded section of "How Do We Know? Virtually all of the testable terms, concepts, persons, places, and events from the textbook are included. Cram Just the FACTS studyguides give all of the outlines, highlights, notes, and quizzes for your textbook with optional online comprehensive practice tests. Only Cram is Textbook Specific. Accompanys: This concise anthropology text presents a balanced introduction to the field of physical anthropology using tables, charts, photo essays and multimedia to bring the study of physical anthropology to life for students.
Supported by new chapter opening Learning Objectives, new visual diagrams see Chapter One and other summation pedagogy such as "What's Important" boxes that put key chapter concepts into perspective for students, this text continues to help students master basic biological principles of physical anthropology and so be able to better understand human origins and our place in the biological world.
Cram Just the FACTS studyguides gives all of the outlines, highlights, and quizzes for your textbook with optional online comprehensive practice tests. Toggle navigation. Main Essentials of Physical Anthropology. The big picture of physical anthropology. ISBN Your tags:. Send-to-Kindle or Email Please login to your account first Need help? Please read our short guide how to send a book to Kindle.
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