Chapter 17

How could a paleoanthropologist estimate the brain size and infer the diet of an early hominid?

A paleoanthropologist can estimate brain size by measuring skull fragments and can infer diet by examining the wear on teeth

Name three human characteristics that are adaptations for bipedalism.

Adaptations include a cup shaped pelvis, a s shaped spine, and a foot with short, aligned toes

Two fossils finds of 1995 that shed light on the evolution of bipedalism included

Australopithecus anamensis and Ardipithecus ramidus

humans

Bipedalism Cup-shaped pelvis Speech

How might the evolution of bipedalism have increased the fitness of early hominids?

Bipedalism would have allowed early hominids to see farther and would have allowed early hominids to see farther and would have freed the forelimbs for carrying and manipulating objects and providing defense

What evidence indicates that humans and chimpanzees are closely relates?

Chimpanzee and human DNA have a very high degree of similarity, suggesting that humans and chimpanzees may have shared an ancestor

Why is the human evolutionary tree sometimes described as a bush?

During the course of human evolution, several hominid forms that arose died out, leaving no descendants. the lineages of these various forms would resemble the multiple branches of a bush

What evidence besides fossil bones indicates that some early primates were bipedal?

Fossilized footprints indicate that some very early primates were bipedal

great apes

Gibbons, orangutans, gorillas, chimpanzees

The hominid species with the most sophisticated tool-making abilities was

H. sapiens (cro-magnon)

The hominid species with the largest cranial capacity was

H. sapiens (neanderthal)

What was the earliest Homo species that has been discovered, and what two major traits did it have that distinguished it from australopithecines.

Homo habilis; its larger cranial capacity and tool use distinguished it from australopithecines

recent-African-orgin hypothesis

Homosapiens evolved from one population of H. erectus in Africa about 100,000 to 200,000 years ago and then olonized the world

How did the discovery of Australopithecus afarensis change many ideas about the evolution of humans?

It had been thought that bipedalism and a large brain with areas dedicated to higher reasoning and speech production evolved at the same time. A. afarensis showed that bipedalism evolved first

Some scientists hypothesize that Neanderthals were eliminated by modern Homosapiens through direct aggression or the spread of disease. In what other modern ways might modern H. sapiens have contributed to the disappearance of Neanderthals.

Modern H. sapiens may have outcompeted Neanderthals for food or shelter

primates

Movable fingers and toes Prehensile hands Color vision

anthropoid primates

Opposable thumb Well-developed collarbone Rotating shoulder joint

Explain how mitochondroid DNA evidence supports the recent African-orgin-hypothesis?

The differences in mitochondrial DNA among human populations would have taken only 100,000 years to 200,000 years to accumulate, suggesting that all modern humans arose fairly recently from one small group in Africa

The DNA of humans and chimpanzees is very similiar and their bodies share many features. Name a fundamental difference between humans and chimpanzees that has spurred the rapid intellectual and cultural evolution of humans?

The enlargement of the human brain probably accounts for the rapid intellectual and cultural evolution of humans

What evidence suggests that Australopithecus robustus and A. boisei were not ancestral to modern humans?

The heavy bone structure and large teeth of these hominids suggest that they were not ancestral to modern humans

Describe the position that neanderthals hold in the hominid phylogenetic tree

neanderthals are the earliest group of Homo sapiens. They are probably not ancestral to Cro-Magnons, nor to modern humans. Scientists think that they became extinct and left no descendants.

What are three distinguishing characteristics of the arms and collar of anthropoid primates?

They have a well-develpod collarbone, rotating shoulder joints, and partially rotating elbow joints

prosimian primates

Tree dwelling Resemble early primates Mostly nocturnal

Australopithecus robustus and A. boisei differed from A. afarensis by having

a heavier skull

hominid

a human or one of the immediate ancestors of humans

Fossil evidence regarding hominid evolution indicates that hominids

acquired bipedalsim before they developed a large brain and speech

The high degree of similarity between chimpanzee and human DNA suggests that

chimpanzees and humans are probably descended from a more primitive apelike ancestor

All primates have

color vision

Research on human evolution clearly shows that

different species of hominids lived at the same time

The primary materials that paleoanthropologists study is the

fossilized evidence of early hominids

The oldest hominid fossils to be found along with stone tools are the fossils of

homo habilis

multiregional hypothesis

homosapiens evolved in parallel all over Earth from different populations of H. erectus over a million years ago, and constant gene flow between populations has kept H. sapiens a single species

anthropoid primate

include marmosets, monkeys, apes, and humans

great ape

is a gibbon, orangutan, gorilla, or chimpanzee

opposable thumb

is a thumb that can be positioned opposite the fingers

bipedalism

is the ability to walk primarily on two legs

prehensile

means capable of grasping

quadrupedal

refers to the practice of walking on four limbs

Paleoanthropologists infer that Neanderthals wore clothing made of skins, because they have found

stone tools that were probably used to scrape animal hides near neanderthal fossils

Humans are the only mammals to have

the ability to walk primarily on two legs

Lucy

the nickname given to the original fossil find of Australopithecus afarensis

Paleoanthropologists infer that Homo habilis ate meat, because they have found

tool marks on animal bones discovered near H. habilis fossils

The shape of a fossils hominids pelvis can indicate whether the hominid

walked upright

The fossil primate Lucy

was about as tall as a chimpanzee

australopithecine

was any hominid of the genus australopithecus afarensis

To determine whether a fossil primate was a hominid, paleoanthropologists look mainly at whether the specimen

was bipedal