Prehistoric people.

ROLCAM · Posted: Wed Sep 26, 2007 1:28 pm Post subject: Prehistoric people.

Prehistoric people are human beings who lived before writing was invented about 5,500 years ago. Writing enabled people to record information they wished to save, including descriptions of events in their lives. In this way, the invention of writing marked the beginning of history. The period before human beings learned to write is called prehistory, and people who lived during this period are known as prehistoric people.

Most scientists believe the first human beings lived about 2 million years ago. But early humans probably arose from ancestors who first lived more than 4 million years ago. These prehuman ancestors were small, humanlike creatures who walked erect. This article will discuss both prehistoric people and their near ancestors.

Scientists first discovered evidence of prehistoric people during the mid-1800's. Most of this evidence consisted of ancient, sharp-edged tools that prehistoric people had made of stone. The first fossilized bones of prehistoric people were also found during this time.

As scientists collected more fossils of prehistoric people, they began to form a clearer picture of what these early people looked like. For example, scientists learned from fossil evidence that early human beings had smaller brains than most modern men and women have. This evidence indicated to many scientists that humans had evolved--that is, modified their physical structure over time. Scientists developed a set of ideas about human origins called the theory of human evolution. This theory states that as the environment of the prehistoric world changed, the prehuman ancestors of prehistoric people went through a series of changes that resulted in the first human beings. They, in turn, evolved into modern human beings.

Today, many kinds of scientists work together to learn about prehistoric people. Archaeologists search for and examine such physical evidence as pottery and tools to help explain how prehistoric people lived. Botanists study the remains of prehistoric plants, and zoologists analyze fossils of prehistoric animals that lived during the time of prehistoric people. Geologists study the layers of rock in which fossils are found. All these scientists are called anthropologists if their chief concern is the study of human physical and cultural development.

Evidence of prehistoric people--such as fossils, tools, and other remains--is rare and often fragmented. Evidence of the earliest types of prehistoric people is the most difficult to find. Anthropologists must base their theories on this extremely limited evidence. As a result, scientists cannot yet present a detailed picture of early human life. In addition, new discoveries sometimes disprove theories that scientists already hold.

Prehuman ancestors

Most scientists believe that human beings and apes--such as chimpanzees and gorillas--share a common ancestor. To support this theory, scientists point out that the fossilized remains of ancient humanlike beings and apes reveal many similarities, including similar brain sizes. In addition, studies comparing the physical structure, blood, and genetic material of modern humans with those of apes show that people are more similar to apes than to any other living animal.

The ancestors of human beings probably began evolving separately from the ancestors of apes between about 10 million and 5 million years ago. This evolutionary split marks the beginning of the development of hominids. Hominids are members of the scientific family made up of human beings and early humanlike ancestors. Most anthropologists believe that the first hominids included humanlike creatures called australopithecines (pronounced aw stray loh PIHTH uh seenz).

Where and when they lived. The australopithecines first appeared about 4 million years ago in Africa. Fossil evidence suggests that these creatures became extinct between 2 million and 1 million years ago, about when the first humans appeared.

Scientists have discovered australopithecine fossils in eastern, southern, and north central Africa. Most scientists believe that hominids originated in Africa and prehistoric people later spread to other parts of the world.

What they looked like. The australopithecines looked very different from modern humans. In some ways, such as in their facial features, they may have resembled chimpanzees. But they could stand upright and walk on two legs, and their canine teeth were much smaller and less pointed than those of apes.

The australopithecines had large faces that jutted out. Their brains were about one-third the size of modern human brains. Their molars were large, flat, and suitable for grinding food. Anthropologists believe from the shape of these creatures' teeth that they ate such foods as fruits, vegetables, nuts, seeds, and insects.

Types of australopithecines. The australopithecines were members of the genus Australopithecus (southern ape). According to differences in the shape of the creatures' jaws and teeth and the size of their brains, most scientists have divided the genus Australopithecus into five species: (1) A. anamensis, (2) A. afarensis, (3) A. africanus, (4) A. boisei, and (5) A. robustus.

The earliest known species of Australopithecus was A. anamensis, which appeared in eastern Africa around 4,000,000 years ago. This species seems to have evolved by about 3,700,000 years ago into another Australopithecus species, A. afarensis. The most complete australopithecine that scientists have found is a partial skeleton of a female A. afarensis. It was found at Hadar, Ethiopia. Scientists estimate that this creature, nicknamed "Lucy," was more than 31/2 feet (107 centimeters) tall and weighed about 60 pounds (27 kilograms). A. afarensis had about the same size brain that a chimpanzee has.

By about 3 million years ago, A. africanus replaced A. afarensis. Scientists have found fossils of A. africanus at several sites in South Africa. These creatures had rounder skulls and slightly larger brains than those of A. afarensis, but they were otherwise not much different.

Many scientists believe that an evolutionary split occurred among the australopithecines during the time of A. africanus. This split resulted in the appearance of an additional evolutionary line, separate from A. africanus, that led to A. boisei and A. robustus. Scientists refer to these two species as the robust australopithecines. They had larger molars and more powerful jaws than the other three species of Australopithecus. But their brain size was about the same as that of A. africanus. The earlier three species are called gracile (slender) australopithecines. The robust australopithecines probably became extinct between 1,500,000 and 1,000,000 years ago. The Australopithecus species were closely related to the earliest known hominids, Ardipithecus ramidus, which lived in what is now Ethiopia about 4,400,000 years ago.

The first human beings

Most anthropologists believe that the first human beings evolved from a gracile australopithecine about 2 million years ago. The oldest tools that scientists have found date from about 21/2 million years ago. But because no hominid fossils were found with these tools, scientists do not know whether an australopithecine or an early human made them.

Most prehistoric tools that have been found and studied are made of stone. As a result, this period of time is called the Stone Age. Early toolmakers may also have used wood and other materials, but none of those tools have survived. The Stone Age lasted from the first use of stone tools until bronze replaced stone as the chief toolmaking material. In some areas, this occurred about 3000 B.C. The first part of the Stone Age is called the Paleolithic Period. This period lasted until about 8000 B.C., after people had started farming. Even after some people learned to raise food by farming, many others continued to live by gathering wild plants and by hunting. These Stone Age hunters and gatherers who lived after 8000 B.C. are called Mesolithic people. Farmers from this period are called Neolithic people.

Homo habilis is considered by anthropologists to be the oldest human species. These prehistoric people lived in Africa about 2 million years ago. The Latin word homo means human being. Habilis means handy or skillful. Anthropologists have found important fossils of Homo habilis at sites east of Lake Turkana in northern Kenya and in Olduvai Gorge in Tanzania.

Homo habilis' brain was much larger than that of an australopithecine, but only about half the size of a modern human brain. Homo habilis also had smaller molars and a less protruding face than the australopithecines had. Many anthropologists think fossil evidence indicates that Homo habilis males were much larger than Homo habilis females. This difference, known as sexual dimorphism, appears among many modern primates. Scientists have also detected such a difference among the australopithecines. Among modern human beings, sexual dimorphism is less extreme. Some anthropologists believe that the larger individuals among those traditionally classified as Homo habilis actually belonged to a separate species. They think that this species, which they call Homo rudolfensis, lived at the same time as Homo habilis.

Many anthropologists believe Homo habilis made the first tools. Some of the earliest known tools have been found with Homo habilis fossils. These devices were sharp-edged stones used for cutting, scraping, and chopping. Prehistoric people made them by striking one piece of stone with another, chipping pieces away to produce a cutting edge. These first tools were extremely crude, but over time early human beings began to craft tools of a finer quality. Later toolmakers started using mallets of wood or bone to tap away small chips of stone, producing a straight, sharp cutting edge.

Scientists believe Homo habilis ate meat in addition to fruits, insects, and plants. Archaeologists have found animal bones buried with stone tools from the time of Homo habilis. Many of the bones show scratch marks that were probably made by the cutting action of stone tools. These marks indicate that Homo habilis used tools to butcher game and to scrape meat off bones. But scientists do not know whether these early humans killed large animals themselves or merely ate the meat after the animals had been killed by predators.

Homo erectus. Fossil evidence indicates that more than 13/4 million years ago, Homo habilis evolved into a more advanced human species. Scientists call this species Homo erectus. The term Homo erectus refers to the upright posture of these creatures. One of the best known examples of Homo erectus is a nearly complete fossil skeleton of a boy who was probably about 12 years old. The skeleton, which is over 11/2 million years old, was found west of Lake Turkana in northern Kenya.

Homo erectus probably stood slightly more than 5 feet (150 centimeters) tall. These creatures had thick skulls, sloping foreheads, and large, chinless jaws. Their skulls had a browridge, a raised strip of bone across the lower forehead. Homo erectus also had smaller molars, a smaller face, and a less protruding face than Homo habilis had. The brain size of early Homo erectus was only slightly larger than that of Homo habilis. During the course of Homo erectus evolution, however, brain size increased considerably. It eventually reached a size just slightly smaller than that of a modern human brain. Fossil evidence indicates that Homo erectus males were larger than Homo erectus females.

Some of the earliest Homo erectus fossils have been found in Africa. They date from more than 13/4 million years ago. Members of the species eventually migrated from Africa to Asia and Europe. Homo erectus reached the island of Java, in Indonesia, by 1 million years ago, and perhaps by more than 13/4 million years ago. By 600,000 years ago, the species had spread into northern Asia. Homo erectus reached Europe more than 700,000 years ago.

Homo erectus was probably the first human being to master the use of fire. These people may also have been the first to wear clothing. Scientists believe that as Homo erectus moved into northern areas and faced cold winters, fire and clothing became necessary. Archaeologists have not found any traces of early clothing, but it was probably made from animal hides. The oldest evidence of the use of fire was found in a cave that Homo erectus occupied about 600,000 years ago near what is now Beijing, in northern China. Stone tools and the remains of more than 40 Homo erectus individuals were found in the cave, along with burnt animal bones surrounded by thin layers of ash.

Homo erectus was a more skillful toolmaker than Homo habilis. For example, Homo erectus created double-edged cutting tools called hand axes out of stone. These early human beings probably used hand axes for many tasks, such as shaping wood or bone and cutting up meat. The bones of large animals, including mammoths, have been found at Homo erectus sites. But scientists do not know if these people actually hunted big game. They may have collected the remains of animals that had been killed by predators. The main foods in the Homo erectus diet were probably fruits, vegetables, nuts, seeds, insects, and small animals.

Early Homo sapiens

Most anthropologists believe that between about 400,000 and 300,000 years ago, Homo erectus evolved into a new human species called Homo sapiens. Because evolution took place gradually during this time, anthropologists have found it difficult to say precisely when Homo sapiens first appeared. Anthropologists disagree on whether certain fossil specimens from this period are Homo sapiens or Homo erectus.

The term Homo sapiens means wise human being. All people living today belong to this species. But early Homo sapiens differed greatly from modern people.

The first Homo sapiens strongly resembled Homo erectus. The main difference between the two was that Homo sapiens had a higher and more rounded skull. However, like Homo erectus, the first Homo sapiens individuals had large faces that protruded around the mouth and nose. They also had big browridges and low, sloping foreheads. These people lacked a chin, a feature found only in the modern type of human beings.

The brain size of early Homo sapiens varied over a wide range. Some of these people had brains that were similar in size to those of late Homo erectus. Others had brains nearly as large as modern human brains.

Early Homo sapiens were about as tall as modern human beings. They were solidly built with powerful muscles and were probably much stronger than modern people. The differences in size between males and females that is so well marked in earlier hominids appears to be reduced in Homo sapiens.

Homo sapiens were the first prehistoric people to inhabit large areas of Europe. Anthropologists have found important Homo sapiens fossils in England, France, Germany, Greece, Italy, and Spain. Homo sapiens fossils have also been found in many parts of Asia and Africa.

Some of the most important evidence of Homo sapiens' way of life comes from a site called Terra Amata, which lies near Nice, France, along the coast of the Mediterranean Sea. Terra Amata was a settlement occupied by what some anthropologists believe was a group of Homo sapiens about 250,000 years ago or earlier.

At Terra Amata, scientists found evidence of tentlike structures that a group of Homo sapiens probably built for shelter. Further evidence indicates that this group stayed for periods of time at Terra Amata to hunt and gather food during a yearly round of various campsites. Prehistoric people did not form permanent settlements until farming began about 11,000 years ago. But the studies at Terra Amata suggest that earlier people created temporary settlements at specific locations based on their knowledge of food sources.

Neanderthals were a type of early Homo sapiens who lived in parts of Europe and the Middle East from about 130,000 to 35,000 years ago. Different types of early Homo sapiens occupied other parts of Africa, Europe, and Asia during this period. Neanderthals have become the most widely known of the early Homo sapiens mainly because they were the first prehistoric people discovered. The term Neanderthal, also spelled Neandertal, comes from the Neander Valley near Dusseldorf, Germany. The first Neanderthal fossils identified as prehistoric people were found there in 1856.

The Neanderthals were large and muscular. They had protruding faces, large browridges, and low foreheads. Most of them also lacked a chin. But the Neanderthals had large brains. Their average brain size was larger than that of modern human beings.

Some Neanderthals lived in Europe during the most recent ice age, when vast sheets of ice covered many northern parts of the world. These Neanderthals developed qualities that enabled them to cope with harsh winter conditions. Archaeologists have found most evidence of Neanderthals in caves, where many of these people lived to escape the extreme cold.

However, archaeologists have also discovered sites where Neanderthals camped in the open. These sites provide evidence that the Neanderthals pitched large circular tents around a central hearth area. The tent covering probably consisted of hides, leaves, or bark supported by wooden posts and secured to the ground by stakes made from animal bones.

The Neanderthals were more skilled hunters and toolmakers than earlier prehistoric people. The bones of many animals have been found at Neanderthal sites. Some of the bones indicate these people sometimes hunted such large animals as horses, reindeer, and mammoths. But they were more successful in capturing hares and other small animals. The Neanderthals made a variety of stone tools. They used these tools to butcher animals, prepare vegetable foods, scrape animal hides, and carve wood. They also made sharp, pointed tools that may have been spearheads.

The Neanderthals were the first human beings known to have buried their dead. In Neanderthal sites throughout Europe and the Middle East, archaeologists have uncovered the carefully buried skeletons of women, men, and children. Anthropologists do not understand why the Neanderthals adopted this custom.

The rise of modern human beings

The first prehistoric people with modern human features appeared about 100,000 years ago in either the Middle East or Africa. These people had a chin, a high forehead, and a smaller, less-protruding face than earlier Homo sapiens had. The first physically modern human beings also lacked the large browridge of earlier people and had a higher and more rounded skull. Scientists classify modern human beings as Homo sapiens sapiens, a subspecies of Homo sapiens.

Anthropologists are fairly certain that the first modern human beings evolved from earlier types of Homo sapiens. But scientists have had difficulty understanding the precise evolutionary relationship between modern humans and early Homo sapiens. For example, fossil evidence shows that Neanderthals lived in Europe and the Middle East after the modern type of human beings appeared. This evidence makes it difficult for scientists to determine whether Neanderthals were the ancestors of modern Europeans or were a related type of early human being that became extinct.

The question of human races is related to the origin of modern human beings. Most anthropologists today reject the idea that the human population can be divided into biologically defined races. Physical features of modern human beings change gradually from one region to another, making it difficult to draw a dividing line between them. However, anthropologists have observed that groups of people who have lived in certain parts of the world for many thousands of years tend to differ in appearance from groups in other parts of the world. These differences are probably adaptations to local environments. For example, people whose ancestors have lived for generations in sunny climates tend to have dark skin. Dark pigment helps protect the skin from sunburn and reduces the risk of skin cancer.

Anthropologists have developed two main theories to explain the origin of modern human beings and the development of what are sometimes called "races"--that is, the physical differences among populations in different regions. These theories may be referred to as (1) the multiple origins theory and (2) the single origin theory.

The multiple origins theory. Some anthropologists believe that the origin of separate human populations began with the migration of Homo erectus out of Africa about 13/4 million years ago. According to this theory, Homo erectus split into separate populations in Africa, Asia, and Europe. These groups evolved according to their different environments and developed different physical characteristics. Eventually, Homo erectus in each geographic area evolved into a form of Homo sapiens unique to the area. These multiple types of Homo sapiens, in turn, became the ancestors of the so-called modern human races.

The best evidence supporting this theory comes from a series of skulls found in Indonesia and Australia. In age, these skulls span a period beginning about 1 million years ago and lasting until the appearance of physically modern human beings. All the skulls show similar features that are characteristic of that part of the world. These fossils appear to represent a population that continuously evolved over time and resulted in modern Southeast Asian people.

The single origin theory. Other anthropologists disagree with the multiple origins theory and claim that separate modern human populations had a common ancestor much more recently. According to this single origin theory, modern human beings--Homo sapiens sapiens--first appeared in either Africa or the Middle East between 200,000 and 100,000 years ago. This modern type of human being then spread to other parts of Africa, Asia, and Europe, replacing the older populations of Homo sapiens who were living there. All other populations of early human beings, such as Neanderthals, became extinct. According to this theory, the development of different physical characteristics in today's so-called racial groups began with the spread of Homo sapiens sapiens from Africa or the Middle East.

Some of the best fossil evidence that supports this theory comes from cave sites in Israel. At two of these sites, called Qafzeh and Skhul, archaeologists excavated fossil skeletons of modern-looking human beings that date from about 100,000 years ago. But at a nearby site called Kebara, a Neanderthal skeleton that dates from about 60,000 years ago was found. Supporters of the single origin theory point out that it is difficult to place the Neanderthals as ancestors of modern human beings if they were known to have lived after modern human beings first appeared. Therefore, another group--the first modern humans from either Africa or the Middle East--must have replaced the Neanderthals.

Some scientists also support this theory through use of genetic evidence from living people. Molecular biologists have gained a greater understanding of human evolution by studying the rate of change of human genetic material. By calculating this rate of change, some scientists have concluded that all living human beings must have evolved from one physically modern human ancestor who lived about 200,000 years ago. In one version of this theory, the common ancestor--who has become known as African Eve--was a Stone Age woman in Africa. Although most scientists accept the conclusion of genetic studies that modern human beings originated in Africa, many believe this common ancestor appeared earlier than supporters of the single origin theory claim.

Cultural development of modern human beings

Fossil evidence indicates that the cultural activities of the first physically modern humans were similar to those of other Homo sapiens who lived during that time. For example, the modern-looking human beings from the 100,000-year-old sites of Qafzeh and Skhul were found with the same kinds of stone tools that Neanderthals used at sites nearby. Thus, the appearance of modern human beings did not represent a sudden change in lifestyle or culture from the earlier populations.

Throughout the early stages of human evolution, the rate of cultural change among prehistoric people was extremely slow. Stone tools and other products of human skill remained unchanged for many thousands of years. However, about 35,000 years ago, the rate of cultural change began to accelerate rapidly. This later period is generally referred to as the Upper Paleolithic.

During the Upper Paleolithic, prehistoric people made an extraordinary number of advances in their way of life. The best-known type of human beings from this period are the Cro-Magnons. The Cro-Magnons lived in Europe, the Middle East, and North Africa from about 40,000 to 10,000 years ago. Scientists believe they resembled modern Europeans.

The improvement of tools was one of the major accomplishments of the Cro-Magnons and other Upper Paleolithic people. After 35,000 years ago, new tool types and methods of manufacture appeared at a rapid pace. Stone tools made during this time were much more refined and complex in design. Toolmakers invented many new devices to serve specialized carving, cutting, and drilling functions. Tools made from bone, ivory, and animal horns also became widely used. Archaeologists have found harpoons, fish spears, and needles made from bone that date from this period. These tools suggest the introduction of many new activities, such as sewing close-fitting clothes and fishing with improved equipment.

Upper Paleolithic fossil sites also indicate that these people had become skillful hunters. Some sites hold the remains of thousands of animals. In addition, the bones of mammoths, horses, and reindeer are common, suggesting these people hunted large animals successfully.

The appearance of art was one of the most spectacular developments of the Upper Paleolithic. The oldest works of art that archaeologists have found date from this period. Furthermore, the practice of creating art seems to have spread rapidly--especially in Europe.

Some of the oldest artworks from the Upper Paleolithic were ornaments, such as beads made from polished shells. After about 30,000 years ago, prehistoric people began to produce a variety of artwork. They excelled at carving--creating beautiful sculptures of animals and people, usually from ivory or bone. They also made engravings of people, fish, birds, and other animals on bone, ivory, and stone. The Upper Paleolithic people also sculpted clay, ivory, and stone figurines of women, which may have represented fertility.

A number of caves in Europe are covered with paintings, drawings, and engravings from the Upper Paleolithic. Most distinctive of these are the paintings, which appear on the cave walls and ceilings. Most of the paintings are of the animals early people probably hunted, including bison, mammoths, and horses. Some of the paintings show animals that have been speared.

Many of the paintings are of a high artistic quality. Paleolithic artists used three basic colors: black, red, and yellow. They obtained these pigments from natural sources including charcoal, clay, and such minerals as iron. Often, the artists painted animals on a part of the cave wall where there was a natural swelling, which created a three-dimensional effect.

The development of speech. No one knows when or how spoken language developed. However, many anthropologists think that human beings may have first begun to speak sometime during the Upper Paleolithic. These scientists believe that the many cultural developments which occurred at this time--especially the appearance of art--may be related to the development of speech. The beginnings of speech, the creation of artwork, and the making of complex tools all required advancements in human intelligence and cooperation.

The spread of settlement. Prehistoric people spread into new areas during the Upper Paleolithic period. Many cultural and technological advances enabled them to migrate to such places as Australia, the Pacific Islands, North America, and South America.

Perhaps as early as 50,000 years ago, people used boats to reach Australia. About 20,000 years ago, people from Australia and Asia began to colonize the Pacific Islands. These people employed sophisticated navigational systems that involved knowledge of the stars, water currents, and wind direction. They also used simple navigational instruments.

By 30,000 years ago, human beings had spread to the cold, harsh tundra of northeast Asia. At that time, the Bering Strait was a land bridge that connected Asia and North America. Most scientists believe prehistoric people crossed this bridge and were living in North America by 15,000 years ago. Eventually, early modern human beings populated all of North and South America.

The most recent ice age ended about 11,500 years ago. As the ice receded, the environment of many prehistoric people changed and greatly affected their way of life. In some areas, such as Europe, forests began to spread across the land. The people of these areas learned to hunt new species of animals and gather new varieties of plants from these forests. In other parts of the world, people began to experiment with methods of controlling their supply of food. This led to farming.

The rise of agriculture, according to most scientists, began in the Middle East about 11,000 years ago, or 9000 B.C. The first farmers lived in a region called the Fertile Crescent, which covers what is now Lebanon and parts of Iran, Iraq, Israel, Jordan, Syria, and Turkey. At first, these people probably did not depend entirely on the crops they raised. But as they improved their methods, farming became their most important source of food. The earliest plants grown in the Middle East were probably barley and wheat. Early farmers in the Middle East eventually raised cattle, goats, hogs, and sheep.

The first farmers originated in areas where there were enough wild plants and animals to provide food for large populations. As a result, people often settled in permanent villages for years at a time. At the end of the Ice Age, the climate became warmer and affected the food supply. New plants, such as grains, replaced older plants. Scientists believe that Upper Paleolithic people were able to remain in permanent settlements because they discovered how to control these new plants and increase the amount of food in their area. They learned that they could plant seeds from the plants that they ate. They also learned that they could domesticate animals, perhaps by capturing young ones from the wild and raising them. In time, people began to depend on these planted crops and domestic animals for a steady supply of food.

By about 7000 B.C., agriculture had developed independently in Asia and southern North America. In what are now Thailand and southern China, farmers grew breadfruit, bananas, and rice, while people in what became Mexico raised beans, corn, and squash.

People were herding cattle and growing grain in northern Africa by 6000 B.C. By that time, people had also begun to farm in the Indus River Valley of what is now Pakistan. By 4000 B.C., farming had begun in the Huang He Valley of China. Farming spread throughout most of Europe by 3000 B.C. Farming in most parts of North and South America began after prehistoric times. Food was probably more plentiful in these areas, so farming did not become necessary until later.

Changes in life style. Prehistoric farmers, called Neolithic people, had a way of life that differed greatly from that of Upper Paleolithic people. In some ways, farming made life easier. It provided a steady supply of food and enabled people to stay in one place for a long time. However, farmers also had to work longer and harder than did hunters and gatherers.

Prehistoric farmers set up villages near their fields and lived there as long as their crops grew well. Most fields produced good crops for only a few years. The land then became unproductive because continuous planting used up nutrients in the soil. The early farmers did not know about fertilizers that could replace these nutrients. They shifted their crops to new fields until none of the land near their village was fertile. Then they moved to a new area and built another village. In this way, farmers settled many new areas.

Prehistoric farmers built larger, longer-lasting settlements than the camps that Paleolithic people had built. In the Middle East, for example, early farmers constructed their houses of solid, sun-dried mud. Dried mud was much more resistant to weather than the materials earlier people used, such as skins and bark. The early farmers also learned to build fences to confine and protect their livestock.

The end of prehistoric times. Neolithic people made inventions and discoveries at an even faster rate than did the people of the Upper Paleolithic. Early farmers developed a number of useful tools. These implements included sickles to cut grain, millstones to grind flour, and polished stone axeheads.

By about 11,000 B.C., people had discovered how to make pottery. Before that time, they used animal skins or bark containers to hold water. To boil water, early cooks had to drop hot stones into the water, because they could not hang animal skins or bark over a fire. Pottery containers enabled people to hold and boil water easily. After the rise of agriculture, people used pottery to store grain and other food.

No one knows when people made the first objects out of metal. But metals became important only after metalworkers learned to make bronze, a substance hard and durable enough to make lasting tools. People of the Middle East made bronze as early as 3500 B.C. The Bronze Age began when bronze replaced stone as the chief toolmaking material. In some areas, such as the Near East, the Bronze Age began about 3000 B.C.

The development of farming was an important step toward the rise of civilization. As farming methods improved and food became more plentiful, many people were freed from the jobs of food production. These people developed new skills and trades. In addition, the abundant food supply enabled more people to live in each community. In time, some farming villages became cities. The first cities appeared by about 3500 B.C. These cities were the birthplaces of modern civilization.

Archaeologists believe writing was invented about 3500 B.C. in cities in the Tigris-Euphrates Valley in what is now Iraq. People then learned to record their history, and prehistoric times came to an end.

Studying prehistoric people

Since the mid-1800's, scientists have accumulated much information about prehistoric people and their ways of life. This information has enabled scientists to piece together a general picture of how hominids have evolved. Scientists have used various methods to obtain and study information about prehistoric people.

Studying fossils of prehistoric people has provided anthropologists with much of their most valuable information. Human fossils give direct evidence of what prehistoric people looked like, what they ate, how long they lived, and how their lives were different from ours.

Unfortunately, fossil bones and teeth are extremely rare. This is because certain unusual conditions must be present for a fossil to form. An animal or person must be buried soon after death, and minerals from the soil must gradually replace the bony material to create a fossil. Also, the bones and teeth that do become fossils have often been broken, damaged, or distorted by the weight of the deposits in which they were buried. Soft tissues--such as skin, hair, and internal organs of prehistoric people--decay without leaving any fossil remains. As a result, scientists cannot determine certain characteristics of early humans, such as the color of their skin or the texture of their hair.

After a fossil is discovered, scientists first determine whether it came from an adult or a child, and whether the individual was a male or female. Anthropologists then compare the fossil with similar structures from extinct hominids, living human beings, and apes. These examinations enable scientists to more fully understand the specimen's place in human evolution. Later, anthropologists study the fossil further to determine a relationship between the individual's physical structure and its way of life.

Examining prehistoric sites is another method anthropologists use to gain information about prehistoric people and their way of life. These sites may be places where prehistoric people camped, made tools, butchered animals, or buried their dead.

The excavation of prehistoric sites is a complicated process. Archaeologists carefully scrape away soil, sand, or rock to reveal tools, bones, pottery, and other evidence of early human life. They make detailed notes and maps, often using computers, to record the exact position of all important items. They later use these records to precisely reconstruct the layout of the site. By studying the objects they find and the layout of the site, scientists learn how prehistoric people used the site and how these activities fit into their way of life.

Scientists have found much evidence of prehistoric people's lives at sites up to 100,000 years old. These sites have produced ancient tools, pottery, artwork, bits of clothing, traces of dwellings, and evidence of food, such as animal bones and plant material. These abundant clues enable anthropologists to form a fairly detailed picture of early people's lives. Unfortunately, scientists have found little of this type of evidence at sites older than 100,000 years. As a result, we know much less about hominids who lived before that time.

Placing prehistoric people in time is one of the most important elements of learning about human ancestors. To understand the significance of a newly discovered hominid fossil, scientists must determine how that hominid relates to others that have already been studied. This relationship can be determined by dating the newly found fossil--that is, by determining when it was alive.

Scientists have traditionally dated fossils by studying the deposit in which the fossil was found. Based on knowledge of geological history, scientists can determine the age of the deposit. They then interpret this information to provide an approximate age for the fossil.

Newer dating methods are much more accurate. These methods are based on the fact that certain radioactive isotopes (unstable forms of chemical elements) decay at a known rate and form different isotopes. By measuring the amount of each isotope in a fossil, scientists can determine how long the decay has been going on and therefore how old the fossil is. The most commonly used dating methods of this type are radiocarbon dating and potassium-argon dating.

Molecular analysis of living people is a more recent method of study that scientists have used to better understand prehistoric people. This method largely involves the study of genetic material called deoxyribonucleic acid (DNA).

Molecular biologists in this field extract DNA from living people and compare it with DNA from other people and from other living primates. Scientists also study the rate of change that DNA appears to go through during evolution. Scientists often use computers to help analyze data obtained through this research. From these studies, scientists have gained valuable knowledge about the relationship between living people and their ancestors. In many cases, however, anthropologists have disagreed on how to best interpret the results of these studies.
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Roland Camilleri

Moderator

Sydney , Australia.