Evaluation Only. Created with Aspose.Words. Copyright Aspose Pty Ltd. UNIT 6 EARLY HUMANS

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1 Evaluation Only. Created with Aspose.Words. Copyright Aspose Pty Ltd. UNIT 6 EARLY HUMANS This Word document contains ALL of the readings from the unit. All readings include multiple copies at different Lexile levels. You are free to repurpose these materials as needed for your classroom. Please do remember to properly cite Big History as the source. If you modify the text, it will change the lexile level. As always, only print what you need. LUCY AND THE LEAKEYS...2 JANE GOODALL...17 COLLECTIVE LEARNING (PART 1)...27 FORAGING...35 PIERRE TEILHARD DE CHARDIN...48 When viewing this document in Microsoft Word format, you can Ctrl+Click on the name of each article to go directly to the corresponding page in the reader. UNIT 6 EARLY HUMANS TEXT READER 1

2 Lucy and the Leakeys Up until the mid-twentieth century, it was believed that humans evolved in Europe, or Asia, a mere 60,000 years ago. But the groundbreaking work of Mary and Louis Leakey changed all that. Lucy and the Leakeys (1210L) By Cynthia Stokes Brown Until the 1950s, European scientists believed that Homo sapiens evolved in Europe, or possibly in Asia, about 60,000 years ago. Since then, excavation of fossil bones in East Africa, pioneered by Mary and Louis Leakey, has revealed that Homo sapiens may have emerged in Africa much earlier. Human origins Most scientists agree that the human species emerged somewhere in Africa about 200,000 years ago. This understanding is based on fossilized bones and skulls that have been uncovered in East Africa and dated accurately by radiometric dating. These bones and skulls range from 25,000 to 4.4 million years old and show many different stages of human and primate evolution. These fossils have been uncovered by paleoarchaeologists scientists who study the material remains of the entire human evolutionary line. Based on the fossil evidence, paleoarchaeologists currently tell the following story: For 99.9 percent of our history, from the time of the first living cell, the human ancestral line was the same as that of chimpanzees. Then, about 5 to 7 million years ago, a new line split off from the chimpanzee line, and a new group appeared in open savanna rather than in rain forest jungle. The old group in the rain forest continued to evolve, and two of its species remain in existence: the common chimpanzee and the bonobo. The new group in the savanna evolved over the millennia into several species (how many is not entirely clear, but at least 18 different ones), until only one was left: Homo sapiens. All the species before us back to our common ancestor with chimpanzees are now collectively called hominines. (They used to be called hominids. ) Try visualizing it like this. Imagine your mother holding hands with her mother, who is holding hands with her mother, and keep going back in time for 5 million years. The final clasping hand would belong to an unknown kind of an ape whose descendants evolved into chimpanzees, bonobos, and, ultimately, your mother. If we count each generation as averaging 14 years, there would be about 360,000 hand-holders in the hominine line. (Thanks to Richard Dawkins, a contemporary English biologist, for this metaphor.) Paleoarchaeologists debate what names to put on the bones they find. They have to decide which ones ought to be considered a separate species. No central authority determines this, so paleoarchaeologists discuss it and try to reach a consensus. They more or less agree on UNIT 6 EARLY HUMANS TEXT READER 2

3 three main categories of species before_ Homo sapiens_; these are Australopithecus (2 to 4 million years ago), Homo habilis (1.8 to 2.5 million years ago), and Homo erectus (2 to 4 million years ago). Clearly, some of these species must have overlapped during hominine evolution. What scientists now know took many years to figure out. The first early human fossil bones were found in Europe Neanderthals in Germany in 1857 and Cro-Magnon in France in Java Man was found in Sumatra, Indonesia, in Most paleoarchaeologists in the 1920s and 30s felt certain that Homo sapiens must have evolved in Europe, or possibly Asia, since a group of fossils known as Peking Man was found in China in Africa, widely known then as the Dark Continent, was not considered a possibility largely due to racist thinking. The Leakeys look to Africa When did anyone start looking in Africa for hominine fossils? One German professor found a Homo sapiens skeleton in 1913 in Tanganyika (now Tanzania), and a professor in South Africa found a child s skull there in But archaeologists denied that these bones were significant. The first to make credible finds were an English couple, Louis and Mary Leakey. Louis Leakey was born and grew up in Kenya, in a tiny mission village near Nairobi, now the capital of Kenya but then a small village on the railroad to Lake Victoria, the source of the Nile River. Louis s parents were missionaries from England. They hired English tutors for their children, but mostly Louis spent his childhood hunting and trapping with the local Kikuyu boys. Louis spoke Kikuyu as a native language and went through initiation rites with his Kikuyu peers. At the age of 13, Louis built his own house, as was Kikuyu custom. He also found some relics that he recognized as ancient hand axes, even though they were made of obsidian rather than flint, like the ones in Europe were. World War I prevented Louis from being sent to boarding school in England; he was 16 before he traveled to London to prepare for entrance to Cambridge University to become an archaeologist. Mary Nicol grew up in England, but her father was an artist who took his family traveling for nine months out of each year, mostly in southern France, where he painted pictures that he sold in London. He loved Stone Age history and showed Mary many archaeological sites in France. She was only 13 when he died, and her mother sent her to strict Catholic schools in London, where Mary rebelled and was temporarily expelled several times. At 17, she took charge of her own education, learning to fly a glider and to draw, and attending lectures in archaeology. Mary and Louis met in London in 1933 when she was 20 and he 30. Louis was married at the time with one small child and another on the way but he and Mary nevertheless began an affair, and in 1935 she joined him in Tanzania during one of his expeditions. They married the following year once his divorce was complete, though Louis s actions cost him his research fellowship at Cambridge University. Louis chose the Oldowan Gorge, now called Olduvai Gorge, as his main area of research. It lies about 200 miles southwest of Nairobi, in present-day Tanzania. Olduvai Gorge took shape when a river cut through the sediment that had formed over 2 million years at the UNIT 6 EARLY HUMANS TEXT READER 3

4 bottom of a huge ancient lake. About 20,000 years ago, an earthquake drained the lake; after that, the river cut a deep gorge through the sediment of the old lake bed. The river sliced mostly through the shoreline of the lake, revealing the remains of people and other animals that had once gathered there. Almost 2 million years of history are exposed in the 25-mile-long main gorge and in a side gorge 15 miles long, a layer cake of evolution, as Virginia Morell, a biographer of the Leakeys, calls it. Olduvai Gorge lies in the Great Rift Valley, a massive geological fault in the African plate. The fault line runs from the Red Sea southward through Ethiopia and Tanzania, down to the mouth of the Zambezi River in Mozambique. Eventually this crack in the plate will deepen so much that the eastern piece of Africa will break off and move away. Mountains and volcanoes frame the edge of the Great Rift Valley. The volcanic eruptions produce ash, which easily buries and fossilizes bones, making this ideal territory for finding fossils. After being buried under layers of soil for millions of years, the fossils are moved upward as the Earth continues to shift. Life in the field Life was an adventure for Louis and Mary at Olduvai and other sites in the Great Rift Valley. They lived in tents or mud huts with dirt floors and kerosene lamps. Often they had no fresh vegetables or fruit, living on fresh fish, canned food, rice and corn meal, and coffee and tea. (They both smoked cigarettes heavily.) Sometimes Louis shot a gazelle for its meat. Prides of lions prowled their camps at night. Keeping the cars and trucks running in the wilderness proved a monumental task. On occasion, the only water available came from watering holes where rhinoceroses wallowed; the soup, coffee, and tea would taste of rhino urine. African servants cooked and served their meals and washed their clothes. Their reward came in living outdoors amid some of the most beautiful scenery in the world gorgeous volcanic mountains with the Serengeti Plain spread out before them, hosting flamingos, rhinos, giraffes, lions, leopards, antelope, and zebra. The couple worked early and late in the day to avoid the hottest sun, in sand that radiated heat. They used a dental pick and an artist s brush to reveal, ever so slowly, the hidden fossils of long ago, buoyed by the excitement of finding clues to how humans came to be. Louis and Mary found many ancient tools and fossils of extinct animals, but finding human fossils proved more difficult. In 1948, Mary found a primate skull that they thought might be the missing link connecting apes and humans, but it turned out not to be. In 1959, Mary discovered a skull that dated at 1.75 million years old, a find that made the Leakeys famous and led to funding from National Geographic. In 1960, Louis found the hand and foot bones of a 12-year-old, whom he named Homo habilis, thus classifying this species of hominine. Until the 1950s, fossil hunting was filled with confusion because no one had a way to date the bones except by estimating the age of the rocks in which they were found. Every expedition had to have a geologist to study the layers of rock, but even those scientists were just approximating the age. Things changed that decade with the advent of radiometric dating, which allowed fossil ages to be identified much more accurately. Carbon-14 atoms would not work for dates that go as UNIT 6 EARLY HUMANS TEXT READER 4

5 far back as early hominines; instead, potassium found in the volcanic ash was used in a potassium-argon radiometric-dating technique. Louis Leakey was convinced that humans had evolved from the apes, which he realized were fast losing their territory in Africa. They had never been studied in the wild, only in captivity. Since knowing more about them would provide insights into hominine behavior, Leakey took the initiative to raise funds for people chosen by him to study apes in their own habitat before it was too late. He looked for young women who could do this work. In 1960, he helped a young Jane Goodall begin her study of chimpanzees in the wild; later, Dian Fossey studied gorillas and Biruté Mary Galdikas studied orangutans. Finding Lucy Meanwhile, others had begun searching for fossil bones in Africa. After Louis Leakey died of a heart attack in 1972, Mary Leakey continued working at Olduvai Gorge; however, the next spectacular find occurred in the Ethiopian part of the Great Rift Valley, at Afar. In 1974, Donald Johanson, an archaeologist from Case Western Reserve University in Cleveland, Ohio, found parts of a skeleton there that dated back 3.2 million years the oldest hominine bones yet discovered. Johanson nicknamed the skeleton Lucy, because that night, as he and the others in camp celebrated their discovery, they listened repeatedly to the Beatles song Lucy in the Sky with Diamonds. Lucy was assumed to be female because the bones were of a small hominine, roughly 3and a half feet tall. Only about 20 percent of a full skeleton was found, and most of the skull was missing. Fragments suggest it was small, while the foot, leg, and pelvis bones showed that Lucy walked upright. This was important evidence that, in the human line, bipedalism came earlier than brain growth, which previously had been supposed to come first. The Leakey legacy Mary and Louis Leakey raised three sons, who lived with them in the field Jonathan, Richard, and Philip. These sons stayed in Kenya as grown men, and Richard carried on his parents work on human origins, making his first major find in After discovering another significant skull, he went on to build up the National Museum of Kenya and to run the Kenya Wildlife Service, focusing on saving elephants. After Louis s death in 1972, Mary became a leading scientist in her own right. She initiated a camp at Laetoli, 35 miles from Olduvai, where the soil dated to 3.59 to 3.77 million years old. There, in 1976, she found an astonishing set of hominine footprints preserved in volcanic ash, more evidence that hominins of that time walked upright. Mary Leakey received honorary degrees from many universities, including Oxford, Yale, and Chicago. She lived at Olduvai long enough to see leopards and rhinos dwindle to near extinction. In 1983, she ended her fieldwork and moved to Nairobi, where she died in 1996 at age 84. Her granddaughter Louise Leakey, daughter of Richard and Meave Leakey, carries on the Leakey tradition, working in the scorching sun to piece together the story of human origins in Africa. UNIT 6 EARLY HUMANS TEXT READER 5

6 Thanks to the pioneering work of Louis and Mary Leakey, there s overwhelming evidence to back that story. Confirmed by recent genetic testing, it is clear that Homo sapiens originated in Africa much longer ago than previously thought after separating from the chimpanzee line 5 to 7 million years earlier. The Leakeys spent their lives digging in the earth and tirelessly raising funds in the search for human origins. At a time when few others could entertain the thought, Louis demonstrated that our species had its beginnings on the African continent. Lucy and the Leakeys (1070L) By Cynthia Stokes Brown, adapted by Newsela Until the 1950s, European scientists believed that Homo sapiens evolved in Europe, or possibly in Asia, about 60,000 years ago. Since then, the excavation of fossil bones in East Africa, pioneered by Mary and Louis Leakey, has revealed that Homo sapiens may have emerged in Africa much earlier. Human origins Most scientists agree that the human species emerged somewhere in Africa about 200,000 years ago. This understanding is based on fossilized bones and skulls that have been uncovered in East Africa and dated accurately by radiometric dating. These bones and skulls range from 25,000 to 4.4 million years old, and show many different stages of human and primate evolution. These fossils have been uncovered by paleoarchaeologists scientists who study the material remains of the entire human evolutionary line. Based on the fossil evidence, paleoarchaeologists currently tell the following story: For 99.9 percent of our history, from the time of the first living cell, the human ancestral line was the same as that of chimpanzees. Then, about 5 to 7 million years ago, a new line split off from the chimpanzee line. The new group appeared in open savanna rather than in rain forest jungle. The old group in the rain forest continued to evolve, and two of its species remain in existence: the common chimpanzee and the bonobo. The new group in the savanna evolved over the millennia into several species. It's unclear how many, but at least 18 different ones. Finally, only one was left: Homo sapiens. All the species before us back to our common ancestor with chimpanzees are now collectively called hominines. (They used to be called hominids. ) Try visualizing it like this. Imagine your mother holding hands with her mother. She, in turn, is holding hands with her mother. Keep going back in time for 5 million years. The final clasping hand would belong to an unknown kind of ape whose descendants evolved into chimpanzees, bonobos, and, ultimately, your mother. If we count each generation as averaging 14 years, there would be about 360,000 hand-holders in the hominine line. We can thank Richard Dawkins, a contemporary English biologist, for this metaphor. Paleoarchaeologists debate what names to put on the bones they find. They have to decide which ones ought to be considered a separate species. No central authority determines this. So paleoarchaeologists discuss among themselves and try to reach a consensus. They UNIT 6 EARLY HUMANS TEXT READER 6

7 more or less agree on three main categories of species before Homo sapiens; these are Australopithecus (2 to 4 million years ago), Homo habilis (1.8 to 2.5 million years ago), and Homo erectus (2 to 4 million years ago). Clearly, some of these species must have overlapped during hominine evolution. What scientists know took many years to figure out. The first early human fossil bones were found in Europe Neanderthals in Germany in 1857 and Cro-Magnon in France in Java Man was found in Sumatra, Indonesia, in Most paleoarchaeologists in the 1920s and 30s felt certain that Homo sapiens must have evolved in Europe, or possibly Asia, since a group of fossils known as Peking Man was found in China in Africa, widely known then as the Dark Continent, was not considered a possibility, largely due to racist thinking. The Leakeys look to Africa When did anyone start looking in Africa for hominine fossils? One German professor found a Homo sapiens skeleton in 1913 in Tanganyika (now Tanzania). A professor in South Africa found a child s skull there in But archaeologists denied that these bones were significant. The first to make credible finds were an English couple, Louis and Mary Leakey. Louis Leakey was born and grew up in Kenya, in a tiny mission village near Nairobi, now the capital of Kenya. Louis s parents were missionaries from England. Louis spent much of his childhood hunting and trapping with the local Kikuyu boys. He spoke Kikuyu as a native language and went through initiation rites with his Kikuyu peers. At the age of 13, Louis built his own house, as was Kikuyu custom. He also found some relics that he recognized as ancient hand axes. At 16, he traveled to London to enter Cambridge University and become an archaeologist. Mary Nicol grew up in England, but her father was an artist who took his family traveling each year, mostly in southern France. He loved Stone Age history and showed Mary archaeological sites in France. She was only 13 when he died, and her mother sent her to strict Catholic schools in London. Mary rebelled and was expelled several times. At 17, she took charge of her own education, learning to fly a glider and to draw, and attending lectures in archaeology. Mary and Louis met in London in 1933 when she was 20 and he 30. Louis was married at the time with one small child and another on the way but he and Mary nevertheless began an affair. In 1935, she joined him in Tanzania during one of his expeditions. They married the following year once his divorce was complete. Louis s actions cost him his research fellowship at Cambridge University. Louis chose the Oldowan Gorge, now called Olduvai Gorge, as his main area of research. It lies about 200 miles southwest of Nairobi, in present-day Tanzania. Olduvai Gorge took shape when a river cut through the sediment that had formed over 2 million years at the bottom of a huge ancient lake. About 20,000 years ago, an earthquake drained the lake; after that, the river cut a deep gorge through the sediment of the old lake bed. The river sliced mostly through the shoreline of the lake, revealing the remains of people and other UNIT 6 EARLY HUMANS TEXT READER 7

8 animals that had once gathered there. Almost 2 million years of history are exposed in the 25-mile-long main gorge and in a side gorge 15 miles long. Olduvai Gorge lies in the Great Rift Valley, a massive geological fault in the African plate. The fault line runs from the Red Sea southward through Ethiopia and Tanzania, down to the mouth of the Zambezi River in Mozambique. Eventually this crack in the plate will deepen so much that the eastern piece of Africa will break off and move away. Mountains and volcanoes frame the edge of the Great Rift Valley. The volcanic eruptions produce ash, which easily buries and fossilizes bones, making this ideal territory for finding fossils. After being buried under layers of soil for millions of years, the fossils are moved upward as the Earth continues to shift. Life in the field Life was an adventure for Louis and Mary in the Great Rift Valley. They lived in tents or mud huts with dirt floors and kerosene lamps. Often they had no fresh vegetables or fruit, living on fresh fish, canned food, rice and corn meal, and coffee and tea. Sometimes Louis shot a gazelle for its meat. Lions prowled their camps at night. On occasion, the only water available came from watering holes where rhinoceroses wallowed; the soup, coffee, and tea would taste of rhino urine. African servants cooked and served their meals and washed their clothes. Their reward came in living outdoors amid some of the most beautiful scenery in the world. Gorgeous volcanic mountains with the Serengeti Plain spread out before them, hosting flamingos, rhinos, giraffes, lions, leopards, antelope, and zebra. The couple worked early and late in the day to avoid the hottest sun. They used a dental pick and an artist s brush to reveal, ever so slowly, the hidden fossils of long ago. Louis and Mary found many ancient tools and fossils of extinct animals. But finding human fossils proved more difficult. In 1948, Mary found a primate skull that they thought might be the missing link connecting apes and humans, but it turned out not to be. In 1959, Mary discovered a skull that dated at 1.75 million years old. The find made the Leakeys famous and led to funding from National Geographic. In 1960, Louis found the hand and foot bones of a 12-year-old, whom he named Homo habilis, thus classifying this species of hominine. Until the 1950s, fossil hunting was filled with confusion because no one had a way to date the bones. Geologists could only make an estimate based on the age of the rocks in which they were found. Things changed that decade with the arrival of radiometric dating. Now fossil ages could be identified much more accurately. Carbon-14 atoms would not work for dates that go as far back as early hominins; instead, potassium found in the volcanic ash was used in a potassium-argon radiometric-dating technique. Louis Leakey was convinced that humans had evolved from the apes, which he realized were fast losing their territory in Africa. They had never been studied in the wild, only in captivity. Since knowing more about them would provide insights into hominine behavior, Leakey took the initiative to raise money for people chosen by him to study apes in their own habitat before it was too late. He looked for young women who could do this work. In 1960, UNIT 6 EARLY HUMANS TEXT READER 8

9 he helped a young Jane Goodall begin her study of chimpanzees in the wild. Later, he raised money for Dian Fossey to study gorillas and Biruté Mary Galdikas to study orangutans. Finding Lucy Meanwhile, others had begun searching for fossil bones in Africa. After Louis Leakey died of a heart attack in 1972, Mary Leakey continued working at Olduvai Gorge; however, the next spectacular find occurred in the Ethiopian part of the Great Rift Valley, at Afar. In 1974, Donald Johanson, an archaeologist, found parts of a skeleton there that dated back 3.2 million years. They were the oldest hominine bones yet discovered. Johanson nicknamed the skeleton Lucy. Lucy was assumed to be female because the bones were of a small hominine, roughly 3 and a half feet tall. Only about 20 percent of a full skeleton was found, and most of the skull was missing. Importantly, the foot, leg, and pelvis bones showed that Lucy walked upright. This was evidence that, in the human line, bipedalism came earlier than brain growth, which previously had been supposed to come first. The Leakey legacy Mary and Louis Leakey raised three sons, who lived with them in the field. Their son Richard went on to run the Kenya Wildlife Service, focusing on saving elephants. After Louis s death in 1972, Mary became a leading scientist in her own right. She initiated a camp at Laetoli, 35 miles from Olduvai, where the soil dated to 3.59 to 3.77 million years old. There, in 1976, she found an astonishing set of hominine footprints preserved in volcanic ash, more evidence that hominins of that time walked upright. Mary Leakey lived at Olduvai long enough to see leopards and rhinos dwindle to near extinction. In 1983, she ended her fieldwork and moved to Nairobi, where she died in 1996 at age 84. Thanks to the pioneering work of Louis and Mary Leakey, there s overwhelming evidence that Homo sapiens originated in Africa. Confirmed by recent genetic testing, it is clear that humans separated from the chimpanzee line 5 to 7 million years earlier. The Leakeys spent their lives digging in the earth in the search for human origins. At a time when few others could entertain the thought, Louis demonstrated that our species had its beginnings on the African continent. Lucy and the Leakeys (930L) By Cynthia Stokes Brown, adapted by Newsela Most scientists agree that the human species emerged somewhere in Africa about 200,000 years ago. This belief is based on fossilized bones and skulls that have been uncovered in East Africa and dated accurately by radiometric dating. These bones and skulls range from 25,000 to 4.4 million years old. They show many different stages of human and primate UNIT 6 EARLY HUMANS TEXT READER 9

10 evolution. These fossils have been uncovered by paleoarchaeologists scientists who study the material remains of the entire human evolutionary line. Based on the fossil evidence, paleoarchaeologists can tell this story: For 99.9 percent of our history, from the time of the first living cell, the human ancestral line was the same as that of chimpanzees. Then, about 5 to 7 million years ago, a new line split off from the chimpanzee line. The new group appeared in open savanna rather than in rain forest jungle. The old group in the rain forest continued to evolve. Two of its species still exist: the common chimpanzee and the bonobo. The new group in the savanna evolved over the thousands of years into several species. It's unclear how many, but there were at least 18 different ones. Finally, only one was left: humans, or Homo sapiens. All the species before us back to our common ancestor with chimpanzees are now collectively called hominins. They used to be called hominids. Imagine your mother holding hands with her mother. She is holding hands with her mother. Now picture this chain going back in time for 5 million years. The final hand would belong to an unknown kind of ape, sometimes called the "missing link." His descendants evolved into chimpanzees, bonobos, and, ultimately, your mother. If each generation averaged 14 years, there would be about 360,000 hand-holders in the hominine line. Paleoarchaeologists debate what names to put on the bones they find. They have to decide which ones ought to be considered a separate species. They more or less agree on three main categories of species before Homo sapiens; these are Australopithecus (2 to 4 million years ago), Homo habilis (1.8 to 2.5 million years ago), and Homo erectus (2 to 4 million years ago). Clearly, some of these species must have overlapped during hominine evolution. What scientists now know took many years to figure out. The first early human fossil bones were found in Europe. Neanderthals were first discovered in Germany in 1857 and Cro- Magnons in France in Java Man was found in Indonesia in Most paleoarchaeologists in the 1920s and 30s felt certain that Homo sapiens must have evolved in Europe. The other possibility was Asia, since a group of fossils known as Peking Man was found in China in Africa, widely known then as the Dark Continent, was not considered a possibility. The racist thinking of the time ruled it out in scientists' minds. The Leakeys look to Africa When did anyone start looking in Africa for hominine fossils? One German professor found a Homo sapiens skeleton in 1913 in Tanganyika (now Tanzania). A professor in South Africa found a child s skull there in But archaeologists denied that these bones were significant. The first to make finds that others took seriously was an English couple, Louis and Mary Leakey. Louis Leakey was born and grew up in Kenya, in a tiny village near Nairobi, now the capital of Kenya. Louis s parents were missionaries from England. Louis spent much of his childhood hunting and trapping with the local Kikuyu boys. He spoke Kikuyu as a native language and went through ceremonies with his Kikuyu peers. At the age of 13, Louis built UNIT 6 EARLY HUMANS TEXT READER 10

11 his own house, as was Kikuyu custom. He also found some ancient hand axes. At 16, he traveled to London to enter Cambridge University and become an archaeologist. Mary Nicol grew up in England, but her father took the family traveling each year, mostly to southern France. He loved Stone Age history and showed Mary archaeological sites in France. She was only 13 when he died. After, her mother sent her to strict Catholic schools in London. Mary rebelled and was expelled several times. At 17, she took charge of her own education, learning to fly a glider, and attending lectures in archaeology. Mary and Louis met in London in 1933 when she was 20 and he 30. In 1935, she joined him in Tanzania during one of his expeditions. They married the following year. Louis chose the Olduvai Gorge as his main area of research. It lies about 200 miles southwest of Nairobi, in present-day Tanzania. Olduvai Gorge took shape when a river cut through the sediment that had formed over 2 million years at the bottom of a huge ancient lake. About 20,000 years ago, an earthquake drained the lake; after that, the river cut a deep gorge through the sediment of the old lake bed. The river sliced mostly through the shoreline of the lake. By doing so, it revealed the remains of people and other animals that had once gathered there. Almost 2 million years of history are exposed in the 25-mile-long main gorge and in a side gorge 15 miles long. Olduvai Gorge lies in the Great Rift Valley, a massive geological fault in the African plate. The fault line runs from the Red Sea southward through Ethiopia and Tanzania, down to the mouth of the Zambezi River in Mozambique. The fault is deepening in the plate. Eventually this crack will deepen so much that the eastern piece of Africa will break off and move away. Mountains and volcanoes frame the edge of the Great Rift Valley. The volcanic eruptions produce ash, which easily buries and fossilizes bones. This makes the valley an ideal spot to find fossils. After being buried under layers of soil for millions of years, the fossils are moved upward as the Earth continues to shift. Life in the field Life was an adventure for Louis and Mary in the Great Rift Valley. They lived in tents or mud huts with dirt floors and kerosene lamps. Often they had no fresh vegetables or fruit, living on fresh fish, canned food, rice and corn meal. Sometimes Louis shot a gazelle for its meat. Lions prowled their camps at night. African servants cooked and served their meals and washed their clothes. The Leakeys lived outdoors in some of the most beautiful scenery in the world. Gorgeous volcanic mountains surrounded them. The Serengeti Plain spread out before them, hosting flamingos, rhinos, giraffes, lions, leopards, antelope, and zebra. The couple worked early and late in the day to avoid the hottest sun. They used a dental pick and an artist s brush. Ever so slowly, they unearthed hidden fossils of long ago. Louis and Mary found many ancient tools and fossils of extinct animals. But finding human fossils proved more difficult. In 1948, Mary found a primate skull that they thought might be UNIT 6 EARLY HUMANS TEXT READER 11

12 the missing link connecting apes and humans, but it turned out not to be. In 1959, Mary discovered a 1.75-million-year-old skull. The find made the Leakeys famous. In 1960, Louis found the hand and foot bones of a 12-year-old, whom he named Homo habilis, a new species of hominine. Until the 1950s, fossil hunting was filled with confusion. There was no accurate way to date the bones. Geologists could only make an estimate based on the age of the rocks in which they were found. Things changed with the arrival of radiometric dating. Now fossil ages could be identified much more accurately. Carbon-14 atoms would not work for dates that go as far back as early hominins; instead, potassium found in the volcanic ash was used in a potassium-argon radiometric-dating technique. Louis Leakey was convinced that humans had evolved from the apes, which he realized were fast losing their territory in Africa. They had never been studied in the wild, only in captivity. Leakey was sure knowing more about them would provide insights into hominine behavior. He began to raise money for people to study apes in their own habitat before it was too late. He chose the people himself. He looked for young women who could do this work. In 1960, he helped a young Jane Goodall begin her study of chimpanzees in the wild. Later, he raised money for Dian Fossey to study gorillas and Biruté Mary Galdikas to study orangutans. Finding Lucy Meanwhile, others had begun searching for fossil bones in Africa. The next spectacular find occurred in the Ethiopian part of the Great Rift Valley. In 1974, Donald Johanson, an archaeologist, found parts of a skeleton there that dated back 3.2 million years. They were the oldest hominine bones yet discovered. Johanson nicknamed the skeleton Lucy. Lucy was assumed to be female because the bones were of a small hominine, roughly 3 and a half feet tall. Only about 20 percent of a full skeleton was found, and most of the skull was missing. Importantly, the foot, leg, and pelvis bones showed that Lucy walked upright. This was evidence that as humans evolved they began walking upright before their brains grew. Previously scientists had thought brain growth came first. The Leakey legacy Mary and Louis Leakey raised three sons, who lived with them in the field. Their son Richard went on to run the Kenya Wildlife Service, focusing on saving elephants. Louis died in Afterward, Mary became a leading scientist in her own right. She opened a camp 35 miles from Olduvai, where the soil dated to 3.59 to 3.77 million years old. There, in 1976, she found an astonishing set of hominine footprints preserved in volcanic ash, more evidence that hominins of that time walked upright. Mary Leakey lived at Olduvai long enough to see leopards and rhinos dwindle to near extinction. She died in 1996 at age 84. UNIT 6 EARLY HUMANS TEXT READER 12

13 Thanks to the pioneering work of Louis and Mary Leakey, there s overwhelming evidence that Homo sapiens originated in Africa. It has been confirmed by genetic testing that humans separated from the chimpanzee line 5 to 7 million years earlier. The Leakeys spent their lives digging in the earth in the search for human origins. At a time when few others could entertain the thought, Louis demonstrated that our species had its beginnings on the African continent. Lucy and the Leakeys (770L) By Cynthia Stokes Brown, adapted by Newsela Most scientists agree that humans emerged in Africa about 200,000 years ago. Scientists believe this because fossilized bones and skulls were uncovered in East Africa. Ash from volcanoes was found near the bones. By testing the ash, scientists could tell their ages. The bones and skulls range from 25,000 to 4.4 million years old. They show many different stages of human and primate evolution. Paleoarchaeologists uncovered the fossils. These scientists study the remains of humans throughout evolution. Based on the fossil evidence, paleoarchaeologists tell this story: For 99.9 percent of our history, humans and chimpanzees shared the same line. Even from the time of the first living cell, humans and chimps were part of the same line. Then, about 5 to 7 million years ago, a new line split off from the chimpanzees. The new group lived in open savanna rather than in rain forest jungle. The old group in the rain forest continued to evolve. Two of its species still exist: the common chimpanzee and the bonobo. The new group in the savanna evolved over thousands of years. If formed into several species. It's unclear how many, but we know of at least 18. Finally, only one was left: humans, or Homo sapiens. All the species before us back to our common ancestor with chimpanzees are now called hominins. They used to be called hominids. Try visualizing it like this. Imagine your mother holding hands with her mother. She holds hands with her mother. Imagine this chain continuing. Go back in time 5 million years. The final hand would belong to an unknown kind of ape, sometimes called the "missing link." His descendants evolved into chimpanzees, bonobos, and, ultimately, your mother. If each generation averaged 14 years, there would be about 360,000 hominins holding hands. Paleoarchaeologists have to decide which bones belong to separate species. They mostly agree on three main categories of species before Homo sapiens. The oldest was Australopithecus who lived 2 to 4 million years ago. Homo habilis lived 1.8 to 2.5 million years ago. The closest to our times was Homo erectus who lived 2 to 4 million years ago. Clearly, some of these species lived at the same time. What scientists now know took many years to figure out. The first early human fossil bones were found in Europe. Neanderthal bones were discovered in Germany in 1857 and Cro- Magnon bones in France in Java Man was found in Indonesia in Most paleoarchaeologists in the 1920s and 30s were certain that Homo sapiens evolved in Europe. The other possibility was Asia, since a group of fossils known as Peking Man was UNIT 6 EARLY HUMANS TEXT READER 13

14 found in China in Africa was not considered a possibility. Racist thinking was common among scientists then. Africa was widely known as the Dark Continent. The ignorance of the time ruled out Africa in scientists' minds. The Leakeys look to Africa When did anyone start looking in Africa for hominine fossils? One German professor found a Homo sapiens skeleton in 1913 in Tanzania. Then in 1924, a South African professor found a child s skull there. But archaeologists didn't believe these bones were meaningful. The first discovery that scientists took seriously was made by an English couple, Louis and Mary Leakey. Louis Leakey was born and grew up in Kenya. Louis s parents were missionaries from England. Louis spent much of his childhood hunting and trapping with the local Kikuyu boys. He spoke Kikuyu as a native language. As a child, he went through ceremonies with other Kikuyu. At the age of 13, Louis built his own house, as was Kikuyu custom. He also found some ancient hand axes. At 16, he traveled to London to enter Cambridge University and become an archaeologist. Mary Nicol grew up in England. Each year her father took the family traveling, mostly to southern France. He loved Stone Age history and showed Mary archaeological sites in France. She was only 13 when he died. After, her mother sent her to strict Catholic schools in London. Mary rebelled and was expelled several times. At 17, she took charge of her own education. She learned to fly a glider, and began attending lectures in archaeology. Mary and Louis met in London in 1933 when she was 20 and he 30. In 1935, she joined him in Tanzania during one of his expeditions. They married the following year. Louis chose the Olduvai Gorge as his main area of research. It lies about 200 miles southwest of Nairobi, Kenya. Today the area is part of Tanzania. Olduvai Gorge took shape where sediment had formed over 2 million years at the bottom of a huge ancient lake. About 20,000 years ago, an earthquake struck and the lake emptied. After, a river cut through the sediment of the old lake bed. A deep gorge formed. The river sliced through the shoreline of the lake. By doing so, the remains of people and other animals that had once gathered there were revealed. Almost 2 million years of history are exposed in the gorge. Olduvai Gorge lies in the Great Rift Valley, a massive fault, or crack, in the African plate. The fault line starts from the Red Sea, which separates Africa and Asia. Then it runs southward through Ethiopia and Tanzania. It ends down in Mozambique. The crack in the plate is slowly getting deeper. Eventually it will deepen so much that part of eastern Africa will break off. Mountains and volcanoes line the Great Rift Valley. When the volcanoes erupt they shoot off ash. As the ash lands, it buries and fossilizes bones. This makes the valley an ideal spot to find fossils. The fossils remained buried under layers of soil for millions of years. But, as the Earth shifts, the fossils are moved closer to surface where we can find them. UNIT 6 EARLY HUMANS TEXT READER 14

15 Life in the field Life was an adventure for Louis and Mary in the Great Rift Valley. They lived in tents or mud huts. Kerosene lamps provided light at night. Often they had no fresh vegetables or fruit, living on fish, canned food, rice and corn meal. Sometimes Louis hunted gazelles for meat. Lions prowled their camps at night. African servants cooked their meals and washed their clothes. The Leakeys lived outdoors in some of the most beautiful scenery in the world. Volcanic mountains surrounded them. The Serengeti Plain spread out before them. Rhinos, giraffes, lions, leopards, antelope, and zebra lived on the plains. The couple worked with a dental pick and an artist s brush. Ever so slowly, they unearthed fossils hidden long ago. Louis and Mary found many fossils of extinct animals. But finding human fossils proved more difficult. In 1948, Mary discovered a primate skull that they thought might be the missing link connecting apes and humans. It turned out not to be. In 1959, Mary discovered a million-year-old skull. The find made the Leakeys famous. In 1960, Louis found the hand and foot bones of a 12-year-old. He named it Homo habilis, a new species of hominine. Until the 1950s, fossil hunting was filled with confusion. No accurate way to date the bones existed. Geologists could only make an estimate based on the age of the rocks they were found in. Things changed with the arrival of radiometric dating. Now fossil ages could be identified much more accurately. Carbon-14 atoms would not work for dates that go as far back as early hominins; instead, potassium found in the volcanic ash was used in a new radiometricdating technique. Louis Leakey was convinced that humans had evolved from apes. Leakey thought knowing more about the apes would help understand hominine behavior. But, no one had studied them in the wild, only in captivity. Leakey realized apes were losing their territory to humans. He wanted to study them before it was too late. So he set out to raise money for people to study apes in their own habitat. In 1960, he helped Jane Goodall begin her study of chimpanzees in the wild. Finding Lucy Meanwhile, others had begun searching for fossil bones in Africa. The next spectacular find occurred in the Ethiopian part of the Great Rift Valley. In 1974, Donald Johanson, an archaeologist, found parts of a 3.2-million-year-old skeleton. They were the oldest hominine bones yet discovered. Johanson nicknamed the female skeleton Lucy. Lucy was just 3 and a half feet tall. Importantly, the foot, leg, and pelvis bones showed that Lucy walked upright. This was evidence that as humans evolved they began walking upright before their brains grew larger. UNIT 6 EARLY HUMANS TEXT READER 15

16 The Leakey legacy Mary and Louis Leakey raised three sons in Africa. Their son Richard went on to run the Kenya Wildlife Service, focusing on saving elephants. Louis died in Afterward, Mary opened a camp 35 miles from Olduvai, where the soil dated to 3.59 to 3.77 million years old. There, in 1976, she found an astonishing set of hominine footprints. They had been preserved in volcanic ash. The discovery added more evidence that hominins of that time walked upright. Mary Leakey lived at Olduvai long enough to see leopards and rhinos become nearly extinct. She died in 1996 at age 84. Thanks to the work of Louis and Mary Leakey, there s overwhelming evidence that Homo sapiens originated in Africa. It is clear that humans separated from chimpanzees 5 to 7 million years earlier. Recent genetic testing has confirmed it. The Leakeys spent their lives searching for human origins. At a time when few others could think it, Louis demonstrated that humankind began in Africa. UNIT 6 EARLY HUMANS TEXT READER 16

17 Jane Goodall Goodall pioneered the study of chimpanzees in the wild, demonstrating how similar chimpanzee behavior is to that of humans, and helping to show the close evolutionary relationship of the two species. Jane Goodall: Biography of a Primatologist (1170L) By Cynthia Stokes Brown In 1960 Jane Goodall pioneered the study of chimpanzees in the wild, showing the world how similar chimpanzee behavior is to that of humans, and helping to demonstrate the close evolutionary relationship of the two species. An early interest in animal life Jane Goodall's parents were Mortimer Herbert Morris-Goodall, a car-racing businessman, and Margaret Myfanwe Joseph, a novelist who published under the name Vanne Morris- Goodall. When Jane was just over a year old, her father gave her a stuffed toy, a lifelike replica of a chimpanzee, named Jubilee after the first chimpanzee infant ever born at the London Zoo. The toy horrified some of her mother s friends, who thought that it would give Jane nightmares. They could not foresee the favorable influence it would have on her. Goodall s interest in observing animal life showed up early. When she was 4, she wanted so badly to know how an egg came out of a hen that she hid inside a small henhouse for nearly four hours waiting to see it happen. Meanwhile, the whole household had been searching for her and had even reported her missing to the police. Goodall s fascination with Africa was aroused by reading The Story of Doctor Dolittle by Hugh Lofting. Lofting depicts Dolittle as a kindly doctor who travels to Africa and talks to animals. Jane also read all of the Tarzan books. Her mother encouraged her dream of studying animals in Africa assuring her that she could do it if she worked hard and believed in herself. Goodall s parents divorced when she was 12, and when she graduated from secondary school in 1952, her family could not afford to send her to college. Instead, she went to secretarial school and then worked as a secretary, including a job at Oxford University typing and filing. In 1956, a school friend invited her to visit the friend s family farm in the highlands of Kenya. Goodall went back to live at home, worked hard as a waitress, and in five months saved enough money for the round-trip fare on a ship to Mombasa. UNIT 6 EARLY HUMANS TEXT READER 17

18 A meeting with Louis Leakey In 1957, Goodall visited her friend s family on their farm outside Nairobi and subsequently found a job as a secretary in the city. Her interest in animals led her to contact Louis Leakey, the famous seeker of hominine bones, who was then working in Africa. He promptly hired her as his secretary. Leakey had been looking for someone to study chimpanzees in the wild and, after he got to know Goodall, felt that she would be perfect. Leakey believed that a woman would be more patient than a man in the field and would be less likely to kindle the aggressions of male chimps. She returned to London to study primates in the London Zoo while he raised funds to support her field studies and arranged her equipment. In 1960, when she was 26, Goodall eagerly traveled 600 miles southwest of Nairobi to live at Gombe Stream Chimpanzee Preserve, on Lake Tanganyika. There, about 150 chimpanzees made their home in a 20- to 30-square-mile area. It took her months to accustom the chimps to her presence but, after nearly a year, most of them would allow her to approach closer than a hundred yards. Observing chimpanzee culture Goodall had little professional training in animal studies. She worked unconventionally, doing things like giving the chimpanzees names instead of numbers and perceiving the individual personality of each one. She also found that baiting the animals with bananas helped to attract them close enough for her to observe their social behavior and to photograph them. Within four months, Goodall had observed behavior that contradicted a belief strongly held by archaeologists: that only humans used tools. Man the tool-maker was the phrase they used. But Goodall saw a chimp break off a twig, strip its bark, and insert it into a termite mound. When the chimp withdrew the twig, it was covered with delicious termites ready to be licked off. Since then, other researchers have observed chimpanzees using more than half a dozen tools for assorted purposes. Chimp societies across Africa vary in their use of tools. Other animals, including some birds and dolphins, are now known to use tools. Chimps were also widely believed to be vegetarians, but Goodall observed them hunting, killing, and eating small colobus monkeys. Goodall made her findings public in her book In the Shadow of Man (1971). Leakey believed that having a PhD would help give credibility to Goodall s work. He raised the funds to send her to Cambridge University, where she received in 1965 a PhD in ethology (the scientific study of animal behavior) with a dissertation titled Behavior of the Free-Ranging Chimpanzee. Leakey also sent a professional photographer, Hugo Van Lawick, to Gombe to record Goodall s work there. The two fell in love and married in Their son, Hugo Eric Louis Van Lawick, was born in They called him Grub and raised him in Gombe with the chimpanzees. In 1972, Goodall and her husband published a children s book about their son called Grub: The Bush Baby. But their marriage deteriorated. They divorced in 1974, and a year later she married Derek Bryceson, director of Tanzania s national parks, who proved to UNIT 6 EARLY HUMANS TEXT READER 18