First Class Introduction

Homework Assignment #1:

Read excerpts from the fields of Astronomy, Geology, Paleontology, and the Biology (Reilly, Worlds of History). Create your timelines for each of these fields of vision choosing events, or benchmarks, to place on the timelines in patterns that may stimulate thought, questions, or even answers to questions. Write a short paragraph at the end of each timeline discussing some advantages and disadvantages of each for understanding human history. Turn-in your timelines by the next class period.

Astronomy Instructions: The astronomer Carl Sagan was one of the great popularizers of science in the twentieth century. In this selection from one of his book, Dragons of Eden, he finds a simple way to demonstrate the vastness of Earth's history. He plots the history of the planet on a calendar for a single year and, in this framework, he notes that the first humans appeared at 10:30 P.M. on New Year's Eve. What does this approach show you about the relationship between the history of the Earth and the history of humankind?
Transfer some of the important dates of Sagan's calendar to a time line. Draw a 12-inch line horizontally on a piece of paper, marking inch designations. The Big Bang is at the left end (0), and today is at the right end (12). Your world history course will deal only with the last hour on Sagan's log of events £or December 31. Where would that be on your time line? Where would you place your own life on this time line? Where would you place the life of one of your grandparents? What is the major disadvantage of a time line drawn to this scale? What is its advantage?

The world is very old, and human beings are very young. Significant events in our personal lives are measured in years or less; our lifetimes in decades; our family genealogies in centuries; and all of recorded history in millennia. But we have been preceded by an awesome vista of time, extending for prodigious periods into the past, about which we know little -both because there are no written records and because we have real difficulty in grasping the immensity of the intervals involved.
Yet we are able to date events in the remote past. Geological stratification and radioactive dating provide information on archaeological, paleontological, and geological events; and astrophysical theory provides data on the ages of planetary surfaces, stars, and the Milky Way Galaxy, as well as an estimate of the time that has elapsed since that extraordinary event called the Big Bang -an explosion that involved all of the matter and energy in the present universe. The Big Bang may be the beginning of the universe, or it may be a discontinuity in which information about the earlier history of the universe was destroyed. But it is certainly the earliest event about which we have any record.
The most instructive way I know to express this cosmic chronology is to imagine the fifteen-billion-year lifetime of the universe (or at least its present incarnation since the Big Bang) compressed into the span of a single year. Then every billion years of Earth history would correspond to about twenty-four days of our cosmic year, and one second of that year to 475 real revolutions of the Earth about the sun. [Following] I present the cosmic chronology in three forms: a list of some representative pre-December dates; a calendar for the month of December; and a closer look at the late evening of New Year's Eve. On this scale, the events of our history books -even books that make significant efforts to de-provincialize the present -- are so compressed that it is necessary to give a second-by-second recounting of the last seconds of the cosmic year. Even then, we find events listed as contemporary that we have been taught to consider as widely separated in time. In the history of life, an equally rich tapestry must have been woven in other periods -for example, between 10:02 and 10:03 on the morning of April 6th or September 16th. But we have detailed records only for the very end of the cosmic year .
The chronology corresponds to the best evidence now available. But some of it is rather shaky. No one would be astounded if, for example, it turns out that plants colonized the land in the Ordovician rather than the Silurian Period; or that segmented worms appeared earlier in the Precambrian Period than indicated. Also, in the chronology of the last ten seconds of the cosmic year, it was obviously impossible for me to include all significant events; I hope I may be excused for not having explicitly mentioned advances in art, music, and literature or the historically significant American, French, Russian, and Chinese revolutions.
The construction of such tables and calendars is inevitably humbling. It is disconcerting to find that in such a cosmic year the Earth does not condense out of interstellar matter until early September; dinosaurs emerge on Christmas Eve; flowers arise on December 28th; and men and women originate at 10:30 P.M. on New Year's Eve. All of recorded history occupies the last ten seconds of December 31; and the time from the waning of the Middle Ages to the present occupies little more than one second. But because I have arranged it that way, the first cosmic year has just ended. And despite the insignificance of the instant we have so far occupied in cosmic time, it is clear that what happens on and near Earth at the beginning of the second cosmic year will depend very much on the scientific wisdom and the distinctly human sensitivity of mankind.

Pre December Dates (approximate)

Big Bang
Origin of the Milky Way
Origin of the Solar System
Formation of the Earth
Origin of life on Earth
Formation of the oldest rocks known on Earth
Date of oldest fossils (bacteria and blue-green algae
Invention of sex (by micro-organisms)
Oldest fossil photosynthetic plants
Eukaryotes (first cells with nuclei) flourish

January 1
May 1
September 9
September 14
September 25
October 2
October 9
November 1
November 12
November 15

Cosmic Calendar / December

SUNDAY	MONDAY	TUESDAY	WEDNESDAY	THURSDAY	FRIDAY	SATURDAY
	1 Significant oxygen atmosphere develops	2	3	4	5	6
7	8	9	10	11	12	13
14	15	16 First Worms.	17 Precambrian ends. Paleozoic Era and Cambrian Period Begin. Invertebrates flourish.	18 First oceanic plankton. Trilobites flourish	19 Ordovician Period. First fish. First vertebrates	20 Silurian Period. First Vascular plants. Plants begin colonization of land
21 Devonian Period begins. First insects. Animals begin colonization of land	22 First amphibians. First winged insects.	23 Carboniferous Period. First trees. First reptiles.	24 Permian Period begins. First dinosaurs.	25 Paleozoic Era ends. Mesozoic Era begins.	26 Triassic Period. First mammals.	27 Jurassic Period. First birds.
28 Cretaceous Period. First flowers. Dinosaurs become extinct.	29 Mesozoic Era ends. Cenozoic Era and Tertiary Period begin. First cetaceans. First primates.	30 Early evolution of frontal lobes in the brains of primates. First hominids. Giant mammals flourish	31 End of the Pliocene Period. Quaternary (Pleistocene and Holocene) period. First humans.

Cosmic Calendar / December 31, last 12 hours

Origin of Proconsul and Ramapithecus, probable ancestors of apes and men	--1:30 P.M
First Humans	--10:30 P.M.
Widespread use of tools	11:00 P.M.
Domestication of fire by Peking man	11:46 P.M.
Beginning of most recent glacial period	11:56 P.M.
Seafarers settle Australia	11:58 P.M.
Extensive cave painting in Europe	11:59 P.M.
Invention of agriculture	11:59:20 P.M.
Neolithic civilization; first cities	11:59:35 P.M.
First dynasties in Sumer, Ebla, and Egypt; development of astronomy	11:59:50 P.M.
Invention of the alphabet; Akkadian Empire	11:59:51 P.M.
Hammurabic legal codes in Babylon; Middle Kingdom in Egypt	11:59:52 P.M.
Bronze metallurgy; Mycenaen culture; Trojan War; Olmec culture; invention of the compass	11:59:53 P.M.
Iron metallurgy; First Assyrian Empire; Kingdom of Israel; founding of Carthage by Phoenicia	11:59:54 P.M.
Asokan India; Ch'in Dynasty China; Periclean Athens; birth of Buddha	11:59:55 P.M.
Euclidean geometry; Archimedean physics; Ptolemaic astronomy; Roman Empire; birth of Christ	11:59:56 P.M.
Zero and decimals invented in Indian arithmetic; Rome falls; Moslem conquests	11:59:57 P.M.
Mayan civilization; Sung Dynasty China; Byzantine Empire; Mongol invasion; Crusades	11:59:58 P.M.
Renaissance in Europe; voyages of discovery from Europe and from Ming Dynasty China; emergence of the experimental method in science.	11:59:59 P.M.

Paleontology Instructions: Draw another timeline, including turning points that you, or the author, feel are significant using this field of vision.

Three Fossil Discoveries Clarify the Murky Origins of Life
from John Noble Wilford's "Three Fossil Discoveries Clarify the Murky Origins of Life," New York Times, Oct. 31,1995, C1-C7 (excerpted in Reilly's Worlds of History reader.

This article from the New York Times was written to inform readers about developments in science. What current developments does the author report? What is the significance of the date for the first multi-cellular life forms? What was the "Cambrian Explosion" of life forms?

Life, as far as scientists can tell, gained a foothold on earth almost as rising above its tell, gained a foothold on earth almost as soon as possible, then took an exceedingly long time rising above its simple origins, and finally, 530 million years ago, erupted in a springtime of riotous proliferation. In an astonishingly brief time, insects, earthworms, corals, sponges, mollusks, and animals with rudimentary backbones -all the major body plans of today -made their first appearance in what is known as the Cambrian Explosion.
But there are many yawning gaps in this early history of life, and so scientists welcomed reports last week of three discoveries. The reports offered important refinements in the timing of three events that have puzzled scientists trying to reconstruct the mysterious first steps in the emergence of life. The events are the introduction of large multi-cellular organisms, the existence of some flat jellyfish-like organisms as possible predecessors of Cambrian life, and the emergence of chordates, the core group of vertebrates that would eventually include humans.
Dr. Steven M. Stanley, a paleontologist at Johns Hopkins University in Baltimore, said the findings were the latest manifestation of a "really exciting and most important activity in the field, the development of much better chronologies that constrain our views of what actually happened."
In the beginning, 4.6 billion years ago, the planet was covered with molten rock and bombarded steadily by swarms of meteorites. Not until the surface cooled down about 4 billion years ago could there be life, the first evidence for which are 3.8 billion-year-old fossils of a kind of blue-green algae similar to pond scum. These were simple organisms with single cells lacking nuclei. It was apparently another 2 billion years before more complex cells with nuclei evolved. Until recently, little evidence existed for multi-cellular organisms before a billion years ago.
Now, digging in sediments in northern China near Jixian, Chinese geologists say they have gathered evidence suggesting a much earlier emergence of more complex life than previously thought. They found more than 300 fossils of leaf-like multi-cellular plants that lived on the sea floor 1.7 billion years ago. These were described as resembling longfengshanids, which lived 700 million years later and were assumed to be the earliest reliably dated multi-cellular organisms.
The Chinese scientists acknowledged the discovery in Michigan of an even older spaghetti-shaped organism, but suggested that it and other early fossils " are not confidently interpreted " as multi-cellular plants.
Writing in the current issue of the journal Science, Dr. Zhu Shixing and Dr. Chen Huineng of the Chinese Academy of Geological Sciences in Tianjin said the newly discovered fossils "imply that mega-scopic multi-cellular organisms originated 1.7 billion years ago or earlier. " As such, they added, the new data "have implications for the understanding of the evolution and other related aspects of Precambrian life. "
Another discovery may solve the mystery of what has been called a "broken link" in the poorly understood evolutionary chain prior to the Cambrian Explosion.
For half a century, scientists have not known what to make of creatures resembling jellyfish that were found in ancient sediments of the Ediacara Hills of southern Australia and subsequently in fossil beds elsewhere in the world. Were these plants or animals? Precursors of later life or a failed experiment in biological innovation that came to a dead end? The problem was determining exactly when they lived and if, as it once seemed, they died out before the Cambrian Explosion and thus could not be directly ancestral to any of the new life forms.
Applying more precise dating technologies to Ediacaran fossils from the deserts of Namibia in southern Africa, geologists at the Massachusetts Institute of Technology and Harvard University determined that the youngest organisms had indeed survived into the early period of the Cambrian, 543 million years ago. The team, led by Dr. John Grotzinger of M.I. T ., reported the results in Science.
"If Grotzinger and company are correct, that's excellent news," Dr. Simon Conway Morris, a paleontologist at Cambridge University in England, was quoted as saying in an accompanying article in the journal.
Scientists said the new evidence left open the possibility that there was after all no broken link in the evolutionary chain and that Ediacaran organisms could have played a role in the development of a multitude of flora and fauna that characterize the Cambrian period and are the predecessors of life on earth today.
Dr. Samuel Bowring, an M.I. T. geologist on the research team, said, "What this shows is that evolution likely proceeded smoothly as opposed to having a period of evolution followed by an extinction, which would open ecological niches allowing other life forms to develop."
The dating was done on grains of the mineral zircon found in trace amounts in volcanic ash. By analyzing the decay rates of uranium into lead, the geologists obtained dates for the fossil-bearing sediments that they say are accurate to within plus or minus one million years, a refinement previously unattainable on samples that old.
"Five to ten years ago, being able to date something to within five million years was a major achievement," Dr. Bowring said. "The more precisely we can resolve time, the more sophisticated the evolutionary questions we can address. "
Dr. Stanley of Johns Hopkins suggested that the Ediacaran fossil record might have been deceptive. Evidence for these soft-bodied organisms from the sea floors was found in such profusion in sediments just before the Cambrian period because nothing was scavenging on them at that time. Then the fossils seemed to disappear. Was this the sign of a true extinction, or merely an absence of fossil remains of that particular life? With the greater diversity of life in the Cambrian, he said, there could have been many scavengers munching on the Ediacara organisms before they had a chance to become fossils.
The most abundant remains of animal life originating in the Cambrian period are found in the Burgess Shale, fossil beds in the Canadian Rockies that have been the main source of knowledge about this time. But for the last decade, paleontologists have been mining an important new source at Chengjiang in the Chinese province of Yunnan, which was the site of the third discovery reported last week.
An international team of scientists described finding what may be the earliest known representative of the Chordate, the branch of the animal kingdom that includes vertebrates and two lesser known allied forms of life. Previous generations of scientists had thought that chordates evolved in the later Ordovician geological period. Later evolution, they liked to think, could imply advanced and special status to the branch of life leading to humans.
In a report in the journal Nature, Dr. Lars Ramskold, a paleontologist at the University of Uppsala in Sweden, and colleagues said they had identified 525-million-year-old fossils of a strange, fishlike creature, which they have named Yunnanozoon lividum. One of the characteristics linking the specimen to chordates is its notochord, the precursor of a spinal column.
The researchers said Yunnanozoon appeared to belong to the division of chordates known as cephalochordates, which are closely related to backboned animals, including humans, but not of them. Current representatives of the group include amphioxus, a shy marine creature.
The identification of the new specimen as a chordate will be controversial, scientists said. The only other possible chordate from the Cambrian period, the Pikaia from the Burgess Shale, has not been described in a sufficiently detailed report and so has yet to be accorded full scientific standing. But the discoverers of the Chengjiang fossil said that the presence of one division of chordates in the Cambrian period indicated that the entire branch probably existed then as well.
In a commentary accompanying the chordate report, Dr. Stephen Jay Could, a Harvard paleontologist and evolutionary biologist, said the "unambiguously identified chordate from the still earlier Chengjiang fauna now seals the fate" of previous efforts to assert the specialness of human ancestry by separating it from the herd of new Cambrian animal forms.

"So much for chordate uniqueness marked by slightly later evolution," he wrote." As for our place in the history of life, we are of it, not it."

Anthropology Introduction: Mary Kilbourne Matossian, "From Hominids to Human Beings," in Shaping World History (Armonk, NY: M. E. Sharpe, 1997),9-14 Here are some hints to help you construct your timeline: What, according to the author, happened in East Africa around 15 million years ago? What happened as a long-term result of this change around 4.5 million years ago? What happened about 2.5 million years ago? 200,000 years ago? 35,000 years ago? 27,000 years ago? What happens if you try to place the dates in this selection on the time line you drew for the previous article?
Draw a time line specific to this selection. Mark the left-most notch " 5 million years ago," then add ten equally spaced notches, ending with "today" on the far right. Label notches in increments of 0.5 million years. Now plot the major dates referred to in the article, indicating to what the dates refer.
If you were to extend this time line to include 15 million years ago-using the same incremental scale -how many pages more would you need? If you wanted to include the dates mentioned in this chapter's first selection by Carl Sagan, how many pages more would you need? To understand the geography of this selection, locate the Great Rift Valley on a topographic map.

Anthropologists have named us Homo sapiens sapiens, the clever, clever hominid. Over a century ago certain scientists abandoned the Western creation myth and began to seek human origins in nature among the primates (apes and monkeys). If apes and people had many resemblances, what kind of creatures linked the two species? When and where did this linking happen?
The discoveries of physical anthropologists and geneticists have indeed established that we belong to the primate family. The line of hominids (bipedal apes, apes who walk on two legs) differentiated from that of other apes about five million years ago. We share with chimpanzees and bonabos (pygmy chimpanzees) between 98 percent and 99 percent of our structural genes. Who can watch primates in a zoo without experiencing a shock of recognition?
In December 1992 in Ethiopia, Tim White, an anthropologist from the University of California at Berkeley, and his team discovered the earliest hominid yet known. They announced their discovery in September 1994. Anthropologists believe that the bones discovered are almost 4.5 million years old. These hominids walked upright, were four feet tall, and lived in a woodland setting. Their skull capacity was about one third that of ours. They lived very close to the time of separation between hominids and apes estimated by geneticists -'-- five million years ago.
In August 1995 Mary Leakey and her team discovered in Kenya similar hominids that were 4.1 million years old. These hominids are estimated to have weighed between 101 and 121 pounds. This is the most recent of a long sequence of discoveries. It now seems likely that hominids differentiated from apes in northeast Africa, in or near the Great Rift Valley of Ethiopia, Kenya, and Tanzania. Hominids had habitually upright posture and walked on two legs. They lived mainly on the ground, not in trees. These attributes appeared long before their brain expanded and they began to make tools.
About fifteen million years ago the environment in East Africa was changing. The earth's crust was splitting apart in places, while highland domes of up to nine thousand feet formed in Ethiopia and Kenya. These domes blocked the west-to-east airflow and threw the land to the east into rain shadow. Lacking moisture, the continuous forests in the east fragmented into patches of forest, woodland, and shrub-land. About twelve million years ago the Great Rift Valley , running north to south, appeared in East Africa.
This development had two major biological consequences. First, the Great Rift Valley was an east-west barrier to the migration of animal populations. Second, although the apes in the dense jungle on the west side of the valley were already adapted to a humid climate and thus were not forced to adjust to a new environment, in the east a rich mosaic of ecological conditions emerged. Biologists believe that mosaic environments drive evolutionary innovation, since competing successfully in such an environment requires new adaptations. The hominids -bipedal apes -developed in such a place. This is the first example of the influence of climatic change on prehistory.
According to Peter Rodman and Henry McHenry, on the east side of the Great Rift Valley, where woodlands were scattered, a bipedal ape had an advantage. It could move more easily from one grove of food-bearing trees to a more distant grove. An ape who walked habitually on two legs was more energy-efficient than an ape who walked on four. Upright posture was also more efficient for cooling the body in thc daytime heat. Other anatomical changes made it easier for hominids to stride and to run. The beginning of brain expansion in hominids began in Africa around 2.5 million years ago with Homo-habilis and was associated with the appearance of the earliest stone tools. By 1.8 million years ago a more advanced hominid, Homo erectus, was making sharp-edged tools. The process involved knocking one rock against another, chipping off a sharp flake from the "core" stone and using the flake as a knife. Hominids could use this knife to cut through the hides of most animals and get to the meat quickly. Evidence shows that with this innovation hominid meat eating soon increased.
There was probably a positive feedback loop between the expansion of the hominid brain and meat eating. The hominid brain is three times as big as that of an ape of similar body size. Meat is an excellent source of protein and, because of its fat content, is high in calories; this helps to support the larger brain. At the same time the growth of the brain in relation to body weight favored the improvement of human hunting skills and higher meat consumption. In hominid females, the pelvic opening widened to compensate for the increased brain size of the hominid infant. However, that was not enough, and any greater widening would reduce bipedal mobility. A solution to the problem of increased hominid brain size was the natural selection of those hominids that produced children born "too early," with brain size only one third that of an adult. These infants are slow to mature and so depend on their parents for a longer period. This extends the time that parents can transmit culture (patterns of behavior) to their offspring. In contrast, baby apes are born with a brain one half the size of that of an adult ape. They mature more quickly than hominids do, but have fewer years of dependency to learn from their parents.
What sort of culture did prehistoric humans transmit? Cultural anthropologists who have studied the way of life of foragers (hunter-gatherers) today say that the usual size of a human band is twenty-five persons, including children and adults. A larger unit, the dialectical tribe, includes about five hundred persons. Foragers use only temporary camps and move about on their range. Since longevity was usually only twenty-five to thirty years, many children were raised by relatives, their parents being dead. The band, not the nuclear family, was the principal social unit. A band acquires food cooperatively, by hunting and gathering, and shares it. Adults teach their children, who are born self-centered, to become sensitive to the needs of others and to share food.
Is such sharing, social behavior unique to humans? Frans de Waal, a researcher at the Yerkes Primate Research Center in Atlanta, Georgia, discovered that chimpanzee groups consist of caring, sharing individuals who form self-policing networks. He believes that the roots of morality may be far older than we are. A chimpanzee seems to realize that social disorder is a threat to its individual well-being. When rivals embrace, signaling an end to their fight, the whole colony may break into loud, joyous celebration.
However, chimpanzees share food and other treasures only when it is to their advantage. They cheat when they can get away with it by hiding a private stock of food. When cheating, they try to deceive other members of the group. Fortunately, they live in groups of less than a hundred, so they can watch each other and identify the cheaters. Older chimpanzees deny food to young cheaters by excluding them from sharing in the next windfall.
It appears that both our moral and immoral tendencies are part of the natural order. Both "good" and "evil" are aspects of our adaptive and competitive strategies. We can imagine that human goodness developed out of the need to adjust to a cooperative group. By belonging to such a group an individual had a major advantage in the struggle to survive and reproduce.
No more can we think of stone-tool making and sharing behavior as unique to our species. Nor are we unique in our capacity for tactical deception and savagery. Rather, we have a place in a natural mammalian continuum.
The only behavior unique to humans appears to be the ability to communicate quickly with a large number of phonemes ( discrete sounds). We can make fifty phonemes; apes can make only twelve. Humans can speak more quickly and articulately than any other species. The placement of our vocal organs makes this possible. When did our ancestors acquire spoken language involving more than twelve phonemes? Some anthropologists think it was as far back as 2.5 million years ago (the time of Homo habilis). Most agree that complex spoken language goes back at least thirty-five thousand years to the time of the cave paintings in Europe. They think that language evolved as a means of social interaction, allowing individuals to prevent fights or settle them more easily.
Recent discoveries in the Pavlov Hills of the Czech Republic indicate that ceramics and weaving go back twenty-seven thousand years -to before the beginning of settled life. These skills were probably the innovations of women, because women could make pots and weave while they took care of children.
When did people exactly like us, anatomically speaking, appear?
Many anthropologists think that our species (Homo sapiens sapiens) differentiated around two hundred thousand years ago in either south or northeast Africa. From northeast Africa people spread across the earth. They went to the Near East, Europe, China, Southeast Asia, Australia, the Pacific Islands, and the Americas. Lucky humans settled on lands suited to agriculture. Only they could look forward to sustained population growth and civilization.
They were especially lucky if the relationship between Land and water in their region was favorable for water transportation, as the cost of moving bulk goods by water for a given distance was one eighth to one twentieth that of moving them by land. Waterborne commerce may have been just as fundamental as the development of farming for the birth of civilization.