ON DEMAND EXPOSITORY ESSAY

Prompt:

Student Directions

You will now review your notes and sources, and plan, draft, revise, and edit your writing. You may use your notes and refer to the sources. Now read your assignment and the information about how your writing will be scored; then begin your work.

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Your Assignment:

Your school has begun a new science elective for all the dinosaur enthusiast. Some of the fun task the students will do are reassemble replica dinosaur bones, visit natural history museums, and even go on a trip to actually dig up fossils. In order to make sure the class has extremely interested participants, the teachers managing the elective have asked all students to write a five paragraph essay explaining why anthropologists believe the fossils found on the island of Flores are a new human species.

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Expository Essay Scoring:

Your expository essay will be scored using the following:

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1. Organization/purpose: How well did you present your topic, support the main idea, and maintain your neutral tone with a logical progression of ideas from beginning to end? How well did your ideas thoughtfully flow from beginning to end using effective transitions? How effective was your introduction and your conclusion?

2. Evidence/elaboration: How well did you integrate relevant and specific information from the sources? How well did you elaborate your ideas? How well did you clearly state ideas in your own words using precise language that is appropriate for your audience and purpose? How well did you reference the sources you used by title or number?

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3. Conventions: How well did you follow the rules of grammar usage, punctuation, capitalization, and spelling?

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Now begin work on your expository essay. Manage your time carefully so that you can

1. Plan your multi-paragraph expository essay.

2. Write your multi-paragraph expository essay.

3. Revise and edit the final draft of your multi-paragraph expository essay.

For Part 2, you are being asked to write a multi-paragraph expository essay, so please be as thorough as possible.

Remember to check your notes and your prewriting/planning as you write and then revise and edit your expository essay.

A Big Discovery about Little People

by Peter Brown and Emily Sohn

Long ago, many species of humanlike creatures shared space on Earth. These different types of humans walked upright and had intelligent minds. At some point, however, all but one of those species went extinct. We, members of the species Homo sapiens (H. sapiens), were the sole survivors.

For years, scientists thought they knew when H. sapiens became the only kind of human species in existence. The scientists thought that the big change happened about 24,000 years ago, with the extinction of the Neandertals (Homo neanderthalensis).

Recently, however, scientists have found evidence of a previously undiscovered species of humans. The scientists made the find on the island of Flores in Indonesia.

The newly discovered species, called Homo floresiensis after the island of its discovery and nicknamed "hobbit" because of its tiny size, lived as recently as 12,000 years ago. Many scientists consider the hobbit to be the most important discovery in anthropology in 50 years.

The finds on Flores indicate that for thousands of years, "we were not alone as a human species," says Bert Roberts, a senior research fellow at the University of Wollongong in Australia. "Until very recently, there would have been another type of walking, talking, interacting kind of human running around the planet," he adds. Roberts was a member of the team that discovered H. floresiensis.

Finding Hobbits

The first signs of the hobbit's existence emerged in 2001, when a team of Australian and Indonesian researchers started finding small teeth and bones on Flores. The scientists were looking for H. sapiens fossils at the time.

At first, the scientists didn't suspect anything unusual. They thought that the small fossils belonged to H. sapiens children.

Then, on the last day of the digging season in September 2003, an Indonesian researcher named Thomas Sutikna stumbled across what looked like the top of a skull in the ground. To protect the fossil, he dug out the entire block of sand surrounding it.

"It was only when he started uncovering what was in this block of sand that [the team] realized [he] had [found] a whole new human species," Roberts says. Skulls often reveal more about a species than other bones can, he adds, and this skull was a clincher. "This really was something completely, remarkably new."

The tiny skull looked different from any Homo skull ever unearthed. It had a sloping forehead and thick ridges above the eye sockets. It had a receding chin. Its brain—about 23 cubic inches in volume—was just one-fourth as big as a modern human brain.

Further excavations revealed that the creature's skeleton was different from that of H. sapiens, too. The skull and bones belonged to a woman who was about 30 years old and about 3 feet tall—the size of a typical 4-year-old today. Her feet were flat and broad. And she had long arms, with hands that hung down to her knees.

Those features resembled those of some of our ancient ancestors who lived 2 or 3 million years ago, says Chris Turney, a research fellow at the University of Wollongong who became involved soon after the discovery. So, he expected the new fossils to be that old, too.

Much to everyone's surprise, Turner's analysis of the skeleton showed that the bones were just 18,000 years old. The hobbit was a completely new species of human. What's more scientists had never seen anything like it living so recently. It was a huge discovery. "I was blown away by this," Turney says. "I just walked around with a great big grin all day."

The Great Debate

The scientists announced their find in 2004. Some anthropologists, like Turner, were amazed by the news. But critics quickly disputed the findings. They claimed that the new skeleton was not a new species. It was simply a member of our own species suffering from a disease called microcephaly. Among other symptoms and deformities, people with microcephaly have smaller than average heads and bodies.

The debate gained steam. Meanwhile, further digging in the island's limestone caves turned up bones from eight other hobbitlike people with similar bone structures. Analyses revealed that these individuals lived between 95,000 and 12,000 years ago, strengthening the case that the scientists had indeed discovered a new species. As Roberts says, it would be very unusual that an entire population would have microcephaly over that many years.

Most scientists do now believe that H. floresiensis was indeed a separate species from H. sapiens, Roberts says. "I'd say 99.5 percent [of scientists] are in our favor," he claims.

Getting to the Bones of the Matter

Because of arguments between researchers, further excavations, which could answer the many remaining questions about the hobbits, stopped in 2004. But now, the anthropologists are ready to pick up their shovels again. This June and July, digging on Flores will resume.

The researchers hope to find more skeletons with features similar to those of H. floresiensis as well as samples of DNA, which should "settle the dispute once and for all," Roberts says. More fossils would also give more details about the lives of the hobbits. 

Evidence to date suggests that the hobbits were clever, despite their small brains, Roberts says. Explorations of the sites where the bones were found shows that the hobbits used specialized stone tools. They hunted komodo dragons and pygmy elephants. They could make fires. And they found a way to travel to Flores, probably from the mainland of Asia, on their own.

Despite the enthusiasm of Roberts and many others, scientists still cannot prove that H. sapiens and H. floresiensis lived on Flores at the same time. Only more digging, and additional studies of the bones, will resolve this question.

"A Big Discovery about Little People" by Peter Brown and Emily Sohn. From Science News for Kids, June 6, 2007 issue. Copyright ©2007 by Science News for Kids. Reprinted by permission of Science News.

Small Wonder: The Discovery of Ancient Tiny People is One Big Find

by Kirsten Weir

Once upon a time, a group of hairy, elf-sized men and women lived on an island far away. In the shadows of a towering volcano, they pursued with sharp spears the pygmy elephants, enormous dagger-toothed lizards, and golden retriever-sized rats that also inhabited the island.

A scene from a fairy tale? Nope. Scientists recently unearthed the remains of the smallest and strangest humans ever found. The find is shaking up the field of anthropology, the scientific study of the origin, behavior, and physical and cultural development of humans.

Island Hobbits

The peculiar mini people, nicknamed "hobbits" by the researchers who discovered them, lived thousands of years ago on Flores, an island in Indonesia. The researchers found the first set of remains in a limestone cave on the island and assumed that the bones were those of a child. Just 1 meter (3 feet) tall, the individual was about the same size as a modem 3-year-old!

Studying the bones more closely, codiscoverers Peter Brown and Mike Morwood from the University of New England in Australia realized that the skeleton belonged to a full-grown 30-year-old female who walked bipedally. Bipeds, including modern humans and their close ancestors, walk upright on two feet. Since that discovery, Brown and Morwood have pulled the remains of six other tiny people from the cave. They have named the people Homo floresiensis, or "Flores Man."

Brown and Morwood believe that the Flores species was a downsized version of Homo erectus, an early human species that lived roughly 1.5 million to 50,000 years ago. Previous archaeological digs have turned up evidence that H. erectus arrived on Flores by 840,000 years ago. Marooned on the island, the species apparently began to evolve a body better suited to life on Flores, eventually developing into the tiny H. floresiensis.

Islands are often home to "extreme" animals, such as the huge Komodo dragons that inhabit another Indonesian island. Only a few animal species ever successfully migrate from mainlands to distant islands. When they do, they often evolve unusually large or small body sizes to take advantage of vacant niches on the island that, on the crowded mainland, are filled by other species. A niche is the particular area that an organism occupies within a habitat. Mammals isolated on islands often evolve smaller bodies, which are easier to maintain on an island's limited food supply.

The scaled-down size of the Flores people isn't the only reason that anthropologists are excited about the find. The H. floresiensis bones range in age from 95,000 to just 13,000 years old. Modern humans, Homo sapiens, are thought to have migrated to Australia by at least 40,000 years ago. So H. sapiens and H. floresiensis lived right around the corner from each other for as long as 30,000 years!

So far, scientists haven't found evidence that H. sapiens and H. floresiensis cohabited Flores. But they haven't ruled out the possibility.

Fancy Tools

In the cave on Flores, Brown and Morwood discovered a variety of stone tools they believe were made by the Flores people. The tools, which include cutting and chopping utensils as well as small blades that might have been attached to wooden spears, were much more complex than any tools known to have been made by H. erectus.

Also found in the cave were the charred bones of pygmy elephants and other animals— evidence that the Floresians hunted and cooked their food. Although the elephants were small, they still weighed more than a ton. Morwood says the tiny hunters must have worked together to take the elephants down. He believes the Flores people also possessed some form of language that helped them coordinate hunts and fashion their sophisticated tools. Such traits are especially impressive in a people whose brains were slightly smaller than those of chimpanzees!

Ebu Gogo

The newfound bones may hold more clues about the Flores people. Researchers plan to try to extract DNA from the bones, hoping to clarify the relationship between H. floresiensis and other human species. Whether or not the attempt is successful, one thing is certain: The tiny Flores people continued to thrive for thousands of years after other early human species disappeared around the globe.

Then, about 12,000 years ago, a volcanic eruption on Flores wiped out many of the island's unusual species, including the pygmy elephants. The Flores people, too, seem to have perished in the blast.

Or did they? Modem inhabitants of Flores tell detailed stories about small, hairy humans called Ebu Gogo, who murmured to one another in an unfamiliar language. According to legend, the Ebu Gogo lived in caves until just a few hundred years ago. Maybe that's just a myth. Or maybe our ancient relatives weren't so ancient after all.

"Small Wonder" by Kirsten Weir. From Current Science, January 21, 2005 issue. Copyright © 2005 by Weekly Reader Corporation. Reprinted by permission of Scholastic Inc.