Molars provide insight into evolution of apes, humans

December 28, 2009

The timing of molar emergence and its relation to growth and reproduction in apes is being reported by two scientists at Arizona State University's Institute">http://iho.asu.edu/">Institute of Human Origins in the Dec. 28 online early edition of the Proceedings of the National Academy of Sciences (PNAS).

From the smallest South American monkeys to the largest African apes, the timing of molar development and eruption is closely attuned to many fundamental aspects of a primate's biology, according to Gary Schwartz, a researcher at the Institute of Human Origins and an associate professor in the School">http://shesc.asu.edu/">School of Human Evolution and Social Change in ASU's College">http://clas.asu.edu/">College of Liberal Arts and Sciences. Download Full Image

"Knowing the age when the first molar appears in the mouths of most primates allows researchers to predict a host of life history attributes, such as gestation length, age at sexual maturity, birth spacing and overall lifespan," said Schwartz. "Humans are unique among primates because our life histories are so slow and thus our molars emerge relatively late. Given that apes are our closest living relatives, understanding the broader context of when the characteristic slower development of humans evolved is of great interest."

"We've known quite a bit about the timing of molar development in chimpanzees, which is important because they are our closest living relative. However, we've known virtually nothing about when this important event occurs in other wild-living ape species – until now," said lead author Jay Kelley, a research affiliate at ASU's Institute of Human Origins and an associate professor in the Department of Oral Biology at the University of Illinois, Chicago.

Because of the difficulties in obtaining tooth emergence ages from animals in the wild, Kelley opted for other means; he searched for specimens in museums. At the Zoologische Staatssammlung in Munich he found skulls of a wild-shot orangutan (Pongo pygmaeus pygmaeus) and gorilla (Gorilla gorilla gorilla) that preserved emerging first molars.

"Like annual growth rings inside trees, the cells that produce teeth (both the enamel and underlying dentine) leave behind a trace of their presence, not as annual markers, but as growth lines that appear every day," said Kelley. By slicing the teeth in half, he and Schwartz were able to examine these incremental growth lines in ape individuals that died as their first molars were just erupting into their mouths.

"Because teeth preserve this phenomenal internal chronometer, we were able to count up how many days it took the first molars to form," said Schwartz. "In apes and monkeys, first molars start forming very close to the time of birth. As the first molars were still erupting in our specimens, development was incomplete and the final growth line was laid down on the day those animals died. Therefore, by counting backwards from the final growth line to the day of birth, we determined their age at death and thus the age at which that molar was erupting."

Using this novel approach, the two scientists were able to mark the age of the gorilla's first molar emergence at 3.8 years, nearly identical to that of a wild chimpanzee's. The orangutan's age at first molar emergence was surprisingly much later, at 4.6 years, which falls closer to the age of approximately 6 years in modern humans.

"We were excited to discover this much older age for the orangutan, since orangutans have much slower life histories than the other two great apes," said Kelly.

However, he and Schwartz caution that though the later emergence age in these large Asian apes is closer to that for modern humans, these latest findings should not be taken to indicate some special evolutionary relationship between the two.

"Rather, it is in keeping with what you would expect given the relatively slow pace of growth and long period of infant dependency that evolved separately in the lineage leading to orangutans and that leading to modern humans," said Schwartz.

The work by Kelley and Schwartz also has implications for understanding the evolution of human life history.

"We can use the same techniques to calculate ages at first molar emergence from the fossils of early hominids that just happened to die while their first molars were erupting," said Kelley. "The close correspondence between age at first molar emergence and the timing of life history events that we found in great apes and modern humans means that we can have confidence that first molar emergence ages in the early hominids will provide equally accurate knowledge about their life histories."

Their findings are detailed in the article "Dental development and life history in living African and Asian apes."

Arts and Crafts movement: a life's passion explored

Few scholars know more about the Arts and Crafts movement, and its impact on today’s home and interior designs, than ASU design professor Beverly Brandt.

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Arts and Crafts movement: a life's passion explored

December 28, 2009

Take a look around your home. That chair you’re sitting in. The silverware on your table. The vase that holds your favorite flowers. Are they useful? Most probably. But are they beautiful, too?

Today, consumers probably don’t think about their home and its furnishings in those terms, but from around 1860 to 1920, those questions mattered – and they formed the basis of the Arts and Crafts movement. Download Full Image

Few scholars know more about the Arts and Crafts movement, and its impact on today’s home and interior designs, than Beverly Brandt, professor of design in the Herberger Institute for Design and the Arts.

Brandt’s first book on the subject, “The Craftsman and the Critic: Defining Usefulness and Beauty in Arts and Crafts-Era Boston,” was recently published by the University of Massachusetts Press.

Though craftsman and poet William Morris advised English consumers in the 1880s to “have nothing in your houses that you do not know to be useful or believe to be beautiful,” the idea took off in the United States too, and was centered in Boston.

“The Craftsman and the Critic” looks at Boston in the Gilded Age as a center for reform, epitomized by the Aesthetic and the Arts and Crafts movements; the evolution of the profession of design criticism in the 19th century; the formative years of Boston’s influential Society of Arts and Crafts; important people in the movement; and the Arts and Crafts revival that has flourished in the United States since the 1970s.

Brandt’s book is a labor of love that was nine years in the making. It reflects her career-long fascination with the Arts and Crafts movement and Boston of that era, and is meant, also, to be useful as well as beautiful.

“So much that is written about the Arts and Crafts movement is in the form of glossy coffee-table books,” Brandt said. “I wanted to explore how people got those ideas, and shaped them. To tell the back stories of the objects that are part of the movement.”

She also questions why was Boston the center of the movement, and why the ideas of usefulness and beauty resonate today.

The Arts and Crafts movement, Brandt said, is defined as an Anglo-American design reform movement that lasted from about 1860 to 1920. “Its goal was to unite architects, designers, artists, and craftspeople in an effort to improve the quality of design and hence the quality of life."

It has endured, she said, because Morris, its proponent, upheld beauty and usefulness as ideals, but “did not prescribe what either must be, according to a single theory.

“Morris – along with his contemporaries and his followers – ensured that the products of the design reform movement would transcend the particulars of style and thus age gracefully, as they have into the 21st century,” Brandt wrote.

“The downside to such openness to interpretation was this: at the time, the Arts and Crafts ideal was not always easy to comprehend or to assimilate. Where did one begin in one’s quest for Usefulness and Beauty? How might one recognize them on the pages of a sketchbook, at the potter’s wheel or jeweler’s bench, at an art exhibition, in a store window, or within the confines of one’s own home?

“Enter the design critic – that arbiter of taste, midwife to the creative process, champion of integrity and truth in the designed environment.”

Brandt has been fascinated with the Arts and Crafts movement since she was a graduate student at Michigan State University.

In her first design history class, she sat in a darkened lecture hall, seeing “slides of jewel-toned Morris chintzes for the first time.”

She spent the summer of 1975 in London on an overseas studies program that enabled her to see exhibits and hear lectures on the Arts and Crafts movement. In 1980, she decided to pursue an academic career and enrolled in Boston University’s American and New England Studies Program, where she learned about the Society of Arts and Crafts in Boston.

After perusing the microfilmed records about the society that are housed in the Smithsonian Institution Archives of American art, and becoming further fascinated, she decided to writer her dissertation about the first 20 years of the society.

Unlike those coffee table books that focus on objects in the movement, Brandt’s book looks at the processes. “What intrigues me most,” she wrote, “are the processes by which arts and crafts products came to be, and the ideas that informed them.”

“The Craftsman and the Critic” is lavishly illustrated with portraits of the major players in the Boston Arts and Crafts movement, objects of usefulness and beauty, photographs of buildings and interiors, reproductions of advertisements and much more.

“It took me a year and a half just to work on the illustrations,” Brandt said. “I had to winnow them down to 210.”

The book also has extensive appendices, notes, a bibliography and an index, providing the reader with what seems to be everything there is to know about the Arts and Crafts movement and its Boston iteration.

“It was a fun book to write. I’m a creative person and putting this together was a dream – it’s things I’ve been thinking about for 30 years,” Brandt said.

Though “The Craftsman and the Critic” is a scholarly book, it was recently ranked in the “Top 100 Bestsellers” in Massachusetts, and has received enthusiastic reviews from general readers and respected scholars in the field.

“This is an excellent book. Beverly Brandt is a top-notch expert on the Arts and Crafts movement, especially Boston. Besides all that, she is an excellent writer. Highly recommended,” one reviewer wrote.

Another concluded, “This book is essential for all students of the Arts and Crafts movement in North America. Boston was the first city to institutionalize it and give it focus. Brandt has the whole story and tells it well.”