Posts tagged CU study
CU study: We’re not so different than the Ancients
Feb 12th
rules of development, says CU-Boulder researcher
Recently derived equations that describe development patterns in modern urban areas appear to work equally well to describe ancient cities settled thousands of years ago, according to a new study led by a researcher at the University of Colorado Boulder.
“This study suggests that there is a level at which every human society is actually very similar,” said Scott Ortman, assistant professor of anthropology at CU-Boulder and lead author of the study published in the journal PLOS ONE. “This awareness helps break down the barriers between the past and present and allows us to view contemporary cities as lying on a continuum of all human settlements in time and place.”
Over the last several years, Ortman’s colleagues at the Santa Fe Institute (SFI), including Professor Luis Bettencourt, a co-author of the study, have developed mathematical models that describe how modern cities change as their populations grow. For example, scientists know that as a population increases, its settlement area becomes denser, while infrastructure needs per capita decrease and economic production per capita rises.
Ortman noticed that the variables used in these equations, such as cost of moving around, the size of the settled area, the population, and the benefits of people interacting, did not depend on any particular modern technology.
“I realized that if these models are adequate for explaining what’s going on in contemporary cities, they should apply to any settlements in any society,” he said. “So if these models are on the right track, they should apply to ancient societies too.”
To test his idea, Ortman used data that had been collected in the 1960s about 1,500 settlements in central Mexico that spanned from 1,150 years B.C. through the Aztec period, which ended about 500 years ago. The data included the number of dwellings the archaeologists were able to identify, the total settled area and the density of pottery fragments scattered on the surface. Taken together, these artifacts give an indication of the total population numbers and settlement density of the ancient sites.
“We started analyzing the data in the ways we were thinking about with modern cities, and it showed that the models worked,” Ortman said.
The discovery that ancient and modern settlements may develop in similar and predictable ways has implications both for archaeologists and people studying today’s urban areas. For example, it’s common for archaeologists to assume that population density is constant, no matter how large the settlement area, when estimating the population of ancient cities. The new equations could offer a way for archaeologists to get a more accurate head count, by incorporating the idea that population density tends to grow as total area increases.
In the future, the equations may also guide archaeologists in getting an idea of what they’re likely to find within a given settlement based on its size, such as the miles of roads and pathways. The equations could also guide expectations about the number of different activities that took place in a settlement and the division of labor.
“There should be a relationship between the population of settlements and the productivity of labor,” Ortman said. “So, for example, we would expect larger social networks to be able to produce more public monuments per capita than smaller settlements.”
The findings of the new study may also be useful to studies of modern societies. Because ancient settlements were typically less complex than today’s cities, they offer a simple “model system” for testing the equations devised to explain modern cities.
“The archaeological record actually provides surprisingly clear tests of these models, and in some cases it’s actually much harder to collect comparable data from contemporary cities,” Ortman said.
Other co-authors of the study include Andrew Cabaniss of Santa Fe Institute and the University of North Carolina Chapel Hill and Jennie Sturm of the University of New Mexico.
The study is available at http://dx.plos.org/10.1371/journal.pone.0087902.
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CU study: Some primates sleep in caves for safety
Dec 4th
The ring-tailed lemurs may be opting to sleep in caves for several reasons, said University of Colorado Boulder anthropology Associate Professor Michelle Sauther, who led the study. While the cave-sleeping behavior is likely important because it provides safety from potential predators, it also can provide the primates with access to water and nutrients, help to regulate their body temperatures during cold or hot weather and provide refuge from encroaching human activities like deforestation, she said.
“The remarkable thing about our study was that over a six-year period, the same troops of ring-tailed lemurs used the same sleeping caves on a regular, daily basis,” she said. “What we are seeing is a consistent, habitual use of caves as sleeping sites by these primates, a wonderful behavioral adaptation we had not known about before.”
A paper on the subject appeared in the November issue of the journal Madagascar Conservation and Development. Funding for the project came from Primate Conservation Inc., the International Primate Society, the American Society of Primatologists, the National Geographic Society, CU-Boulder, the University of North Dakota, Colorado College and the National Science Foundation.
Although sleeping in caves by ring-tailed lemurs — which are found only in Madagascar — has likely been going on for millennia, it is only now being recognized as a regular behavior, said Sauther. The endangered Fusui langurs, slender, long-tailed Asian monkeys roughly 2 feet tall, also have been documented sleeping in caves but as a direct result of extreme deforestation, moving from cave to cave every few days. There also have been isolated reports of South African baboons sleeping in caves.
Ring-tailed lemurs are easily identified by their characteristic, black and white ringed tails, which can be twice as long as their bodies. They weigh roughly 5 pounds with a head-body length of up to 18 inches and are highly social, congregating in groups of up to 30 individuals. Sporting fox-like snouts and slender frames, they are unusual among lemurs, spending a considerable amount of time on the ground feeding on leaves and fruit and socializing, said Sauther.
In “gallery forests” near rivers, ring-tailed lemurs regularly sleep high in the canopies of tall trees. But in “spiny forests,” most of the trees with woody stems are covered in rows of spines, making them uncomfortable as well as dangerous sleeping sites because predators can easily climb them, Sauther said. The new study documents their cave sleeping behavior in the dry spiny forest habitat adjacent to limestone cliffs.
The lemur observations were made at the 104,000-acre Tsimanampesotse National Park and the Tsinjoriake Protected Area in southwestern Madagascar between 2006 and this year. The research team used field observations and motion-detector camera traps to chart the behavior and movements of 11 different troops of ring-tailed lemurs.
One of the early clues to the cave sleeping by the lemurs was their presence on limestone cliffs adjacent to spiny forest trees or on the ground when Sauther’s research team arrived at the study sites early in the morning. “They seemed to come out of nowhere, and it was not from the trees,” she said. “We were baffled. But when we began arriving at the study sites earlier and earlier in the mornings, we observed them climbing out of the limestone caves.”
The primary predator of the lemurs is a cat-like, carnivorous mammal called a fossa native only to Madagascar that is closely related to the mongoose and may weigh up to 20 pounds. Fossil evidence shows a cougar-sized relative of the fossa that only became extinct several thousand years ago likely preyed on lemurs as well, she said.
There is evidence that some early ancestors of humans in South Africa may have used caves to protect themselves from predators, said Sauther. The remains of hominids going back several million years have been found inside or near limestone caves there, and some fossil bones have evidence of damage consistent with the bite of saber-toothed cats.
“We think cave-sleeping is something ring-tailed lemurs have been doing for a long time,” she said. “The behavior may be characteristic of a deep primate heritage that goes back millions of years.”
Co-authors of the new study included Associate Professor Frank Cuozzo of the University of North Dakota, Ibrahim Antho Youssouf Jacky, Lova Ravelohasindrazana and Jean Ravoavy of the University of Toliara in Madagascar, Krista Fish of Colorado College in Colorado Springs, Colo., and Marni LaFleur of the University of Veterinary Medicine in Vienna. Fish and LaFleur are former CU-Boulder students of Sauther.
Sauther co-directs the Beza Mahafalay Lemur Biology Project in southwestern Madagascar with Cuozzo, a former CU-Boulder doctoral student. Centered at the roughly 1,500-acre Beza Mahafalay Special Reserve, the research focuses on how climate- and human-induced change affects lemur biology, behavior and survival.
Sauther and her team were aided by field observations made by students and faculty from the University of Toliara in Madagascar. In addition, undergraduate and graduate students from CU-Boulder regularly travel to Madagascar to conduct research under Sauther, including students from CU’s Undergraduate Research Opportunities Program, which provides hands-on research and fosters student-faculty relationships.
“I never thought I would have a chance as a CU undergraduate to conduct research in an exotic place like Madagascar,” said former UROP student Anthony Massaro, who was part of a team that trapped ring-tailed lemurs, measured their physical characteristics including dentition, and released them back into the wild. “Dr. Sauther and Dr. Cuozzo mentored and guided me through the process of creating and conducting a unique research project.”
Unfortunately, habitat destruction, including deforestation, is increasing in many parts of Madagascar. In southwestern Madagascar, trees are being harvested for cattle forage, construction materials and firewood, and the mining of limestone there — used for the production of cement, fertilizer and other products — is increasing. Ring-tailed lemurs are now listed as an endangered species by the International Union for the Conservation of Nature’s Species Survival Commission.
Sauther has been conducting research on Madagascar for 25 years, beginning as a University of Washington graduate student. Today she has several CU-Boulder doctoral students working with her, including James Millette, who is studying how the tooth wear of lemurs relates to their foraging behaviors.
“Madagascar is a challenging place to conduct research,” Millette said. “Part of our job is to work with local communities, because without the support of these people there would be no lemur conservation. We consider Beza, where we have been working with the community for several decades, to be a real success story.”
A video of ring-tailed lemurs climbing into a cave is available at https://www.youtube.com/watch?v=vjWF3_SmYS0&feature=youtu.be.
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CU study: Foreign students should stay
Nov 5th
foreign Ph.D. students to stay, CU-led study finds
Encouraging more talented foreign students to study at U.S. universities and encouraging them to launch entrepreneurial ventures here could help “revitalize innovation and economic growth” in this country, a trio of economists led by University of Colorado Boulder Professor Keith Maskus concludes.
Maskus and co-authors Ahmed Mushfiq Mobarak, associate professor at the Yale School of Management, and Eric T. Stuen, assistant professor at the University of Idaho College of Business and Economics, make this case in the Policy Forum of the Nov. 1 edition of the journal Science.
The economists’ perspective draws on their study of 100 research-intensive U.S. universities in 23 science and engineering fields, which found that both U.S. and foreign students are “essential causal inputs into scientific discovery.” The trio has also found evidence that increased student diversity boosts innovative research.
Maskus and his collaborators have found that high-performing foreign-born Ph.D. students improve the “creation of knowledge” in U.S. universities. When knowledge is created, it tends to drive entrepreneurial investment and economic growth.
In fact, the researchers found, “The productivity of the average American university science and engineering laboratory in generating publications is a bit higher if it has students from 10 different countries than if it has 10 students from one country.”
That might not seem intuitive, Maskus acknowledged. “What it comes down to is that people trained in different traditions tend to have different specialties in terms of how they come to a teamwork environment. And teamwork is more productive, more efficient if you have people with divergent ideas, so they can play off of each other.”
Such diversity of intellect, capacities and specializations makes a measurable difference, Maskus added. “It doesn’t matter so much on a factory line, but it matters a lot in an intellectual sense when you’re trying to be innovative and creative.”
The publication comes as Congress weighs whether and how to change the U.S. immigration system. A bipartisan bill that cleared the U.S. Senate in June but has stalled in the House includes provisions that partly mirror those recommended by Maskus and his team.
Based on data showing that highly skilled Ph.D.s in science and engineering tend to generate new jobs where they work, the bill would pave the way for Ph.D.s in science and engineering who are from foreign countries to gain permanent U.S. residency after graduation.
U.S. law requires foreign students to leave the country after earning their Ph.D.s unless they find employers willing to sponsor their visas, which, Maskus and his colleagues note, might not lead to permanent U.S. residency. In recent years, the percentage of foreign Ph.D.s remaining in the United States after graduation has declined.
The Senate bill would grant a green card, or permanent residence, to foreign students who get a Ph.D. in science or engineering at American universities. The bill would also facilitate green-card status to those who have recently earned doctoral degrees in science and engineering at recognized scientific institutions worldwide.
Maskus and his colleagues also recommend an entrepreneurship visa. Such a visa could be granted to those who have secured a patent and met certain milestones for getting that idea commercialized. The idea is similar to an investment visa—granted based on immigrants’ investment in the U.S. economy.
This year, Canada implemented an entrepreneurship visa that includes inventive foreign Ph.D.s. The program aims to attract science and engineering graduates from U.S. universities.
“Ultimately we think this is an important way of reinvigorating economic growth and technological change in the U.S.,” Maskus said.
Additionally, the trio contends that decisions to grant student visas to prospective graduate students from foreign countries should be granted on more factors than just their ability to pay. Historically, the ability-to-pay requirement has been used by immigration officials as an indicator that foreign students will return to their countries of origin.
In the case of foreign Ph.D.s in science and engineering, such a requirement “is short-sighted,” Maskus said. “The country should welcome people who can contribute in developing innovation and new technology and permit them to stay.”
“You have to have access to the best innovative inputs and resources in the world,” Maskus said. “The Europeans recognize that, the Australians, the Canadians.”
Addressing a commonly expressed fear, Maskus and his collaborators do not find evidence that granting green cards to high-performing foreign Ph.D.s would displace American Ph.D.s.
The research of Maskus, Mobarak and Stuen reinforces recommendations of groups ranging from the U.S. Chamber of Commerce to the National Academy of Sciences.
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