New Fossil Cache Hints at Human Ancestry

By Erin Weeks

In October 2013, three South African cavers made a discovery that may change our understanding of human origins.

Just 25 miles outside Johannesburg lies the Cradle of Humankind, a World Heritage Site marked by limestone caves, in which decades of research have unearthed an abundance of early hominin remains. Five years ago, the caves yielded a new species, Australopithecus sediba, whose classification has divided the anthropology community. And as recent months have shown, the Cradle of Humankind holds many more secrets.

At the bottom of one cave complex, past a fissure just eight inches wide, the cavers discovered what looked like hominin fossils lying undisturbed in soft dirt. The findings triggered a frenzy of activity, as researchers scrambled to assemble a team to investigate the promising fossils. One member was Duke paleoanthropologist Steve Churchill, who discussed his work on A. sediba and the new, as-of-yet unclassified fossils last week in a lecture on campus called “The 2-Million-Year-Old Boy.”

The research tents at the Rising Sun excavation site in South Africa (Photo: Steve Churchill)

The research tents at the Rising Sun excavation site in South Africa (Photo: Steve Churchill)

The National Geographic Society provided emergency funding for a three-week endeavor dubbed the Rising Star Expedition, which has been chronicled online by scientist Lee Berger (the blog has great pictures of the caves and fossils).

In those marathon three weeks, the team catalogued 1,200 fossils. By comparison, Churchill explained, 65 years of excavation yielded just 400 and 500 hominin fossils, respectively, in two nearby sites.

At first, the team hoped they might have a full skeleton from one individual on their hands–but as the expedition progressed, they realized that the fossils came from 12 to 20 different individuals.

Perhaps most fascinating is what researchers haven’t found at Rising Star: other animals. At most sites in the Cradle of Humankind, hominin knucklebones and teeth are scattered indiscriminately among antelope and leopard fossils. Researchers may never know why so many primates, yet nothing else, were preserved in Rising Star’s remote chambers, but it’s clear the assemblage formed under conditions very different than those of the nearby cave sites.

A peek inside the science tent. All of the equipment for the three-week expedition had to be hauled out to the cave site. (Photo: Steve Churchill)

A peek inside the science tent. All of the equipment for the three-week expedition had to be hauled out to the cave site. (Photo: Steve Churchill)

Where these primates belong on the hominid family tree is another lightning-rod question the team is working to answer. The age of the fossils is currently unknown, but there are indications they may fall into the time range in which early members of the genus Homo were first beginning to arise. If so, they may help to upend current theory, which holds that our Homo forebears evolved in East Africa rather than present-day South Africa.

Whatever the final word on their taxonomy, it’s clear the Rising Star fossils will lead to anthropological insights for years to come.

Finding Order in Insect and Orc Swarms

Ouellette's model of insect swarming

Ouellette’s model of insect swarming

By Olivia Zhu

Dr. Nicholas Ouellette looks for the organization in disorder.

Ouellette, associate professor in the mechanical engineering department at Yale University, studies collective motion in animal systems. On February 17, he presented his models of swarming of Chironomus riparius, the non-biting midge, as part of Duke’s Physics Colloquium. Ouellette ultimately hopes to pin down fundamental laws of biology through his physics research.

In the lab, Ouellette has found that Chironomus insects swarm in a columnar, teardrop shape in the center of their container. They only live in their flying state for two to three days, during which they mate, lay eggs and die. During this period, swarming affords them protection from predators and the opportunity to mate.

Ouellette and his lab have devised various methods of modeling the insects’ swarming. They found that the insect density remains constant, and that the “scattering,” or collisions of insects, mirrors that of an ideal gas over long periods of time. Interestingly, the graph of individual insect speed follows a Maxwell-Boltzmann distribution, even though the lab did not track the usual factors that create such a distribution, like temperature.

The most pressing question Ouellette would like to answer is which factors create a swarm—he has determined that close insect-insect repulsion contributes to swarming, but distant insect-insect attraction does not. To pursue this question, Ouellette is testing how many insects it takes to make a swarm.

Wildebeest stampede modeled in The Lion King

Wildebeest stampede modeled in The Lion King

Other animals that exhibit collective motion are mackerel, wildebeests and starlings. Some familiar examples of collective motion modeling are visible as the Orcs storm the castle in Lord of the Rings and as the wildebeests charge the canyon in The Lion King.

Four Things You May Not Know about Ecologist E.O. Wilson

By Erin Weeks

Edward O Wilson Red Hills, Aalabama  2010 by Beth Maynor Young 6x9_0

(Photo: Beth Maynor Young)

Edward O. Wilson is one of the most renowned living biologists, the world’s foremost authority on ants, and for a little while at least, a member of the Duke faculty.

Wilson is on campus teaching the first of an annual course, part of a recent partnership between the E.O. Wilson Biodiversity Foundation and Duke’s Nicholas School of the Environment. Feb. 11, he spoke to a sold-out auditorium about “The Diversity of Life,” a lecture that was equal parts awe-inspiring facts, humorous anecdotes from a life in science and call to arms for future generations.

Here are four things the audience learned last night about E.O. Wilson.

1. He’s dabbled in dreams of Jurassic Park. When asked what he thought of de-extinction, the plan to resurrect vanished species using their DNA, Wilson enumerated all the reasons why the efforts may be futile: we have only genetic shreds; the appropriate habitat may be gone; we can’t produce breeding populations from limited DNA.

But then he paused. “I’ll tell you frankly,” he said, “I’d like to see a mammoth.”

2. He made his first scientific discovery as an adolescent. An eye permanently damaged in a fishing accident led the young Wilson to his interest in ants, which he could view up close. One day in his native Alabama, he discovered a ferocious mound-building species he’d never seen before. He didn’t recognize it then, but those were among the first of the destructive red fire ants that would soon invade the entire Southeast, causing billions of dollars of economic and medical damage.

3. The man is 84 and still going strong. Professor Wilson closed his talk with a passage from his newest book, arriving in April, called “A Window on Eternity: A Biologist’s Walk Through Gorongosa National Park.” He’s written two dozen other books, including a foray into fiction at age 80 (the novel, called Anthill, won him the 2010 Heartland Prize for fiction).

4. The future is in nematodes. Or fungi. Or Archaea. Throughout the talk, Wilson reiterated his hopes for young scientists to become the cataloguers and guardians of Earth’s immense biological diversity. Only a fraction of the planet’s estimated species of nematodes, fungi and Archaea are known to science, and “these little things run the world,” he said.

The need for “-ologists” has never been greater, he said.

(Photo: Jared Lazarus)

(Photo: Jared Lazarus)

VIEW THE ENTIRE TALK (YouTube, 1:10 with introductions)

Inside the Monkey Brain

By Ashley Mooney

Both in the lab and on a tropical island, primate behaviors can shed light on social-decision making.

To fully understand the biology of social-decision making, Michael Platt, director of the Duke Institute for Brain Science, conducts lab work at Duke and field research an island off the coast of Puerto Rico called Cayo Santiago. His research focuses on understanding both the physiological and social aspects of decision making.

“Our brains are exquisitely tuned to making [social] decisions and acquiring the information to inform them,” Platt said. “When these processes go awry, as occurs in disorders like autism, schizophrenia or anxiety disorders, the consequences can be devastating.”

Courtesy of Lauren Brent.

Courtesy of Lauren Brent.

Platt’s group uses rhesus macaques as model animals because of their strong behavioral, physiological and neurobiological similarity to humans. But understanding how the monkey brain—and thus the human brain—works requires both laboratory-based biological information and social studies in a natural environment.

Researchers can combine the knowledge they gain from lab and field studies to create a holistic picture of the biological basis of behavior, said Lauren Brent, associate research fellow at the University of Exeter who did her post-doc with Platt at Duke.

Lab studies are best suited for quantitative, repeatable studies in which variables can be precisely controlled, Platt said. On the other hand, field studies emphasize external validity and an animal’s response in its natural conditions, but are not suitable for determining precise measurements of internal processes.

In the lab, Platt’s group studies the neural mechanisms that mediate prosocial and antisocial decisions, Platt said. They can also study the ways in which humans can enhance prosocial decisions using pharmacological or behavioral interventions.

On Cayo, the researchers are exploring the genetic factors that shape individual differences in social behavior and decision-making in free-living monkeys. They use observations, behavioral experiments and blood and fecal samples to study the monkeys non-invasively.

“The project on Cayo and the work that goes on the lab are complementary in the best sense because we can do things on Cayo that we can’t do in the lab,” Brent said. “For example, we have hundreds of monkeys, of known pedigree, interacting with each other in a purely spontaneous and naturalistic fashion. You can’t get that in a lab.”

Lauren Brent conducting behavioral observations on Cayo. Courtesy of Lauren Brent.

Lauren Brent conducting behavioral observations on Cayo. Courtesy of Lauren Brent.

Although working with free-ranging monkeys can produce more naturalistic results, Brent noted that there are drawbacks to working in the field.

“Working with monkeys in the field is painstaking,” Brent said. “You need to be physically fit, but moreover it is a mentally demanding thing to do because you need to pay close attention to everything that is going on in the group at all times so that the data are as finely detailed and accurate as possible.”

Brent found that a monkey’s position in its social network is heritable and can impact the survival of its infants. She determined a monkey’s social connections using grooming and spatial proximity, or how long one monkey spends sitting next to other monkeys.

“Regardless of how big your family is, monkeys who are better connected in the grooming network have greater reproductive success,” Brent said. “Together, these results suggest that social interactions have adaptive benefits and are something on which selection has acted.”

Student Melissa Chieffe: Budding Conservation Biologist

By Nonie Arora

Melissa Chieffe, a Junior Biology major, grew up outside Cleveland, Ohio and arrived at Duke enthusiastic about following a pre-vet path. As a freshman, she began volunteering at the Duke Lemur Center as a technician assistant. Through her work, she became interested in conservation in Madagascar and decided to apply to OTS – South Africa.

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A map of Chieffe’s travels. Credit: Melissa Chieffe using Google Maps. (click on map to learn more)

Through OTS – South Africa, she had the opportunity to travel all around the region and work on three group research projects, focusing mainly on ecology and conservation in the Kruger National Park.

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Melissa Chieffe. Credit: Liza Morse

In the first, she collected data for the Kruger long-term research initiative on vegetation changes caused by elephants. Specifically, she honed in on damage done to AppleLeaf trees (Philenoptera violacea) and assessed damage done to 175 trees of that species in the Kruger National Park. The study looked at bark stripping and toppling of trees caused by elephants. Bark stripping happens when elephants rub their tusks on trees; if the elephants remove too much mark the trees are more likely to die, according to Chieffe.

From their study, her team observed a bottleneck in tree size: the elephants generally knocked trees over before they could reach their mature height. Their preliminary data indicated that higher elephant population densities - combined with frequent burnings in the savannah - made it harder for trees to reach the mature stage.

In their independent research project, Chieffe and her group had the opportunity to work with a population of captive elephants. The elephant population in the Kruger National Park has been growing exponentially since the termination of culling operations in the 1990s, which is causing problems for the vegetation and the nearby rural farms, according to Chieffe. The elephants are known to destroy crops, fences, and storage facilities. The students looked into using bee hives as a deterrent for elephants. Chieffe explained that beehive fences could have great applications for conservation through community based conservation initiatives.

They used the sound of bees buzzing & the scent of honey to stand in as surrogates for bee hives. Wild elephants exhibited defensive retreating behaviors when exposed to the bee sounds and scents.

Camera traps

Chieffe learns to use camera traps (above) and photo of lion cubs taken by a camera trap (below). Credit: Melissa Chieffe

Chieffe learned to use camera traps (above) and made a photo of lion cubs with a camera trap (below). Credit: Melissa Chieffe

In her faculty field project, Chieffe worked with Professor Jeremy Bolton, an expert in the field, and Professor Tali Hoffman from the University of Cape Town to study camera traps. Chieffe’s team set up four camera traps at five different watering holes, which are known to act as “nodes of activity” for wildlife, to compare efficacy of two types of camera traps: field scan and motion sensor. Camera traps can be used to to record endangered animals and to survey biodiversity of an area.

“I enjoyed living in nature reserves, the national park, constantly surrounded by amazing researchers and scientists and others who are involved in conservation management. It was inspiring to live near them. We also got to present our findings to park management, which was awesome,” Chieffe said.

The program has helped her further her ambitions in conservation biology.

“I thought it was a dream [to become a conservation biologist]. But meeting people who are actually doing what I now want to do has made it seem realistic,” Chieffe said. She hopes to continue with  her research in South Africa on elephants and vegetation this summer.

Volunteer Network Shouldn’t be Stranded and Dying

measurements on a dead dolphin (Photo: Susan Farley)

During a lab necroscopy, Dr. Vicky Thayer (left) takes measurements on a dead dolphin as student Samantha Emmert records the data. (Photo: Susan Farley)

Guest Post by Samantha Emmert, a Biology and Evolutionary Anthropology undergraduate at the Duke Marine Lab

The rolling sand dunes and gentle waves of Emerald Isle are so picturesque that I almost forget why I am there: to conduct a necropsy (autopsy on a non-human) on a stranded bottlenose dolphin. Vicky and I have been searching for the animal for about an hour now, driving up and down the beach. Suddenly, I catch a whiff of rotting flesh. Great! We’ve found it!

During my year at the Duke Marine Lab, I am volunteering for the North Carolina Central Coast Marine Mammal Stranding Network. This is no normal year for the network and others like it on the east coast. In the last seven months, 1081 bottlenose dolphins have stranded between New York and Florida. This magnitude of strandings is almost ten times the average, and has therefore been declared an “Unusual Mortality Event” by the National Oceanic and Atmospheric Administration. The cause of these deaths? Morbillivirus, the disease family that includes human measles.

For Independent Study credit I have been collecting data about the stranded dolphins and comparing them to data from 1987-88, the last and only other time there was a morbillivirus Unusual Mortality Event affecting bottlenose dolphins. I have found that this event is following the patterns of 87-88 almost exactly, particularly in terms of the sex and age of dolphins, and when and where they are stranding. These patterns may be a strong indicator for the path of future events.

Dolphin strandings in the area are reported to Dr. Vicky Thayer, the network’s coordinator and a Duke alumna (M.E.M. 1982, Ph.D. 2008). Vicky then calls her volunteers, such as myself, to assist in a response. Today, the dolphin was freshly dead and in good shape for a full necropsy. As Vicky assesses the dolphin for signs of human interaction, I sharpen knives and prepare vials to hold tissue samples. I put on my boots, coveralls, and gloves (things are about to get bloody). Together, Vicky and I peel back blubber and slice through flesh in order to reach the organs that are most impacted by morbillivirus: the lungs, associated lymph nodes, and spinal cord.

This Unusual Mortality Event is not the only problem that the network has been facing this year. Their federal funding for the upcoming year was not renewed.

Many marine mammal rescue networks, such as this one, rely on the John H. Prescott Marine Mammal Rescue Assistance Grant Program, established under amendments to the Marine Mammal Protection Act. However, the number of networks that received awards declined from 39 in 2012 to 12 in 2013. Only two of those 2013 recipients are in the geographic range affected by the dolphin mortality, compared to 13 in 2012. Particularly during a time when they are busiest, the loss of funding has been a huge stress for the networks.

Samantha climbs out of a freshly dug beach grave for yet another dead dolphin.

Samantha and Vicky got to this dolphin just before town workers buried it on the beach and were able to get their tissue samples.

Throughout the necropsy, several fishermen stop by to ask what we are doing. They’ve been fishing on this beach for decades and are aware of the increased occurrence of strandings in the area. It is vital to us that they understand the importance of reporting stranded animals.

“As top predators in coastal waters, these animals are sentinels of ocean health. When they wash ashore in unprecedented numbers, we should direct our attention and funding to learn as much as we can about the cause,” Vicky explains while taking apart the carcass.

We reach the lungs and, sure enough, they are discolored and covered in lesions. We cut chunks from the lung, lung lymph node, and spinal cord and I squish them into small vials. They will be sent to a lab in California to be tested for morbillivirus. The data we record and samples we take will be useful for the many researchers interested in this event across the nation.

It is hard to say what will become of the NC Central Coast Marine Mammal Stranding Network and others like it. Without renewed funding in the 2014 year, Vicky will be unable to continue the network and stranding response will stop in this area. Valuable data for long-term research on stranded animals will be lost. Live-stranded animals will die on beaches unaided. In order to protect and conserve these beloved species, the Prescott Grant and other funding sources must be made more readily available.