Photos available

GAINESVILLE, Fla. — With Halloween around the corner, it’s time to look out for those fabled creepy night-flyers, from ghosts and ghouls to blood-sucking bats. But don’t confuse fact with legend – bats are too busy eating insects to worry about sucking blood or getting tangled in your hair.

It’s no wonder these flying mammals have suffered centuries of misconceptions. Yet, bats have proven more intriguing than spooky when provided a home in an urban setting, as the University of Florida campus sees thousands of visitors to its stilted bat structures every year. UF has the world’s largest continuously occupied bat houses, located in a field across from Lake Alice on Museum Road, and for the first time beginning at 10 a.m. EDT today, the Florida Museum of Natural History will launch 24-hour streaming videos of the colony.

UF boasts the world’s largest occupied bat houses, located in a field across from Lake Alice on Museum Road. Combined, the structures house nearly 300,000 bats. © Photo by Kristen Grace

“Bats are often portrayed in movies as just sleeping all day, but that’s not the way they operate – if you have the opportunity to see them up close, they’re amazingly attractive animals, and they’re not as menacing as you might think,” said Florida Museum mammalogy curator David Reed. “They may have ugly faces, but they’re brightly colored and you don’t get to see that at night.”

Three bat-cams are installed in and around the structures, including one inside the bat house with tilt, pan and zoom capabilities controlled remotely by museum technicians. Internet users may access the streaming videos by visiting www.flmnh.ufl.edu/bats, where there are also facts about the colony, links to bat conservation organizations and daily sunset times.

UF environmental health and safety pest management coordinator Ken Glover installs a webcam in one of two bat houses across from Lake Alice on Museum Road. UF’s bat colony may be viewed via three cameras on the Florida Museum website, www.flmnh.ufl.edu/bats. © Photo by Kristen Grace

“The bat-cams are really cool for an educational tool, for one thing,” Reed said. “Also, having that many bats in one concentrated area always gives opportunity for study.”

Combined, the structures currently house nearly 300,000 individuals and the vast majority are Brazilian free-tailed bats, Tadarida brasiliensis, a non-migratory, maternity colony that birth their young and dwell in the area year-round. The best time to observe the bats is when they exit the structures after sunset.

“In the winter here, the bats who are most eager to get out first will wake in the early afternoon and start warming up, doing laps up top before they exit,” Reed said. “And consequently, the exodus of the bats during winter is slower and over a longer period of time. But in the summer time, they can leave more en masse because they don’t have to warm up their muscles first.”

On weeknights, about 50 to 60 people observe the exodus, but on weekends, there may be between 150 and 200 spectators, said UF environmental health and safety pest management coordinator Ken Glover, who helped build the structures and implement the bat-cam project. With the streaming videos, hundreds of people may watch the colony at the same time, and researchers hope the accessibility will help dispel some of the common misconceptions about bats and educate viewers about their important ecological value.

“My feelings for bats have always been most appreciative – they’re non-game wildlife and they’re the world’s largest predators of night-flying insects,” Glover said. “So they’re one of our most reliable forms of natural pest control and they’re largely misunderstood because they come out at night and you only see them when they’re flying.”

Glover picks up an injured bat that fell from the Bat House Oct. 7, 2011. The majority of bats in the UF colony are Brazilian free-tailed bats, Tadarida brasiliensis.© Photo by Kristen Grace

The bat house was constructed in March 1991 to accommodate a bat colony that had inhabited the James G. Pressly Stadium at the track and Scott Linder Tennis Stadium on the north side of campus. The University Athletic Association supported its construction so the droppings (guano) and urine would be contained at a safe distance from humans. The alternative habitat was deemed a success when the structure was permanently occupied in 1995.

“A pest’s status is determined usually by its location, not species,” Glover said. “So a bat is considered a pest when it’s living in the wrong place, just as a house fly is a pest when it’s not living on a pile of manure.”

In August 2009, the weight of the bats combined with deterioration of some of the interior fins caused the inside of the bat house to collapse. It was renovated within a few months and construction of a second structure, the bat barn, began in March 2010.

“We incorporated some changes, such as a different roof style so there would be more room for the bats to fly inside,” Glover said. “We also better insulated it to keep it warmer and there are now between 20,000 and 30,000 bats living there.”

Although the unexpected collapse of the bat house’s internal structure killed about 100 of its inhabitants, the victims were preserved as specimens at the Florida Museum and helped kick-start a research project on biogeographical distribution of the species.

Roosting bats are illuminated with sunlight reflected from a hand-held mirror through fins in the UF Bat House. © Photo by Kristen Grace

“Because we had specimens here, we started collecting specimens of the free-tail in the Bahamas and the DNA showed some were dramatically different from the ones in Florida, which tells us the Bahamas has a really interesting history in terms of this species.” Reed said.

“It’s a project that never would have started if not for the bat house.”

The videos are being made available during the “Year of the Bat,” a two-year, worldwide species awareness initiative whose founding partners include the United Nations Environment Programme, the Convention on Migratory Species and the Agreement on the Conservation of Populations of European Bats.

“We’re happy to launch this project during the Year of the Bat,” said Beverly Sensbach, associate director of museum operations. “We felt the timing was appropriate, during this global effort to raise awareness about bats and bat conservation.”

- 30 -

Source: Beverly Sensbach, 352-273-1900, sensbach@flmnh.ufl.edu
Writer: Danielle Torrent, dtorrent@flmnh.ufl.edu
Media contact: Paul Ramey, 352-273-2054, pramey@flmnh.ufl.edu

The study shows the trickle-down effect the loss of large mammals has on other species, and researchers say it is a lesson from the past that should be remembered when making conservation, game and land-use decisions today.

“There’s nothing worse for a terrestrial ecosystem than the loss of large mammals – and the loss of apex predators like sharks, tuna and other large fish will have the same negative impact on the oceans,” said study co-author David Steadman, ornithology curator at the Florida Museum of Natural History on the UF campus. “We’re seeing it with the loss of lions and elephants in parts of Africa, as well as in Florida with the decline of panthers. There’s no question these losses will have a negative domino effect on our ecosystems.”

The fossil study of eight songbird species from northern Mexico by Florida Museum ornithologists is currently available online and will appear in Tuesday’s print edition of the journal Palaeogeography, Palaeoclimatology, Palaeocology.

An extinct cowbird, Pandanaris convexa, is the most common bird found at the fossil site called Térapa, in Sonora, Mexico, about 150 miles south of Arizona. This is the first time fossils of the large bird, a member of the blackbird family, have been found in Mexico.

Finding the extinct cowbird at the fossil site was unpredictable and unexpected, according to Jim Mead, chair of the department of geosciences at East Tennessee State University, who has collected a variety of fossils at the site, including the birds used in the study. Mead described the findings at Térapa as “bizarre and exciting.”

“The tropical environment is unusual because the site is so far from the coast,” Mead said. “The fossil record also provides evidence animals migrated from north to south and, unexpectedly, from south to north.”

The cowbird has previously only been found at the Rancho La Brea fossil site in California and a site in Reddick, between Gainesville and Ocala in North Central Florida. The study expands the bird’s known range and creates new questions about whether it may have lived across the southern U.S.

“The extinct cowbird needed grasslands and these big mammals to survive,” said lead author Jessica Oswald, a National Science Foundation predoctoral fellow at the Florida Museum. “Those two things play into each other because mega mammals maintain grasslands. They keep big trees from coming in and colonizing the areas because they graze, stomp and trample little saplings.”

Like modern cowbirds, this species probably fed on seeds and insects large mammals exposed, Oswald said. The mammals included extinct species of ground sloth, mammoth, horse, tapir, camel and bison.

About 20,000 years ago, most of these large mammals went extinct, which lead to the extinction of scavengers like condors and vultures, as well as cowbirds, Steadman said. Extinctions, especially mass extinctions, can cause radical species loss and changes in species distribution.

“Big species can’t exist in a vacuum, nor can smaller species,” Steadman said. “When one piece of the puzzle goes extinct, there is no good way of predicting what sort of trickle-down effect, what kind of cascade effect that will have.”

The study also confirms the area was once marshy grassland, possibly surrounded by a savanna near a river. Fossils of plants, reptiles and mammals of all sizes, and 31 species of birds other than songbirds have been recovered from the Térapa site over the past 10 years. Most of these species are found today in grasslands or wetlands, Steadman said.

Steadman and Oswald used the Florida Museum’s more than 24,000 skeletal specimens of birds to identify the Mexican fossils.

Songbirds make up more than 50 percent of the world’s living bird species, but the fossil record is poorly developed, especially in Central and South America. Oswald said this study helps build the fossil record of songbirds in Mexico.

Finding bird fossils, as well as bones of other small animals, is a time-consuming and labor-intensive process. Sediment is placed in a fine mesh sieve and water is used to remove dirt and debris from the bones.

- 30 -

Source: Jessica Oswald, 352-273-1977, oswaldj3@ufl.edu
David Steadman, 352-273-1969, dws@flmnh.ufl.edu
Writer: Leeann Bright
Media Contact: Paul Ramey, pramey@ufl.edu, 352-273-2054

Principal investigator David Reed, associate curator of mammals at the Florida Museum of Natural History on the UF campus, studies lice in modern humans to better understand human evolution and migration patterns. His latest five-year study used DNA sequencing to calculate when clothing lice first began to diverge genetically from human head lice.

Funded by the National Science Foundation, the study is available online and appears in this month’s print edition of Molecular Biology and Evolution.

“We wanted to find another method for pinpointing when humans might have first started wearing clothing,” Reed said. “Because they are so well adapted to clothing, we know that body lice or clothing lice almost certainly didn’t exist until clothing came about in humans.”

The data shows modern humans started wearing clothes about 70,000 years before migrating into colder climates and higher latitudes, which began about 100,000 years ago. This date would be virtually impossible to determine using archaeological data because early clothing would not survive in archaeological sites.

The study also shows humans started wearing clothes well after they lost body hair, which genetic skin-coloration research pinpoints at about 1 million years ago, meaning humans spent a considerable amount of time without body hair and without clothing, Reed said.

“It’s interesting to think humans were able to survive in Africa for hundreds of thousands of years without clothing and without body hair, and that it wasn’t until they had clothing that modern humans were then moving out of Africa into other parts of the world,” Reed said.

Lice are studied because unlike most other parasites, they are stranded on lineages of hosts over long periods of evolutionary time. The relationship allows scientists to learn about evolutionary changes in the host based on changes in the parasite.

Applying unique data sets from lice to human evolution has only developed within the last 20 years, and provides information that could be used in medicine, evolutionary biology, ecology or any number of fields, Reed said.

“It gives the opportunity to study host-switching and invading new hosts—behaviors seen in emerging infectious diseases that affect humans,” Reed said.

A study of clothing lice in 2003 led by Mark Stoneking a geneticist at the Max Planck Institute in Leipzig, Germany, estimated humans first began wearing clothes about 107,000 years ago. But the UF research includes new data and calculation methods better suited for the question.

“The new result from this lice study is an unexpectedly early date for clothing, much older than the earliest solid archaeological evidence, but it makes sense,” said Ian Gilligan, lecturer in the School of Archaeology and Anthropology at The Australian National University. “It means modern humans probably started wearing clothes on a regular basis to keep warm when they were first exposed to Ice Age conditions.”

The last Ice Age occurred about 120,000 years ago, but the study’s date suggests humans started wearing clothes in the preceding Ice Age 180,000 years ago, according to temperature estimates from ice core studies, Gilligan said. Modern humans first appeared about 200,000 years ago.

Because archaic hominins did not leave descendants of clothing lice for sampling, the study does not explore the possibility archaic hominins outside of Africa were clothed in some fashion 800,000 years ago. But while archaic humans were able to survive for many generations outside Africa, only modern humans persisted there until the present.

“The things that may have made us much more successful in that endeavor hundreds of thousands of years later were technologies like the controlled use of fire, the ability to use clothing, new hunting strategies and new stone tools,” Reed said.

Study co-authors were Melissa Toups of Indiana University and Andrew Kitchen of The Pennsylvania State University, both previously with UF. Co-author Jessica Light of Texas A&M University was formerly a post-doctoral fellow at the Florida Museum. The researchers completed the project with the help of Reed’s NSF Faculty Early Career Development Award, which is granted to researchers who exemplify the teacher-researcher role.

- 30 -

Source: David Reed, 352-273-1971, dreed@flmnh.ufl.edu
Writer: Danielle Torrent, dtorrent@flmnh.ufl.eduMedia contact: Paul Ramey, 352-273-2054, pramey@flmnh.ufl.edu

The study, scheduled to appear in the Oct. 11 online edition of the Zoological Journal of the Linnean Society, describes the cranial anatomy of the extinct mammal, Labidolemur kayi. High resolution CT scans of the specimens allowed researchers to study minute details in the skull, including bone structures smaller than one-tenth of a millimeter. Similarities in bone features with other mammals show L. kayi’s living relatives are rodents, rabbits, flying lemurs, tree shrews and primates.

Researchers said the new information will aide future studies to better understand the origin of primates.

“The specimens are among the only skulls of apatemyids known that aren’t squashed completely flat,” said study co-author Jonathan Bloch, an associate curator of vertebrate paleontology at the Florida Museum of Natural History on the UF campus. “They’re preserved in three dimensions, which allows us to look at the morphology of the bones in a way that we never could before.”

Scientists have disputed the relationships of Apatemyidae, the family that includes L. kayi, for more than a century because of their unusual physical characteristics. With can opener-shaped upper front teeth and two unusually long fingers, apatemyids have been compared to a variety of animals, from opossums to woodpeckers.

“There are only a few examples in the history of mammals where you get such an incredibly odd ecological adaptation,” Bloch said.

Like a woodpecker’s method of feeding, L. kayi used percussive foraging, or tapping on trees, to locate insects. It stood less than a foot tall, was capable of jumping between trees and looked like a squirrel with a couple of really long fingers, similar to the aye-aye, a lemur native to Madagascar, Bloch said.

Apatemyids have been preserved for tens of millions of years and are well known from Europe and North America.

The skeletons analyzed in the publication were recovered from freshwater limestone in the Bighorn Basin by co-author Peter Houde of New Mexico State University. Located just east of Yellowstone National Park in Wyoming, the site is known as one of the best in the world for studying the evolution of mammals during the 10 million years following the extinction of the dinosaurs, Bloch said.

Mary Silcox, first author of the study and a research associate at the Florida Museum, said scans of the specimens began about 10 years ago, during her postdoctoral work at The Pennsylvania State University.

“It’s not like medical CT, it’s actually an industrial CT scanner,” said Silcox, an assistant professor of anthropology at the University of Toronto Scarborough. “Because this is a small animal, we needed to be able to study it at a very high resolution. The high resolution CT data were a critical part.”

Doug Boyer of Stony Brook University is also a co-author of the study, part of the team’s larger research to understand the relationships of apatemyids to other mammals. Bloch and colleagues are currently writing a detailed analysis of L. kayi’s skeleton.

John Wible, curator of mammals at the Carnegie Museum of Natural History and one of the researchers who reviewed the study, said it provides valuable information for understanding the evolutionary relationships of mammals.

“It is now clear that any assessment of the origins of primates in the future will have to include apatemyids,” Wible said. “Apatemyids are not some freakish dead-end, but significant members of our own history.”

- 30 -

Source: Jon Bloch, 352-273-1938, jbloch@flmnh.ufl.edu
Writer: Danielle Torrent, dtorrent@flmnh.ufl.edu
Media contact: Paul Ramey, 352-273-2054, pramey@flmnh.ufl.edu

The study, scheduled to appear in the December print edition of the Journal of Mammalian Evolution and now available online, describes a new species that evolved to half the size of its ancestors during this period of global warming.

The hyena-like animal, Palaeonictis wingi, evolved from the size of a bear to the size of a coyote during a 200,000-year period when Earth’s average temperature increased about 15 degrees Fahrenheit. Following this global warming event, Earth’s temperature cooled and the animal evolved to a larger size.

“We know that plant-eating mammals got smaller during the earliest Eocene when global warming occurred, possibly associated with elevated levels of carbon dioxide,” said lead author Stephen Chester, a Yale University doctoral student who began the research at UF with Jonathan Bloch, curator of vertebrate paleontology at the Florida Museum of Natural History. “Surprisingly, this study shows that the same thing happened in some carnivores, suggesting that other factors may have played a critical role in their evolution.”

Researchers discovered a nearly complete jaw from the animal in Wyoming’s Big Horn Basin in 2006 during a fossil-collecting expedition, led by Bloch, a co-author on the study. Bloch said the new findings could help scientists better understand the impact of current global warming.

“Documenting the impact of global climate change in the past is one of the only real experiments that can inform us about what the effects global warming might have on mammals in the near future,” said Bloch, who has studied this climate change event for nearly a decade.

Scientists think the Earth experienced increased levels of carbon dioxide and a drier environment during the warmer time period, but they do not completely understand what caused mammals to shrink.

One theory is that carbon dioxide levels reduced plant nutrients, causing herbivorous mammals to shrink. The newly described species primarily consumed meat, meaning plant nutrients couldn’t have been the only factor, Bloch said.

Mammals in warmer climates today tend to be smaller than mammals in colder climates, Chester said. For example, brown bears in Montana are generally smaller than those found in Alaska.

The study’s other authors are Ross Secord, assistant professor at the University of Nebraska, and Doug Boyer, assistant professor at Brooklyn College.

Bloch said a tooth from this animal was described in a paper about 20 years ago, but scientists did not have enough information to name the new species until finding the jaw.

The species was named after Scott Wing, a paleobotanist at the Smithsonian National Museum of Natural History. He studies the impact the global warming event had on forests in the past, and has played an important role in the collaborative research in the Big Horn Basin, Bloch said.

- 30 -

Source: Jon Bloch, 352-273-1938, jbloch@flmnh.ufl.edu
Stephen Chester, 352-222-2245, stephen.chester@yale.edu
Writer: Leeann Bright
Media contact: Paul Ramey, 352-273-2054, pramey@flmnh.ufl.edu

Reed, an associate curator of mammalogy at the Florida Museum, will use the five-year, $934,498 grant to trace the evolutionary history of lice, and he hopes the study will shed light on human migration, development and evolution.

“Parasitic lice have evolved alongside, but much faster than their human hosts,” Reed said. “The lice have given researchers a more detailed look at the process of species migration and evolution.”

The study also will analyze genetic similarities between the evolution of lice and humans as they have evolved over time. Reed said human and chimpanzee lice branched from a single evolutionary line at about the same time their hosts did and the study will use DNA sequencing data to more closely examine other similarities between the two types of lice.

The study will require samples from around the world, collected with the help of medical professionals. The grant also provides funding to support a postdoctoral fellow, two graduate students and up to 10 undergraduates, and includes a training program to teach UF graduate students how to communicate their research to lay audiences.

“Scientists often lack the skills needed to translate their technical research findings into information that is relevant to a broad public audience, “which is why we are creating this graduate opportunity,” Reed said. “Being able to employ both graduate and undergraduate students is a real benefit to the department and the university.”

The research opportunities will provide training in skills such as collecting specimens, working in the molecular lab and conducting genetic analysis, allowing students to enter the work force with specialized skills.

Human lice have been a nuisance for centuries. The rapid changes that make lice ideal candidates for a study centered on evolutionary processes also play havoc on everyday life among the general human population.

Head lice in school children, one common form of parasitic lice, have built a resistance to insecticidal shampoos in developed countries, which is why their numbers are increasing in the U.S. In underdeveloped countries where insecticidal treatments are not widely used, lice are still susceptible and easily controlled with existing medicines, Reed said.

The grant also includes the purchase of a high definition imaging system to document, compare and study specimens collected worldwide for the project.

The National Science Foundation is an independent federal agency created by Congress in 1950 and currently funds about 20 percent of all federally supported research at U.S. colleges and universities. NSF creates about 10,000 new awards each year including the Faculty Early Career Development Award, which is given to researchers who exemplify the teacher-researcher role.

- 30 -

Source: David Reed, 352-273-1971; 352-226-0976, dreed@flmnh.ufl.edu
Writer: Morgan Lamborn, mlamborn@flmnh.ufl.edu
Media contact: Paul Ramey, 352-273-2054, pramey@flmnh.ufl.edu

GAINESVILLE, Fla. — Researchers at the University of Florida and the University of Winnipeg have developed the first detailed images of a primitive primate brain, unexpectedly revealing that cousins of our earliest ancestors relied on smell more than sight.

The analysis of a well-preserved skull from 54 million years ago contradicts some common assumptions about brain structure and evolution in the first primates. The study also narrows the possibilities for what caused primates to evolve larger brain sizes. The study is scheduled to appear online the week of June 22 in the Proceedings of the National Academy of Sciences.

The skull belongs to a group of primitive primates known as Plesiadapiforms, which evolved in the 10 million years between the extinction of the dinosaurs and the first traceable ancestors of modern primates. The 1.5-inch-long skull was found fully intact, allowing researchers to make the first virtual mold of a primitive primate brain.

“Most explanations on the evolution of primate brains are based on data from living primates,” said lead author Mary Silcox, an anthropologist at the University of Winnipeg and research associate at UF’s Florida Museum of Natural History. “There have been all these inferences about what the brains of the earliest primates would look like, and it turns out that most of those inferences are wrong.”

Researchers used CT scans to take more than 1,200 cross-sectional X-ray images of the skull, which were combined into a 3-D model of the brain.

“A large and complex brain has long been regarded as one of the major steps that sets primates apart from the rest of mammals,” said Florida Museum vertebrate paleontologist and study co-author Jonathan Bloch. “At our very humble beginnings, we weren’t so special. That happened over tens of millions of years.”

The animal, Ignacius graybullianus, represents a side branch on the primate tree of life, Bloch said. “You can think of it as a cousin of the main line lineage that would have given rise ultimately to us.”

In previous research, Bloch and Silcox established that Plesiadapiforms were transitional species. Ignacius was similar to modern primates in terms of its diet and tree-dwelling but did not leap from tree to tree like modern fast-moving primates.

In many ways, the early primate behaved like living primates but with a brain that was one-half to two-thirds the size of the smallest modern primates. This means that factors such as tree-dwelling and fruit-eating can be eliminated as potential causes for primates evolving larger brain sizes, Silcox said, because “the smaller brained Ignacius was already doing those things.”

[EDITORS: STORY CAN END HERE]

The mold suggests a “startling combination” of features in the early primate that requires a rethinking of primate brain evolution, said Florida State University anthropologist Dean Falk, who was not involved in the study.

“Hypotheses about early primate brain evolution often link keen smell with nocturnal insect-eating, and a more recently evolved increase in visual processing with fruit-eating in arboreal habitats,” Falk said.

The move to larger brain size occurred during an evolutionary burst that happened 10 million years after the extinction of the dinosaurs. At that point, visual features in the brain became much more prominent while the olfactory bulbs became proportionately smaller.

More than likely, Bloch said, this change in brain structure and size was related to primates living in closed canopy forests that brought trees closer together and allowed for more leaping. But answering that will require the discovery and analysis of new fossils.

Changes in brain size and brain structure in the early stages of primate evolution have generated enormous debates for decades. But until now, fossil evidence has been lacking.

Many models of the ancestral primate brain are based on tree shrews, which come from southeast Asia and are distantly related to humans. But with some 70 million years of evolution between them and humans, “it turns out tree shrew brains are not a good model,” Silcox said.

- 30 -

Sources: Jonathan Bloch, 352-273-1938, jbloch@flmnh.ufl.edu
Mary Silcox, 204-782-5414, m.silcox@uwinnipeg.ca
Writer: Bill Kanapaux, bkanapaux@flmnh.ufl.edu
Media contact: Paul Ramey, 352-273-2054, pramey@flmnh.ufl.edu

GAINESVILLE, Fla. — A new University of Florida study shows mammals change their dietary niches based on climate-driven environmental changes, contradicting a common assumption that species maintain their niches despite global warming.

Led by Florida Museum of Natural History vertebrate paleontologist Larisa DeSantis, researchers examined fossil teeth from mammals at two sites representing different climates in Florida: a glacial period about 1.9 million years ago and a warmer, interglacial period about 1.3 million years ago. The researchers found that interglacial warming resulted in dramatic changes to the diets of animal groups at both sites. The study appears in the June 3 issue of PLoS ONE.

“When people are modeling future mammal distributions, they’re assuming that the niches of mammals today are going to be the same in the future,” DeSantis said. “That’s a huge assumption.”

Co-author Robert Feranec, curator of vertebrate paleontology at the New York State Museum, said scientists cannot predict what species will do based on their current ecology.

“The study definitively shows that climate change has an effect on ecosystems and mammals, and that the responses are much more complex than we might think,” Feranec said.

The two sites in the study, both on Florida’s Gulf Coast, have been excavated quite extensively, DeSantis said. During glacial periods, lower sea levels nearly doubled Florida’s width, compared with interglacial periods. But because of Florida’s low latitude, no ice sheets were present during the glacial period. Despite the lack of glaciers in Florida, the two sites show dramatic ecological changes occurred between the two periods.

Both sites include some of the same animal groups, allowing DeSantis, Feranec and Bruce MacFadden, Florida Museum curator of vertebrate paleontology, to clarify how mammals and their environments responded to interglacial warming.

The research examined carbon and oxygen isotopes within tooth enamel to understand the diets of medium to large mammals, including pronghorn, deer, llamas, peccaries, tapirs, horses, mastodons, mammoths and gomphotheres, a group of extinct elephant-like animals.

Differences in how plants photosynthesize give them distinct carbon isotope ratios. For example, trees and shrubs process carbon dioxide differently than warm-season grasses, resulting in different carbon isotope ratios. These differences are incorporated in mammalian tooth enamel, allowing scientists to determine the diets of fossil mammals. Lower ratio values suggest a browsing diet (trees and shrubs) while a higher ratio suggests a grazing diet (grasses).

Animals at the glacial site were predominantly browsing on trees and shrubs, while some of those same animals at the warmer interglacial site became mixed feeders that also grazed on grasses. Increased consumption of grasses by mixed feeders and elephant-like mammals indicates Florida’s grasslands likely expanded during interglacial periods.

Tooth enamel locks in the chemical signatures of the plants and water an animal consumes, allowing paleontologists to understand the diets and associated climate of fossil specimens that are millions of years old. To find these signatures, researchers run samples of tooth enamel through a mass spectrometer.

DeSantis and her collaborators analyzed enamel samples from 115 fossil teeth. For two of the specimens she took serial samples, small samples that run perpendicular to the growth axis and give insight into how the diet and climate changed over a specific period of time.

“That’s one of the cool things about using mammal teeth,” she said. “We can actually look at how variable the climate was within a year, millions of years ago.”

The study highlights the importance of the fossil record in understanding long-term ecological responses to changes over time, DeSantis said. While ecological studies of modern impacts can cover only limited spans of time, “this study emphasizes the importance of using the fossil record to look at how mammals and other animals responded to climate change in the past, also helping us gain a better understanding of how they might respond in the future.”

- 30 -

Source: Larisa DeSantis, 203-494-0442, larisa.desantis@gmail.com
Writer: Bill Kanapaux, bkanapaux@flmnh.ufl.edu
Media contact: Paul Ramey, 352-273-2054, pramey@flmnh.ufl.edu

“It’s kind of quirky that a parasite we love to hate can actually inform us how we traveled around the globe,” said David Reed, an assistant curator of mammals at the Florida Museum of Natural History on the UF campus and one of the study’s authors.

DNA sequencing found the strain of lice to be genetically the same as the form of body lice that spawns several deadly diseases, including typhus, which was blamed for the loss of Napoleon’s grand army and millions of other soldiers, he said.

The discovery of these parasites on 11th-century Peruvian mummies proves they were infesting the native Americans nearly 500 years before Europeans arrived, Reed said. His findings are published this week in an online edition of the Journal of Infectious Diseases.

“This definitely goes against the grain of conventional thought that all diseases were transmitted from the Old World to the New World at the time of Columbus,” he said.

It came as a surprise to Reed and his research team that the type of lice on the mummies was of the same genetic type as those found as far away as the highlands of Papua, New Guinea, instead of the form of head lice that is widespread in the Western Hemisphere, Reed said. This latter version, the bane of many school children, accounts for more than half the cases of lice that appear in the United States, Canada and Central America, he said.

“Given its abundance in the Americas on living humans, we thought for sure that this form of lice was the one that was here all along and had been established in the New World with the first peoples,” he said.

“We hope to be able to understand human migration patterns by investigating their parasites since people have carried these parasites with them as they moved around the globe,” he said. “Called a parascript, it’s a whole other transcript of our evolutionary history that can either add to what we know or in some cases inform us about things we didn’t know.”

Looking at evidence from parasites’ perspectives, for example, may yield valuable clues about when the first Americans arrived on the continent and which route they took, Reed said. Building upon this DNA sequencing work, scientists may be able to link the 1,000-year-old lice found in the Western Hemisphere with those in Siberia or Mongolia, confirming existing theories that America’s earliest residents originated there, he said.

Had these immigrants traveled by land masses, there was a very small window of time, about 13,000 years ago, when the glaciers retreated enough to allow passage through the Bering Strait on the way to South America, Reed said. Another proposed theory is a seafaring route, but this would have required sophisticated oceangoing vessels for which no evidence from the time exists, he said.

Being able to chart these early migration patterns would give insight into how these early immigrants lived, Reed said. “If you’re skirting the edge of glaciers, it’s obviously a very cold time period and humans would have needed certain creature comforts just to stay alive, such as tight clothing to maintain warmth,” he said.

Today, the people who don’t have the opportunity to change their clothes are the ones at risk for epidemic typhus, which along with the lesser-known diseases of relapsing fever and trench fever are carried by body lice, Reed said. These pests lay their eggs in clothing fibers and washing the clothes is all it takes to get rid of them, he said.

“The disease pops up primarily in refugees who have been displaced from their homeland with the clothes on their backs and nothing else,” he said. “They’re living in crowded conditions where hygiene is poor.”

Reed said he hopes the team’s lice research might someday increase human understanding of typhus by pinpointing where the disease originated.

Studying parasites to learn about their hosts’ history has been around for only about 20 years, Reed said. “By looking at things like tapeworms, pinworms, lice or bedbugs that humans have carried around for at least tens of thousands of years, and in some cases millions of years,” he said, “we can learn much more about human evolutionary history.”

Writer: Cathy Keen, 352-392-0186, ckeen@ufl.edu
Media Contact: Paul Ramey, 352-273-2054, pramey@flmnh.ufl.edu
Source: David Reed, 352-273-1971, dreed@flmnh.ufl.edu

Rather than close encounters of the intimate kind, humans most likely got the gorilla’s lice from sleeping in their nests or eating the giant apes, said David Reed, assistant curator of mammals at the Florida Museum of Natural History on the University of Florida campus, one of the study’s authors. The research is published in the current edition of the BMC Biology journal.

“It certainly wouldn’t have to be what many people are going to immediately assume it might have been, and that is sexual intercourse occurring between humans and gorillas,” he said. “Instead of something sordid, it could easily have stemmed from an activity that was considerably more tame.”

About 3.3 million years ago, lice found on gorillas began to infest humans, Reed said. That they took up residence in the pubic region may have coincided with humans’ loss of hair on the rest of their bodies and the lack of any other suitable niche, he said.

Reed and his co-workers’ research stemmed from their fascination with humans’ unique position among primates in being host to two different kinds of lice: one on the head and body (Pediculus), which has become the bane of many schoolchildren, and pubic or crab lice (Pthirus). In contrast, chimps have only head lice and gorillas pubic lice.

Understanding the history of lice is important because the tiny insects give clues about the lifestyles of early hominids and evolution of modern humans, Reed said. Because the human fossil record is patchy and finding early DNA samples is extremely difficult, parasites such as head lice, pubic lice, tapeworms and pinworms that have existed for millions of years provide valuable clues, he said.

“These lice really give us the potential to learn how humans evolved when so many parts of our evolutionary history are obscure,” he said. Lice also can serve as a model in understanding how parasites move from one species to another, Reed said.

“If you look at emerging infectious diseases that affect humans all over the world, most have their origins on some other host before threatening humans,” he said. “Studying what it takes for a parasite to be successful in switching hosts adds to our knowledge about what makes a good host for the spread of disease.”

Working with other scientists who collected lice from primates in Ugandan wildlife sanctuaries, the research team extracted DNA from the lice and used fossil data from humans and gorillas to estimate how long ago these two types of lice shared a common ancestor. In particular, the researchers looked at whether pubic lice developed on their own in humans or whether humans acquired them from gorillas. They believed humans were more likely to have had lice all along because this was a simpler explanation than acquiring lice from gorillas, but they were proved wrong.

It is not unusual for lice to switch hosts, with this occurring in both birds and mammals, Reed said. Lice that lived on the passenger pigeon before it became extinct persist today because they switched to another species of pigeon, he said.

Lice need either direct physical contact or very recent contact to switch hosts, Reed said. In this specific case, the parasite might have been transmitted to humans sleeping in a depression in the ground where a gorilla had slept and nested the night before or even by humans feeding on gorillas, he said.

“Unfortunately, even today among modern humans there’s a bush meat trade where gorillas are killed for their meat,” he said. “If archaic humans were butchering or scavenging those animals 3.3 million years ago, it would be a simple thing to transfer those lice from prey to predator.

“Because humans and gorillas are so closely related and have so many potential interactions of a nonsexual nature, it would have been less likely for the lice to have been transmitted through sexual intercourse, he said.

Reed did the study with postdoctoral researcher Jessica Light at the Florida Museum of Natural History and zoology graduate students Julie Allen and Jeremy Kirchman.

“This paper makes one’s imagination run wild, giving graphic new meaning to that ’800 pound gorilla,’” said Dale Clayton, a University of Utah biology professor. “However, as the authors point out, the inferred host switch of pubic lice from gorillas to humans did not require sexual contact. Human pubic or ‘crab’ lice get transmitted between people on bath towels all the time. So it is easy to imagine that gorilla lice could have transmitted to humans via shared sleeping quarters, or predation, as the authors suggest.”

Contact: Paul Ramey, pramey@flmnh.ufl.edu
Writer: Christine Eschenfelder