Predation Linked To Evolution, Study Suggests

Source:	Virginia Tech
Date:	September 14, 2007

science Daily.... The fossil record seems to indicate that the diversity of marine creatures increased and decreased over hundreds of millions of years in step with predator-prey encounters, Virginia Tech geoscientists report in the Proceedings of the National Academy of Science.

For decades, there has been a debate between paleontologists, biologists, and ecologists on the role of ecological interactions, such as predation, in the long term patterns of animal evolution.

John Warren Huntley, a postdoctoral scientist in the Department of Geosciences at Virginia Tech, and Geosciences Professor Micha³ Kowalewski decided to look at the importance of ecology by surveying the literature for incidents of predation in marine invertebrates, such as clams and their relatives.

"Today, certain predators leave easy to identify marks on the shells of their prey, such as clean, round holes," said Huntley. "Such holes drilled by predators can also be found in fossil shells."

The researchers also looked for repair scars on the shells of creatures that survived an attack.

The study was conducted by looking at studies which reported the frequency of drill holes and repair scars in fossil species from the last 550 million years.

First Huntley and Kowalewski found that predation increased notably about 480 million years ago, some 50 million years earlier than previous studies have found. "The earlier studies were based on changes in morphology -- predators with stronger claws and jaws and prey with more ornamented shells. We looked at the frequency of attacks, which increased about 50 million years before the changes in armor," said Huntley.

But the most notable discovery is the observation that the incidence of drill holes and repair scars are strikingly parallel to Sepkoski's diversity curve for marine invertebrates. This diversity curve, compiled by the late Jack Sepkoski of the University of Chicago, records the origination and extinction of marine animal genera through the last 540 million years (Phanerozoic). "There is a strong correlation between predation intensity and global marine biodiversity in the Phanerozoic," Huntley said.

In their article, "Strong Coupling of Predation Intensity and Diversity in the Phanerozoic Fossil Record," the researchers offer three rival hypotheses to explain the correlation. "It's the classic problem with interpreting a correlation," said Huntley "you have to be careful when ascribing a cause. Let's say factors X and Y are correlated. A change in X could cause a change in Y, a change in Y could cause a change in X, or X and Y could both be controlled by another factor."

The first hypothesis is that predation intensity could be driving diversity. "In this case, ecological interactions would matter in evolution," said Huntley. "Organisms evolve over the long term in response to their enemies, and with increased predation intensity more species evolve."

The second hypothesis is that as biodiversity increased, by chance predators with more complex feeding strategies evolved. "Predatory techniques like drilling and peeling shells are more evolutionarily-derived than more primitive forms of predation like whole ingestion. In this scenario you would expect to evolve sophisticated forms of predation only when diversity is high," said Huntley.

And the third hypothesis is that something else is driving both predation and biodiversity. "Some periods have more sedimentary rocks, and therefore more fossils, preserved than others," said Huntley. "There is less diversity to be observed when there are fewer fossils to study. Perhaps this sampling bias affects our ability to find samples with high predation intensities as well."

"Now we will try to pick this apart," said Huntley. "We can test these hypotheses by examining relevant linkages between predation intensity and diversity in modern oceanic environments. Also, understanding the true nature of Sepkoski's curve will help us interpret our findings. Is it biological? Is it the product of uneven sampling?"

Note: This story has been adapted from a news release issued by Virginia Tech.

Fossil Whale Puts Limit On Origin Of Oily, Buoyant Bones In Whales

Source: University of California - Berkeley
Date: September 14, 2007


Science Daily.... A fossilized whale skeleton excavated 20 years ago amid the stench and noise of a seabird and elephant seal rookery on California's Año Nuevo Island turns out to be the youngest example on the Pacific coast of a fossil whale fall and the first in California, according to University of California, Berkeley, paleontologists.

Whale falls, first recognized in the 1980s, are whale carcasses that fall to the deep-ocean floor where, like an oasis in the desert, they attract a specialized group of clams, crabs and worms that feed for up to decades on the oil-rich bones and tissues.

Some scientists think these random, deep-ocean oases are stepping stones for organisms moving from one ocean floor environment to another - whether a hot vent, a cold seep or a whale carcass - in search of sustenance from energy-rich chemicals.

"The fossil whale fall shows that these deep-sea communities didn't need especially large whales as a source of nutrients - in fact, the fossil whale from Año Nuevo Island was no longer than a VW bug," said Nick Pyenson, a graduate student in UC Berkeley's Department of Integrative Biology.

Pyenson and museum scientist David M. Haasl, both of UC Berkeley's Museum of Paleontology, recently published their findings in the journal Biology Letters.

The Año Nuevo skeleton, discovered in 1987 by then-UC Santa Cruz graduate student Brian Fadely and excavated by Graham Worthy and local fossil expert Frank Perry, was considered a rather small and unremarkable fossil whale - at 11 feet, it was less than half the size of today's smallest baleen whales. The bones, including skull, spine and ribs, were displayed at Long Marine Laboratory in Santa Cruz until the lab donated the partially articulated skeleton to the Museum of Paleontology in 2005.

As Pyenson prepared it for the museum's collection, however, he noticed small clams in the nooks and crannies of the skull. He found 21 clams in all, each less than a centimeter in length, or two-fifths of an inch, plus one snail. Most of these organisms were on the skull, but some were nestled in the vertebrae. Haasl, a mollusk expert, thought the clams might be similar to those that cluster around whale falls today and that are able to extract energy from chemicals in bones with the help of specialized symbiotic bacteria. At whale fall depths of more than 1,000 meters, there is no light for photosynthesis.

Based on the shape of the fossil clam shells attached to the whale skeleton, Pyenson and Haasl determined that they belong to the same group of mollusks whose living relatives are chemosynthetic, confirming their initial hypothesis that this was a whale fall. A visit by Pyenson and Haasl to Año Nuevo Island in January 2007 showed that the whale came from 15 million-year-old sediments, the Monterey Formation, making the Año Nuevo find much younger than most fossil whale falls discovered around the globe, the oldest of which date from 40 million years ago, Pyenson said.

Whale falls were unknown to science until 1989, when the first example of a deep-sea community living on recently deceased whale carcasses was reported from southern California.

"The ocean floor is pretty much a desert until you get a whole whale carcass sinking to the bottom," Pyenson said. "We don't know how these creatures know to colonize it. Are they ever-present on the sea floor waiting for an animal to fall? But when the whale carcass hits, it forms this island refuge of high nutrient levels that can sustain an undersea community, some scientists calculate, for decades."

Over the past 18 years, more whale falls have been found around the world, and paleontologists have found examples in the fossil record as well. Most fossil examples, however, consist of isolated bones adjacent to deep-sea mollusks, Pyenson said. Little is known about the size or identity of the whale host.

In contrast, the Año Nuevo skeleton was unusually complete and hosted multiple mollusks. It also was small, which suggested to Pyenson that these specialized deep-sea communities didn't need large whale carcasses to evolve. Previous researchers had hypothesized that whale-fall communities evolved with the origin of large baleen whales, such as blue whales, and oil-rich bones. Pyenson and Haasl proposed instead that the oil content of the whale's bones was the more crucial factor.

"What we have are relatives of modern chemosynthetic clams associated directly with the skeleton of a tiny, tiny whale, smaller than any other known from modern whale falls," Pyenson said. "That tells us that you don't need very large whales to sustain a whale fall, but what you probably need is a really oily skeleton."

Because they are more buoyant, oil-rich bones are likely one adaptation to allow deep diving, Pyenson said. The Año Nuevo whale fall find puts a lower limit of 11 million years on the origin of oily bones in whales, he added.

Pyenson and Haasl are currently working with scientists at the Monterey Bay Aquarium Research Institute who routinely study recent whale falls in Monterey Bay. They hope to do "side-by-side comparisons of the fossil and modern whale-fall clam shells" to better characterize those from the fossil whale fall.

The work was supported by funds from the UC Museum of Paleontology and a fellowship to Pyenson from the National Science Foundation.

Note: This story has been adapted from a news release issued by University of California - Berkeley.

New Evidence On The Role Of Climate In Neanderthal Extinction

Source: University of Leeds
Date: September 13, 2007


Science Daily... The mystery of what killed the Neanderthals has moved a step closer to resolution after an international study led by the University of Leeds has ruled out one of the competing theories -- catastrophic climate change -- as the most likely cause.

The bones of more than 400 Neanderthals have been found since the first discoveries were made in the early 19th century. The finds suggest the Neanderthals, named after the Neander Valley near Düsseldorf, where they were first recognized as an extinct kind of archaic humans, inhabited Europe and parts of western Asia for more than 100,000 years.

The causes of their extinction have puzzled scientists for years -- with some believing it was due to competition with modern humans, while others blamed deteriorating climatic conditions. But a new study recently published in Nature has shown that the Neanderthal extinction did not coincide with any of the extreme climate events that punctuated the last glacial period.

The research was led by Professor Chronis Tzedakis, a palaeoecologist at the University of Leeds, who explained: "Until now, there have been three limitations to understanding the role of climate in the Neanderthal extinction: uncertainty over the exact timing of their disappearance; uncertainties in converting radiocarbon dates to actual calendar years; and the chronological imprecision of the ancient climate record."

The team's novel method -- mapping radiocarbon dates of interest directly onto a well-dated palaeoclimate archive -- circumvented the last two problems, providing a much more detailed picture of the climate at the possible times of the Neanderthal disappearance.

The researchers applied the new method to three alternative sets of dates for the timing of the Neanderthal extinction from Gorham's Cave, Gibraltar, a site which is thought to have been occupied by some of the latest surviving Neanderthals:

• a set of generally accepted but older dates (around 30-32,000 radiocarbon years ago)
• newly-suggested younger dates (around 28,000 radiocarbon years ago)
• more contentious dates (around 24,000 radiocarbon years ago).

The team showed that during the first two sets of dates, Europe was experiencing conditions similar to the general climatic instability of the last glacial period -- conditions the Neanderthals had already proved able to survive.

The much more controversial date of around 24,000 radiocarbon years ago placed the last Neanderthals just before a large expansion of ice sheets and the onset of cold conditions in northern Europe. "But at that time, Gibraltar's climate remained relatively unaffected, perhaps as a result of warm water from the subtropical Atlantic entering the western Mediterranean," explained palaeoceanographer Isabel Cacho of the University of Barcelona.

"Our findings suggest that there was no single climatic event that caused the extinction of the Neanderthals," concludes palaeonthropologist Katerina Harvati of the Max Planck Institute for Evolutionary Anthropology. "Only the controversial date of 24,000 radiocarbon years for their disappearance, if proven correct, coincides with a major environmental shift. Even in this case, however, the role of climate would have been indirect, by promoting competition with other human groups."

The work also has wider implications for other studies, as paleoclimatologist Konrad Hughen of the Woods Hole Oceanographic Institution explained: "Our approach offers the huge potential to unravel the role of climate in critical events of the recent fossil record as it can be applied to any radiocarbon date from any deposit."

The article Placing late Neanderthals in a climatic context (Tzedakis, P.C., Hughen, K.A., Cacho, I. & Harvati, K) is published in Nature on September 13. The study was conducted by Chronis Tzedakis (University of Leeds); Konrad Hughen (Woods Hole Oceanographic Institution); Isabel Cacho (University of Barcelona); Katerina Harvati (Max Planck Institute for Evolutionary Anthropology).

Note: This story has been adapted from a news release issued by University of Leeds.

Bog Mummies Yield Secrets

Source: North Dakota State University
Date: September 10, 2007



Science Daily.... Human remains yield secrets. Researchers, including Dr. Heather Gill-Robinson, assistant professor of anthropology at North Dakota State University, are now probing the secrets of 'bog mummies' some dating back 2000 years, preserved from the Iron Age with amazing detail in peat bogs of Europe.

Bog mummies have particularly interesting stories to tell. Physical anthropologists draw conclusions from the eerily preserved hair, leathery skin and other features that emerge from the bogs.

During the Iron Age from approximately 500BC to 500AD, bodies were often cremated, often leading experts to believe that mummies uniquely preserved by the bogs were people who met their demise through particularly violent means or were used as sacrifices, although there are numerous possible other explanations. A violent demise was thought to be the case for a mummy known as Windeby Girl, studied by Dr. Gill-Robinson. Discovered in northern Germany in 1952, experts thought she may have been an adulteress whose head was shaved, after which she was blindfolded and drowned in the bog.

But, on closer inspection, Heather Gill-Robinson of North Dakota State University determined that the Windeby Girl was actually more likely to have been a young man. He may have lost his hair when archaeologists’ trowels dug up the body. Physical examination of the mummy showed that growth interruptions in the bones of the specimen indicated a sick young man who may have died from natural causes.

The water and other substances in peat bogs create a natural preservative for the bodies found in them, though Dr. Gill-Robinson says researchers are still trying to determine why. The lack of oxygen, antimicrobial action and the sphagnum found in bogs seem to conspire to preserve the bodies tossed into them thousands of years ago. Bogs were once seen as homes for gods and outcast spirits.

But increasingly sophisticated computer programs and use of medical technology such as CT scans, radiocarbon dating and 3-D imaging have resulted in additional and potentially more accurate answers to the mysteries of the peat bog mummies. In her research, which includes the study of other mummies in addition to “Windeby Girl,” Gill-Robinson can also determine other details such as what they ate and their possible occupations.

The research being conducted at NDSU also gives students an opportunity to learn more about physical anthropology, according to Gill-Robinson. Two recent NDSU graduates, for example, analyzed CT scans of mummy specimens for a year and four more students are involved in image analysis projects this year. The mummies studied in Gill-Robinson’s research were found between 1871 and 1960. She has studied them for the past four years.

“Detailed analysis of the bog bodies provides us a window into cultures, heritage and the way people lived thousands of years ago,” says Gill-Robinson. “When we think we may have discovered something new about a mummy, we can re-visit it several years later and with new technology, refine our research results. In these cases, we need to present a revised interpretation to the public. Communities where discoveries are made have a high level of interest in what is found. Respectfully addressing folklore surrounding such discoveries in communities also plays a role.”

Gill-Robinson’s areas of research interest have focused on a collection of seven bodies (six mummies and one skeleton) from peat bogs in northern Germany. After a receiving a three-month research grant from the German Academic Exchange Service, Bonn, Germany, Gill-Robinson spent the summer exploring aspects of peat bog mummies in conjunction with Stiftung Schleswig-Holsteinische Landesmuseen Schloss Gottorf, a museum in Schleswig, Germany. Her research was included in a recent National Geographic article in September of 2007 and previously cited in the article, “Rehabilitation of a Moorland Corpse,” in Abenteuer Archaeologie, a German popular press archaeology magazine.

Note: This story has been adapted from a news release issued by North Dakota State University.

Ancient 'Escape Tunnel' Discovered In Israel

Source: Israel Antiquities Authority
Date: September 10, 2007

Science daily.... In excavations the Israel Antiquities Authority is conducting in the City of David in order to expose the main road of Jerusalem from the time of the Second Temple period, the city’s main drainage channel was discovered. According to the writings of Josephus Flavius, the residents of the city fled to this channel at the time of the revolt in order to hide from the Romans.

In excavations the Israel Antiquities Authority is jointly carrying out with the Elad Association in the Walls around Jerusalem National Park, approximately 70 meters of Jerusalem’s main drainage channel from the time of the Second Temple period have been exposed so far. The channel is located along the route from the Temple Mount to the Shiloah Pool. The channel, which passes beneath the main road of the city and apparently continues to Nahal Kidron on its way to the Dead Sea, drained the rainfall of ancient Jerusalem; the Jewish quarter, the western region of the City of David and the Temple Mount.

The channel is built of ashlar stones and is covered with heavy stone slabs that are actually the paving stones of the street. In some places the channel reaches a height of about 3 meters and is one meter wide, so that it is possible to walk in it comfortably.

According to the excavation directors, Professor Ronny Reich of the University of Haifa and Eli Shukron of the Israel Antiquities Authority, in the last two thousand years the valley has become blocked with thick layers of alluvium and collapse. Therefore the Israel Antiquities Authority was asked to excavate some 10 meters for the purpose of uncovering the main road of Jerusalem and the channel below it.

“There is evidence in the writings of Josephus Flavius, the historian who described the revolt, the conquest and the destruction of Jerusalem, that numerous people took shelter in the channel and even lived in it for a period until they succeeded to flee the city through its southern end”, they added.

Pottery shards, fragments of vessels, and coins from the end of the Second Temple period, prior to the destruction of Jerusalem by the Romans in the year 70 CE, were discovered inside the channel.

The northern part of the channel, which is still unexcavated, apparently reaches the area of the Western Wall where in the past a large drainage channel was found that is the continuation of the channel that was exposed in the southern part of the City of David. The construction of the channel is characterized by its advanced technology. The further south one goes in the channel the deeper it is below the surface level so as to allow the rainwater to flow to Nahal Kidron.

Note: This story has been adapted from a news release issued by Israel Antiquities Authority.

Physics Reveals The Secrets Of Saint Francis

Source: Istituto Nazionale di Fisica Nucleare
Date: September 11, 2007


Science Daily....The tunic believed to have been worn by Saint Francis of Assisi preserved in the Church of Saint Francis in Cortona (Province of Arezzo) dates back to the period in which the saint lived, whereas the tunic preserved in the Church of Santa Croce in Florence was made after his death.

Carbon 14 measurements, which allow a relic to be dated, show that the tunic in Santa Croce dates back to some time between the late 13th century and late 14th century and thus could not have belonged to the “Poor Man of Assisi”, who died in 1226. These and other discovers were made possible through the analysis of the relics with a tandem particle accelerator, which was performed by the Laboratory of Nuclear Techniques for Cultural Heritage (LABEC) of the INFN of Florence.

The results of the study were presented in Florence at the European Conference on Accelerators in Applied Research and Technology (ECAART) and will be published in the volume “L’eredità del Padre: le reliquie di San Francesco a Cortona” (which will be released in a few weeks by Edizioni Messaggero di Sant’Antonio). The volume will include the complete results of an interdisciplinary investigation which included both scientific and humanist research and which was promoted by the Tuscany Province Chapter of the Franciscan Order “Friars Minor Conventual”.

The analyses were conducted with a radiocarbon method, measuring the radiocarbon using Accelerator Mass Spectrometry (AMS). From each tunic, researchers took from 5 to 7 samples of fabric, each of which was smaller than one square centimetre and weighed around 10 milligrams. Multiple samples were taken to avoid doubts or ambiguities (due to, for example, the presence of patches that were added to the tunic at a later time), thus increasing the analysis’ validity.

Each sample of wool was then treated so as to extract only the carbon, obtaining a small graphite pellet weighing about 0.8 milligrams. The pellet was then placed in the accelerator’s chamber, where it was exposed to a beam of cesium ions, “scratching” the pellet’s surface and extracting carbon isotopes 12, 13, and 14. The accelerator used by the INFN separately measured the quantity of the three isotopes. Relics are dated by calculating the ratio of carbon 14 to carbon 12, the quantities of which are “counted” in the accelerator’s detectors. Both great delicacy and exceptional sensitivity are required for taking these measurements; in fact, the ratio of carbon 14 to carbon 12 is only around one to one trillion, or even lower.

The analysis of the tunic preserved in the Basilica of Santa Croce in Florence showed that it dates back to a period between the end of the 1200s and the end of the 1300s, revealing that it was made at least 80 years after Saint Francis’ death and thus could not have belonged to him.

By contrast, the dates of all of the fragments taken from the tunic in the church in Cortona coincide with the period of Saint Francis’ life (the average results show that the tunic was made between 1155 and 1225). The tunic is one of three Franciscan relics, which also include a finely embroidered cushion and a book of gospels believed to have been brought to Cortona by Friar Elia, Saint Francis’ first successor as leader of the order.

LABEC researchers also analysed the composition of the precious metal thread used to embroider the cover of the cushion on which the Saint’s head was placed upon his death, and they used the carbon 14 method to date the fabric of the cushion itself. Moreover, the book of gospels was subjected to in-depth codicological and paleographic investigations by researchers at the University of Siena. Based on both the scientific evidence and humanistic research, the cushion and the book of gospels were also found to date back to the period in which Saint Francis lived.

Note: This story has been adapted from a news release issued by Istituto Nazionale di Fisica Nucleare.

Ancient Human DNA Extracted From Yucca Leaves Spat Out

Source: Harvard University


Science Daily In a groundbreaking study, two Harvard scientists have for the first time extracted human DNA from ancient artifacts. The work potentially opens up a new universe of sources for ancient genetic material, which is used to map human migrations in prehistoric times.

Before this, archaeologists could only get ancient DNA from relics of the human body itself, including prehistoric teeth, bones, fossilized feces, or — rarely — preserved flesh. Such sources of DNA are hard to find, poorly preserved, or unavailable because of cultural and legal barriers.

By contrast, the genetic material used in the Harvard study came from two types of artifacts — 800 to 2,400 years old — that are found by the hundreds at archaeological sites in the American Southwest.

“Quids” — small fibrous bundles of stripped yucca leaves — are the spit-out remnants of a kind of ancient chewing gum. Cells from long-dried saliva yield usable DNA. And “aprons” were thong-like woven garments worn by women. They are stained with traces of apparent menstrual blood, a source of DNA.

The Harvard study, featured in the summer 2007 issue of the Journal of Field Archaeology, “opens up the possibility of utilizing a much larger variety of human-handled artifacts” for DNA evidence, said project co-director Steven LeBlanc, director of collections at Harvard’s Peabody Museum of Archaeology and Ethnology.

Among the likely future sources of ancient DNA, he said, are “sandals, textiles, and cane cigarettes,” a reedlike smoke favored by early humans. LeBlanc’s co-director in the project was Thomas Benjamin, a professor of pathology at Harvard Medical School.

LeBlanc and others sampled 48 quids from four Southwestern archaeological sites — some of them on Harvard museum shelves for nearly 100 years — and 18 aprons found in Canyon de Chelly, a National Park Service site in Arizona still occupied by the Navajo Nation.

Aprons, and especially quids, are very common in archaeological collections, and are recovered from rock shelters or caves in the Southwest, Utah, Texas, California, and central Mexico. The DNA is preserved by the extreme dryness of such sites.

The Harvard study brings other good news for historians of ancient times. LeBlanc said the DNA captured from quids and aprons shows — in a preliminary way — that early farming populations in the Southwest descended from farmers in what is now central Mexico. That helps answer an old question among those who study the ancient Southwest: Was the idea of farming imported, or was it adopted by indigenous populations?

More broadly, archaeologists interested in migration patterns anywhere now have a new source for the DNA that can be used to track the movement of ancient people — though LeBlanc cautioned that the methods have to be retested and refined.

The origins of the earliest North American farmers are still officially a puzzle, and center on a now-lost tribe known as the Western Basketmakers. More than 2,000 years ago, these indigenous Americans started growing corn in what is now southeastern Utah and northern Arizona.

In what is now a boon to archaeologists who look at DNA, early farmers rested in the shade of rock formations, and spit out quids of chewed yucca leaves.

“The team was as surprised as everyone else that we could learn something about a possible migration over 2,000 years ago from ancient spit,” said LeBlanc. “Every artifact that we recover from such ancient sites now needs to be thought of in a new light, and handled in new ways, to ensure we preserve this DNA for future studies.”

To make sure the DNA was from ancient farmers and not from modern handlers, samples were taken from the cores of the quids and not from their surfaces.

Peabody Museum experts say future studies of ancient DNA from quids, aprons, and other appropriate artifacts are needed to test and refine Harvard’s preliminary findings.

The study was a collaborative project. Harvard researchers worked with genetic anthropologist Shawn W. Carlyle at the University of Utah; pathologist Lori S. Cobb Kreisman at Case Western Reserve University School of Medicine; curator Anna N. Dhody at the Mütter Museum at the College of Physicians of Philadelphia; anthropologist Brian M. Kemp at Vanderbilt University; and Francis E. Smiley, an anthropologist at Northern Arizona University. Ancient DNA expert David Glenn Smith offered his advice and the use of his laboratory at the University of California, Davis.

Some of the artifacts used in the DNA analysis were from collections at the Brooklyn Museum of Art, the Southwest Museum, and Northern Arizona University.

The study was supported by the Provost’s Fund for Interfaculty Collaboration at Harvard University and by the Peabody Museum of Archaeology and Ethnology.

Note: This story has been adapted from a news release issued by Harvard University.

Note: This story has been adapted from a news release issued by Harvard University.