Wednesday March 23, 2005 * news@michigandaily. corn rIe Stdriga Ng SCIENCE 5 . . THE DEATH OF A MASTODON Prof claims the recently excavated tusk of the Ice Age mammal reveals that human hunting caused its extinction By Scott Siglin For the Daily s it time to add yet another species to the list of human-caused extinction? Mastodons, a once free- ly roaming wooly mammoth-like mammal that lived during the Ice Age, have been extinct for more than 10,00 years --an extinction that many scientists the- orize was due to massive climate change. But some say their tusks prove otherwise. Daniel Fisher, Curator of Paleontology at the Universi- ty's Exhibit Museum of Natural History, said that by examining recently excavated mast- odon tusks, he believes that human-hunting instead of climate change played the primary role in their extinction. x As part of the Natural History museum's series of titled "Mast- odons and the Ice Age," Fisher, ASHLEY HARPER/Daily The head of a fossil- ized male mastodon in the Exhibit Museum of Natu- ral History. The ice Age mam- mal dates back to more than 10,000 years ago. who is also a professor of geology, will present his findings in a lecture on May 20. Fisher is currently researching the extinction of these elephant- like creatures by studying the tusks of a mastodon that was recently found in Fort Wayne, Ind. Mastodons were common in the Great Lakes area and recently became the state fos- of the bones sil of Michigan. The mastodon found in Indiana will be shown can show a in the exhibition in May. The results of Fisher's record of the research rely on the dissec- lie tion of the tusks. The interior animals life of the bones can show a record of the animal's life and provide and provide a a vast array of information of vast aray of the animal and its surrounding environment. information on Mastodon tusks grow throughout the animal's life the animal. and are very responsive to changes in the animal, Fisher said. Growing up to nine feet in length for males, the tusks are very similar to human teeth except they have no enamel coating. But Fisher said what makes the tusks grow in a fascinating way is that they resemble ice cream cones stacked on top of each other with a hollow center where blood vessels and nerves were. Due to the special growth pattern of the tusks, a cross-sectional picture of the bones is strikingly analogous to a cross sectional view of a tree; both grow by forming concentric circles around the previous circle. The sections of the tusk are grown in 14-day increments, although Fisher said it was also common for mastodons to only take a few days or even one night to a grow a new section to the bone in their tusks. "By analyzing material (in the tusk) that year, we can determine the diet, climate, reproductive and health status of the animal," Fisher said. Fisher examines the tusk by subjecting the material of the tusk to various experimental procedures, such as filing down and grind- ing. These samples can then be used to examine certain minerals and vitamins that could be present in the tusk. Calcium levels can indicate bone growth in a certain period, which could have possibly been a result of increased eating. By researching the maturation of Mastodons, Fisher said he has not only compiled more evidence against the climate theory, but also evidence that supports the second theory of their extinction, in which humans killed off the mastodons through hunting. Accord- ing to the results from the tusk, the Mastodon that he examined matured much earlier in life, Fisher said, evidence in support of the human-hunting extinction theory. "Increased predation would lead the animal to reproduce earlier in life, therefore maturing earlier as well," he added. At the same time, Fisher said earlier maturation and reproductive capabilities would only occur in favorable environmental conditions, thus dis- proving that climate change led to their extinction. ASHLEY HARPER/Daily Side view of the mastodon currently being assembled by curators in the Exhibit Museum of Natural History. Man hunted these animals continuously for food and the ani- mal's hide and bones, for heating purposes, he said. "I think at least with my specimens of the Great Lakes region, it seems to not be a climate or vegetation change, therefore it becomes an obvious extrapolation that humans are the cause," Fisher said. Still, not all scientists agree with Fisher's evidence. Kenneth Tankersley, an anthropologist at North Kentucky Uni- versity, maintains the viability of the climate theory. "The climate at the end of the Ice Age was unstable, and as it changed, so did the distribution of plants and animals," Tankersley said. Due to this climate shift, the abundance of certain plants and animals decreased because of their lack of tolerance to these new climatic conditions, he added. Tankersley said he believes some animals migrated toward more accommodating environments. This could account for the growth of Fisher's tusk which suggest that the mastodon lived in a favorable environment. "Would (mastodons) have gone extinct in the complete absence of people. The paleoclimatic data suggests that the answer is an absolute 'yes.' " Tankersley said. The new exhibit of the mastodon from Indiana will join with the Exhibit Museum's current display of a female mastodon. The male mastodon is 20 percent larger than the female skel- eton and stands at a height of nine feet, while the tusks extend to seven feet long. The mastodon most likely weighed 6,000 pounds and the skeleton of the exhibit are composed of a fiberglass cast made from the molds of the real bones, which are currently being studied by the museum. 'U' sets sights on a return to Mercury with NASA probe NASA/JH U/APL/Carnegie Institution Artist's interpretation of MESSENGER orbiting the planet Mercury after completing its seven year journey. By Eric Sweeney For the Daily More than 30 years ago, the Mariner 10 spacecraft shot past Mer- cury three times, beaming back most of what we know today about this enigmatic world. "We got sort of a tantalizing glimpse," said Patrick Koehn, assistant research scientist at the University's Space Physics Research Labora- tory, of the first mission to Mercury. Now scientists are venturing back to Mercury with NASA's MES- SENGER spacecraft, which was launched last August, and will begin a yearlong orbit of the planet in 2011. MESSENGER, which stands for Mercury Surface, Space Environment, Geochemistry and Ranging, will be the first spacecraft ever to orbit Mercury and study the planet in detail. This time, scientists hope to finally crack some of Mercury's mysteries through new technologies, particularly the Fast Imaging Plas- ma Spectrometer developed by University researchers. Mercury, the Earth's neighbor closest to the sun, basks in sunlight 11 times greater than that on Earth, scorching the planet with tempera- "From that orbit, it will explore the planet and all its properties: the interior, the surface, the environment of the planet." Zurbuchen said. "We expect to learn where the planet came from, and how it is part of the solar system." Zurbuchen and Koehn, with the help of SPRL faculty and students, and backed by a $3 million grant from NASA, built the small, three-pound FIPS, a first-of-its-kind instrument that will take the first ever measure- ments of the activity of charged particles in Mercury's environment. As MESSENGER cruises through Mercury's magnetosphere - the region surrounding the planet that contains charged particles controlling Mercury's magnetic field - FIPS will function like a camera to detect different types of these particles and their velocities. It is the most com- pact instrument of this type ever developed, and, unlike previous narrow- lensed models, provides scientist with a wider, "fish eye" view. "It was a real innovation," said Zurbuchen. "We're going to go to a place with an instrument that has never been there. We're going to learn new science." Data gathered by FIPS will provide new insight into how the solar wind interacts with planetary magnetic fields. By having an unsubstantial atmo- sphere and a magnetosphere, Koehn said, Mercury is perfect for studying interaction between the solar wind and planetary magnetic fields. While both Earth and Mercury each have a magnetosphere, Earth's atmosphere is much thicker, while- Mercury's is very light, similar to that of the Moon's. As Earth's magnetosphere is hit by the solar wind, it responds by interacting with Earth's underlying atmosphere. Mercury, having virtually no atmosphere, gives scientists the opportunity to study the interaction between the solar wind and a magnetosphere without interference from an atmosphere. In effect, Mercury allows for a controlled experiment that will test scientists' general understanding of how the solar wind interacts with planets. "With the Mercury system we have one less variable," Koehn said. "You can think of it as a planetary laboratory." But the overall goals of MESSENGER are even more far-reaching. According to NASA's website, surface com- position measurements will reveal how Mer- cury became the dense planet it is today. If the surface is similar to other terrestrial planets, then Mercury's density was caused simply by an accumulation of dense particles as the solar "We're going to go to a place with an instrument that has never been there. We're going to learn new science." - Thomas Zurbuchen AOSS Professor and director of FIPS construction oxygen, it would suggest that this crust was stripped of Mercury by giant impacts soon after the planet formed. Mercury's magnetic field will also be explored. For the most part, planetary magnetic fields are generated by an active liquid interior, but observations of Mercury's rotation indicate that it must have a solid iron core, Zurbuchen said. "So how can it have a magnetic field? All these things we use to explain the Earth's magnetic field, or the sun's magnetic field, all these theories can't apply." Zurbuchen said. Before MESSENGER begins to orbit Mercury, it will have traveled 4.9 billion miles by conducting five deep space maneuvers, acclerating the speed of the spacecraft in short bursts so that it can travel along the gravitational pull of the planets to jump from the Earth to Venus and then on to its final destination - Mercury. . ............