Thursday, October 18, 2007

Earliest Evidence Of Modern Humans Detected


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Science Daily — Evidence of early humans living on the coast in South Africa, harvesting food from the sea, employing complex bladelet tools and using red pigments in symbolic behavior 164,000 years ago, far earlier than previously documented, is being reported in the journal Nature.
The international team of researchers reporting the findings include Curtis Marean, a paleoanthropologist with the Institute of Human Origins at Arizona State University and three graduate students in the School of Human Evolution and Social Change.
"Our findings show that at 164,000 years ago in coastal South Africa humans expanded their diet to include shellfish and other marine resources, perhaps as a response to harsh environmental conditions," notes Marean, a professor in ASU's School of Human Evolution and Social Change. "This is the earliest dated observation of this behavior."
Further, the researchers report that co-occurring with this diet expansion is a very early use of pigment, likely for symbolic behavior, as well as the use of bladelet stone tool technology, previously dating to 70,000 years ago.
These new findings not only move back the timeline for the evolution of modern humans, they show that lifestyles focused on coastal habitats and resources may have been crucial to the evolution and survival of these early humans.
Searching for beginnings
After decades of debate, paleoanthropologists now agree the genetic and fossil evidence suggests that the modern human species -- Homo sapiens -- evolved in Africa between 100,000 and 200,000 years ago.
Yet, archaeological sites during that time period are rare in Africa. And, given the enormous expanse of the continent, where in Africa did this crucial step to modern humans occur?
"Archaeologists have had a hard time finding material residues of these earliest modern humans," Marean says. "The world was in a glacial stage 125,000 to 195,000 years ago, and much of Africa was dry to mostly desert; in many areas food would have been difficult to acquire. The paleoenvironmental data indicate there are only five or six places in all of Africa where humans could have survived these harsh conditions."
In seeking the "perfect site" to explore, Marean analyzed ocean currents, climate data, geological formations and other data to pin down a location where he felt sure to find one of these progenitor populations: the Cape of South Africa at Pinnacle Point.
"It was important that we knew exactly where to look and what we were looking for," says Marean. This type of research is expensive and funding is competitive. Marean and the team of scientists who set out to Pinnacle Point to search for this elusive population, did so with the help of a $2.5 million grant from the National Science Foundation's Human Origins: Moving in New Directions (HOMINID) program.
Their findings are reported in the Nature paper "Early human use of marine resources and pigment in South Africa during the Middle Pleistocene." In addition to Marean, authors on the paper include three graduate students in ASU's School of Human Evolution and Social Change: Erin Thompson, Hope Williams and Jocelyn Bernatchez. Other authors are Miryam Bar-Matthews of the Geological Survey of Israel, Erich Fisher of the University of Florida, Paul Goldberg of Boston University, Andy I.R. Herries of the University of New South Wales (Australia), Zenobia Jacobs of the University of Wollongong (Australia), Antonieta Jerardino of the University of Cape Town (South Africa), Panagiotis Karkanas of Greece's Ministry of Culture, Tom Minichillo of the University of Washington, Ian Watts from London and excavation co-director Peter J. Nilssen of the Iziko South African Museum.
The Middle Stone Age, dated between 35,000 and 300,000 years ago, is the technological stage when anatomically modern humans emerged in Africa, along with modern cognitive behavior, says Marean. When, however, within that stage modern human behavior arose is currently debated, he adds.
"This time is beyond the range of radiocarbon dating, yet the dates on the finds published here are more secure than is typical due to the use of two advanced and independent techniques," Marean says.
Uranium series dates were attained by Bar-Matthews on speleothem (the material of stalagmites), and optically stimulated luminescence dates were developed by Jacobs. According to Marean, the latter technique dates the last time that individual grains of sand were exposed to light, and thousands of grains were measured.
Migrating along the coast
"Generally speaking, coastal areas were of no use to early humans -- unless they knew how to use the sea as a food source" says Marean. "For millions of years, our earliest hunter-gatherer relatives only ate terrestrial plants and animals. Shellfish was one of the last additions to the human diet before domesticated plants and animals were introduced."
Before, the earliest evidence for human use of marine resources and coastal habitats was dated about 125,000 years ago. "Our research shows that humans started doing this at least 40,000 years earlier. This could have very well been a response to the extreme environmental conditions they were experiencing," he says.
"We also found what archaeologists call bladelets -- little blades less than 10 millimeters in width, about the size of your little finger," Marean says. "These could be attached to the end of a stick to form a point for a spear, or lined up like barbs on a dart -- which shows they were already using complex compound tools. And, we found evidence that they were using pigments, especially red ochre, in ways that we believe were symbolic," he describes.
Archaeologists view symbolic behavior as one of the clues that modern language may have been present. The earliest bladelet technology was previously dated to 70,000 years ago, near the end of the Middle Stone Age, and the modified pigments are the earliest securely dated and published evidence for pigment use.
"Coastlines generally make great migration routes," Marean says. "Knowing how to exploit the sea for food meant these early humans could now use coastlines as productive home ranges and move long distances."
Results reporting early use of coastlines are especially significant to scientists interested in the migration of humans out of Africa. Physical evidence that this coastal population was practicing modern human behavior is particularly important to geneticists and physical anthropologists seeking to identify the progenitor population for modern humans.
"This evidence shows that Africa, and particularly southern Africa, was precocious in the development of modern human biology and behavior. We believe that on the far southern shore of Africa there was a small population of modern humans who struggled through this glacial period using shellfish and advanced technologies, and symbolism was important to their social relations. It is possible that this population could be the progenitor population for all modern humans," Marean says.
The research is detailed in the October 18 issue of Nature.
Note: This story has been adapted from material provided by Arizona State University.

Fausto Intilla

Wednesday, October 10, 2007

Early Apes Walked Upright 15 Million Years Earlier Than Previously Thought, Evolutionary Biologist Argues


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Science Daily — An extraordinary advance in human origins research reveals evidence of the emergence of the upright human body plan over 15 million years earlier than most experts have believed. More dramatically, the study confirms preliminary evidence that many early hominoid apes were most likely upright bipedal walkers sharing the basic body form of modern humans.
Research from Harvard University¹s Museum of Comparative Zoology and from the Cedars Sinai Institute for Spinal Disorders connects several recent fossil discoveries to older fossils finds that have eluded adequate explanation in the past. The report deals with the "homeotic" genetic mechanisms that encode anatomical assembly in the embryo, and their relevance to a series of discoveries of hominoid fossil vertebrae.
The report analyses changes in homeotic embryological assembly of the spine in more than 200 mammalian species across a 250 million year time scale. It identifies a series of modular changes in genetic assembly program that have taken place at the origin point of several major groups of mammals including the newly designated 'hominiform' hominoids that share the modern human body plan.
It concludes that a specific gene change ­ in the Pax system -- that generated the upright bipedal human body form -- may soon be identified. The various upright "hominiform" hominoids appear to share this morphogenetic innovation with modern humans. Homeotics concerns the embryological assembly program for midline repeating structures such as the human vertebral column and the insect body segments.
The critical event involves a dramatic embryological change unique to the human lineage that was not previously understood because the unusual human condition was viewed as "normal."
"From an embryological point of view, what took place is literally breathtaking," says Dr. Aaron Filler, a Harvard-trained evolutionary biologist and a medical director at Cedars Sinai Medical Center's Institute for Spinal Disorders.
In most vertebrates (including most mammals), he explains, the dividing plane between the front (ventral) part of the body and the back (dorsal) part is a "horizontal septum" that runs in front of the spinal canal. This is a fundamental aspect of animal architecture. A bizarre birth defect in what may have been the first direct human ancestor led to the "transposition" of the septum to a position behind the spinal cord in the lumbar region. Oddly enough, this configuration is more typical of invertebrates.
The mechanical effect of the transposition was to make horizontal or quadrupedal stance inefficient. "Any mammal with this set of changes would only be comfortable standing upright. I would envision this malformed young hominiform -- the first true ancestral human -- as standing upright from a young age while its siblings walked around on all fours."
The earliest example of the transformed hominiform type of lumbar spine is found in Morotopithecus bishopi an extinct hominoid species that lived in Uganda more than 21 million years ago. "From a number of points of view," Filler says, "humanity can be redefined as having its origin with Morotopithecus. This greatly demotes the importance of the bipedalism of Australopithecus species such as Lucy (Australopithecus afarensis) since we now know of four upright bipedal species that precede her, found from various time periods on out to Morotopithecus in the Early Miocene."
Citation: Filler AG (2007) Homeotic Evolution in the Mammalia: Diversification of Therian Axial Seriation and the Morphogenetic Basis of Human Origins. PLoS One 2(10): e1019. doi:10.1371/journal.pone.0001019, http://www.plosone.org/doi/pone.0001019
Note: This story has been adapted from material provided by Public Library of Science.

Fausto Intilla

Thursday, October 4, 2007

Even Without Math, Ancients Engineered Sophisticated Machines

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Science Daily — Move over, Archimedes. A researcher at Harvard University is finding that ancient Greek craftsmen were able to engineer sophisticated machines without necessarily understanding the mathematical theory behind their construction.
Recent analysis of technical treatises and literary sources dating back to the fifth century B.C. reveals that technology flourished among practitioners with limited theoretical knowledge.
"Craftsmen had their own kind of knowledge that didn't have to be based on theory," explains Mark Schiefsky, professor of the classics in Harvard's Faculty of Arts and Sciences. "They didn't all go to Plato's Academy to learn geometry, and yet they were able to construct precisely calibrated devices."
The balance, used to measure weight throughout the ancient world, best illustrates Schiefsky's findings on the distinction between theoretical and practitioner's knowledge. Working with a group led by J├╝rgen Renn, Director of the Max Planck Institute for the History of Science in Berlin, Schiefsky has found that the steelyard--a balance with unequal arms--was in use as early as the fourth and fifth centuries B.C., before Archimedes and other thinkers of the Hellenistic era gave a mathematical demonstration of its theoretical foundations.
"People assume that Archimedes was the first to use the steelyard because they suppose you can't create one without knowing the law of the lever. In fact, you can--and people did. Craftsmen had their own set of rules for making the scale and calibrating the device," says Schiefsky.
Practical needs, as well as trial-and-error, led to the development of technologies such as the steelyard.
"If someone brings a 100-pound slab of meat to the agora, how do you weigh it?" Schiefsky asks. "It would be nice to have a 10-pound counterweight instead of a 100-pound counterweight, but to do so you need to change the balance point and ostensibly understand the principle of proportionality between weight and distance from the fulcrum. Yet, these craftsmen were able to use and calibrate these devices without understanding the law of the lever."
Craftsmen learned to improve these machines through productive use, over the course of their careers, Schiefsky says.
With the rise of mathematical knowledge in the Hellenistic era, theory came to exert a greater influence on the development of ancient technologies. The catapult, developed in the third century B.C., provides evidence of the ways in which engineering became systematized.
With the help of literary sources and data from archaeological excavations, "We can actually trace when the ancients started to use mathematical methods to construct the catapult," notes Schiefsky. "The machines were built and calibrated precisely."
Alexandrian kings developed and patronized an active research program to further refine the catapult. Through experimentation and the application of mathematical methods, such as those developed by Archimedes, craftsmen were able to construct highly powerful machines. Twisted animal sinews helped to increase the power of the launching arm, which could hurl stones weighing 50 pounds or more.
The catapult had a large impact on the politics of the ancient world.
"You could suddenly attack a city that had previously been impenetrable," Schiefsky explains. "These machines changed the course of history."
According to Schiefsky, the interplay between theoretical knowledge and practical know-how is crucial to the history of Western science.
"It's important to explore what the craftsmen did and didn't know," Schiefsky says, "so that we can better understand how their work fits into the arc of scientific development."
Schiefsky's research is funded by the National Science Foundation and the Max Planck Institute for the History of Science in Berlin.
Note: This story has been adapted from material provided by Harvard University.

Fausto Intilla
www.oloscience.com

Wednesday, October 3, 2007

Huge New Dinosaur Had A Serious Bite


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Science Daily — The newest dinosaur species to emerge from Grand Staircase-Escalante National Monument had some serious bite, according to researchers from the Utah Museum of Natural History at the University of Utah.
"It was one of the most robust duck-billed dinosaurs ever," said museum paleontologist Terry Gates, who is also with the U.'s Department of Geology and Geophysics. "It was a monster."
Researchers from the Utah museum, the national monument and California's Raymond M. Alf Museum of Paleontology unearthed fossils of this ancient plant-eater from the rocks of the Kaiparowits Formation. Researchers announced the name of the creature -- Gryposaurus monumentensis. (Gryposaurus means "hook-beaked lizard" and monumentensis honors the monument where the fossils were found.)
This duck-billed dinosaur dates to the Late Cretaceous Period 75 million years ago. "Gryposaurus monumentensis is probably the largest dinosaur in the 75-million-year-old Kaiparowits fossil ecosystem," said Alan Titus, paleontologist for the national monument.
Gates, lead author on the study, explained that this creature could have eaten just about any vegetation it stumbled across. "With its robust jaws, no plant stood a chance against G. monumentensis," he said.
Scott Sampson, another paleontologist with the Utah museum who was involved with the project, emphasized the massively-built skull and skeleton, referring to the animal as the "Arnold Schwarzenegger of duck-billed dinosaurs."
Finding the skull
In 2002, a team from the Alf Museum, in Claremont, Calif., located at the Webb School, discovered the site that contained the skull used to describe the new creature. Every summer, the California institution, the only nationally-accredited paleontology museum on a high school campus, gives Webb students and volunteers the chance to participate in scientific field work.
The California team was working a stretch of Grand Staircase that Utah researchers had not examined. Duncan Everhart, a Pennsylvania furniture maker, is credited with finding the skull.
Don Lofgren, curator of the Alf Museum, said the team received permission from the monument to dig deeper in 2003.
"We determined it was a skull sitting upside down with the jaw on top," he said.
Once Gates went out to take a look in 2004, he quickly realized the California team had a potentially-important find. The Alf Museum gave the Utah researchers permission to prepare and study the skull.
Titus noted the discovery of this new species was a team effort involving the Alf Museum, the Utah Museum of Natural History and the national monument.
"The cooperative effort put into its collection and research has truly been a model for scientific investigation on public lands," he said.
It wasn't until Utah researchers began working on the skull in 2005 that the full significance of the find began to emerge, Gates said.
The well-preserved skull was initially missing key pieces from the nose region. Fortunately, the California museum had collected a box full of eroded bones, including bits of the nose bone, which was critical for identifying the creature.
"I knew immediately that we had some species of Gryposaurus," Gates said.
A toothy beast
The creature's large number of teeth embedded in the thick skull is among the features that made G. monumentensis, as well as other closely related duck-billed dinosaurs, such a successful herbivore.
At any given time, the dinosaur had over 300 teeth available to slice up plant material. Inside the jaw bone, there were numerous replacement teeth waiting, meaning that at any moment, this Gryposaur may have carried more than 800 teeth.
"IIt was capable of eating most any plant it wanted to," Gates said. "Although much more evidence is needed before we can hypothesize on its dietary preferences."
While the diet is unknown, given the considerable size of the creature, the massive teeth and jaws are thought to have been used to slice up large amounts of tough, fibrous plant material.
The teeth may hold important clues the dinosaur's eating habits. The Utah museum plans to study the composition of the dinosaur teeth, which when compared to other plant-eating dinosaurs from the Kaiparowits Formation, will help researchers decipher differences in diet.
G. monumentensis is one of several new dinosaur species found in Grand Staircase, including: a Velociraptor-like carnivore named Hagryphus, a tyrannosaur, and several kinds of horned dinosaurs. In all, more than a dozen kinds of dinosaurs have been recovered from these badlands, and most represent species that are new to science.
"This is a brand new and extremely important window into the world of dinosaurs," said Sampson.
Under ideal circumstances, paleontologists will find the skull and other key bones at the same site. In this case, the head was the only thing they managed to find from where the Alf team searched.
Researchers believe the head of this particular Gryposaur likely rolled into a bend of a river, where it was partly buried. The right half of the head remained exposed to the river current, dislodging several bones before this side was buried as well.
In other parts of the monument, Utah researchers have excavated bones believed to be from the same species. Gates estimates G. monumentensis may have grown up to 30 feet long as an adult.
"As each new find such as this new Gryposaur is made," Titus said, "it is placed into the greater context of an entire ecosystem that has remained lost for eons, and is only now coming under scientific scrutiny."
Life in 'West America'
Around 75 million years ago, southern Utah differed dramatically from today's arid desert and redrock country. During much of the Late Cretaceous, a shallow sea split North America down the middle, dividing the continent into eastern and western landmasses.
In what Sampson terms "West America," G. monumentensis and its fellow dinosaurs lived in a narrow strip of land sandwiched between the seaway to the east and rising mountains to the west. Due in large part to the presence of the seaway, the climate was moist and humid.
Thanks to more than 100 years of fossil collection, scientists know more about the Cretaceous dinosaurs from North American than they do from any other time or continent on Earth, Sampson noted.
While G. monumentensis gulped down its greens and tried to avoid predatory tyrannosaurs down in Utah, closely related but different species of duck-billed dinosaurs were doing the same thing farther north, in places like Montana and Alberta, Canada.
The new Utah species is proving crucial for determining patterns of duck-billed dinosaur evolution and ecology during the Late Cretaceous of North America, Gates said. He added that "this calls for a re-evaluation of previous ideas about the evolution of duck-billed dinosaurs across the world."
Earlier explanations of dinosaurs undertaking long distance migrations have gone out the window. "Now we have to figure out how so many different kinds of giants managed to coexist in such small areas," said Sampson. "We're just beginning to unravel this story."
Bones from G. monumentensis are on display at Big Water Visitor Center in Grand Staircase-Escalante National Monument, and for a short time at the Utah Museum of Natural History before returning to the Alf Museum.
This research was published in the Oct. 3 issue of the Zoological Journal of the Linnean Society.
Note: This story has been adapted from material provided by University of Utah.

Fausto Intilla