September 7, 2006, 5:03 AM CT

How did our Ancestors' Minds really work?

How did our evolutionary ancestors make sense of their world? What strategies did they use, for example, to find food? Fossils do not preserve thoughts, so we have so far been unable to glean any insights into the cognitive structure of our ancestors. However, in a study recently published in Current Biology (September 5, 2006), researchers at the Max Planck Institute for Psycholinguistics and their colleagues at the Max Planck Institute for Evolutionary Anthropology were able to find answers to these questions using an alternative research method: comparative psychological research. In this way, they discovered that some of the strategies shaped by evolution are evidently masked very early on by the cognitive development process unique to humans.

Being able to remember and relocate particular places where there is food is an asset to any species. There are two basic strategies for remembering the location of something: either remembering the features of the item (it was a tree, a stone, etc.), or knowing the spatial placement (left, right, middle, etc.). All animal species tested so far - from goldfish, pigeons and rats though to humans - seem to employ both strategies. However, if the type of recall task is designed so that the two strategies are in opposition, then some species (e.g. fish, rats and dogs) have a preference for locational strategies, while others (e.g. toads, chickens and children) favor those which use distinctive features.........

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September 5, 2006, 10:02 PM CT

Mammoth Site Photo

Field jacket in storage at Mammoth Site.

Mammoth Site photo.........

Posted by: William      Permalink         Source

September 5, 2006, 5:09 AM CT

Good Times Ahead For Dinosaur Hunters

The golden age of dinosaur discovery is yet upon us, as per Peter Dodson at the University of Pennsylvania. In a forthcoming issue of the Proceedings of the National Academy of Sciences, Dodson revises his groundbreaking 1990 census on the diversity of discoverable dinosaurs upward by 50%, offering a brighter outlook about the number of dinosaurs waiting to be found. His findings also add evidence that dinosaur populations were stable, and not on the decline, in the time shortly before their extinction 65 million years ago.

Dodson proposes that 1,850 genera (the plural of genus, an organizational group comprised of one or more separate species) will eventually be discovered, in total. Since the dinosaur research began in earnest in the 19th century, only 527 genera have so far been found, eventhough that number is currently changing at the rate of 10 to 20 per year.

"It's a safe bet that a child born today could expect a very fruitful career in dinosaur paleontology," said Dodson, professor of anatomy in Penn's School of Veterinary Medicine and professor in Penn's Department of Earth and Environmental Sciences. "Unfortunately, there is a finite limit to what can be discovered, so our estimates show that the child's grandchildren won't be so fortunate as new discoveries will likely decline sharply in the early 22nd century".........

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August 29, 2006, 9:26 PM CT

Ancient Raptors Likely Feasted On Early Man

A new study suggests that prehistoric birds of prey made meals out of some of our earliest human ancestors.

Scientists drew this conclusion after studying more than 600 bones from modern-day monkeys. They had collected the bones from beneath the nests of African crowned eagles in the Ivory Coast's Tai rainforest. A full-grown African crowned eagle is roughly the size of an American bald eagle, which typically weighs about 10 to 12 pounds.

Punctures and scratches on a number of of the monkey skulls have led some scientists to rethink which animals may have preyed on our human ancestors, said W. Scott McGraw, the study's lead author and an associate professor of anthropology at Ohio State University.

"It seems that raptors have been a selective force in primate evolution for a long time," he said. "Before this study I thought that eagles wouldn't contribute that much to the mortality rate of primates in the forest.

"I couldn't have been more wrong".

The results may also have important implications for the mystery surrounding the death of one human ancestor who lived about 2.5 million years ago.

Archaeologists discovered the skull of a 3½-year old ape-like child in a cave in South Africa in 1924. Scientists believed this child, called the Taung child (Australopithecus africanus), had been killed by a predatory cat. But McGraw said that puncture marks on the monkey skulls he examined closely resemble those found on the skull of the Taung child.........

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August 27, 2006, 8:03 PM CT

Remote Island Provides Clues On Population Growth

Halfway between South America and New Zealand, in the remote South Pacific, is Rapa. This horseshoe-shaped, 13.5 square-mile island of volcanic origin, located essentially in the middle of nowhere, is "a microcosm of the world's situation," says a University of Oregon archaeologist.

Until only recently, little was known about the French Polynesian Island, where the current population is less than 500. Archaeological, linguistic and genetic data suggest that the island, like much of East Polynesia, was inhabited in a final pulse of colonization by seafaring travelers who originated from Island Southeast Asia. New research, led by the University of Oregon's Douglas Kennett, has shed fresh new light on Rapa, particularly on what life may have been like for as a number of as 1,500 to 2,000 people who lived there before the arrival of European explorers.

Kennett's team, which included scientists from three institutions, published in the recent issue of the journal Antiquity that Polynesians arrived on the island around A.D. 1200, much later than long assumed. The settlers spread across the island, splintering from a shoreline-based society into competing groups that built and likely defended a growing number of spectacular fortifications carved from mountaintops in the years before English explorer George Vancouver sailed by in 1791, ushering in European contact.........

Posted by: Tyler      Permalink         Source

August 25, 2006, 5:05 AM CT

Insect Predation Sheds Light On Food Web Recovery

The recovery of biodiversity after the end-Cretaceous mass extinction was much more chaotic than previously thought, as per paleontologists. New fossil evidence shows that at certain times and places, plant and insect diversity were severely out of balance, not linked as they are today. The extinction took place 65.5 million years ago. Labeled the K-T extinction, it marks the beginning of the Cenozoic Era and the Paleocene Epoch.

"The K-T caused major extinction among North American plants and insects. The Western Interior U.S. was a dead zone for plants and plant-insect food webs," said Dr. Peter Wilf, assistant professor of geosciences and the David and Lucile Packard Fellow. "We know that right after the extinction, for 800,000 years, there was very low insect predation and plant diversity. We know that 9 million years afterwards, there was renewed diversity in both plants and insects. What happened in the 8 million years in between?.

"In modern forests, insect diversity tracks plant populations. If there are few plants, there are few insects, and that is what we expected to see and mostly found throughout the 10-million-year Paleocene. However, we looked extremely hard to test this conventional wisdom and found some shocking exceptions that have given us new ideas about how food webs recover from mass extinction," he added.........

Posted by: William      Permalink         Source

August 24, 2006, 10:09 PM CT

How modern were European Neanderthals?

Neandertals were much more like modern humans than had been previously thought, as per a re-examination of finds from one of the most famous palaeolithic sites in Europe by Bristol University archaeologist, Professor Joao Zilhao, and his French colleagues.

Professor Zilhao has been able to show that sophisticated artefacts such as decorated bone points and personal ornaments found in the Chtelperronian culture of France and Spain were genuinely linked to Neandertals around 44,000 years ago, rather than acquired from modern humans who might have been living nearby. His findings appear in the Proceedings of the National Academy of Sciences (PNAS) USA.

The site from which this Neandertal culture derives its name is the Grotte de Fes at Chtelperron in Central France, first excavated in the 1840s. It has been one of the most important and controversial places to understand how modern humans that had previously moved out of Africa replaced the Neandertals, often portrayed as more 'primitive'.

In the conventional interpretation of the rock strata of the site, the cave was thought to have evidence of both modern human and Neandertal occupation in interleaved layers. The fact that Neandertals came back to the site after modern humans had lived in it for quite some time would prove the long-term contemporaneity of the two groups, and validate the notion that the cultural novelties seen among the latest Neandertals represented immitation or borrowing, not innovation.........

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August 11, 2006, 9:30 PM CT

Fossils Links from Ape-men

A team of scientists working in an eastern Ethiopian desert has discovered fossil bones and teeth from individuals they believe link the genus Australopithecus--precursors of humans--to a decidedly more ape-like animal of the genus Ardipithicus. Because the fossils were found in areas known to contain evidence of both older and younger specimens, the scientists say evidence of when the three hominid types existed will provide valuable information about human evolution.

Still, 'it is fair to say that some species of Ardipithicus gave rise to Australopithecus," said Tim White, a professor of integrative biology at the University of California-Berkeley and one of the team leaders.

White and coworkers from 17 countries have published their findings in the April 13 issue of the journal Nature.

The fossils are from the most-primitive Australopithecus species, known as Au. anamensis, dating from about 4.1 million years ago, said White, and push the species closer in time to its last known ancestor. "This new discovery closes the gap between the fully blown Australopithecines and earlier forms we call Ardipithecus," White said. "We now know where Australopithecus came from before 4 million years ago".

Even though the two are separated by only 300,000 years, Au. anamensis could have rapidly evolved from Ardipithecus. Or, fossils placing the two hominid types on Earth at the same time may yet be found. Nevertheless, White said, the new fossils show clear descent from the genus Ardipithecus, two species of which have been identified over the genus's 2 million years of existence.........

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August 11, 2006, 9:14 PM CT

Drilling Into Fossil Magma Chamber Deep Under the Ocean

Scientists aboard the research drilling ship JOIDES Resolution have, for the first time, drilled into a fossil magma chamber under intact ocean crust. There, 1.4 kilometers beneath the sea floor, they have recovered samples of gabbro: a hard, black rock that forms when molten magma is trapped beneath Earth's surface and cools slowly.

The scientists, affiliated with the Integrated Ocean Drilling Program (IODP), published their findings on April 20 in Science Express, the online edition of the journal Science.

Although gabbro has been sampled elsewhere in the oceans where faulting and tectonic movements have brought it closer to the seafloor, this is the first time gabbro has been recovered from intact ocean crust.

The borehole into the magma chamber took nearly five months to drill, and required the use of twenty-five hardened steel and tungsten carbide drill bits. Getting there "is a rare opportunity to calibrate geophysical measurements with direct observations of real rocks," said geophysicist Doug Wilson of the University of California at Santa Barbara, lead author on the Science Express paper. "Finding the right place to drill was probably the key to this success".

Wilson and his IODP colleagues found that place by identifying a region of the Pacific Ocean that formed some 15 million years ago when the East Pacific Rise was spreading at a "superfast" rate of more than 200 millimeters per year, faster than any mid-ocean ridge on Earth today.........

Posted by: William      Permalink         Source

August 9, 2006, 11:46 PM CT

New Mammal Discovered

Fossils of a new hoofed mammal that resembles a cross between a dog and a hare which once roamed the Andes Mountains in southern Bolivia around 13 million years ago was discovered by Darin A. Croft, assistant professor of anatomy at the Case Western Reserve University School of Medicine and a research associate at the Cleveland Museum of Natural History

With Federico Anaya from Universidad Autónoma Tomás Frías, Croft reported on the new mammal find named Hemihegetotherium trilobus in the Journal of Vertebrate Paleontology article, "A New Middle Miocene Hegetotherid (Notoungulata: Typotheria) and a Phylogeny of the Hegetotheriidae." It is named for the distinctive three lobes on its back lower molar teeth.

The animal belonged to a group of animals called notoungulates—hoofed mammals native only to South America. The group originated in South America soon after the dinosaurs went extinct and evolved to include hundreds of species over a span of more than 50 million years; all of them are now extinct. Eventhough most notoungulates were gone before humans got to South America, some of the earliest humans to journey to that continent may have seen the last living notoungulates.........

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