6 million years of savanna

Public release date: 3-Aug-2011
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Contact: Lee Siegel
lee.siegel@utah.edu
801-581-8993
University of Utah

SALT LAKE CITY, Aug. 3, 2011 ? University of Utah scientists used chemical isotopes in ancient soil to measure prehistoric tree cover ? in effect, shade ? and found that grassy, tree-dotted savannas prevailed at most East African sites where human ancestors and their ape relatives evolved during the past 6 million years.

"We've been able to quantify how much shade was available in the geological past," says geochemist Thure Cerling, senior author of a study of the new method in the Thursday, Aug. 4, 2011 issue of the journal Nature. "And it shows there have been open habitats for all of the last 6 million years in the environments in eastern Africa where some of the most significant early human fossils were found."

"Wherever we find human ancestors, we find evidence for open habitats similar to savannas ? much more open and savanna-like than forested," adds Cerling, a University of Utah distinguished professor of geology and geophysics, and biology.

Fossils of early humans and their ancestors and extinct relatives have been found in both wooded and open environments in East Africa. Even 4.3-million-year-old Ardipithecus ? which lived in the woods, according to its discoverers ? had a small component of tropical grasses in its diet, Cerling says.

"The fact it had some means it was going into the savanna, unless it was eating takeout food," he says.

Scientists have spent a century debating the significance of savanna landscape in human evolution, including the development of upright walking, increased brain size and tool use.

Part of the problem has been a fuzzy definition of "savanna," which has been used to describe "virtually everything between completely open grasslands and anything except a dense forest," Cerling says. He adds the most common definition is a fairly open, grassy environment with a lot of scattered trees ? a grassland or wooded grassland.

Open Landscapes throughout the Evolution of Humans and Their Relatives

In the new study, Cerling says he and colleagues developed "a new way to quantify the openness of tropical landscapes. This is the first method to actually quantify the amount of canopy cover, which is the basis for deciding if something is savanna."

Cerling does not dispute that East African savannas became more expansive within the past 2 million years, or that human ancestors and relatives likely spent time in narrow "gallery forests" along river corridors.

But he says the new method shows grasslands and wooded grasslands ? in other words, savannas ? have prevailed for more than 6 million years in the cradle of humanity, with tree cover less than about 40 percent at most sites. By definition, woodland has more than 40 percent tree cover, and a forest has more than 80 percent tree cover.

"In some periods, it was more bushy, and other times it was less bushy," he says. "Hardly anything could have been called a dense forest, but we can show some periods where certain environments were consistently more wooded than others. We find hominins (early humans, pre-humans and chimp and gorilla relatives) in both places. How early hominins partitioned their time between 'more open' and 'more closed' habitats is still an open question."

Cerling says even sparse woody canopy provided hominins with shade, some foods and refuge from predators.

Fossil evidence of hominins ? humans, their ancestors and early relatives such as chimps and gorillas ? date back to 4.3 million years and possibly 6 million years, Cerling says. The new method was used to look for and find savanna up to 7.4 million years ago.

"Currently, many scientists think that before 2 million years ago, things were forested [in East Africa] and savanna conditions have been present only for the past 2 million years," Cerling says. "This study shows that during the development of bipedalism [about 4 million years ago] open conditions were present," even predominant.

Cerling conducted the study with biologists Samuel Andanje and David Kimutai Korir of the Kenya Wildlife Service; geologist Michael Bird of James Cook University, Cairns, Australia; University of Utah graduate students William Mace of geology, Anthony Macharia of geography and Christopher Remien of mathematics; and former Utah geology graduate students Jonathan Wynn of the University of South Florida, Naomi Levin of Johns Hopkins University and Jay Quade of the University of Arizona.

The National Science Foundation and the Leakey Foundation funded the study.

Deducing Prehistoric Tree Cover from Soil Isotopes

The new method was developed by correlating carbon isotope ratios in 3,000 modern soil samples with satellite photos of tree and vegetation cover at 75 tropical sites worldwide ? half in Africa ? representing everything from closed forest to open grassland. That allowed scientists to determine the percent of tree and woody shrub cover millions of years ago based on carbon isotope ratios in fossil soils known as paleosols.

"This study is based on the geological axiom that the present is the key to the past," says Cerling. "We assume soils in the past had similar relationships to vegetation as what we observe today."

The researchers collected soil samples at Kenyan and Ethiopian sites and used published data on soil samples collected by others during the past decade at the other sites throughout the tropics. Modern soil samples came from national parks and reserves and non-agricultural areas so that carbon isotope rations reflected natural vegetation.

The ratio of rare carbon-13 to common carbon-12 in decayed plant material in soils reveals the extent to which the landscape was covered by plants that use what is known as the C3 pathway of photosynthesis versus plants that use C4 photosynthesis.

Trees, shrubs, herbs, forbs and cool-season grasses are C3 plants, which include beans and most vegetables. C4 plants are warm-season or tropical grasses that dominate savannas, and plants called sedges. C4 plants have a higher ratio of carbon-13 than C3 plants.

The isotope composition of fossil soil gives a measure of the total makeup of the ecosystem in terms of how much canopy versus how much open landscape, Cerling says. So in a forest, even soil from open gaps shows the C3 signature because of non-woody C3 plants growing there, while on a savanna, soil from under a C3 tree will show the C4 signature because of grasses growing under the tree.

The Findings: A History of Savanna

Cerling and colleagues used the new method to analyze fossil soils and infer plant cover back to 7.4 million years ago, a period that includes when human ancestors and apes split from a common ancestor.

Their analysis of 1,300 fossil soil samples from sites at or near where human ancestors and their relatives evolved shows that more than 70 percent of the sites had less than 40 percent woody cover, meaning they were wooded grasslands or grasslands. Less than 1 percent of the samples reflected sites where tree cover exceeded 70 percent.

"Therefore, 'closed' forests (more than 80 percent woody cover) represent a very small fraction of the environments represented by these paleosols," the researchers write.

"We conclude there have been open savannas all the time for which we have hominin fossils in the environments where the fossils were found during the past 4.3 million years" ? the oldest fossils now accepted as human ancestors, Cerling says.

The researchers also created vegetation chronologies of the Awash Valley of Ethiopia and the Omo-Turkana Basin of Ethiopia and Kenya ? home to many fossils of human ancestors, including Ardipithecus, Australopithecus, Paranthropus and our own genus, Homo.

They found that during the past 7.4 million years, woody cover ranged from 75 percent (closed woodlands) down to 5 percent or less (open grasslands), but significant areas with woody cover below 40 percent (savanna woodlands to savanna grasslands) were consistently present.

University of Utah Public Relations
201 Presidents Circle, Room 308
Salt Lake City, Utah 84112-9017
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The last 3 million years at a snail's pace

Public release date: 4-Aug-2011
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Contact: David Garner
david.garner@york.ac.uk
44-019-043-22153
University of York

Scientists at the University of York, using an 'amino acid time capsule', have led the largest ever programme to date the British Quaternary period, stretching back nearly three million years.

It is the first widespread application of refinements of the 40-year-old technique of amino acid geochronology. The refined method, developed at York's BioArCh laboratories, measures the breakdown of a closed system of protein in fossil snail shells, and provides a method of dating archaeological and geological sites.

Britain has an unparalleled studied record of fossil-rich terrestrial sediments from the Quaternary, a period that includes relatively long glacial episodes ? known as the Ice Age --interspersed with shorter 'interglacial' periods where temperatures may have exceeded present day values.

However, too often the interglacial deposits have proved difficult to link to global climatic signals because they are just small isolated exposures, often revealed by quarrying..

Using the new method, known as amino acid racemization, it will be possible to link climatic records from deep sea sediments and ice cores with the responses of plants and animals, including humans, to climate change over the last three million years. The research is published in the latest issue of Nature.

The new method was developed by Dr Kirsty Penkman, of the Department of Chemistry, alongside Prof. Matthew Collins of the Department of Archaeology at York, and measures the the extent of protein degradation in calcareous fossils such as mollusc shells. It is based on the analysis of intra-crystalline amino acids ? the building blocks of protein --preserved in the fossil opercula (the little 'trapdoor' the snail uses to shut itself away inside its shell) of the freshwater gastropod Bithynia. It provides the first single method that is able to accurately date such a wide range of sites over this time period.

Dr Penkman said: "The amino acids are securely preserved within calcium carbonate crystals of the opercula. This crystal cage protects the protein from external environmental factors, so the extent of internal protein degradation allows us to identify the age of the samples. In essence, they are a protein time capsule.

"This framework can be used to tell us in greater detail than ever before how plants and animals reacted to glacial and interglacial periods, and has helped us establish the patterns of human occupation of Britain, supporting the view that these islands were deserted in the Last Interglacial period."

In a close collaboration with palaeontologist Dr. Richard Preece in the Department of Zoology at the University of Cambridge, the study examined a total of 470 fossil remains from 71 sites in the UK and three on continental Europe. The method proved highly reliable with more than 98 per cent of samples yielding useful results, resulting in the largest ever geochronological programme of the British Pleistocene.

Professor Collins said: "When we started this work 11 years ago, we thought it was going to be relatively straightforward to identify a good material for dating, but the first 3 years of research on shells showed that the stability of the mineral itself was vital. The tiny trapdoor of a snail proved to be the key to success."

Dr Preece added: "Luckily, fossil opercula are common in Quaternary sediments around the world, so the new technique can be used to build regional Ice Age chronologies everywhere, giving it enormous international scope".

Vital to the study were the inter-disciplinary collaborations with Quaternary scientists, the core team of which involved researchers at the Department of Geography, University of Durham; Institute of Archaeology and Antiquity, University of Birmingham; Institute of Archaeology, University College London; the Netherlands Centre for Biodiversity, Leiden and the Department of Palaeontology, The Natural History Museum.

The analyses were funded by English Heritage, Natural Environment Research Council and the Wellcome Trust. The research is a contribution to the Ancient Human Occupation of Britain (AHOB) project funded by the Leverhulme Trust.

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6 million years of African savanna

Public release date: 4-Aug-2011
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Contact: Cheryl Dybas
cdybas@nsf.gov
703-292-7734
National Science Foundation

Scientists using chemical isotopes in ancient soil to measure prehistoric tree cover--in effect, shade--have found that grassy, tree-dotted savannas prevailed at most East African sites where human ancestors and their ape relatives evolved during the past six million years.

"We've been able to quantify how much shade was available in the geological past," says University of Utah geochemist Thure Cerling, lead author of a paper titled "Woody cover and hominin environments in the past 6 million years" on the results in this week's issue of the journal Nature.

"It shows there have been open habitats for the last six million years in the environments in East Africa where some of the most significant early human fossils were found.

"Wherever we find human ancestors, we find evidence for open habitats similar to savannas--much more open and savanna-like than forested."

Scientists have spent a century debating the significance of open, savanna landscape in human evolution, including the development of upright walking, increased brain size and tool use.

Part of the problem has been an imprecise definition of "savanna," which has been used to describe "virtually everything between completely open grasslands and anything except a dense forest," Cerling says.

He adds that the most common usage is a fairly open, grassy environment with many scattered trees--a grassland or wooded grassland.

In the study, Cerling and colleagues developed a new way to quantify the openness of tropical landscapes. This is the first method to quantify the amount of canopy cover, the basis for deciding whether something is savanna.

The National Science Foundation (NSF) and the Leakey Foundation funded the study.

"The development of a paleo-shade proxy for soil temperature and woody cover, and its application to ancient fossil sites, reinforces the long-held theory that the roots of human origins are in the open grassland/savanna environments of East Africa," says H. Richard Lane, program director in NSF's Division of Earth Sciences.

Adds Kaye Reed of NSF's Division of Behavioral and Cognitive Sciences, "These investigators have done an amazing job of collecting modern comparative isotope and soil temperature samples to compare with paleosol [fossil soil] samples from hominin localities. Their newly developed method for calculating 'paleo-shade' is very innovative."

Cerling does not dispute that East African savannas became more expansive within the past two million years, or that human ancestors and relatives likely spent time in narrow "gallery forests" along river corridors.

But he says the new method shows that grasslands and wooded grasslands--savannas--have prevailed for more than six million years in the cradle of humanity, with tree cover less than about 40 percent at most sites.

By definition, woodland has more than 40 percent tree cover; forest has more than 80 percent tree cover.

"In some periods, it was more bushy, and other times it was less bushy," he says.

"Hardly anything could have been called a dense forest, but we can show some periods where certain environments were consistently more wooded than others.

"We find hominins in both places. How early hominins partitioned their time between 'more open' and 'more closed' habitats is still an open question."

Cerling says that even sparse woody canopy provided hominins with shade, some foods and refuge from predators.

Fossil evidence of hominins dates back 4.3 million years and possibly 6 million years, Cerling says. The new method was used to look for and find savanna up to 7.4 million years ago.

"Currently, many scientists think that before 2 million years ago, the region was forested, and that savanna conditions have been present only for the past 2 million years," Cerling says. "This study shows that during the development of bipedalism [about 4 million years ago] open conditions were present, even predominant."

Cerling conducted the study with biologists Samuel Andanje and David Kimutai Korir of the Kenya Wildlife Service; geologist Michael Bird of James Cook University, Cairns, Australia; University of Utah graduate students William Mace, Anthony Macharia and Christopher Remien; and Jonathan Wynn of the University of South Florida, Naomi Levin of Johns Hopkins University and Jay Quade of the University of Arizona.

The new method was developed by correlating carbon isotope ratios in 3,000 modern soil samples with satellite photos of tree and vegetation cover at 75 tropical sites worldwide--half in Africa--representing closed forest to open grassland.

That allowed scientists to determine the percent of tree and woody shrub cover millions of years ago based on carbon isotope ratios in fossil soils known as paleosols.

"This study is based on the geological axiom that the present is the key to the past," says Cerling. "We assume soils in the past had similar relationships to vegetation as what we observe today."

The researchers collected soil samples at Kenyan and Ethiopian sites and used published data on soil samples collected by others during the past decade at sites throughout the tropics.

Modern soil samples came from national parks and reserves and non-agricultural areas so that carbon isotope ratios reflected natural vegetation.

The ratio of rare carbon-13 to common carbon-12 in decayed plant material in soils reveals the extent to which the landscape was covered by plants that use what is known as the C3 pathway of photosynthesis, versus plants that use C4 photosynthesis.

Trees, shrubs, herbs, forbs and cool-season grasses are C3 plants, which include beans and most vegetables. C4 plants are warm-season or tropical grasses that dominate savannas, and plants called sedges. C4 plants have a higher ratio of carbon-13 than C3 plants.

The isotope composition of fossil soil gives a measure of the total makeup of the ecosystem in terms of how much was canopy versus how much was open landscape, Cerling says.

In a forest, even soil from open gaps shows the C3 signature because of non-woody C3 plants growing there, while on a savanna, soil from under a C3 tree will show the C4 signature because of grasses growing under the tree.

Cerling and colleagues used the new method to analyze fossil soils and infer plant cover back to 7.4 million years ago, a period that includes the time when human ancestors and apes split from a common ancestor.

Their analysis of 1,300 fossil soil samples from sites at or near where human ancestors and their relatives evolved shows that more than 70 percent of the sites had less than 40 percent woody cover, meaning they were wooded grasslands or grasslands. Less than one percent of the samples reflected sites where tree cover exceeded 70 percent.

"Therefore, 'closed' forests (more than 80 percent woody cover) represent a very small fraction of the environments represented by these paleosols," the researchers write.

"We conclude there have been open savannas all the time for which we have hominin fossils in the environments where the fossils were found during the past 4.3 million years--the oldest fossils now accepted as human ancestors," Cerling says.

The researchers also created vegetation chronologies of the Awash Valley of Ethiopia and the Omo-Turkana Basin of Ethiopia and Kenya--home to many fossils of human ancestors, including Ardipithecus, Australopithecus, Paranthropus and our own genus, Homo.

They found that during the past 7.4 million years, woody cover ranged from 75 percent (closed woodlands) down to 5 percent or less (open grasslands), but significant areas with woody cover below 50 percent (savanna woodlands to savanna grasslands) were consistently present.

Fossils of early humans and their ancestors and extinct relatives have been found in both wooded and open environments in East Africa.

Even 4.3-million-year-old Ardipithecus--which lived in the woods, according to its discoverers--had a small component of grasses or other C4 plants in its diet, says Cerling.

"The fact that it had this means it was going into the savanna," he says, "unless it was eating takeout food."

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Deadly medication?

Public release date: 19-Aug-2011
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Contact: Michael Hoeveler-Mueller
aegyptisches-museum@uni-bonn.de
49-228-739-710
University of Bonn

The corpus delicti is a plain flacon from among the possessions of Pharaoh Hatshepsut, who lived around 1450 B.C., which is on exhibit in the permanent collection of the Egyptian Museum of the University of Bonn. For three and a half millennia, the vessel may have held a deadly secret. This is what the Head of the collection, Michael H?veler-M?ller and Dr. Helmut Wiedenfeld from the university's Pharmacology Institute just discovered. After two years of research it is now clear that the flacon did not hold a perfume; instead, it was a kind of skin care lotion or even medication for a monarch suffering from eczema. In addition, the pharmacologists found a strongly carcinogenic substance. Was Hatshepsut killed by her medicine?

When Michael H?veler-M?ller became the curator of the Egyptian Museum of the University of Bonn in 2009, it occurred to him to examine the interior of the vessel that, according to an inscription, belonged to Pharaoh Hatshepsut. Its neck had been blocked with what was generally considered "dirt," but H?veler-M?ller suspected that it might also be the original clay stopper. So possibly, some of the original contents might still be inside. In Dr. Helmut Wiedenfeld from the Pharmacy Institute, he found just the right partner, to get to the bottom of this question and of the flacon.

At the Radiology Clinic of the Bonn Universit?tsklinikum, the flacon was subjected to a CAT scan. Here, the Egyptologist's suspicion was confirmed ? not only was the closure intact, but the vessel also held residue of a dried-up liquid. In the summer of 2009, Professor Dr. Friedrich Bootz from the Klinik und Poliklinik f?r Hals-, Nasen- und Ohrenheilkunde (laryngology, rhinology and otology) of the University of Bonn took samples, using an endoscope.

Too greasy for perfume

This allowed Dr. Wiedenfeld and his team to analyze the old substances for their ingredients. And it became obvious very quickly that what they had found was not dried-up perfume. The mix contained large amounts of palm oil and nutmeg apple oil. "I didn't think anybody would put so much grease on her face," said Dr. Wiedenfeld. "That would make her look as greasy as a plate of ribs." Two additional components clued the pharmacologist in to the actual purpose of the mix, "We found a lot of unsaturated fatty acids that provide relief for people with skin diseases." And this is where the Egyptologist was able to add another piece of the puzzle, "It is indeed known that there were cases of skin disease in Hatshepsut's family." Inflammatory skin diseases such as psoriasis have a largely genetic component.

And the third group of ingredients also points to the fact that this substance was not about providing a nice fragrance, but instead, for fighting a big itch ? the pharmacologists found a lot of hydrocarbons derived from creosote and asphalt. To this day, creams containing creosote are used to treat chronic skin diseases. Due to the potentially carcinogenic effects of some of its ingredients, creosote has meanwhile been banned from cosmetics completely, and medications containing creosote are now prescription-only.

What the pharmacologists detected in Hatshepsut's little bottle was in particular benzo(a)pyrene, a hazardous aromatic hydrocarbon consisting of several carbon rings. "Benzo(a)pyrene is one of the most dangerous carcinogenic substances we know," explained Dr. Wiedenfeld. For example, the risk of contracting lung cancer from cigarette smoke results essentially from this substance.

Did the lotion cause the Pharaoh's death from cancer?

Did Hatshepsut maybe poison herself without knowing it? "There is a lot that speaks for this hypothesis," Dr. Wiedenfeld said. "If you imagine that the Queen had a chronic skin disease and that she found short-term improvement from the salve, she may have exposed herself to a great risk over the years." The Egyptologist also thinks that this is very likely. "We have known for a long time that Hatshepsut had cancer and maybe even died from it," said Michael H?veler-M?ller. "We may now know the actual cause."

But at this point, the Bonn scientists can only surmise how Hatshepsut obtained her lotion. "Egyptian physicians were general practitioners and good surgeons, but they were lousy internists," explained Dr. Wiedenfeld. "It is quite possible that they owe their knowledge of certain medications to their contacts with Persia and India where the healing arts were very advanced even in Antiquity."

For photos regarding this press release, please go to: http://www3.uni-bonn.de/Pressemitteilungen/236-2011

Contact:

Michael H?veler-M?ller
?gyptisches Museum der Universit?t Bonn
Tel.: 0228/73-9710
aegyptisches-museum@uni-bonn.de

Dr. Helmut Wiedenfeld
Pharmazeutisches Institut der Universit?t Bonn
(abroad starting on 22 August)
Email: wiedenfeld@uni-bonn.de

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The Sign of an Advancing Society? An Organized War Effort

A wave of new research is supporting this second view. Charles Stanish and Abigail Levine, archaeologists at the University of California, Los Angeles, have traced the rise of the pristine states that preceded the Inca empire. The first villages in the region were formed some 3,500 years ago. Over the next 1,000 years, some developed into larger regional centers, spaced about 12 to 15 miles apart. Then, starting around 500 B.C., signs of warfare emerged in the form of trophy heads and depictions of warriors, the two archaeologists report in last week’s Proceedings of the National Academy of Sciences.

One of the regional centers, Taraco, was destroyed in the first century A.D., probably by forces from Pukara, the other principal regional center of the area. Pukara enjoyed its status as a pristine state until about 500, when it was absorbed by Tiwanaku, the principal state on the other side of the Lake Titicaca basin.

A similar process of an early state’s arising from warring chiefdoms has been described in the Oaxaca Valley of Mexico by Kent V. Flannery and Joyce Marcus, archaeologists at the University of Michigan. By 4,500 years ago, there were some 80 villages in the valley. As population increased, a period of intense warfare lasted from 2,450 to 2,000 years ago, culminating in the victory of one town over all the others in the valley and the formation of the Zapotec state.

With the same process now documented in both North and South America, “we are coming closer to having a model for pristine state formation that may have worldwide significance,” Dr. Marcus said. “It also shows that our species, when thrust into almost identical circumstances, behaves in almost identical ways.”

Dr. Stanish believes that warfare was the midwife of the first states that arose in many regions of the world, including Mesopotamia and China as well as the Americas.

The first states, in his view, were not passive affairs driven by forces beyond human control, like climate and geography, as some historians have supposed. Rather, they were shaped by human choice as people sought new forms of cooperation and new institutions for the more complex societies that were developing. Trade was one of these cooperative institutions for consolidating larger-scale groups; warfare was the other.

Warfare may not usually be thought of as a form of cooperation, but organized hostilities between chiefdoms require that within each chiefdom people subordinate their individual self-interest to that of the group.

“Warfare is ultimately not a denial of the human capacity for social cooperation, but merely the most destructive expression of it,” the anthropologist Lawrence H. Keeley writes in his book “War Before Civilization” (Oxford, 1996).

Compared with other species, humans are highly cooperative and altruistic, at least toward members of their own group. Evolutionary biologists have been hard pressed to account for this self-sacrificing behavior, given that an altruist who works for the benefit of others will have less time for his family’s interests and leave fewer surviving children. Genes for altruistic behavior should therefore disappear.

Darwin’s solution to this riddle was that groups of altruists would prevail over less cohesive groups. This implies that natural selection can operate on groups, not just individuals, a thesis that many biologists reject.

But group-level selection is more likely to operate the fiercer the competition is between groups. Samuel Bowles, an economist at the Santa Fe Institute, believes warfare between early human groups was intense, and explains the very slow growth of population prior to 20,000 years ago.

Warfare “may have contributed to the spread of human altruism,” he and his colleague Herbert Gintis write in their new book, “A Cooperative Species”(Princeton, 2011). “We initially recoiled at this unpleasant and surprising conclusion. But the simulations and the data on prehistoric warfare tell a convincing story.”

Archaeology lends some support to the idea. “Groups that successfully organize themselves to raid others will acquire external resources and, in the long run, will be at a selective advantage against groups that are less well organized,” Dr. Stanish and Dr. Levine write of their findings in the Central Andes.

“Both war and trade are sources of outside wealth,” Dr. Stanish said in an interview. The leaders of early states had to keep people working. They relied on religious rituals to organize the labor force and material inducements from war and trade to satisfy the elite.

As the population in a region grew larger and richer, regional chiefdoms would form and start raiding one another for plunder. “Once this kicks in, it sets up a dynamic in which it’s hard to be peaceful,” Dr. Stanish said. “You either organize on a regional level or get killed or absorbed.”

Of the regional chiefdoms that start a war for dominance, all but one will perish before the pristine state is formed. So why not form nonaggression pacts rather than take such a gamble?

Dr. Marcus suggests two reasons. One is that human social skills evolved in the small hunter-gatherer groups in which everyone lived until 15,000 years ago. “When humans try to run larger and more complex societies, with hereditary inequality, they are pushing their sociopolitical skills to the utmost,” Dr. Marcus said.

Another reason is that elites who run chiefly societies “are very aggressive and competitive — they assassinate rivals even when they are siblings or half-siblings,” Dr. Marcus said. “Competitive interaction is one of the most powerful driving forces in evolution, whether biological or social.”

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Ancient whale skulls and directional hearing: A twisted tale

Public release date: 23-Aug-2011
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Contact: Cheryl Dybas
cdybas@nsf.gov
703-292-7734
National Science Foundation

Skewed skulls may have helped early whales find the direction of sounds in water and are not solely, as previously thought, a later adaptation related to echolocation.

Scientists affiliated with the University of Michigan and funded by the National Science Foundation (NSF) report the finding in a paper published online this week in the journal Proceedings of the National Academy of Sciences.

Asymmetric skulls are a well-known characteristic of the modern whale group known as "odontocetes" or toothed whales.

These whales also have highly modified nasal structures with which they produce high-frequency sounds for echolocation--a sort of biological sonar used to navigate and find food.

The other modern whale group, "mysticetes" or baleen whales, has symmetrical skulls and does not echolocate.

These observations led scientists to believe that archaeocetes--the extinct, ancient whales that gave rise to all modern whales--had symmetrical skulls, and that asymmetry later developed in toothed whales in concert with echolocation, according to H. Richard Lane, program director in NSF's Division of Earth Sciences, which funded the research.

But a new analysis of archaeocete skulls by University of Michigan paleontologist Julia Fahlke and coauthors shows that asymmetry evolved much earlier, as part of a suite of traits linked to directional hearing in water.

"This means that the initial asymmetry in whales is not related to echolocation," said Fahlke, who is working with scientist Philip Gingerich at the University of Michigan Museum of Paleontology.

Fahlke intended to study a completely different aspect of whale evolution: tooth form and function.

"Modern whales don't chew their food," Fahlke said. "Toothed whales just bite it and swallow it, and baleen whales filter-feed. But archaeocetes have characteristic wear patterns on their teeth that show that they've been chewing their food."

By studying those wear patterns, she hoped to piece together how and what early whales ate and how their eating habits changed over time.

She started by studying the skull of Basilosaurus isis, a serpent-like, predatory whale that lived 37 million years ago, using a three-dimensional digital model generated from CT scans of the fossil that were acquired at the University of Michigan Medical School D epartment of Radiology.

The actual skull on which the model was based was asymmetrical, but Fahlke and colleagues at first dismissed the irregularity.

"We thought, like everyone else before us, that this might have happened during burial and fossilization," Fahlke said.

"Under pressure from sediments, fossils often deform."

To correct for the deformation, coauthor Aaron Wood of the University of Florida straightened out the skull in the digital model.

But when Fahlke began working with the "corrected" model, the jaws just didn't fit together right. "Finally it dawned on me: maybe archaeocete skulls really were asymmetrical," she said.

Fahlke began examining archaeocete skulls, and to her astonishment, "they all showed the same kind of asymmetry--a leftward bend when you look at them from the top down," she said.

To study the asymmetry in a more rigorous way, Fahlke and colleagues selected six well-preserved skulls that showed no signs of artificial deformation and measured their deviation from a straight line drawn from snout to back of skull.

For comparison, they made similar measurements of the symmetrical skulls of artiodactyls, the group of terrestrial mammals from which whales evolved.

"Taken together, the six skulls deviate significantly from symmetry," Fahlke said. "Taken individually, four of them deviate significantly."

The other two appear asymmetrical, but their measurements fall within the range of the symmetrical comparative sample.

"This shows that asymmetry existed much earlier than previously thought--before the baleen whales and toothed whales split," Fahlke said.

"This means that the earliest baleen whales must have had asymmetrical skulls, which later became symmetrical."

The authors also show in their paper that archaeocete asymmetry is a three-dimensional torsion, or twist that affects the whole skull, rather than only a two-dimensional bend.

Interestingly, archaeocetes have structures similar to those that are known in toothed whales to function in directional hearing in water: fat bodies in their lower jaws that guide sound waves to the ears, and an area of bone on the outside of each lower jaw thin enough to vibrate and transmit sound waves into the fat body.

This adaptation, along with the acoustic isolation of the ear region from the rest of the skull, appears to have evolved in concert with asymmetry.

The link between asymmetry and directional hearing is not unique to whales, Fahlke said.

"Owls have asymmetrical ear openings, which help them discriminate the rustling of leaves from the rustling of a mouse," Fahlke said.

"Such ability would also be helpful when you're trying to detect prey in the water, so we interpret that the same kind of mechanism was operating for archaeocetes."

In addition to Fahlke, Gingerich and Wood, the paper's authors include Robert Welsh of the University of Michigan Medical School.

Funding was also provided by the Alexander von Humboldt Foundation and the National Geographic Society.

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Adovasio continues underwater search for new frontier

Public release date: 8-Aug-2011
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Contact: Debbie Morton
dmorton@mercyhurst.edu
814-824-2552
Mercyhurst College

After two years of painstakingly searching for targets, a team of dedicated researchers believes it is within striking distance of uncovering cultural evidence of early human occupation in the now submerged continental shelf of the eastern Gulf of Mexico.

The expedition of the National Oceanic and Atmospheric Administration (NOAA) Office of Ocean Exploration and Research commenced off the Florida coast in the summer of 2008 when a distinguished group of scientists led by Mercyhurst College archaeologists James M. Adovasio and C. Andrew Hemmings identified and mapped buried river channels that could potentially help document the late Pleistocene landscape. In the summer of 2009, they further traced the river systems along whose beaches prehistoric people may have populated and identified raw materials that they may have used in tool-making.

This summer, using sophisticated sub-bottom profiling and side-scan sonar technology, divers will return to these previously identified high-potential locations with an airlift dredge to remove the sediment apron and attempt to excavate archaeological materials. The third installment of the NOAA-funded expedition ? "Exploring the Submerged New World 2011" ? is slated for Aug. 9-18. (The underwater expedition did not proceed in the summer of 2010 due to the BP Oil disaster and related concerns.)

"We understand the prehistoric landscape far better than we did when we started and we have fine-tuned our methods and our technology to put us in the best position to recover enough data both artifactually and in plant and animal remains to get a sense of what life may have been like along these now submerged coastlines," Adovasio said. "We stand at the threshold of discovering lifestyles that may not have a parallel in the archaeological record of North America because they are underwater and never before seen."

Adovasio, best known for his work at the pre-Clovis Meadowcroft Rockshelter in southwestern Pennsylvania that revealed human artifacts dating back 14,000 to 16,000 years, has stood at the vanguard of First Americans studies for decades. The opportunity to extend his reach from the terrestrial to the nautical comes with the recognition that as far back as 22,000 years ago a substantial portion of Earth's water was in the form of glacial ice atop the continents. Today, he said, more than 9 million square miles of what used to be coastlines around the world are underwater and may well represent the first chapter in the peopling of the Americas.

Hemmings, one of the leading Paleoindian underwater archaeologists in North America, is optimistic about this summer's project.

"My feeling is, given a little time to probe the sediments with a dredge, we will find human artifacts," he said.

In addition to Adovasio and Hemmings, the research team includes Dr. Thomas Loebel of the University of Illinois-Chicago Circle and six graduate students from colleges and universities across the U.S., among them Ben Wells and Kimberly Smith, who earned their undergraduate degrees at Mercyhurst. The expedition will also include a NOAA Teacher-at-Sea, Steven Allen.

Besides NOAA, the operation is funded by Mercyhurst College, much of the latter institution's commitment in in-kind services. The research vessel and crew are leased through the University of South Florida.

Adovasio has made multiple presentations on the expedition's progress in the past year, including an address to The Smithsonian Associates, Washington, D.C., as part of a program on "Underwater Settlements: Our New Frontier;" and at the 76th Annual Meeting of the Society for American Archaeology, Sacramento, Calif. Adovasio and Hemmings also presented a paper titled "The Inundated Landscape from Florida's West Coast to the LGM Shoreline: Recent Investigations of Buried Features and Potential Early Human Site Locations" at the Bureau of Ocean Energy Management, Regulation and Enforcement (BOEMRE) meetings in New Orleans, La.

For more information, please visit: http://mai.mercyhurst.edu/new-world/

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