3 Diseases We May Be Able to Blame on Our Ancient Ancestors

The ADHD children of the world may have their wandering ancestors to blame. A genetic variant associated with impulsivity, novelty seeking, and attention deficit hyperactivity disorder (ADHD) might have actually been adaptive in nomadic populations, according to a a recent study by Dan Eisenberg at Northwestern University. Kenyan nomads with this variant, he says, may have been better at searching for food and defending their resources, giving them a survival advantage. But the study shows that the nomads’ settled descendants who carried this gene were more often malnourished than those without the gene. “Just because we don’t see a trait as being currently advantageous,” Eisenberg says, “does not preclude the trait from having had a function in the past.” Geneticists continue to unravel our ancestral evolution in hopes of better understanding how formerly advantageous genes have led to modern-day health problems.
High Blood PressureHigh blood pressure may be caused by a gene that was key to nomadic survival. The ability to retain salt—controlled in part by a gene called CYP3A5—varies by latitude, according to scientists at the University of Chicago. The closer a population lives to the equator, the better individuals are at retaining salt. “Since hunter-gatherers weren’t assured of getting sodium every day, they needed to be sure not to lose what they did acquire,” says Alan Weder, a hypertension specialist. But bring this gene to a modern setting—with couch lounging and salty snacking—and it is easy to retain more salt than is needed, which can lead to medical problems like high blood pressure.

3 Diseases We May Be Able to Blame on Our Ancient Ancestors
Obesity, lactose intolerance, and high blood pressure may all be traceable to hunter-gatherer survival. by Emily Anthes. Source: Discover Science,Technology and the Future. 8/1/09

Life on Earth got bigger in 2-million-fold leaps, our feet had to start somewhere!

Extremes are exciting. Does anyone really think dinosaurs would capture our imagination the way they do if they hadn't been so huge? You don't see natural history museums vying for fossil skeletons of prehistoric rodents. It's the Tyrannosaurus rex fossils they salivate and squabble over. And would the Hollywood glitterati cart around those little teacup pups if they weren't so dang tiny and cute? Not likely.
Earth's creatures come in all sizes, yet they (and we) all sprang from the same single-celled organisms that first populated the planet. So how on Earth did life go from bacteria to the blue whale?
"It happened primarily in two great leaps, and each time, the maximum size of life jumped up by a factor of about a million," said Jonathan Payne, assistant professor of geological and environmental science at Stanford.
Payne, along with a dozen other paleontologists and ecologists at 10 different research institutions, pooled their existing databases, combed the scientific literature and consulted with taxonomic experts in a quest to determine the maximum size of life over all of geological time.
That might sound like a rather large undertaking, but, fortunately, the quest was made easier because even the professionals have a fascination with the size of the fossilized.
"The nice thing about maximum size is that people tend to remark on very large fossils, so they are much easier to track down in the geologic literature than anything else," Payne said.
In addition to quantifying the enormity of the two leaps in maximum size, the researchers also pinned down when those leaps took place. Both leaps coincided with periods when there was a major increase in the amount of oxygen in the atmosphere.
Payne said that many researchers already recognized, in a qualitative way, that the change in maximum size had occurred this way. "But our study really reflects the first time that anybody has tried to quantify exactly how stepwise it was and how big those size jumps were," he said.
A paper detailing the research by Payne and his colleagues is scheduled to be published in the Dec. 22, 2008, online early edition of the Proceedings of the National Academy of Sciences and is available online through EurekAlert.
The two other principal investigators of the research group, funded through the National Evolutionary Synthesis Center, are Michal Kowalewski of Virginia Tech and Jennifer Stempien of the University of Colorado-Boulder.
So how did it all happen? The first fossilized bacterial cells date to approximately 3.4 billion years ago, although life likely originated several hundred million years before. Between 2.7 and 2.4 billion years ago, cyanobacteria, formerly known as blue-green algae, originated and were of particular evolutionary and geological importance because they excrete oxygen as a waste product during photosynthesis. So far as science can tell, they were the first and only organisms to evolve oxygen-producing photosynthesis.
"All of the oxygen in the atmosphere ultimately exists because of the evolution of cyanobacteria," Payne said. "Plants that produce oxygen today during photosynthesis, their ability to do that is ultimately derived from cyanobacteria."
Single-celled bacteria remained the largest life form on Earth, cranking out the oxygen, until about 1.6 billion years ago. At that point, a new life form shows up in the fossil record.
"The first jump in maximum size happens when the first eukaryotic organisms show up as fossils," Payne said. "And those fossils are approximately a million times bigger than anything that had come before on Earth."
Although the first fossil eukaryotes were likely also single-celled organisms, the eukaryotes distinguish themselves by means of their internal structure and functioning. Instead of having the cellular processes of life take place by means of diffusion in the cell, eukaryotes have organized innards, with a nucleus and other cellular structures that are dedicated to specific functions in the respiratory process.
"The fossil record indicates pretty clearly that you need a eukaryotic cell to make that first size jump," Payne said. "It isn't just that the bacteria don't get there as fast, it is that bacteria still haven't gotten there 1.6 billion years later.
"Clearly, organismal organization matters," Payne said. "Not just at the time the size increase happens, but it continues to be a limitation on size.
For approximately the next billion years, life on Earth stayed about the same size, with only modest increases. Then about 600 million years ago, at the same time as another major boost in the amount of oxygen in the atmosphere, life leaped in size again.
This time, it was a million-fold size leap of multi-cellularity. Payne said there are clearly multi-cellular eukaryotes in the fossil record for several million years before this size leap, but the real explosion of size increase didn't happen until the oxygen level bumped up.
So why do the size leaps seem to hinge on the amount of oxygen in the air?
"There are a few things that could be going on," Payne said. "The first thing is that eukaryotic cells require oxygen for metabolism. So if they want to take organic matter and burn it up to have energy in their cell, they need oxygen. That sets the first and probably most important limitation."
Payne said this limitation also applies to multi-cellular eukaryotes, which likewise depend on extracting oxygen from the surrounding environment and using that in their cells to obtain energy. "There is also evidence that oxygen may mediate some other biochemical processes," he said.
As for just what triggered both the boosts in atmospheric oxygen, Payne said that isn't quite as clear. It may be that the first jump in oxygen came because cyanobacteria simply proliferated to the point that they were cranking out more oxygen than could be consumed through chemical reactions with material at Earth's surface, the only way that oxygen wouldn't have been released back into the atmosphere in the era before oxygen breathing creatures existed.
The possible causes of the second jump in oxygen are less clear, Payne said, but regardless of the puzzles that remain to be sorted out, the timing and magnitude of the jumps up in maximum size are clear. And Payne said the size jumps applied to a vast number of species.
"Whatever is controlling this second size increase appears to operate across many different groups. It is not something limiting one group alone," he said. "There also appears to be an increase even in the maximum size of groups of organisms like multi-cellular algae, so the size increase doesn't appear to be limited just to animals."
One other question remains to be answered: Can we look forward to another great leap in size? Will we see housecats larger than our houses?
"We've speculated on that a little bit, just sort of thinking about what if you went up another step," Payne said.
"The next level of organization, going along this kind of theme, presumably would be something like insect societies, where you have individual multicellular eukaryotes that specialize in terms of what kind of function they carry out in a larger organization of these individuals. Something like an ant colony or a human society would be in some ways the next organizational level.
"But, if you look at human society as an example, we use so much of the gross primary productivity on Earth, it doesn't appear there would be room for a lot of species at that next level of organization and maximum size. At that point you're actually getting towards the physical size limits just imposed by the size of our planet."

Source:Eurekalert 23/12/08.

Gibbon feet provide model for early human walking.

Scientists at the University of Liverpool have found that early humans could have walked successfully on a ‘flexible’ flat foot, similar to modern day gibbons.The arched ‘rigid’ foot of modern humans – thought to have appeared approximately 1.8 million years ago – is best adapted for upright walking, but scientists have found that early humans once had ‘flexible’ feet and could have walked on the ground some years earlier. Scientists originally thought that a flexible foot could have been ‘restrictive’ for humans learning to walk upright as it lacked the necessary power to push off the ground. To understand the mechanisms of the flexible foot, scientists studied the movements of gibbons – small apes living in the rainforest of South East Asia – which walk upright both on the ground and in the trees.Dr Evie Vereecke, from the University’s School of Biomedical Sciences, explains: “Gibbons have a flexible joint mid-way along the foot that supports them in walking and climbing. Human ancestors also had this joint for tree dwelling and ground walking, but modern humans have now lost its flexibility in favour of a ‘rigid’ foot. “To understand how successful or ‘restrictive’ the flexible foot might have been for early humans we set up a high-speed camera at Belgium’s Wild Animal Park to capture the gibbon’s foot movements. We built a computer model to digitise the footage we collected so that we could analyse the mechanisms employed in the foot and compare it to how humans walk today. “We found that gibbons hit the ground with their toes first, similar to the ‘forefoot’ strike of professional sprint runners, which stretches the tendons in the toes. We also found that instead of lifting the foot at the end of a stride, the gibbon raised its heel first, making an upward arch and stretching the tendons in the sole of the foot.“These stretched tendons allow storage of elastic energy and once the toe leaves the ground the tendons in the foot recoil, releasing the stored energy and generating the necessary propulsion to push off the ground and walk upright quite successfully. “The structure of the modern human foot is different to the gibbon, but the energy storage mechanism is similar. The human foot is spanned by an elastic band along its sole which is stretched when we put our weight on it and stores elastic energy ready for release when the foot leaves the ground.”The work - published in the Journal of Experimental Biology - shows that it is possible that human ancestors could have walked successfully with an upright-gait on a ‘flexible’ flat foot and may have similar energy storage mechanisms to modern humans.

Source:The University of Liverpool 17/12/08.

The enigma of Lake Ontario's 11,000-year-old footprints.

In the fall of 1908, while building a waterworks tunnel east of Hanlan's Point in Toronto Bay, a work crew came across 100 footprints in a layer of blue clay. The prints appeared to have been left by people wearing moccasins – 11,000 years ago.
It was an astounding discovery, perhaps the first evidence of human habitation on Lake Ontario, but few recognized its significance.
"It looked like a trail ...," city inspector W. H. Cross told the Toronto Evening Telegram about what he saw that November day. "You could follow one man the whole way. Some footprints were on top of the others, partly obliterating them. There were footprints of all sizes, and a single print of a child's foot, three and a half inches..."
He went on to describe the way the clay had shot up under the imprints of the heels, how the prints appeared to be heading north, and how he had tried to lift a piece of the clay to preserve the prints, but it broke away in his hand.
The group – likely a family, judging by the different sized prints – could have been walking from a hunting camp on the shore of Lake Ontario to what is now downtown Toronto. Back then, the shoreline would have been more than a kilometre further south.
The story is told in a new book, Toronto: A Short Illustrated History of its First 12,000 Years, which, unlike most others that look at Toronto's past, begins at the very beginning, before recorded history. Tragically, the prints were not preserved. The tunnel workers were in a hurry to complete the job, and simply poured concrete over the clay.
"If they were found to be authentic, it would have been the only discovery of footprints of the first people of Ontario," says archaeologist Ron Williamson, who edited the book and wrote the chapter on pre-European contact. "It would have been amazing."
Though it seems shocking that a find of such potential importance was unceremoniously buried, a similar attitude toward the archaeological history of First Nations people prevails, he says.
"The fact that it was almost immediately destroyed ... I can't tell you how many times, even today, construction crews make the same argument when something significant is found: They have no time for this, they have to get going."
Without seeing the prints, it's difficult to evaluate their authenticity, Williamson says, though there's no reason to believe that Cross and company were exercising a hoax.
Hunters pursuing caribou, mastodon or mammoth were known to inhabit the shoreline, then a landscape of spruce forest and tundra, similar to Canada's sub Arctic.
Mammoth remains have been found in Toronto, most notably during excavation for the former Eaton's College Street department store at College and Yonge Sts., and at Christie Pits.
Archaeologists have found 11,000-year-old spear points east of Buffalo with mastodon bone that appear to have been shaped into tools.
The Toronto Daily Star, in fierce competition with the Toronto Telegram, also reported on the footprints story, but dismissed it. At the turn of the 19th century, it was wrongly believed that the clay in which the footprints were found dated to more than 100,000 years.
One expert consulted by the Daily Star said that since the shale was there long before man arrived, the source of the prints was not early hunters but more likely "a lobster-like animal."
"Now that we know it was only 11,000 years ago," says Williamson, "it's much more sensible."
Along with exploring the footprint mystery, the book also contains essays by local historians: Robert MacDonald on Toronto's natural history, Carl Benn on colonial transformations, and Christopher Andreae on the city's industrial development.
Roger Hall's concluding essay brings Toronto into the 21st century, with observations on the nature of the modern city, unrecognizable to the travellers whose footprints were revealed under Lake Ontario.
After World War II, Toronto was no longer the "introverted capital" it had been in 1939. The arrival of manufacturing and newcomers from southern Europe and Asia led to a strengthening economy and new cultural vibrancy. Still, Toronto was not a world-class city.
"Flattering, at least to some, but not true," Hall writes.
It was not as ancient as Delhi or, like Beijing, trying to invent itself in the modern world.
Nor was it a global power broker, like New York.
"What it was," Hall writes, "was something more attractive to most of the world's inhabitants: safe, prosperous, predictable, substantial, decent. In short, it was a good place to live in a country that could boast the same qualities."

Source: TheStar.com 30/11/08 ; credit:Leslie Scrivener.

Pelvis reflects "intelligence" of H.erectus.

Pelvis dated to 1.2 million years ago shows our ancestors were born with bigger heads.

A recently discovered female pelvis is changing minds about the head size of an ancient human ancestor, Homo erectus, and consequently revising notions about how smart they may have been. Found in Gona, Ethiopia, not far from the site that yielded the 3.2 million year old remains of the famed Australopithecus afarensi "Lucy," the pelvis indicates that Homo erectus, which lived in Africa roughly 2 million years ago, had a larger birth canal than originally suspected and could have given birth to babies with bigger brains.
Before the female pelvis was found, evidence from the pelvis of a juvenile male led researchers to project that the cranial circumference and capacity of newborn Homo erectus babies was 30 percent smaller than more recent projections based on the newly discovered pelvis.
Sileshi Semaw, a paleoanthropologist at the Stone Age Institute and Indiana University-Bloomington, and his colleagues assert that the head of a baby born from this Homo erectus could have been 318 millimeters in circumference. This is at the lower end of the spectrum of modern day human beings whose cranial circumferences at birth typically range from 320-370 millimeters. Semaw and colleagues present their findings in the Nov. 14 issue of Science. The research is funded in part by the National Science Foundation.

Zina Deretsky, NSF

Source :Eurekalert 15/11/08

Prehistoric pelvis offers clues to human development

A reconstruction of the 1.2 million-year-old pelvis discovered in 2001 in the Gona Study Area at Afar, Ethiopia, that has led researchers to speculate early man was better equipped than first thought to produce larger-brained babies. The actual fossils remain in Ethiopia.

Credit: Scott W. Simpson, Case Western Reserve University.

Discovery of the most intact female pelvis of Homo erectus may cause scientists to reevaluate how early humans evolved to successfully birth larger-brained babies. "This is the most complete female Homo erectus pelvis ever found from this time period," said Indiana University Bloomington paleoanthropologist Sileshi Semaw. "This discovery gives us more accurate information about the Homo erectus female pelvic inlet and therefore the size of their newborns."
A reconstruction of the 1.2 million-year-old pelvis discovered in 2001 in the Gona Study Area at Afar, Ethiopia, that has led researchers to speculate early man was better equipped than first thought to produce larger-brained babies. The actual fossils remain in Ethiopia.
The discovery will be published in Science this week (Nov. 14) by Semaw, leader of the Gona Project in Ethiopia, where the fossil pelvis was discovered with a group of six other scientists that includes IU Department of Geosciences graduate student Melanie Everett.
Reconstructing pelvis bone fragments from the 1.2 million-year-old adult female, Semaw and his co-workers determined the early ancestor's birth canal was more than 30 percent larger than earlier estimates based on a 1.5-million-year-old juvenile male pelvis found in Kenya. The new female fragments were discovered in the Gona Study Area in Afar, Ethiopia, in 2001 and excavation was completed in 2003.
Scientists also were intrigued by other unique attributes of the specimen, such as its shorter stature and broader body shape more likely seen in hominids adapted to temperate climates, rather than the tall and narrow body believed to have been efficient for endurance running.
Early humans became taller and narrower over time, scientists believe, partly due to long distance running and to help them maintain a constant body temperature. One consequence, however, is that a narrower pelvis would have been less accommodating to producing larger-brained offspring.
But rather than a tall, narrow hominid with the expected slight pelvic region, Semaw and the Gona researchers found evidence of a hominid ready to produce offspring with a much larger brain size.
"The female Homo erectus pelvic anatomy is basically unknown," Semaw said. "And as far as the fossil pelvis of ancestral hominids goes, all we've had is Lucy (dated at 3.2 million years and also found in Ethiopia), and she is very much farther back in time from modern humans."
Scientists studying early man predominantly find fragments of craniums and dental remains, while fossil bones from the neck down are rarely discovered. Even more difficult to verify are Homo erectus fossil bones that can be identified as those belonging to a female.
Scientists had thought early adult Homo erectus females, because of the assumed small birth canal, would produce offspring with only a limited neonatal brain size. These young would have then experienced rapid brain growth while still developmentally immature, leading researchers to envision a scenario of maternal involvement and child-rearing on par with that of modern humans. But those theories had been based upon extrapolations from the existing male skeleton from Kenya.
"This find will give us far more accurate information," Semaw said. Semaw is also a research scientist at the Stone Age Institute, a research center near Bloomington dedicated to the study of early human evolution and culture. It is affiliated with Indiana University's CRAFT, the Center for Research into the Anthropological Foundations of Technology.
Gona has turned out to be a productive dig site for Semaw. In 1997 Semaw and colleagues reported the oldest known stone tools used by ancestral humans. Then in 2004 he coauthored a paper summarizing Gona's geological properties and the site's cornucopia of hominid fossils spanning several million years. At the time, Science gave the article an "Editor's Choice" recognition. In 2005 he and colleagues published an article in Nature announcing the discovery of Ardipithecus ramidus, one of the earliest ancestral hominids, dating between 4.3 and 4.5 million years ago.

Source: Eurekalert 14th Nov 2008

Skeleton of 12,000-year-old shaman discovered buried with leopard, 50 tortoises and human foot

Credit :Naftali Hilger.

The skeleton of a 12,000 year-old Natufian Shaman has been discovered in northern Israel by archaeologists at the Hebrew University of Jerusalem. The burial is described as being accompanied by "exceptional" grave offerings - including 50 complete tortoise shells, the pelvis of a leopard and a human foot. The shaman burial is thought to be one of the earliest known from the archaeological record and the only shaman grave in the whole region.
Dr. Leore Grosman of the Institute of Archaeology at the Hebrew University, who is heading the excavation at the Natufian site of Hilazon Tachtit in the western Galilee, says that the elaborate and invested interment rituals and method used to construct and seal the grave suggest that this woman had a very high standing within the community. Details of the discovery were published in the PNAS journal on November 3, 2008.

What was found in the shaman's grave?

The grave contained body parts of several animals that rarely occur in Natufian assemblages. These include fifty tortoises, the near-compete pelvis of a leopard, the wing tip of a golden eagle, tail of a cow, two marten skulls and the forearm of a wild boar which was directly aligned with the woman's left humerus.
A human foot belonging to an adult individual who was substantially larger than the interred woman was also found in the grave.
Dr. Grosman believes this burial is consistent with expectations for a shaman's grave. Burials of shamans often reflect their role in life (i.e., remains of particular animals and contents of healing kits). It seems that the woman was perceived as being in close relationship with these animal spirits.

Method of burial

The body was buried in an unusual position. It was laid on its side with the spinal column, pelvis and right femur resting against the curved southern wall of the oval-shaped grave. The legs were spread apart and folded inward at the knees.
According to Dr. Grosman, ten large stones were placed directly on the head, pelvis and arms of the buried individual at the time of burial. Following decomposition of the body, the weight of the stones caused disarticulation of some parts of the skeleton, including the separation of the pelvis from the vertebral column.
Speculating why the body was held in place in such a way and covered with rocks, Dr. Grosman suggests it could have been to protect the body from being eaten by wild animals or because the community was trying to keep the shaman and her spirit inside the grave.
Analysis of the bones show that the shaman was 45 years old, petite and had an unnatural, asymmetrical appearance due to a spinal disability that would have affected the woman's gait, causing her to limp or drag her foot.

Fifty tortoises

Most remarkably, the woman was buried with 50 complete tortoise shells. The inside of the tortoises were likely eaten as part of a feast surrounding the interment of the deceased. High representation of limb bones indicates that most tortoise remains were thrown into the grave along with the shells after consumption.
The recovery of the limb bones also indicates that entire tortoises, not only their shells, were transported to the cave for the burial. The collection of 50 living tortoises at the time of burial would have required a significant investment, as these are solitary animals. Alternatively, these animals could have been collected and confined by humans for a period preceding the event.
Shaman graves in archaeology
According to Dr. Grosman, the burial of the woman is unlike any burial found in the Natufian or the preceding Paleolithic periods. "Clearly a great amount of time and energy was invested in the preparation, arrangement, and sealing of the grave." This was coupled with the special treatment of the buried body.
Shamans are universally recorded cross-culturally in hunter-gatherer groups and small-scale agricultural societies. Nevertheless, they have rarely been documented in the archaeological record and none have been reported from the Paleolithic of Southwest Asia.
The Natufians existed in the Mediterranean region of the Levant 15,000 to 11,500 years ago. Dr. Grosman suggests this grave could point to ideological shifts that took place due to the transition to agriculture in the region at that time.

Natufian grave site

Hilazon Tachtit is a small cave site next to Carmiel that functioned first and foremost as a Natufian burial ground for at least 28 individuals representing an array of ages.
The collective graves found at the site likely served as primary burial areas that were later re-opened to remove skulls and long bones for secondary burial – a practice common to the Natufian and the following Neolithic cultures.
Only three partially complete primary burials were recovered at Hilazon Tachtit. One was a skeleton of a young adult (sex unknown) reposed in a flexed position on its right side with both hands under his face. The scattered bones of a newborn were found in the area of the missing pelvis and it appears that the newborn and the young adult, possibly the mother, were buried together.

Source:Eurekalert 5/11/08