Our great-ape cousins such as chimpanzees have feet that are very flexible in their middle region due to something called the midtarsal break that allows their feet to bend in the middle, enabling them to grasp at branches for easier climbing through trees. So when a chimp lifts his foot off the ground, it just flops about - there's nothing to hold the bones together. Most humans, on the other hand (or should I say foot?), have the same joint but have ligaments that stretch across it making the foot more rigid and stable for upright walking. Australopithecus sediba, a human ancestor that lived 2 million years ago, has a foot structure that is more ape-like than human, so somewhere along the line our feet evolved probably to accommodate our bipedalism.
The study was done by Jeremy DeSilva, a functional morphologist from Boston University, whose main interest is the evolution of the human foot and ankle. In this recent study, museum visitors were requested to walk barefoot across a mechanized carpet while DeSilva's team observed their gaits and the structure of their feet as they walked.
The surprising results showed that 8 percent of the nearly 400 participants possessed a flexible midtarsal break in their foot, and displayed a pressure signature in their footprint that looked like that found in the footprints of non-human primates. Perhaps more surprising is the fact that those subjects who had the unusual foot-joint structure weren't even aware of it until DeSilva revealed it to them.
The study was published in the American Journal of Physical Anthropology.
Sorry for the short notice, but this evening (May 5, 2011) at 6:30pm EDT (5:30 here in the Twin Cities) the American Museum of Natural History will present a live streamed discussion with famed paleoanthropologists Richard Leakey and Donald Johanson entitled Human Evolution and Why It Matters: A Conversation with Leakey and Johanson. Here's what the AMNH website says about it:
"Celebrating decades of groundbreaking exploration in East Africa, renowned paleoanthropologists Donald Johanson and Richard Leakey will share the stage to discuss the overwhelming evidence for evolution in the hominid fossil record and why understanding our evolutionary history is so important.
Known for such landmark discoveries as "Lucy" (Johanson) and "Turkana Boy" (Leakey), the work of these two scientists has produced much of the fossil evidence which forms our understanding of human evolution.
Looking back over careers spanning 40-plus years, these men will share the stories behind their monumental finds and offer a look at what's ahead in human evolutionary research.
Want to join in? Then go to the AMNH live streaming website around 5:30 CDT to catch this rare opportunity to watch two giants of the field of paleoanthropology exchange ideas and stories.
Courtesy Mark RyanThe bone of a single pinky finger found in a cave in southern Siberia may indicate a new branch in the human family tree. The find could show that besides Neanderthals and Homo sapiens, a third lineage of humans may have shared the ancient landscape of prehistoric Russia.
The piece of finger was found in Denisova cave located in Russia’s Altai mountains by scientists from the Russian Academy of Science. The bone was recovered from sediment layers that have also yielded signs of Neanderthals (Homo neanderthalensis) and modern humans (Homo sapiens). Radiocarbon dating set the age of the layers between 48,000 and 30,000 years old.
Scientists from Germany’s Max Planck Institute and others sequenced 16,569 base pairs of the finger bone’s mitochondrial DNA genome, and the results indicate the new hominen shared a common ancestor with both neanderthals and ancient modern humans sometime around a million years ago. The research team included Michael Shunkov and Anatoli Derevianko, the two Russian archaeologists who discovered the bone in 2008. The study appears in the journal Nature.
Further sequencing of DNA from cell nucleuses will be done next, and could help pinpoint the hominen’s exact origins. If confirmed, the discovery would mean four different species of humans (the 4th would be the Indonesian Hobbit Homo floresiensis) co-existed on Earth some 40,000 years ago.
Courtesy Lord JimWhat makes human beings so special? How did we evolve into an agriculture-developing, city-building, history-making, world-changing species that can live on every continent and even in outer space?
Scientists have been asking questions about our evolutionary trajectory and human "uniqueness" for as long as there's been science - and guess what? We still don't know the answer! Some of our best theories are explored by anthropologists in the PBS television series The Human Spark, airing throughout the month and also online at the PBS website. If you're curious, you might want to watch, but don't do it on an empty stomach! Many of the theories that anthropologists have developed to explain how we became human involve food.
That food and evolution would go hand in hand is not really surprising, since food is necessary to survival and an important and dynamic part of our environment. Did a search for nutritious plants and animals lead our ancestors to new environments, causing our species to adapt and change? Did hunting and eating meat mean the evolution of new physical characteristics? How has agriculture changed our environment and species over time? How will present and future foods change what it means to be human in the future?
Some evolutionary theories involving food look not just at what we ate, but how we ate it - namely the invention of fire and the use of heat to cook food. Think about it: our Hominid ancestors needed calories in order to develop into the big-brained humans we all know and love. How did they do it? And what did this mean for human evolution?
Sure, eating meat was an important dietary step, but cooking root vegetables can transform hard-to-chew or even poisonous plant parts into nutritious food that can be consumed out of season. With cooking, environments that would otherwise provide few nutritious options suddenly become bountiful. This change in diet may also have led to changes in body size and shape - even social structures! Large teeth and jaws were less desirable once food could be more easily chewed, and delaying the gratification of food until it could be cooked may also have meant that our species had to develop new social skills.
Those social skills - the same ones that mean you and I can now share a burger or beer without fighting each other for scraps - may be one of many "sparks" that makes us human.
If you live in the Twin Cities, you can meet an anthropologist and here how he thinks food impacted human evolution by attending tonight's Cafe Scientifique program in Minneapolis.
Courtesy Thomas RocheJust a reminder, the Twin Cities Public Television presentation of “Our Origins: The Human Spark” will be airing Sunday, January 24th at 4 PM on tpt2 and statewide on tptMN at 8 PM. It will re-air on tptLIFE on Sunday the 31st at Noon. This excellent program was produced in collaboration with the Science Museum of Minnesota and features interdisciplinary research from University of Minnesota faculty in several departments including the Department of Anthropology's Evolutionary Anthropology Lab and researchers with the Jane Goodall Institute’s Primate Center (The U of MN Evolutionary Lab is currently updating their website to incorporate 3-D interactive videos of evolutionary teaching casts so check back in the future for more interactive learning). Internationally significant work on early human evolution is being done at the University of Minnesota and there were several faculty members interviewed for the production including: Professors Michael Wilson, Gillian Monnier, Kieran McNulty, and one of my mentors Professor Martha Tappen. Don’t miss it! Check out more details at Science Buzz.
After some three and a half billion years of life’s evolution on this planet – and after almost two million years since people recognizable as human first walked its surface – a new human burst upon the scene, apparently unannounced.
It was us.
Until then our ancestors had shared the planet with other human species. But soon there was only us, possessors of something that gave us unprecedented power over our environment and everything else alive. That something was – is – the Human Spark.
What is the nature of human uniqueness? Where did the Human Spark ignite, and when? And perhaps most tantalizingly, why?
In a three-part series to be broadcast on PBS in 2010, Alan Alda takes these questions personally, visiting with dozens of scientists on three continents, and participating directly in many experiments – including the detailed examination of his own brain.
Courtesy TmkeeseyMove over Lucy, there is a new hominid in town. Her name is Ardi. One could say Ardipithecus ramidus to be formal. She is a 4.4 million year old ancestor of ours and nearly a million years older than Lucy (Australopithecus afarensis). She is by far the most complete of all the older hominids. Researchers have recovered feet, a leg and pelvis, hands and lower arm, along with the majority of a skull and its teeth. As an added bonus, parts of nearly three dozen more specimens were recovered during the work in the Western Afar Rift of northeastern Ethiopia. This is the same region that gave us Lucy and some early Homo species.
Ardi and her kin walked upright, although their gait was debatably awkward. She retained an opposable toe which could still be used to grasp tree branches, but the remainder of the foot was built for the ground. Like later hominids, the teeth reveal a modern structure and lack enlarged canines. Her pelvis is a mosaic between chimps and Lucy. The Ilium developed short and broad more like a human, while the lower pelvis remains similar to a chimp. Ardi’s skull shows that her brain was still the size of a chimp, being smaller than Lucy’s. Its shape, however was more hominid and had begun evolve more advanced functions.
Unlike Lucy in her savannah habitat, Ardi roamed lush but temperate woodlands. More than 150,000 plant and animal fossils were recovered from the sites. Included are 20 new species of small mammals along with monkeys, antelope, elephants, and multitudes of birds. This was a much different environment than that of the savannah. Theories of the development of bipedalism on the open grasslands will be challenged now because of Ardi and her habitat.
This isn’t a recent find. The original excavations of the search teams started in 1992. But years of field work followed by more than a decade of lab time have really unearthed a mass of data about this time and place in history. 47 diverse researchers from all over the world have included excerpts of their findings about Ardi and her environment. The October 2009 special issue of the publication Science details the discovery and ongoing analysis of this latest find in the continuing quest to uncover the origins of man. With debate well underway, I’m positive we’ll all continue to learn more about our past.
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