Contradicting earlier claims, “The Family That Walks on All Fours,” a group of quadrapedal humans made famous by a 2006 BBC documentary, have simply adapted to their inability to walk upright and in fact do not represent an example of backward evolution, according to new research conducted by Liza Shapiro, an anthropologist at The University of Texas at Austin.
Five siblings in a family, who live in a remote corner of Turkey, walk exclusively on their hands and feet. Since they were discovered back in 2005, scientists have debated over the nature of their disability, specifically the speculation that they represent a backward stage of evolution.
Shapiro’s study, published online this month in PLOS ONE, displays that contrary to previous claims, people with the condition, called Uner Tan Syndrome (UTS), do not walk in the diagonal pattern characteristic of nonhuman primates such as apes and monkeys.
According to a new theory developed by Uner Tan of Cukurova University in Turkey, people with UTS are a human model for reverse evolution, or “devolution,” offering new views of the human transition from four-legged to two-legged walking.
Previous research countering this view has proposed that the quadrupedalism associated with UTS is simply an adaptive response to the impaired ability to walk bipedally in individuals with a genetic mutation, but this is the first study that disproves claims that this form of walking is reminiscent of nonhuman primates.
Co-authors of the study are Jesse Young of Northeast Ohio Medical University; David Raichlen of the University of Arizona; and Whitney Cole, Scott Robinson and Karen Adolph of New York University.
The researchers analysed 518 quadrupedal walking strides from several videos of people with various forms of UTS, including footage from the BBC2 documentary of the five Turkish siblings. The team compared these walking strides to previous studies of the walking habits of healthy adults who were asked to move around a laboratory on all fours.
The study found that nearly all the human subjects (in 98% of the total strides) walked in lateral sequences, meaning they placed a foot down and then a hand on the same side and then moved in the same sequence on the other side. Nonhuman primates, however, walk in a diagonal sequence, meaning they put down a foot on one side and then a hand on the other side, continuing that pattern as they walk along.
“Although it’s unusual that humans with UTS habitually walk on four limbs, this form of quadrupedalism resembles that of healthy adults and is thus not at all unexpected,” Shapiro says. “As we have shown, quadrupedalism in healthy adults or those with a physical disability can be explained using biomechanical principles rather than evolutionary assumptions.”
The study also concluded that Tan and his colleagues appeared to have misidentified the walking patterns among people with UTS as primate-like by confusing the diagonal sequence with diagonal couplets. Sequence refers to the order in which the limbs touch the ground, while couplets (independent of sequence) indicate the timing of movement between pairs of limbs.
People with UTS more frequently use diagonal couplets rather than lateral couplets, but the sequence associated with the couplets is almost exclusively lateral.
“Each type of couplet has biomechanical advantages, with lateral couplets serving to avoid limb interference, and diagonal couplets providing stability,” Shapiro says. “The use of diagonal couplets in adult humans walking quadrupedally can thus be explained on the basis of biomechanical considerations, not reverse evolution.”
Contributing Source: University of Texas at Austin
Header Image Source: Wikimedia
Through measuring the speed that the Earth conducts electricity and seismic waves, a University of Utah researcher, and colleagues, made a detailed picture of Mount Rainier’s deep volcanic plumbing and partly molten rock that will erupt again someday.
“This is the most direct image yet capturing the melting process that feeds magma into a crustal reservoir that eventually is tapped for eruptions,” says geophysicist Phil Wannamaker, of the university’s Energy & Geoscience Institute and Department of Civil and Environmental Engineering. “But it does not provide any information on the timing of future eruptions from Mount Rainier or other Cascade Range volcanoes.”
The study was published in the journal Nature by Wannamaker and geophysicists from the Woods Hole Oceanographic Institution in Massachusetts, the College of New Jersey and the University of Bergen, Norway.
In a strange turn of events, the image appears to show that at least part of Mount Rainier’s partially molten magma reservoir resides approximately 6 to 10 miles northwest of the 14,410-foot volcano, which is 30 to 45 miles southeast of the Seattle-Tacoma area.
Wannamaker says a possible reason for this is due to the 80 electrical sensors used for the experiment were placed in a 190-mile-long, west-to-east line about 12 miles north of Rainier. So the main part of the magma chamber could be directly below the peak, but with a lobe extending northwest under the line of detectors.
The top of the magma reservoir in the image is 5 miles underground and “appears to be 5 to 10 miles thick, and 5 to 10 miles wide in east-west extent,” he says. “We can’t really describe the north-south extent because it’s a slice view.”
According to Wannamaker’s predictions the reservoir is roughly 30 percent molten. Magma chambers are like a sponge of hot, soft rock containing pockets of molten rock.
The new image does not reveal the plumbing tying Mount Rainier to the magma chamber located 5 miles below it. Instead, it displays water and partly molten and molten rock are generated 50 miles underground where one of Earth’s seafloor crustal plates or slabs is “subducting” or diving eastward and downward beneath the North America plate, and how and where those melts rise to Rainier’s magma chamber.
The National Science Foundation’s Earthscope programme funded the study, which also made underground images of the United States using seismic or sound-wave tomography, much like CT scans show the body’s interior using X-rays.
The new study used both seismic imaging and magnetotelluric measurements, which make images by showing how electrical and magnetic fields in the ground vary due to differences in how much underground rock and fluids conduct or resist electricity.
Wannamker states that it is the most detailed cross-section view yet under a Cascades volcanic system using electrical and seismic imaging. Earlier seismic images indicated water and partly molten rock atop the diving slab. The new images show melting “from the surface of the slab to the upper crust, where partly molten magma accumulates before erupting,” he adds.
Wannamaker and Rob L.Evans, from the Woods Hole Oceanographic Instituation, conceived the study. First author R Shane McGary- then at Woods Hole and now the College of New Jersey- conducted the data analysis. Other co-authors were Jimmy Eisenbeck of Woods Hole and Stéphane Rondenay from the University of Bergen.Mount Rainier: Hazardous Backdrop to Metropolitan Seattle- Tacoma
Mount Rainier, the tallest peak in Cascades, “is an active volcano that will erupt again,” says the U.S. Geological Survey. Rainier resides atop volcanic flows up to 36 million years old. An ancestral Rainier existed 2 million to 1 million years ago. The mountain’s modern edifice was constructed due to frequent eruptions during the past 500,00 years. During the past 11,000 years, Rainier has experienced multiple explosive eruptions, spewing ash and pumice.
Rainier was once a tall volcano until it collapsed during an eruption 5,600 years ago to form a large crater open to the northeast, similar to the crater formed by Mount St Helens’ 1980 eruption. The 5,600-year-old eruption sent a huge mudflow west to Puget Sound, covering parts or all of the present site of the Port of Tacoma, Seattle suburbs and Kent and Auburn, and the towns Puyallup, Orting, Buckley, Sunner and Enumclaw.
Rainier’s last lava was 2,200 years ago, the last flows of hot rock and ash occurred 1,100 years ago and the last big mudflow was 500 years ago. Also there are disputed reports of steam eruptions in the 1800s.Subduction Made- and a Peek beneath a Peak
The “ring of fire” is a zone of active volcanoes and frequent earthquake activity surrounding the Pacific Ocean. It is located where the Earth’s tectonic plates collide- specifically, plates that make up the seafloor converge with plates that carry continents.
From Cape Mendocino in northern California and north past Oregon, Washington State and into British Columbia, an oceanic plate is being pushed eastward and downward- a process called subduction-beneath the North American plate. This relatively small Juan de Fuca lies between the huge Pacific plate and the Pacific Northwest.
New seafloor rock- rich with water and cracks and minerals-emerges from an undersea volcanic ridge 250 miles off the coast, from Northern California into British Columbia. That seafloor adds to the western edge of the Juan de Fuca plate and pushes it east-northeast under the Pacific Northwest, as far as Idaho.
The particular part of the plate diving eastward and downward is called the slab, which ranges from 30 to 60 miles thick as it is stuck under the North American plate. The part of the North American plate above the diving slab is shaped like a wedge.
When the leading, eastern edge of the diving slab descends so deep where the pressures and temperatures are high, water-bearing minerals such as chlorite and amphibole release water from the slab, and the slab and surrounding mantle rock start to melt. This is the reason the Cascade Range of active volcanoes extends north-to-south, above the slab and parallel but approximately 120 miles inland from the coast, from British Columbia south to Mount Shasta and Lassen Peak in northern California.
In the new image, yellow-orange-red areas correspond to higher electrical conductivity (or lower resistivity) in places where fluids and melts are located.
The underground image created by the new study displays where waters and molten rock accumulate atop the descending slab, and the route they undertake to the magma chamber that feeds eruptions of Mount Rainier:
The rock starts to melt atop the slab approximately 50 miles beneath Mount Rainier. Wannamaker says it is best described as partly molten rock that contains 2 percent water and “is a mush of crystals within an interlacing a network of molten rock.”
Some of the water and partly molten rock gets dragged downwards atop the descending slab, to depths of 70 miles or possibly more.
Other partly molten rock rises up through the mantle wedge and crosses into the crust at a depth of approximately 25 miles, it then rises into Rainier’s magma chamber- or at least the lobe of the chamber that crosses under the line of sensors used in the study. Evidence collected suggests that the magma moves upward at a rate of at least 0.4 inches per year.
The new magnetotelluric image also exposes a shallow zone of fluid about 60 miles west of Rainier and 25 miles deep at the crust-mantle boundary. Wannamaker says it is mainly water released from minerals as the slab is squeezed and heated as it dives.
The seismic data was collated during 2008-2009 for other studies. The magnetotelluric data were gathered during 2009-2010 by authors of a new study.
Wannamaker, a long with his colleagues, placed an east-west line of magnetotelluric sensors: 60 that made one-day measurements and appeared as deep as 30 miles into the earth, and 20 that made measurements for a month and looked at even greater depths.
Contributing Source: University of Utah
Header Image Source: Wikimedia
The only known example of the spotted green pigeon is the Liverpool pigeon, which is currently residing in the World Museum, Liverpool. Unfortunately the only other known specimen has been lost, and there are no records of the bird in the wild. There is no record of where the pigeon was found, and it wasn’t even known if the spotted green pigeon was a species, or just an unusual form of the Nicobar pigeon from around Indonesia.
The scientists took DNA from two feathers of the spotted green pigeon. Due to the age of the specimen, the DNA was highly fragmented, so the team had to focus in on three DNA ‘mini barcodes’-small sections of DNA which are unique for most bird species. They looked at these sections of the pigeon’s DNA, and compared it to other species.
This confirmed that the spotted green pigeon is indeed a separate species, showing a unique DNA barcode compared to other pigeons. The pigeon’s closest genetic relation is the Nicobar pigeon, along with the dodo and Rodrigues solitaire, both extinct birds from the islands near Madagascar. The green spotted pigeon shows signs of a semi-terrestrial island lifestyle and the ability to fly. The close relation, the Nicobar pigeon, also shows similar habits and has a preference for travelling between small islands.
The scientists say this lifestyle, together with the relationship of both pigeon to the dodo and Rodrigues solitaire, supports an evolutionary theory that the ancestors of these birds were ‘island hoppers’, travelling between islands around India and Southeast Asia. The birds that settled on particular islands proceeded to evolve into the individual species. The dodo’s ancestor managed to hop as far as the island of Mauritius near Madagascar where it famously lost the ability to fly.
Dr. Tim Heupink, Griffith University Australia: “This study improves our ability to identify novel species from historic remains, and also those that are not novel after all. Ultimately this will help us to measure and understand the extinction of local populations and entire species.”
Clemency Fisher, Curator of Vertebrate Zoology at the World Museum says: “We are very pleased that the extinct spotted green pigeon has its correct place in the world of birds after more than 230 years. Tim Heupink’s groundbreaking genetic research, analysing small fragments of DNA from tiny pieces of feather, proves the spotted green pigeon is unique and a distant relation to the Nicobar pigeon, the Rodrigues solitaire and the dodo of Mauritius”.
Header Image Source: BioMed Central
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