Flannel Shirt

More on brain evolution

On Saturday I noted a study that shows how the duplication of a gene that affects brain development caused the evolution of bigger brains. Today, a story points out that the "persistent metopic suture" or that soft spot on a baby's head, was an important evolutionary development that allowed bipeds to give birth to offspring that had rapidly growing brains.

"These findings are significant because they provide a highly plausible explanation as to why the hominin brain might grow larger and more complex," Falk said.

The first feature is a "persistent metopic suture," or unfused seam, in the frontal bone, which allows a baby's skull to be pliable during childbirth as it squeezes through the birth canal. In great apes -- gorillas, orangutans and chimpanzees -- the metopic suture closes shortly after birth. In humans, it does not fuse until around 2 years of age to accommodate rapid brain growth.

The second feature is the fossil's endocast, or imprint of the outside surface of the brain transferred to the inside of the skull. The endocast allows researchers to examine the brain's form and structure.

After examining the Taung fossil, as well as huge numbers of skulls belonging to apes and humans, as well as corresponding 3-D CT (three-dimensional computed tomographic) scans, and taking into account the fossil record for the past 3 million years, Falk and her colleagues noted three important findings: The persistent metopic suture is an adaptation for giving birth to babies with larger brains; is related to the shift to a rapidly growing brain after birth; and may be related to expansion in the frontal lobes.

"The persistent metopic suture, an advanced trait, probably occurred in conjunction with refining the ability to walk on two legs," Falk said. "The ability to walk upright caused an obstretric dilemma. Childbirth became more difficult because the shape of the birth canal became constricted while the size of the brain increased. The persistent metopic suture contributes to an evolutionary solution to this dilemma."

The later fusion of the metopic suture is most likely an adaptation of hominins who walked upright to be able to more easily give birth to babies with relatively large brains. The unfused seam is also related to the shift to rapidly growing brains after birth, an advanced human-like feature as compared to apes.

"The later fusion was also associated with evolutionary expansion of the frontal lobes, which is evident from the endocasts of australopithecines such as Taung," Falk said.

No such extended metopic suture exists in the rest of the ape family.

Mutations in hair color

This story, that the percentage of Solomon Islanders who have blonde hair (estimated between 5 and 10 percent) have it by another genetic mutation than what causes blonde hair in Europeans, has been making the scientific rounds lately.

While it's surprised many that this population of blondes has nothing to do with European blondness, this makes perfect sense. A few years ago there was the discovery that a good percentage of Neanderthals were redheads and that the mutation that caused that was yet another mutation.

 

Dinosaur farts

I'm not kidding.

Dinosaur farts. Global warming.

The hulking sauropods, distinctive for their enormous size and unusually long necks, were widespread about 150 million years ago. As in cows, methane-producing microbes aided the sauropods' digestion by fermenting their plant food.

"A simple mathematical model suggests that the microbes living in sauropod dinosaurs may have produced enough methane to have an important effect on the Mesozoic climate," said Dave Wilkinson of Liverpool John Moores University. "Indeed, our calculations suggest that these dinosaurs could have produced more methane than all modern sources -- both natural and man-made -- put together."

Wilkinson and study coauthor Graeme Ruxton from the University of St Andrews were studying sauropod ecology when a question dawned on them: If modern cows produce enough methane gas to be of interest to climate scientists, what about sauropods? They teamed up with methane expert Euan Nisbet at the University of London to work out the numbers.

"Clearly, trying to estimate this for animals that are unlike anything living has to be a bit of an educated guess," Wilkinson said.

Animal physiologists have studied methane production from a range of modern animals to derive equations that predict methane production from animals of different sizes. It turns out that those calculations depend only on the total mass of the animals in question. A medium-sized sauropod weighed something like 20,000 kilograms, and sauropods lived in densities ranging from a few large adults to a few tens of individuals per square kilometer.

Wilkinson, Ruxton, and Nisbet therefore calculate global methane emissions from sauropods to have been 520 million tons (520 Tg) per year, comparable to total modern methane emissions. Before industry took off on modern Earth about 150 years ago, methane emissions were roughly 200 Tg per year. By comparison, modern ruminant animals, including cows, goats, giraffes, and others, produce methane emission of 50 to 100 Tg per year.

The study's conclusions not only show "just how strange and wonderful the workings of the planet are" but also serve as a useful reminder for the importance of microbes and methane for global climate, the researchers say.

Polar bears

Here's the latest on polar bear evolution. They've been around 600,000 years.

Feathered T. Rex

Scientists have found a cousin of Tyrannosaurus Rex with feathers.

A newly discovered titanic tyrannosaur is the biggest feathered dinosaur yet, reaching up to 30 feet (9 meters) long and weighing more than 3,000 pounds.

While smaller than Tyrannosaurus rex, the new species, named Yutyrannus huali — meaning "beautiful feathered tyrant" — is still 40 times the weight of the largest feathered dinosaur known previously, Beipiaosaurus, which was described in 1999.

"Yutyrannus dramatically increases the size range of dinosaurs for which we have definite evidence of feathers," study researcher Xing Xu of the Chinese Academy of Sciences in Beijing said in a statement. "It’s possible that feathers were much more widespread, at least among the meat-eating dinosaurs, than most scientists would have guessed even a few years ago."

And here is a background story on the discovery process and why it sometimes takes a few years from discovery to scientific announcement.

The biggest turkey ever.

Pee guitar

In my neverending search to find important developments in mankind's growth I give you Pee Guitar.

Reminds me of a joke by George Carlin that involved a group of men, a keg of beer and a Kent micronite filter.

 

Making fire a long, long time ago

Folks were making fires a million years ago.

An international team led by the University of Toronto and Hebrew University has identified the earliest known evidence of the use of fire by human ancestors. Microscopic traces of wood ash, alongside animal bones and stone tools, were found in a layer dated to one million years ago at the Wonderwerk Cave in South Africa.

"The analysis pushes the timing for the human use of fire back by 300,000 years, suggesting that human ancestors as early as Homo erectus may have begun using fire as part of their way of life," said U of T anthropologist Michael Chazan, co-director of the project and director of U of T's Archaeology Centre.

The research was published in theProceedings of the National Academy of Sciences on April 2.

Wonderwerk is a massive cave located near the edge of the Kalahari where earlier excavations by Peter Beaumont of the McGregor Museum in Kimberley, South Africa, had uncovered an extensive record of human occupation. A research project, co-directed by U of T's Chazan and Liora Kolska Horwitz of Hebrew University, has been doing detailed analysis of the material from Beaumont's excavation along with renewed field work on the Wonderwerk site.

Analysis of sediment by lead authors Francesco Berna and Paul Goldberg (pictured below right) of Boston University revealed ashed plant remains and burned bone fragments, both of which appear to have been burned locally rather than carried into the cave by wind or water. The researchers also found extensive evidence of surface discoloration that is typical of burning.

"The control of fire would have been a major turning point in human evolution," said Chazan. "The impact of cooking food is well documented, but the impact of control over fire would have touched all elements of human society.

"Socializing around a camp fire might actually be an essential aspect of what makes us human."

Where McDonald's started

In the Middle East.

 All cattle are descended from as few as 80 animals that were domesticated from wild ox in the Near East some 10,500 years ago, according to a new genetic study.

An international team of scientists from the CNRS and National Museum of Natural History in France, the University of Mainz in Germany, and UCL in the UK were able to conduct the study by first extracting DNA from the bones of domestic cattle excavated in Iranian archaeological sites. These sites date to not long after the invention of farming and are in the region where cattle were first domesticated.

The team examined how small differences in the DNA sequences of those ancient cattle, as well as cattle living today, could have arisen given different population histories. Using computer simulations they found that the DNA differences could only have arisen if a small number of animals, approximately 80, were domesticated from wild ox (aurochs).

The study is published in the current issue of the journal Molecular Biology and Evolution.

Dr Ruth Bollongino of CNRS, France, and the University of Mainz, Germany; lead author of the study, said: "Getting reliable DNA sequences from remains found in cold environments is routine.

"That is why mammoths were one of the first extinct species to have their DNA read. But getting reliable DNA from bones found in hot regions is much more difficult because temperature is so critical for DNA survival. This meant we had to be extremely careful that we did not end up reading contaminating DNA sequences from living, or only recently dead cattle."

The number of animals domesticated has important implications for the archaeological study of domestication.

Prof Mark Thomas, geneticist and an author of the study based at the UCL Research Department of Genetics, Evolution and Environment: "This is a surprisingly small number of cattle. We know from archaeological remains that the wild ancestors of modern-day cattle, known as aurochs, were common throughout Asia and Europe, so there would have been plenty of opportunities to capture and domesticate them."

Prof Joachim Burger, an author of the study based at the University of Mainz, Germany, said: "Wild aurochs are very different beasts from modern domestic cattle.

"They were much bigger than modern cattle, and wouldn't have had the domestic traits we see today, such as docility. So capturing these animals in the first place would not have been easy, and even if some people did manage snare them alive, their continued management and breeding would still have presented considerable challenges until they had been bred for smaller size and more docile behavior."

Lots of different hominins

I love human evolution, and these days it just gets more and more interesting. It turns out that Lucy, the australopithecus sweetheart that wandered East Africa over three million years ago, had a cousin that lived in trees at the same time.

A team of scientists has announced the discovery of a 3.4 million-year-old partial foot from the Woranso-Mille area of the Afar region of Ethiopia. The fossil foot did not belong to a member of “Lucy’s” species, Australopithecus afarensis, the famous early human ancestor. Research on this new specimen indicates that more than one species of early human ancestor existed between 3 and 4 million years ago with different methods of locomotion.

The analysis will be published in the March 29, 2012 issue of the journal Nature.

The partial foot was found in February 2009 in an area locally known as Burtele.

“The Burtele partial foot clearly shows that at 3.4 million years ago, Lucy’s species, which walked upright on two legs, was not the only hominin species living in this region of Ethiopia,” said lead author and project leader Dr. Yohannes Haile-Selassie, curator of physical anthropology at The Cleveland Museum of Natural History. “Her species co-existed with close relatives who were more adept at climbing trees, like ‘Ardi’s’ species, Ardipithecus ramidus, which lived 4.4 million years ago.”

The partial foot is the first evidence for the presence of at least two pre-human species with different modes of locomotion contemporaneously living in eastern Africa around 3.4 million years ago. While the big toe of the foot in Lucy’s species was aligned with the other four toes for human-like bipedal walking, the Burtele foot has an opposable big toe like the earlier Ardi.

“This discovery was quite shocking,” said co-author and project co-leader Dr. Bruce Latimer of Case Western Reserve University. “These fossil elements represent bones we’ve never seen before. While the grasping big toe could move from side to side, there was no expansion on top of the joint that would allow for expanded range of movement required for pushing off the ground for upright walking. This individual would have likely had a somewhat awkward gait when on the ground.”

The new partial foot specimen has not yet been assigned to a species due to the lack of associated skull or dental elements.

The fossils were found below a sandstone layer. Using the argon-argon radioactive dating method, their age was determined to be younger than 3.46 million years, said co-author Dr. Beverly Saylor of Case Western Reserve University. “Nearby fossils of fish, crocodiles and turtles, and physical and chemical characteristics of sediments show the environment was a mosaic of river and delta channels adjacent to an open woodland of trees and bushes,” said Saylor. “This fits with the fossil, which strongly indicates a hominin adapted to living in trees, at the same time ‘Lucy’ was living on land.”

Evolution in New York City

Here is a neat five-minute video about evolution in New York City.

Really neat.