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Science Sunday #13

Posted by Don McLenaghen on September 11, 2011

– and on the seventh day we learn.
Each week I hope to give a synopsis of the interesting science stories I have heard on my plethora of science podcasts I listen to each week plus anything I pick up scanning the inter-web. This week’s top stories:

Words of the Week:

Hominid – A primate of a family (Hominidae) that includes humans and their fossil ancestors.

Hominidae – The Hominidae also known as great apes), as the term is used here, form a taxonomic family, including four extant genera: chimpanzees (Pan), gorillas (Gorilla), humans (Homo), and orangutans (Pongo).
The Hominidae are large, tailless primates.
In all Hominidae, the males are, on average, larger and stronger than the females, although the degree of sexual dimorphism varies greatly among species. Although most living species are predominantly quadrupedal, they are all able to use their hands for gathering food or nesting materials, and, in some cases, for tool use.



Where does all the gold come from? –

During the formation of the Earth, molten iron sank to its centre to make the core. This took with it the vast majority of the planet’s precious metals – such as gold and platinum. In fact, there are enough precious metals in the core to cover the entire surface of the Earth with a four metre thick layer.

If all the gold and other precious metals are in the core, this leave open the question, where did the metal we mine come from?

According to research published in Nature Magazine, we can thank that stars…no, not the nova’s that created these metals (although they do deserve a round of applause), I mean from the sky in the form of meteor bombardment. Ultra high precision analyses of some of the oldest rock samples on Earth by researchers at the University of Bristol provides clear evidence that the planet’s accessible reserves of precious metals are the result of a bombardment of meteorites more than 200 million years after the Earth was formed.

To test this theory, Dr Matthias Willbold and Professor Tim Elliott of the Bristol Isotope Group in the School of Earth Sciences analysed rocks from Greenland that are nearly four billion years old, collected by Professor Stephen Moorbath of the University of Oxford. These rocks would provide a comparison between ‘modern’ rock and rock found on the planet soon after its formation….and prior to the ‘bombardment’ period of planet.

Late Heavy Bombardment

The Late Heavy Bombardment is a period of time approximately 4.1 to 3.8 billion years ago during which a large number of impact craters are believed to have formed on the Moon, and by inference on Earth, Mercury, Venus, and Mars as well.

The researchers determined the tungsten isotopic composition of these rocks. Tungsten (W) is a very rare element (one gram of rock contains only about one ten-millionth of a gram of tungsten) and, like gold and other precious elements, it should have entered the core when it formed. Like most elements, tungsten is comprised of several isotopes, atoms with the same chemical characteristics but slightly different masses. Isotopes provide robust fingerprints of the origin of material and the addition of meteorites to the Earth would leave a diagnostic mark on its W isotope composition.

Dr Willbold observed a 15 parts per million decreases in the relative abundance of the isotope 182W between the Greenland and modern day rocks. This small but significant change is in excellent agreement with that required to explain the excess of accessible gold on Earth as the fortunate by-product of meteorite bombardment.

Dr Willbold continued: “Our work shows that most of the precious metals on which our economies and many key industrial processes are based have been added to our planet by lucky coincidence when the Earth was hit by about 20 billion billion tonnes of asteroidal material.”

Eureka Alert


Science Daily


What’s all the stink about ‘Australopithecus Sediba’ –

Australopithecus Sediba

In a series of five papers in the journal Science, Professor Lee Berger of the University of Witwatersrand and colleagues describe the detailed anatomy of two hominin fossils they announced last year. Named Australopithecus sediba (wellspring in the local language) it is 1.98 million years old and, though the size and brain capacity is similar to earlier species, there are many features including brain architecture that are more like those of later humans.

The new species was discovered in a region of South Africa known as the Cradle of Humanity, by paleontologist Lee Berger of University of the Witwatersrand (Wits) in Johannesburg. After announcing the find in 2010, Berger and colleagues began making the case that A. sediba may be the bridge between more primitive austropiths and the Homo genus. The debate over whether A. sediba is a human ancestor will likely continue, even as more material is excavated from a limestone cave called Malapa, one of the richest hominid fossil sites ever found.

Material World

Quirks & Quarks

Science Friday

Science in Action

Science Daily

Raw Story

Eureka Alert


Sediba Hominid Skull Hints at Later Brain Evolution – 

Paleo-phrenology via x-ray tech

An analysis of a skull from the most complete early hominid fossils ever found suggests that the large and complex human brain may have evolved more rapidly than previously realized, and at a later time than some other human characteristics.

While some features of Australopithecus sediba were more human-like the brain was more ape-like. Emory University anthropologist Dietrich Stout. “It’s basically a primitive brain that looks a lot like other austrolopiths, although you can see what could be the first glimmerings of a reorganization to a more human pattern.”

If A. sediba is a human ancestor, as some have proposed, then its fossils could help resolve long-standing debates about human brain evolution.

The researchers estimate that the brain was 420 cubic centimeters. “That’s tiny and about what you’d expect for a chimpanzee,” Stout says

The face, however, of A. sediba was far less protruded than that of a chimpanzee. “We don’t fully understand how the human face got smaller and tucked under the brain case, although that may have a lot to do with diet and chewing,” Stout says. “That further complicates matters. The relationship of human brain evolution to cognitive changes and other biological and behavioral changes is something we have to keep looking at.”

While the A. sediba brain clearly was not a human configuration, a surface bump shows possible foreshadowing of Broca’s area, a region of the human brain associated with speech and language, Stout says. “It’s a big leap, however, to go from a surface bump to really understanding what the cells were doing beneath it,” he adds.

Science Daily

Science Magazine


Sediba Makes a Better Candidate for an Early Tool-Making Hominin –

Near complete allow better analysis of Sediba's dexterity

Hand bones from a single individual with a clear taxonomic affiliation are scarce in the hominin fossil record, which has hampered understanding of the evolution of manipulative abilities in hominins. An international team of researchers including Tracy Kivell of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany has now published a study that describes the earliest, most complete fossil hominin hand post-dating the appearance of stone tools in the archaeological record, the hand of a 1.98-million-year-old Australopithecus sediba from Malapa, South Africa.

The researchers found that Au. sediba used its hand for arboreal locomotion but was also capable of human-like precision grips, a prerequisite for tool-making. Furthermore, the Au. sediba hand makes a better candidate for an early tool-making hominin hand than the Homo habilis hand, and may well have been a predecessor from which the later Homo hand evolved.

The extraordinary manipulative skills of the human hand are viewed as a hallmark of humanity. Over the course of human evolution, the hand was freed from the constraints of locomotion and has evolved primarily for manipulation, including tool-use and eventually tool-production. Understanding this functional evolution has been hindered by the rarity of relatively complete hand skeletons that can be reliably assigned to a given taxon based on a clear association with craniodental fossils.

Science Daily

Eureka Alert


Evolutionary link between Australopiths and Homo – 

Putting Sediba into context

Skeletal remains found in a South African cave may yield new clues to human development and answer key questions of the evolution of the human lineage, according to a series of papers released in the journal Science co-written by a Texas A&M University anthropology professor.

Researcher Darryl de Ruiter, a member of the team that discovered the new species Australopithecus sediba. Multiple individuals of Australopithecus sediba show both human-like and ape-like characteristics intermediate between Australopithecus and present-day humans.

Australopithecus is a genus of hominins now extinct. Ape-like in structure, yet walking bipedally similar to modern humans, they are believed to have played a significant role in human evolution, and it is generally held among anthropologists that a form of Australopithecus eventually evolved into Homo.

“The skulls are small, which is what you might expect, but their morphology shows it housed a brain shaped much like a human’s,” he notes. “The pelvis and foot are also similar in that regard. The foot, for example, shows an ankle that looks like human-like, but the heel is shaped more like that of an ape. But again, all of the remains appear to represent an evolutionary intermediary between Australopithecus and humans.”

“The skulls are particularly interesting because they show how the brain reorganized and changed in shape over time,” he notes. “We suspect that something happened around two million years ago with Australopithecus. It went from an australopith way of making a living to a more human-like way of making a living. Whatever event that caused these particular individuals to die happened quickly, and their bones appeared to have calcified almost immediately. The skeletons were all found very close to each other, with some basically lying on top of another”.

Science Daily

Science Daily

Science Daily

Eureka Alert



Venus, the forgotten planet – 

Venera 14 took the last lander image of the surface of Venus in 1982

Venus would seem to be a tempting destination for planetary probes: conveniently close, and an extreme laboratory for atmospheric processes familiar on Earth. So why won’t NASA send a mission there? That was the frustrated question coming from scientists at the annual meeting of NASA’s Venus Exploration Analysis Group (VEXAG). They perceive an agency bias against Venus, a planet that hasn’t seen a US mission since the Magellan probe radar-mapped its shrouded surface in the early 1990s, and which won’t see one any time soon, after NASA this year rejected a bumper crop of Venus proposals.

Some of the reasons for the planet’s neglect are obvious: surface temperatures that would melt lead and thick clouds of sulphuric acid make data gathering a challenge for landers and orbiters alike. And — unlike Mars — Venus is neither a plausible haven for life nor a potential destination for astronauts.

In May, Venus researchers got a triple dose of further bad news. In NASA’s New Frontiers medium-class mission line, a mission to return asteroid samples prevailed over a proposed Venus lander that would have lasted a precious three hours on the surface. And there were no Venus missions among the three finalists in the Discovery low-cost planetary-mission competition, although one-quarter of the proposals had targeted the planet. Of the seven Discovery proposals for Venus missions, reviewers gave six the lowest possible ranking, guaranteeing their rejection.

One thing scientest say they could learn from Venus is to know why Earth’s global climate models break down on Venus, which has an atmosphere composed of 97% carbon dioxide — and what that reveals about the hidden fine-tunings of Earth models.


Scientific American


“Akatsuki” space probe – 

Japan said it had successfully test-fired the engine of its “Akatsuki” space probe in preparation for a renewed attempt to get it into orbit around Venus in 2015.

The “Akatsuki”, meaning “Dawn” is fitted with two paddle-shaped solar panels and blasted off in May last year on a 25.2 billion yen ($300 million) mission to observe the toxic atmosphere and super-hot volcanic surface of Venus.

Japanies scientists believe that investigating the climate of Venus would deepen their understanding of the formation of the Earth’s environment and its future.



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