A Complete Skull from Dmanisi, Georgia, and the Evolutionary Biology of Early Homo

kull Fossil Suggests Simpler Human Lineage

The site of Dmanisi, Georgia, has yielded an impressive sample of hominid cranial and postcranial remains, documenting the presence of Homo outside Africa around 1.8 million years ago. Here we report on a new cranium from Dmanisi (D4500) that, together with its mandible (D2600), represents the world's first completely preserved adult hominid skull from the early Pleistocene. D4500/D2600 combines a small braincase (546 cubic centimeters) with a large prognathic face and exhibits close morphological affinities with the earliest known Homo fossils from Africa. The Dmanisi sample, which now comprises five crania, provides direct evidence for wide morphological variation within and among early Homo paleodemes. This implies the existence of a single evolving lineage of early Homo, with phylogeographic continuity across continents.

Website: Science journal
 Newyorktimes

Monkey with prosthetic hand gets sense of touch

Researchers are finding ways for artificial intelligent - started with  laying the groundwork for touch-sensitive prosthetic limbs that could transmit a sense of touch to the brain that bypasses regular routes. The team trained rhesus macaques to focus their gaze in different directions, depending on which finger was being prodded. The team recorded what activity occurred in the brain and where using microelectrodes placed in the macaques’ primary somatosensory cortex. They then stimulated the brain using the same patterns of activity and found the monkeys reacted as if they had been touched, fixing their gaze in the direction they had been taught.

Journal reference: PNAS

Gregg A. Tabot, John F. Dammann, Joshua A. Berg, Francesco V. Tenore, Jessica L. Boback, R. Jacob Vogelstein, and Sliman J. Bensmaia , 'Restoring the sense of touch with a prosthetic hand through a brain interface', PNAS October 14, 2013, doi:10.1073/pnas.1221113110

Citation: Y. C. Pei, S. S. Hsiao, and S. J. Bensmaia, 'The tactile integration of local motion cues is analogous to its visual counterpart', PNAS 2008 105 (23) 8130-8135; published ahead of print June 4, 2008, doi:10.1073/pnas.0800028105 

Weblink: Newscientist

Optical Illusion Explained in Monkey Brain Study

A new study isolates the area of the visual cortex that allows our brains to produce certain types of optical illusions. (Very cool stuff - but don't be fooled by the headline "Optical Illusion Explained!" because, as usual, it's ridiculously overblown.)

"The scientists trained monkeys to stare at a screen with an image of a Kanizsa square (a variant of the Kanizsa triangle) — four "Pac-Man" shapes with their mouths arranged to form the corners of a square. The square doesn't actually exist, but the brain creates one by mentally connecting the dots. When the monkeys were looking at the Kanizsa square, neurons in V4 of their brains that were involved in representing the middle of the square started firing. But when the monkeys saw the same Pac-Man shapes facing outward, so they no longer framed a square, those same neurons turned off."

Article: Receptive field focus of visual area V4 neurons determines responses to illusory surfaces. doi:10.1073/pnas.1310806110 PNAS October 1, 2013

Weblink: Livescience
Article : PNAS
.

Human brain boiled in its skull lasted 4000 years

SHAKEN, scorched and boiled in its own juices, this 4000-year-old human brain has been through a lot.

It may look like nothing more than a bit of burnt log, but it is one of the oldest brains ever found. Its discovery, and the story now being pieced together of its owner's last hours, offers the tantalising prospect that archaeological remains could harbour more ancient brain specimens than thought. If that's the case, it potentially opens the way to studying the health of the brain in prehistoric times.

Brain tissue is rich in enzymes that cause cells to break down rapidly after death, but this process can be halted if conditions are right. For instance, brain tissue has been found in the perfectly preserved body of an Inca child sacrificed 500 years ago. In this case, death occurred at the top of an Andean mountain where the body swiftly froze, preserving the brain.

However, Seyitömer Höyük – the Bronze Age settlement in western Turkey where this brain was found – is not in the mountains. So how did brain tissue survive in four skeletons dug up there between 2006 and 2011?

Meriç Altinoz at Haliç University in Istanbul, Turkey, who together with colleagues has been analysing the find, says the clues are in the ground. The skeletons were found burnt in a layer of sediment that also contained charred wooden objects. Given that the region is tectonically active, Altinoz speculates that an earthquake flattened the settlement and buried the people before fire spread through the rubble.

The flames would have consumed any oxygen in the rubble and boiled the brains in their own fluids. The resulting lack of moisture and oxygen in the environment helped prevent tissue breakdown.

The final factor in the brains' preservation was the chemistry of the soil, which is rich in potassium, magnesium and aluminium. These elements reacted with the fatty acids from the human tissue to form a soapy substance calledadipocere. Also known as corpse wax, it effectively preserved the shape of the soft brain tissue (HOMO – Journal of Comparative Human Biology, doi.org/nz6).

"The level of preservation in combination with the age is remarkable," saysFrank Rühli at the University of Zurich, Switzerland, who has examined medieval brain tissue. Rühli says that most archaeologists don't bother looking for the remains of brain tissue because they assume it is seldom preserved. "If you publish cases like this, people will be more and more aware that they could find original brain tissue too."

In cases where the brain is as well preserved as this, Rühli says it might even be possible to look for pathological conditions such as tumours and haemorrhaging, and maybe even signs of degenerative disease. "If we want to learn more about the history of neurological disorders, we need to have tissue like this."

This article appeared in print under the headline "4000-year-old brain opens window on ancient health" - New Scientist (Weblink: Newscientist)

2013 Nobel Prize in medicine: James Rothman, Randy Schekman and Thomas Südhof win prestigious award

The Nobel Prize in Physiology or Medicine 2013 was awarded jointly to James E. Rothman, Randy W. Schekman and Thomas C. Südhof "for their discoveries of machinery regulating vesicle traffic, a major transport system in our cells"

Three scientists whose work has shed light on the internal “package delivery” system of the cell – which ensures that vital chemicals are delivered to the correct cellular address at the right time – have each won a share of this year’s Nobel Prize in Physiology and Medicine.

Two Americans and a German were jointly awarded the 8 million Swedish Kroner (£776,000) prize for their separate work on how cellular packets or “vesicles” are able to find their way through the maze of compartments in a cell to the correct location for delivering their cargo of chemicals.

Randy Schekman, of the University of California at Berkeley, carried out pioneering work in the 1970s on yeast cells which revealed the genes that played a crucial role in this transport system, with mutant cells leading to visible vesicle congestion within the cell.

James Rothman, now at Yale University in New Haven, Connecticut, worked on mammalian cells in the 1980s and 1990s and showed how proteins enabled vesicles to dock and fuse with their target sites on the complex network of internal membranes that form compartments within a cell.

Meanwhile, German-born Thomas Südhof, now based at Stanford University in California, built on the work of Schekman and Rothman and discovered the precisely-controlled mechanism that allows vesicles to release their load of chemicals at the right location and, crucially, at the right time.

Professor Südhof worked on nerve cells and his findings on this calcium-controlled mechanism of vesicle delivery were critical to understanding how chemical messengers or neurotransmitters are released and re-absorbed across the tiny gap or synapse that links two or more communicating neurons.

“Together, Rothman, Schekmand and Südhof have transformed the way we view transport of molecular cargo to specific destinations inside and outside the cell,” said the Nobel Assembly at the Karolinska Institute in Stockholm.

“Their discoveries explain a long-standing enigma of cell biology and also shed new light on how disturbances in this machinery can have deleterious effects and contribute to conditions such as neurological diseases, diabetes and immunological disorders,” it said.

Nobel Prizes in Physiology or Medicine have been awarded 103 times between 1901 and 2012. In all but 38 cases they were given to more than one recipient.

Famous previous winners include Robert Koch, the German doctor and bacteriologist who won in 1905 for his work on tuberculosis, and Frederick Banting, the Canadian physiologist who with his assistant Charles Best discovered insulin, the principal remedy for diabetes, taking the prize in 1923. 

Weblink: Independent UK

www.nobelprize.org