Skull sheds light on human-Neanderthal relationship

Retrieved from a cave in northern Israel, the partial skull provides the first evidence that Homo sapiens inhabited that region at the same time as Neanderthals. (Reuters: Nikola Solic)

A partial skull, found in a cave in Israel, is shedding light on the pivotal moment in early human history when our species left Africa and encountered our close cousins the Neanderthals.

Anthropologist Israel Hershkovitz, from Tel Aviv University, called the skull "an important piece of the puzzle of the big story of human evolution."

The findings of the research, led by Hershkovitz, are published today in the journal Nature.

The upper part of the skull - the domed portion without the face or jaws - was unearthed in Manot Cave in Israel's Western Galilee.

Scientific dating techniques determined the skull was about 55,000 years old, a time period when members of our species were thought to have been marching out of Africa,

The researchers say characteristics of the skull suggest the individual was closely related to the first Homo sapiens populations that later colonized Europe.

They also say the skull provides the first evidence that Homo sapiens inhabited that region at the same time as Neanderthals, our closest extinct human relative.

Previous genetic evidence suggests our species and Neanderthals interbred around the time the skull is dated to, with all people of Eurasian ancestry still retaining a small amount of Neanderthal DNA as a result.

"It is the first direct fossil evidence that modern humans and Neanderthals inhabited the same area at the same time," says palaeontologist Bruce Latimer of Case Western Reserve University in Cleveland, another of the researchers.

"The co-existence of these two populations in a confined geographic region at the same time that genetic models predict interbreeding promotes the notion that interbreeding may have occurred in the Levant region," Hershkovitz says.

The robust, large-browed Neanderthals prospered across Europe and Asia from about 350,000 to 40,000 years ago, going extinct sometime after Homo sapiens arrived.

Scientists say our species first appeared about 200,000 years ago in Africa and later migrated outwards. The cave is located along the sole land route for ancient humans to take from Africa into the Middle East, Asia and Europe.

Latimer says he suspects the skull belonged to a woman, although the researchers could not say definitively.

The cave, sealed off for 30,000 years, was discovered in 2008 during sewage line construction work. Hunting tools, perforated seashells perhaps used ornamentally and animal bones have been excavated from the cave, along with further human remains.

Source: ABC

Neck manipulation may be associated with stroke

Vertebral artery as it passes through the neck vertebrae of the spine and enters the skull base. Arrows indicate head movement during lateral rotation and lateral flexion, motions that may be performed as part of a neck manipulation. Credit: © 2013 Trial FX.

Manipulating the neck has been associated with cervical dissection, a type of arterial tear that can lead to stroke. Although a direct cause-and-effect link has not been established between neck manipulation and the risk of stroke, healthcare providers should inform patients of the association before they undergo neck manipulation.

Treatments involving neck manipulation may be associated with stroke, though it cannot be said with certainty that neck manipulation causes strokes, according to a new scientific statement published in the American Heart Association's journal Stroke.

Cervical artery dissection (CD) is a small tear in the layers of artery walls in the neck. It can result in ischemic stroke if a blood clot forms after a trivial or major trauma in the neck and later causes blockage of a blood vessel in the brain. Cervical artery dissection is an important cause of stroke in young and middle-aged adults.

"Most dissections involve some trauma, stretch or mechanical stress," said José Biller, M.D., lead statement author and professor and chair of neurology at the Loyola University Chicago Stritch School of Medicine. "Sudden movements that can hyperextend or rotate the neck -- such as whiplash, certain sports movements, or even violent coughing or vomiting -- can result in CD, even if they are deemed inconsequential by the patient."

Although techniques for cervical manipulative therapy vary, some maneuvers used as therapy by health practitioners also extend and rotate the neck and sometimes involve a forceful thrust.

There are four arteries that supply blood to the brain: the two carotid arteries on each side of the neck, and the two vertebral arteries on the back of the neck. The influence of neck manipulation seems more important in vertebral artery dissection than in internal carotid artery dissection.

"Although a cause-and-effect relationship between these therapies and CD has not been established and the risk is probably low, CD can result in serious neurological injury," Biller said. "Patients should be informed of this association before undergoing neck manipulation."

The association between cervical artery dissection and cervical manipulative therapies was identified in case control studies, which aren't designed to prove cause and effect. An association means that there appears to be a relationship between two things, i.e., manipulative therapy of the neck and a greater incidence of cervical dissection/stroke. 

However, it's not clear whether other factors could account for the apparent relationship.

The relationship between neck manipulation and cervical artery dissection is difficult to evaluate because patients who already are beginning to have a cervical artery dissection may seek treatment to relieve neck pain, a common symptom of cervical artery dissection that can precede symptoms of stroke by several days.

You should seek emergency medical evaluation if you develop neurological symptoms after neck manipulation or trauma, such as:

• Pain in the back of your neck or in your head;
• Dizziness/vertigo;
• Double vision;
• Unsteadiness when walking;
• Slurred speech;
• Nausea and vomiting;
• Jerky eye movements.

"Tell the physician if you have recently had a neck trauma or neck manipulation," Biller said. 

"Some symptoms, such as dizziness or vertigo, are very common and can be due to minor conditions rather than stroke, but giving the information about recent neck manipulation can raise a red flag that you may have a CD rather than a less serious problem, particularly in the presence of neck pain."

Source: American Heart Association