Of Neanderthals and men
It has been 330,000 years since we and our hominid cousin, the Homo neanderthalensis, diverged from a common ancestor. Despite the evolutionary distance-and the extinction of the Neanderthals-a recent genome study in Berkeley sequenced DNA from a fossilized Neanderthal femur and found that 99.5 per cent of our genome is identical to that of the Neanderthals. Barely a decade has passed since researchers started using genetic techniques to study Neanderthals, and this innovation has brought important advances to the field. The challenges in sequencing Neanderthal DNA come from both degradation of the DNA in the natural environment and from contamination of DNA from microbes. By making copies of the DNA in a library of fragments, researchers were able to preserve the damaged sequences in an “immortal” collection. The team recovered only about 0.01 per cent of Neanderthal DNA from the contaminated mess extracted from the fossils. Both Homo sapiens and Homo neanderthalensis shared territories in Europe for thousands of years, but no conclusive evidence of crossbreeding has ever been found. While scientists are still unable to come to any conclusions about interbreeding, researchers are confident that studying Neanderthal biology at the genetic level will shed light on the most intriguing question about our long-lost cousins: where they went.
Source: Berkeley Lab news service
-Sandy Huen
Packaging memory
Research conducted by University of California at Irvine graduate student Melina Uncapher has suggested that memory is more than the sum of its parts. In the study, twenty-three subjects underwent brain scans as they were presented with a list of words, appearing in different colours and locations on a screen. Later, participants were presented with the same words and asked to identify those they remembered, and what colour and part of the screen it had appeared in. If subjects remembered the colour, a particular area of the brain associated with colour processing was especially active during the recollection. Activity in an area of the brain associated with spatial processing was particularly strong when subjects recalled the word’s on-screen location. However, if the subject recalled the word, the color and the location, enhanced activity was shown in an area called the intraparietal sulcus. It appears to bind all aspects of a particular memory so that contextual details, as well as central aspects of an event (e.g., word identity) can be recalled. Features of an event must be brought together and processed as a common unit of perception in order to be vividly remembered.
Source: Neuron
-Abigail Slinger
