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How human brain changes with age   

Human brain is subjected to several changes, as a person ages but the structure within which the changes occur does not change with age, a new study has revealed.

Scientists posit a hierarchical structure within which our cognitive abilities are organised. There is the “lowest” level— measured by specific tests, such as story memory or word memory; the second level, which groups various skills involved in a category of cognitive ability, such as memory, perceptual speed, or reasoning; and finally, the “general,” or G, factor, a sort of statistical aggregate of all the thinking abilities. “There are three hypotheses about how this works,” said Timothy A. Salthouse.

“One is that abilities become more strongly integrated with one another as we age.”

That theory suggests the general factor influences cognitive aging the most. The second is based on the idea that connectivity among different brain regions lessens with age “is almost the opposite: that the changes in cognitive abilities become more rather than less independent with age.” The third was Salthouse’s hypothesis: The structure remains constant throughout the aging process.  “The effects of aging on memory, on reasoning, on spatial relations, and so on are not necessarily constant.” “But the structure within which these changes are occurring does not seem to change as a function of age.”

He said that in normal, healthy people, “the direction and magnitude of change may be different” when we are 18 or 88 “But it appears that the qualitative nature of cognitive change remains the same throughout adulthood.”

According to Salthouse, the study could inform other researchers investigating “what allows some people to age more gracefully than others”.

Ravens also make hand gestures like humans

Like humans, ravens also use so-called deictic gestures in order to test the interest of a potential partner or to strengthen an already existing bond, a new study has found. From early childhood on, children frequently use distinct gestures to draw the attention of adults to external objects. So-called deictic gestures like “pointing” and “holding up of objects” are used by children for the first time at the age of nine to twelve months, before they produce their first spoken words.

Scientists believe that such gestures are based on relatively complex intelligence abilities and represent the starting point for the use of symbols and therefore also human language. Deictic gestures are thus milestones in the development of human speech.

According to Simone Pika from the Max Planck Institute for Ornithology and Thomas Bugnyar from the University of Vienna, observations of comparable gestures in our closest living relatives, the great apes, are relatively rare, but they are not restricted to them.

For two years, the researchers investigated the non-vocal behaviour of individually marked members of a wild raven community in the Cumberland Wildpark in Grünau, Austria.

They observed that ravens use their beaks similar to hands to show and offer objects such as moss, stones and twigs. These distinct gestures were predominantly aimed at partners of the opposite sex and resulted in frequent orientation of recipients to the object and the signallers.

Power lines a major risk for migratory birds

When flamingos, storks, pelicans and other migratory birds undertake their long seasonal flights, they risk their lives winging their way through the endless power grids that cover the world. There are some 70 million kilometres (43 million miles) of power lines on the planet. In Africa and Eurasia alone, tens of millions of birds die each year in collisions and hundreds of thousands of others are electrocuted, a study published at this week's Convention on Migratory Species in Bergen, Norway showed.

Alongside hunting, “collision and electrocution are among the most important human-related causes for bird mortality,” Dutch ornithologist Hein Prinsen, the rapporteur of the study.

Migratory birds have in many cases already seen their habitats destroyed by mankind and global warming.

These accidents are pushing their numbers down further, and in some places even putting birds at risk of becoming locally extinct.

Each death is a heavy blow for the bigger species who have relatively slow reproduction patterns.

For cranes and storks, the death of an adult bird can lead to the death of its young, who depend on their two parents for survival.

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