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Pre Historic Puzzles: Rocking the Cradle of Civilization For more than a century, archeologists were convincing that the cradle of civilization lay in Greece, Egypt, and Mesopotamia. The learning of the advanced peoples of this region, it was thought, gradually moved west into Europe. But in the last few decades these theories have been overturned, thanks to Nobel Prize-winning physicist Willard F. Libby and a substance knows as carbon 14. Carbon 14 is a radioactive substance that exists in minute quantities. In the late 1940's Libby discovered that all plants and animals absorb it. When they die, the carbon-like all radioactive substances-begins to decay at a regular rate. Libby was able to measure this rate and could thus use carbon 14 as an archeological calendar. Today it is known that half of the carbon 14 in living organism disappears in 5,730 years, half of what remains in an additional 5,730 years, and so on. How old is old? Many of the items found at prehistoric sites are made of organic material. By measuring the amount of carbon 14 remaining in the shaft of an old ax or a piece of pottery, for example, scientists can accurately determine its age. Radiocarbon dating has proved to be phenomenally accurate: it can date to within 100 years going back to 50,000 B.C. It is particularly useful on wood because it can be checked against Dendron-chronology, dating by tree rings. A new ring forms every year in the trunk of a tree as it grows: counting the number of rings enables one to determine the age of any tree. Where did civilization begin?

Why are we all so different? Here is a toolkit for finding out what people are really like IN THE 4th century BC, the Greek philosopher Theophrastus, Aristotle's student and successor, wrote a book about personality. The project was motivated by his interest in what he considered a very puzzling question: "Why it has come about that, albeit the whole of Greece lies in the same clime, and all Greeks have a like upbringing, we have not the same constitution of character?" Not knowing how to get at the answer, Theophrastus decided to instead focus on categorising those seemingly mysterious differences in personality. The result was a book of descriptions of personality types to which he assigned names such as The Suspicious, The Fearful and The Proud. The book made such an impression that it was passed down through the ages, and is still available online today as The Characters of Theophrastus. The two big questions about personality that so interested Theophrastus are the same ones we ask ourselves about the people we know: why do we have different personalities? And what is the best way to describe them? In the past few decades, researchers have been gradually answering these questions, and in my new book, Making Sense of People: Decoding the mysteries of personality, I take a look at some of these answers. When it comes to the origins of personality, we have learned a lot. We now know that personality traits are greatly influenced by the interactions between the set of gene variants that we happen to have been born with and the social environment we happen to grow up in. The gene variants that a person inherits favour certain behavioural tendencies, such as assertiveness or cautiousness, while their environmental circumstances influence the forms these innate behavioural tendencies take. The ongoing dialogue between the person's genome and environment gradually establishes the enduring ways of thinking and feeling that are the building blocks of personality. This de