6 . Are you a multitasker?

Do you watch TV and cook dinner at the same time? Do you often interrupt your work to check your email? Do you talk on your phone while you’re driving?     1     According to a survey by the magazine Scientific American MIND, 90 percent of American adults multitask regularly.

Most people say they multitask because they are too busy, and multitasking saves time. Popular electronic devices like tablets and smart phone s make it convenient to do several tasks at once.     2     Melissa Brown of Evanston, Illinois, says she has no trouble listening to music, surfing the Internet, and sending text messages to friends while she does her homework.

    3     That’s because with multitasking, there are actually many “micro-interruptions” in which people stop one task, start another, and eventually return to the first one. These stops and starts make it difficult to concentrate, and so multitaskers actually waste time, according to a study at Microsoft Corporation. In the study, workers who interrupted their work to answer an email or text message took an average of 15 minutes to return to the work they were doing before the interruption.

    4     This doesn’t matter if you’re only preparing a salad and listening to the radio, they say. But if you’re doing a difficult task that requires thinking, like writing a report, then multitasking can slow you down and cause mistakes. It can even be dangerous, as in the case of people who talk on the phone, eat, or even apply makeup while driving.

7 . In 1968 a grave dating from about 1100 was uncovered near Hattula, in Finland, Little remained of the occupant’s skeleton, but the inhumation included two swords and a knife. Such grave goods would normally suggest said occupant was a man. The skeleton was, _______ also decorated with brooches (胸针) and woollen clothing of types more usually worn at the time by women. This _______ guess that the burial was actually of a powerful woman, possibly a local ruler in her own right rather than just the wife of a male king.

This would be noteworthy enough. But a re-examination of the remains, just published in the European Journal of Archaeology by Ulla Moilanen of the University of Turku and Elina Salmela of the University of Helsinki, suggests the truth may be yet more _______. Ms. Moilanen and Dr Salmela suspect that the individual _______ may have had outward characteristics of both a man and a woman.

In 1968 working out the _______ of a skeleton in an ancient grave was tricky. After years of deterioration, the bones of men and women look pretty much _______. But that was before the use of DNA became possible. So Ms. Moilanen and Dr Salmela thought it worth trying again.

Most people have two sex chromosomes (染色体): XX in women and XY in men. Find DNA from a Y-chromosome in a skeleton and the chances are the body was _______. And, looking at a fragment of femur brought to her by Ms. Moilanen, who is the archaeologist in the _______, Dr. Salmela, who is the geneticist, did indeed find such DNA. But not much of it. That led her to wonder about contamination (污染), but also to consider whether the individual in the grave had had a(n) _______ X-chromosome that was swamping the signal from the Y.

Having an abnormal number of sex chromosomes is rare, but not vanishingly so. The particular ________ XXY leads to what is known as Klinefelter’s syndrome. To determine the occupant’s karyotype (染色体组型) from the tiny amount of DNA available, Dr. Salmela drew ________ with living people. The grave delivered 8,329 pieces, so she used a computer to draw samples of similar size from the genomes of living people with various karyotypes, including XXY, and also from mixtures of both sexes, to ________ contamination. She then compared these with the DNA from the grave and ________ it was 99.75% probable the individual concerned bad indeed had Klinefelter’s syndrome.

While Dr Salmela was working all this out, Ms. Moilanen and her team had another look at the grave. They confirmed that it was a ________ burial. For instance, they found evidence of fine furs, probably from foxes. Clearly, this was a well-respected human being, but what led to that ________ in a world then dominated by male values is a matter of puzzle. Perhaps the person came from a family powerful enough for such things not to matter.

How and why, roughly 2 million years ago, early human ancestors evolved large brains and began fashioning relatively advanced stone tools, is one of the great mysteries of evolution. Some researchers argue these changes were brought about by the invention of cooking. They point out that our bite weakened around the same time as our larger brains evolved, and that it takes less energy to     1     nutrients from cooked food. As a result, once they had learned the art, early chefs could invest less in their digestive systems and thus invest the     2     energy savings in building larger brains capable of complex thought. There is, however, a problem with the cooking theory. Most archaeologists believe the evidence of controlled fire     3     back no more than 790,000 years.

Roger Summons of the Massachusetts Institute of Technology has a solution. Together with his team, he analyzed 1.7 million-year-old sandstones that formed in an ancient river at Olduvai Gorge in Tanzania. The region is famous for the large number of human fossils (化石) that have been discovered there, alongside an impressive ‘assembly of stone tools. The sandstones themselves have     4     yielded some of the world’s earliest complex hand axes —large tear-drop-shaped stone tools that are associated with Homo erectus (直立人). Creating an ax e by repeatedly knocking thin pieces off a raw stone in order to create two sharp cutting edges requires a significant amount of planning. Their appearance is therefore thought to     5     an important moment in intellectual evolution. During the process, the researchers found distinctive but unusual biological molecules (分子) that are often     6     as biomarkers of heat-tolerant bacteria. Some of these live in water between 85℃ and 95℃. The molecules’     7    suggests that an ancient river within the Gorge was once fed by one or more hot springs.

Dr. Summons and his colleagues say the hot springs would have provided a convenient “pre-fire”     8     of cooking food. In New Zealand, the Maori have traditionally cooked food in hot springs, either by lowering it into the boiling water or fey digging a hole in the hot earth. Similar methods exist in Japan and Iceland, so it makes     9     sense, if difficult to prove, that early humans might have used hot springs to cook meat and roots. Richard Wrangham, who devised the cooking theory, is fascinated by the idea. Nonetheless, fire would have offered a distinct advantage to humans, once they had     10     the art of controlling it since, unlike a hot spring, it is a transportable resource.