高考英语《流行话题 语境识词4500》Unit42 Answer to the Mystery of Life Is Four素材.docVIP

Unit 42　　Answer to the Mystery of Life Is Four　　Scientists have found a simple mathematical relationship that connects the whole nature, from the tiniest cell to the vast forest of the Amazon. The connections are all based on the three dimensions of the physical world -- length, depth and width -- plus one, making the number 4. Four is the magic number of life, says Dr. Geoffrey West of the Santa Fe Institute in New Mexico, a keynote speaker at the NZ Institute of Physics annual conference last week.　　Dr. West, a British-born physicist, and US ecologists James Brown and Brian Enquist have found more than 50 biological relationships, such as between body size and heart rate, which are based on numbers taken to the power of 1/4.　　Much of the theory is based on mathematics that can confuse the mind of anyone who struggled through School Certificate maths. Suffice to say that it centers on equations involving square roots and numbers to the power of 1/4. In simple maths, says Dr. West, if you are 16 times bigger than your dog, your heart rate is half the dogs rate. Average body size and lifetime are also related in the same ratio. So in principle, if you are 16 times the size of your dog, you will live twice as long. We do better than that, thanks to modern medicine, but the average lifetime of pre-European Maori was around 30.　　Remarkably, combining these two relationships means that the heart of every mammal beats roughly the same number of times in its average lifetime -- around 1.5 billion times -- regardless of whether it is a dog or a human, a mouse or an elephant. The implication is clear -- we cant beat nature. This says that there is a maximum lifespan for a given size, Dr. West says.　　He and his colleagues have found that similar quarter-power rules govern every kind of life on Earth, from the rate at which single-celled bacteria absorb energy to the height of those Amazon trees. They believe this uniformity is because every living thing is made up of