【英语时差8,16】果蝇的学习能力（在线收听）

 Fruit Fly Learning You might think those pesky little fruit flies gathering around your fresh produce every summer are too stupid to know a banana from a pear. They’re barely large enough to see. They certainly can’t have that much brain power, can they? Well, fruit flies will never be rocket scientists, but researchers have discovered that they can learn from each other. Fruit flies, known as Drosophila melanogaster, grow from eggs to adults in about a week. Within the first forty-eight hours after emergence into adulthood, female fruit flies mate and start laying eggs. Fruit flies life spans are short, lasting only thirty to sixty days, and the survival of their eggs depends upon where they are laid. So how do females decide where to lay them? Many insect species are pre-wired genetically to lay eggs on a particular plant or group of plants. Fruit flies may be pre-wired to some extent, but scientists have found that novice females, those with no egg laying experience, learn from other females. When novices observed experienced females laying eggs on a specific fruit, they preferred that fruit type later when laying their own eggs. Observing non-laying virgin females, or being exposed to an aggregation pheromone used to attract individuals to a location, did not create the same preference. Now that scientists know fruit flies are capable of social learning, they are excited about possible research into the evolution and neurogenetics of their learning ability. Fruit flies share many genes with humans, and future research may unlock some mysteries of human learning as well. Unfortunately, none of this will probably keep those little flies off your fruit in summer.