考研英语阅读篇章: 大象的嗅觉动物界最灵敏

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    考研英语阅读篇章: 大象的嗅觉动物界最灵敏
    Researchers have discovered that African Elephants have the largest number
of genes dedicated to smell of any mammal.
    研究人员发现，非洲大象拥有数量最多的基因，这些基因有利于所有哺乳动物的嗅觉。
    Given the size of their trunks, and how important it is to their survival,
it is probably unsurprising that an elephant's nose is not only the longest in
the animal kingdom, but also the most effective.
    In comparison, humans and other primates have a poor sense of smell.
    "The functions of these genes are not well known, but they are likely
important for the living environment of African elephants," said author Dr
Yoshihito Niimura of the University of Tokyo.
    "Apparently, an elephant's nose is not only long but also superior.
    The sense of smell is critical to all mammals, and they use it for sniffing
out food, avoiding predators, finding mates and locating their offspring.
    In a study published in Genome Research, scientists examined the 13 mammal
species and found that African Elephants have twice the number of smell genes as
dogs and five times more than humans.
    They have around 2,000 genes alone that are dedicated to scent. Humans in
comparison have just under 400 and other primates like chimpanzees, even
less.
    The study found that 20,000 genes are responsible for the sense of smell in
mammals, of which around half are functional, but the collections differ for
each species.
    Horses have around 1,000 smell genes, rabbits around 750 and rats about
1,200.
    "The large repertoire of elephant (smell) genes might be attributed to
elephants' heavy reliance on scent in various contexts, including foraging(觅食),
social communication, and reproduction," added Dr Niimura