Elephant communication
A
A postdoctoral fellow at StanfordUniversity, O’Connell-Rodwellhas come to Namibia’s premiere wildlife sanctuary ( 保护地)to explore the mysterious and complex world of elephantcommunication. She and her colleagues are part of a scientific revolution thatbegan nearly two decades ago with the stunning revelation that elephantscommunicate over long distances using lowfrequency sounds, also calledinfrasounds ( 次级声波),that are too deep to be heard bymost humans.
B
As might be expected, the African elephant’s ability to sense seismic (地震的) sound may begin in the ears.The hammer bone ( 锤骨)of the elephant’s inner ear is proportionally very large for a mammal, but typicalfor animals that use vibrational signals. It may therefore be a sign thatelephants can communicate with seismic sounds. Also, the elephant and itsrelative the manatee are unique among mammals (哺乳动物)in having reverted to a reptilian-like cochlear (耳蜗的)structure in the inner ear. Thecochlea of reptiles ( 爬行动物)facilitates a keen sensitivity to vibrations ( 震动)and may do the same in elephants.
C
But other aspects of elephant anatomy ( 解剖)also support that ability. First,their enormous bodies, which allow them to generate low-frequency ( 低音频的) sounds almost as powerful asthose of a jet takeoff ( 飞机起飞), provide ideal frames for receiving ground vibrations and conductingthem to the inner ear. Second, the elephant’s toe bones rest on a fatty pad that might help focus vibrations fromthe ground into the bone. Finally, the elephant’s enormous brain lies in the cranial cavity ( 颅腔)behind the eyes in line with theauditory canal ( 耳道).The frontof the skull is riddled with sinus cavities that may function as resonatingchambers for vibrations from the ground.
D
How the elephants sense these vibrations isstill unknown, but O’Connell- Rodwell who just earned a graduate degree in entomology ( 昆虫学)at the University of Hawaii atManoa, suspects the pachyderms ( 迟迟的大家伙)are“listening” with their trunks and feet. Thetrunk may be the most versatile ( 多才艺的)appendage ( 附属物)in nature. Its uses include drinking, bathing,
smelling, feeding and scratching. Bothtrunk and feet contain two kinds of pressure-sensitive nerve endings— one that detects infrasonicvibrations and another that responds to vibrations with slightly higherfrequencies. For O’Connell-Rodwell, the future of the research is boundless andunpredictable:“Our work isreally at the interface of geophysics, neurophysiology ( 神经心理学)and ecology,” she says. “We’re asking questions that no one has really dealt with before.”
E
Scientists have long known that seismiccommunication is common in small animals, including spiders, scorpions ( 蝎子) ,insects and a number of vertebrate species ( 脊椎动物)such as white-lipped frogs,blind mole rats ( 鼹鼠),kangaroo rats and golden moles. They also have found evidence ofseismicsensitivity in elephant seals— 2-ton marine mammals that are not related toelephants. But O’ Connell-Rod well was the first tosuggest that a large land animal also is sending and receiving seismicmessages. O’ Connell-Rodwell noticed something about the freezing behavior of Etosha’s six-ton bulls that reminded herof the tiny insects back in her lab. “I did my masters thesis on seismic communication in planthoppers,” she says‘. I’d put a male planthopper ( 蜡蝉)on a stem and play back a female call, and the male would do thesame thing the elephants were doing: He would freeze, then press down on hislegs, go forward a little bit, then freeze again. It was just so fascinating tome, and it’s what got meto think, maybe there’s something else going on other than acoustic communication.”
F
Scientists have determined that an elephant’s ability to communicate over longdistances is essential for its survival, particularly in a place like Etosha, wheremore than 2,400 savanna elephants range over an area larger than New Jersey.The difficulty of finding a mate in this vast wilderness is compounded by ( 由... 组成)elephant reproductive ( 繁殖的) biology. Females breed only when in estrus ( 发情期)— a period of sexual arousalthat occurs every two years and lasts just a few days. “Females in estrus make these verylow, long calls that bulls home in on, because it’s such a rare event/’ O’Connell-Rodwellsays. These powerful estrus calls carry more than two miles in the air and may beaccompanied by long-distance seismic signals, she adds. Breeding herds also uselow-frequency vocalizations ( 发出的声音)to warn of predators ( 捕食者). Adult bulls and cows have no enemies, except for humans, but youngelephants are susceptible to attacks by lions and hyenas. When a predator appears,older members of the herd emit intense warning calls that prompt the rest ofthe herd to clump together ( 聚集成团)for protection, then flee ( 逃跑). In 1994, O’Connell-Rodwell recorded the dramatic cries of a breeding herdthreatened by lions at Mushara. “The elephants got really scared, and the matriarch ( 象群首领)made these very powerfulwarning calls, and then the herd took off screaming and trumpeting ( 发喇叭声),” she recalls. “Since then, every time we’ve played that particular call at the water hole, we get the sameresponse — theelephants take off.”
G
Reacting to a warning call played in theair is one thing, but could the elephants detect calls transmitted only throughthe ground? To find out, the research team in 2002 devi s ed an expe r iment using electronic equipment that allowed them to send signals through the groundat Mushara. The results of our 2002 study showed us that elephants do indeeddetect warning calls played through the ground,” O’Connell-Rodwell observes. “We expected them to clump up into tight groups and leave the area,and that’s in factwhat they did. But since we only played back one type of call, we couldn’t really say whether they wereinterpreting it correctly. Maybe they thought it was a vehicle or somethingstrange instead of a predator warning.
H
An experiment last year was designed tosolve that problem by using three different recordings— the 1994 warning call fromMushara, an anti-predator call recorded by scientist Joyce Poole in
Kenya and an artificial warble tone ( 人造 颤音). Although still analyzing data from this experiment, O’Connell-Rodwell is able to make afew preliminary observations: “The data I’ve seen so far suggest that the elephants were responding like I hadexpected. When the‘ 94 warning call was played back, they tended to clump together andleave the water hole sooner. But what’s really interesting is that the unfamiliar anti-predator call fromKenya also caused them to clump up, get nervous and aggressively rumble— but they didn’t necessarily leave. I didn’t think it was going to be thatclear cut( 清晰的).”
A段 介绍研究大象交流的背景
斯坦福大学的博士后研究员CR到纳米比亚野生动物保护地去研究大象交流。她和同伴惊讶的发现了大象使用低频率的声音来进行长距离交流,这种低频的声音叫做次级声波,很难被大部分人听到。
B段 非洲大象对震动的感知开始于耳朵。讲了几种耳朵结构。
28.内耳的锤hammer骨,对于一些使用震动信号的动物来说刚刚好。
C段 讲了大象身体其他方面的剖析也支持这种能力。
29.庞大的身躯 body(注意题目是an extremely____)
30.脚趾骨头下的脚板 pad
31.头骨的前面有很多的洞cavities
D段 大象如何感觉这种震动还不得而知,介绍了象鼻的一些功能,包括喝水,洗澡等等。象鼻和脚包括两种感知压力的神经末梢。
32.但是CR怀疑这个家伙使用他们的象鼻和脚trunks and feet在“听”。
33.一种是能检测到infrasonic震动,另一种回应震动。
34.大象感觉这种震动可能涉及到神经学、生态学ecology等等。
E 科学家认为震动交流在一些动物中十分常见,列举了一些动物。
35.但是CR是第一个认为大型的陆地动物同样会发出和接收震动信息seismic messages。
36.她在实验室里研究蜡蝉。蜡蝉的行为让她觉得不是动物的声通讯acoustic communication而是其他原因。
F 大象长距离的交流对于他们的生存至关重要。
37.当寻找配偶mate或者警告捕食者的时候,大象这种长距离交流的能力显得尤为重要。
G段 2002一项实验研究大象是不是能够发现来自地面传来的声音。
39.结果是大象可以检测到来自地面ground的警告声音。但是研究人员只发出了一种类型的声音,所以不能知道他们是不是正确的理解了这种声音。
39.当捕食者如狮子出现时,象群会发出警告(39A),让其他象群聚集在一起保护自己,然后逃跑。
H段 讲了去年的一项实验为了解决声音单一的问题,使用了三种不同的录音。大象都会如期的回应。94年的警告录音会使大象聚集在一起,然后离开。有趣的是,另外一种anti-predator call使大象紧张不安,但是并没有离开。我不认为这个结论很清晰。
40.作者的观点是:研究结果不能确定或是不准确C)
Writing
Task1 小作文
柱图 main reasons for choosing university
Task2 大作文
why more people live by themselves