Young Female Chimps Outlearn Their Brothers

　　Young female chimps are faster and better learners than young male chimps, suggests a new study¹, echoing learning differences seen in human girls and boys².

　　While young male chimps pass their time playing. Young female chimps carefully study their mothers. As a result, they learn how to fish for³ tasty termite snacks over two years before the boys.
　　Elizabeth Lonsdorf, now at Lincoln Park Zoo in Chicago, US, and colleagues at the University of Minnesota, Saint Paul spent four years watching how young chimpanzees in the Gombe National Park in Tanzania⁴ learned “cultural behavior”.
　　The sex differences in learning behavior were “consistent and strikingly apparent”, says the team. The researchers point out that similar differences are seen in human children with regard to⁵  skills such as writing. “A sex-based learning differences may therefore date back⁶ at least to the last common ancestor of chimpanzees and humans.” they write in the journal Nature.

　　Chimps make flexible tools from vegetation and then insert them into termite mounds, extract them and then munch the termites clinging onto the tool. The researchers used video cameras to record this feeding behavior and found that each chimp mother had her own technique, such as how she used tools of different lengths.
　　Analysis of the six infants whose ages were known showed that girl chimps were an average of 31 months old when they succeeded in fishing out their termites, where the boy chimps were aged 58 months on average. Females were also more skillful at getting out more termites with every dip⁷ and used techniques similar to their mothers while males did not.
　　Instead of studying their mothers, the boy chimps spent a significantly greater amount of time frolicking around the termite mound. Behaviors such as playing or swinging might help the male infants later in life when typically male activities like hunting or fighting for dominance become important, suggest the researchers.
　　Lonsdorf adds that there just two main sources of animal protein for chimps — the termites or colobus monkeys. “Mature males often hunt monkeys up trees, but females are almost always either pregnant or burdened with a clinging infant⁸. This makes hunting difficult,” she says .“Adult females spend more time fishing for termites than males.” So becoming proficient at termite fishing⁹ could mean adult females eat better, “They can watch their offspring at the same time. The young of both sexes seen to pursue activities related to their adult sex roles¹⁰ at a very young age.”

词汇：

chimp /tʃɪmp /v.黑猩猩 

outlearn / aʊt"lɜ:n /v.在学习上胜过
munch / mʌntʃ /v.用力嚼；津津有味地吃

frolic / "frɒlɪk /n.嬉戏；v.(-icked;-icking)
termite/ "tɜ:maɪt /n白蚁 

offspring/ "ɒfsprɪŋ /n 子孙，后代 

colobus/ "kɒləbəs /n疣猴

注释：

1.suggest a new study：倒装句，正常语序是a new study suggests（一项新的研究表明）。
2.echoing learning differences seen in human girls and boys：与人类女孩男孩之间的学习差异相仿。
3.fish for：捕获。fish：to catch or pull as if fishing捕鱼似地捞
4.Tanzania：坦桑尼亚，非洲中东部国家，位于印度洋沿岸
5.with regard to：关于，在……方面
6.date back to：回溯至
7.with every dip：猩猩是用植物作为工具来捕食白蚁，因此这里的意思是，每次将植物插入蚁穴。
8.burdened with a clinging infant：身上吊着小猩猩
9.becoming proficient at termite fishing：分词短语在句中充当主语，意为：学会有效地捕获白蚁。
10.pursue activities related to their adult sex roles：进行与它们成年后的性别角色有关的活动。

Why do young female chimps learn faster than young male chimps at fishing for termites?

A:Because young female chimps don’t play with their brothers. B:Because young female chimps begin to study their mothers earlier. C:Because young male chimps never learn to fish for termites. D:Because young male chimps are not interested in termites.

A Dog’s Dilemma

    Finding a babysitter while you go out to work is, for example, an inconvenience. For the African wild dog, one of the continents’s most endangered carnivores, it’s a matter of life and death. New research shows that once packs fall below a certain size, they are not enough animals to both hunt food and stay at home protecting the young.

    The African wild dog has declined drastically over the past century. Habitual loss, persecution and unexplained outbreaks of disease have all been blamed. Only 3,000 to 5,000 animals remain, and the species is expected to go extinct within decades if the trend continues.

    Other large carnivores such as the spotted hyena face similar pressures, yet are not declining. Now Franck Courchamp of CambridgeUniversityhas found a reason why. The dog’s weakness lies in its social organization.

    Within each pack of up to 20 adults and pups, only he dominant male and female bread. The remaining animals help raise the pups, cooperating to hunt prey and defend the kill from other carnivores.

    Because pups can’t keep up on a hunt, large packs leave an adult behind to protect them from predators, which include lions and hyenas. But leaving a babysitter also carries costs. A smaller hunting party is less able to tackle large prey and to defend the kill ¹. There is also one less stomach in which to carry food back to the den, and one more mouth to feed when they get there.

    Courchamp investigated this awkward trade-off by modeling how the costs of a babysitter change with decreasing pack size. This showed that packs of more than five adults should be able to feed all the pups and still spare a babysitter. But with smaller packs, either the hunting or the babysitting suffers, or the animals have to compensate by increasing he number of hunting excursions—which itself carries a cost to the pack.

    Field observations inZimbabwesupported the model. Packs of five animals or fewer left pups unguarded more frequently than larger packs did. There was also evidence that when they did leave a babysitter, they were forced to hunt more often.

    A pack which drops below a critical size becomes caught in a vicious circle, says Courchamp ², who is now atParis-SudUniversity. “Poor reproduction and low survival further reduces pack size, culminating in failure of the whole pack.” And deaths caused by human activity, says Courchamp, may be what reduces pack numbers to below the sustainable threshold. Mammal ecologist Chris Carbone atLondon’sInstituteofZoologyagrees. Maintaining the integrity of wild dog packs will be vital in preserving the species, he says.

词汇

carnivore /"ka: nivɔ:(r)/ n．食肉动物

pup /pʌp/ n．小狗

predator/"predətə(r)/n．捕食者

integrity /in"tegrəti/ n．完整

hyena /hai"inə/ n．鬣狗

prey /prei/ n．被捕食的动物

culminate /"kʌlmineit/ n．告终；达到顶点

Zimbabwe /zim"ba: bwei/ n．津巴布韦

注释：

1.A smaller hunting party is less able to tackle large prey and to defend the kill.：一个较小的捕猎群体不太容易捕捉大动物，也不太容易保卫猎获物。
2. A pack which drops below a critical size becomes caught in a vicious circle, says Courchamp：Courchamp说，“一个群体的规模降到警戒线以下时就会陷入恶性循环。”

The dominant female is always left behind to protect the young.

A:Right B:Wrong C:Not mentioned

Are Online Friends Real Friends?

    Modern computer technology has made a new kind of human relationship possible: online friendship. ____1____. Are online friendships as beneficial as face-to-face friendships? What are the advantages and disadvantages of having virtual friends? Can people form strong bonds online? Today these questions are the subject of lively debate¹.