Single mums are better at raising their kids than two parents 一 at least in the bird world. Mother zebra finches ¹ have to work harder and raise fewer chicks on their own，but they also produce more attractive sons who are more likely to get a mate.

    The finding shows that family conflict is as important an evolutionary driving force as ecological factors 2 such as hunting and food supply. With two parents around, there"s always a conflict of interests 3，which can have a detrimental effect on the quality of the offspring.

    In evolutionary terms 4，the best strategy for any parent in the animal world is to find someone else to care for their offspring，so they can concentrate on breeding again. So it"s normal for parents to try to pass the buck 5 to each other. But Ian Hartley from the UniversityofLancasterand his team wondered how families solve this conflict, and how the conflict itself affects the offspring.

    To find oiit 6，they measured how much effort zebra finch parents put into raising their babies. They compared single females with pairs, by monitoring the amount of food each parent collected, and removing or adding chicks so that each pair of birds was raising four chicks，and each single mum had two — supposedly the same amount of work.

    But single mums, they found, put in about 25 per cent more effort than females rearing with their mate. To avoid being exploited, mothers with a partner hold back from working too hard if the father is being lazy, and it"s the chicks that pay the price. “The offspring suffer some of the cost of this conflict, ” says Hartley.

    The cost does not show in any obvious decrease in size or weight, but in how attractive they are to the opposite sex. When the chicks were mature, the researchers tested the ” fitness" of the male offspring by offering females their choice of partner. Those males reared by single mums were chosen more often than those from two-parent families.

    Sexual conflict has long been thought to affect the quality of care,given to offspring, says zoologist Rebecca Kilner atCambridgeUniversity, who works on conflict of parents in birds. ” But the experimental evidence is not great. The breakthrough here is showing it empirically. ”

    More surprising, says Kilner, is Hartley"s statement that conflict may be a strong influence on the evolution of behaviour, clutch size and even appearance. “People have not really made that link," says Hartley. A female"s reproductive strategy is usually thought to be affected by hunting and food supply. Kilner says conflict of parents should now be taken into account as well.

词汇：

evolutionary /,i: və"lu:ʃənəri/adj．进化的

detrimental /detrimentəl/adj．有害的

offspring /"ɔfspriŋ/n．（单复数同形）儿女，子孙，后代

empirically /em"pirikli/adv．以经验为根据地

ecological /i:kə"lɔdʒikəl/adj．生态的

reproductive /,ri:prədʌktiv/adj．生殖的

experimental /eks,peri"mentəl/adj．实验的，根据实验的

clutch /klʌtʃ/ n．一次产的或孵的卵

注释：

1.zebra finch：斑胸草雀，一种澳大利亚小鸟，它有黑白色条纹，而且是受欢迎的笼养鸟。

2.family conflict is as important an evolutionary driving force as ecological factors：家庭冲突是与生态因素同样重要的进化推动力。

3.a conflict of interests：利益冲突

4.in evolutionary terms：从进化的角度讲。in... terms, in terms of...：从……方面来讲，就……而言。例如：It has been a terrible year in terms. of business．就生意而论，这是很糟糕的一年。

5.pass the buck (to)：推卸责任，把为难的事推给别人。例如：Bus companies are just passing the buck by saying their drivers are responsible for delays．公交公司说司机应该对误点的事负责，这只是在推卸责任。

6.find out：这是一个承上的短语，从逻辑上讲，它的宾语应该是：how families solve this conflict, and how the conflict itself affects the offspring.  

According to the passage, people believe that a female"s reproductive strategy is influenced by________.

A:an evolutionary driving force B:a conflict of interests C:ecological factors D:the quality of the offspring

MEGA(Molecular Evolutionary Genetics Analysis)

Suppose we built a robot to explore the planet Mars. We provide the robot with seeing detectors to keep it away from danger. It is powered entirely by the sun. Should we program the robot to be equally active at all times No, the robot would be using up energy at a time when it was not receiving any. So we would probably program it to stop its activity at night and to wake up at dawn the next morning.
According to evolutionary theory of sleep, evolution equipped us with a regular pattern of sleeping and waking for the same reason. The theory does not deny that sleep provides some important restorative functions. It merely says that evolution has programmed us to perform those functions at a time when activity would be inefficient and possibly dangerous. However, sleep protects us only from the sort of trouble we might walk into; it does not protect us from trouble that comes looking for us. So we sleep well when we are in a familiar, safe place, but we sleep lightly, if at all, when we fear that bears will nose into the tent.
The evolutionary theory explain the differences in sleep among creatures. Why do cats, for instance, sleep so much, while horses sleep so little Surely cats do not need five times as much repair and restoration as horses do. But cats can afford to have long periods of inactivity because they spend little time eating and are unlikely to be attacked while they sleep. Horses must spend almost all their waking hours eating, because what they eat is very low in energy value. Moreover, they cannot afford to sleep too long or too deeply, because their survival depends on their ability to run away from attackers.
Which of the following is the main idea of the passage

A:Evolution has equipped all creatures with a regular pattern of sleeping and waking. B:The study of sleep is an important art of the evolutionary theory. C:Sleeping patterns must be taken into consideration in the designing of robots. D:The sleeping pattern of a living creature is determined by the food it eats.

When it comes to jealousy, men and women aren’t always on the same page. Previous studies have shown that, while men are more likely to see red over a partner’s sexual infidelity, women are more upset by emotional cheating. Evolutionary psychologists- theorize that the difference is rooted in the sexes’ historical roles--men wanted to guarantee that their partners were carrying their children, while women needed to feel secure that they and their children would be cared for by a committed partner. Yet, that evolutionary explanation doesn’t account for a large group of men who say that emotional disloyalty is more upsetting than sexual infidelity, and women who are more upset by sexual betrayal.
To gain a more thorough understanding of gender and jealousy, researchers from Pennsylvania State University (PSU) approached the issue with some modem psychology. In a study published in the journal Psychological Science, researchers found that, while generally speaking, the evolutionary explanation of gender and jealousy held up, when viewed through the lens of attachment theory--broadly, the psychological theory about our tendency to foster intimate relationships with other people--both men and women with secure emotional histories were more likely to experience jealousy over emotional infidelity, and those who were insecure or dismissing, were more likely to be vexed by sexual cheating.
To tackle the issue, researchers recruited 416 college students from New York City, whose attachment styles were assessed through questionnaires containing a series of vignettes (short descriptions or pictures)--each reflecting either secure, fearful, preoccupied, or dismissing attachment styles. Participants were instructed to select the story that most accurately reflected their own attitude about romantic relationships, and were categorized accordingly. In a subsequent questionnaire, participants were asked whether they would be more upset by their partner "having passionate sexual intercourse with another person," or "forming a deep emotional attachment to another person."
They found that, regardless of gender, 77.3% of securely attached participants viewed emotional infidelity as more upsetting, while 64.8% of insecure or dismissing participants thought sexual cheating was worse. These findings, the authors say, shed light on the intricate psychological nature of jealousy, and may help to develop techniques to determine the underlying dynamics of sexual jeaiousy--a well-documented cause of spousal abuse, beating and even murder. The authors suggest that, gaining a better understanding of not only the broad differ ences in jealousy between the sexes, but of the differences in jealousy within genders, may help to identify methods for interrupting abuse by fostering stable, secure attachments.
The theory put forward by evolutionary psychologists

A:maintains that men and women are different when it comes to jealousy. B:asserts that the gender difference in jealousy shaped the sexes’ historical roles. C:fails to obtain a thorough understanding of gender and jealousy. D:is by and large influenced by Darwin’s evolutionary theory.

When it comes to jealousy, men and women aren’t always on the same page. Previous studies have shown that, while men are more likely to see red over a partner’s sexual infidelity, women are more upset by emotional cheating. Evolutionary psychologists- theorize that the difference is rooted in the sexes’ historical roles--men wanted to guarantee that their partners were carrying their children, while women needed to feel secure that they and their children would be cared for by a committed partner. Yet, that evolutionary explanation doesn’t account for a large group of men who say that emotional disloyalty is more upsetting than sexual infidelity, and women who are more upset by sexual betrayal.
To gain a more thorough understanding of gender and jealousy, researchers from Pennsylvania State University (PSU) approached the issue with some modem psychology. In a study published in the journal Psychological Science, researchers found that, while generally speaking, the evolutionary explanation of gender and jealousy held up, when viewed through the lens of attachment theory--broadly, the psychological theory about our tendency to foster intimate relationships with other people--both men and women with secure emotional histories were more likely to experience jealousy over emotional infidelity, and those who were insecure or dismissing, were more likely to be vexed by sexual cheating.
To tackle the issue, researchers recruited 416 college students from New York City, whose attachment styles were assessed through questionnaires containing a series of vignettes (short descriptions or pictures)--each reflecting either secure, fearful, preoccupied, or dismissing attachment styles. Participants were instructed to select the story that most accurately reflected their own attitude about romantic relationships, and were categorized accordingly. In a subsequent questionnaire, participants were asked whether they would be more upset by their partner "having passionate sexual intercourse with another person," or "forming a deep emotional attachment to another person."
They found that, regardless of gender, 77.3% of securely attached participants viewed emotional infidelity as more upsetting, while 64.8% of insecure or dismissing participants thought sexual cheating was worse. These findings, the authors say, shed light on the intricate psychological nature of jealousy, and may help to develop techniques to determine the underlying dynamics of sexual jeaiousy--a well-documented cause of spousal abuse, beating and even murder. The authors suggest that, gaining a better understanding of not only the broad differ ences in jealousy between the sexes, but of the differences in jealousy within genders, may help to identify methods for interrupting abuse by fostering stable, secure attachments.
The study conducted by researchers from PSU has shown that

A:the evolutionary theory of gender and jealousy is valid and true. B:more participants (77.3% to 64.8%) viewed emotional infidelity as more upsetting. C:the evolutionary explanation is untrue when viewed from the angle of attachment theory. D:aside from gender, attachment styles contribute to the difference in terms of jealousy.

A:an evolutionary driving force B:a conflict of interests C:ecological factors D:the quality of the offspring

{{B}}第三篇{{/B}}

A:an evolutionary driving force. B:a conflict of interests. C:ecological factors. D:the quality of the offspring.

Suppose we built a robot to explore the planet Mars. We provide the robot with seeing detectors to keep it away from danger. It is powered entirely by the sun. Should we program the robot to be equally active at all times No, the robot would be using up energy at a time when it was not receiving any. So we would probably program it to stop its activity at night and to wake up at dawn the next morning.
According to evolutionary theory of sleep, evolution equipped us with a regular pattern of sleeping and waking for the same reason. The theory does not deny that sleep provides some important restorative functions. It merely says that evolution has programmed us to perform those functions at a time when activity would be inefficient and possibly dangerous. However, sleep protects us only from the sort of trouble we might walk into; it does not protect us from trouble that comes looking for us. So we sleep well when we are in a familiar, safe place, but we sleep lightly, if at all, when we fear that bears will nose into the tent.
The evolutionary theory explain the differences in sleep among creatures. Why do cats, for instance, sleep so much, while horses sleep so little Surely cats do not need five times as much repair and restoration as horses do. But cats can afford to have long periods of inactivity because they spend little time eating and are unlikely to be attacked while they sleep. Horses must spend almost all their waking hours eating, because what they eat is very low in energy value. Moreover, they cannot afford to sleep too long or too deeply, because their survival depends on their ability to run away from attackers.
Which of the following is the main idea of the passage

A:Evolution has equipped all creatures with a regular pattern of sleeping and waking. B:The study of sleep is an important art of the evolutionary theory. C:Sleeping patterns must be taken into consideration in the designing of robots. D:The sleeping pattern of a living creature is determined by the food it eats.