25．Your biology teacher may insist that science is not a laughing matter，but scientists would argue that laughter is a scientific matter.These scientists have found a basic difference in how men and women laugh.
Jo-Anne Bachorowski and her research team recorded the laughter of 97 volunteers.The volunteers watched clips（電影片段） from funny movies.The scientists were surprised at the variety of sounds people made when they laughed.Rarely did they hear sounds that we stereotype as laughter such as "tee hee hee" or "ho ho ho." More often they heard vowel （元音） sounds such as those heard in "car" （aah） or "glow" （ooh）.What's more，women tended to laugh in a more sing-song way，while men more often grunted （發(fā)出哼聲）.
The researchers caution that this work was limited to people in the United States，so the results may not be universal.Bachorowski predicts that cultural influences may affect what causes people to laugh，but it probably does not change how we laugh.
Although we do laugh at jokes and funny movies，80% of our laughter occurs during everyday comments in everyday social situations.Robert Provine，a neuroscientist who studies laughter，went to places such as shopping malls and collected more than 1，200 conversations.He found that the person speaking laughed 46% more than the listeners and that women laughed more often than men.Furthermore，the response to the speaker depended on the speaker's gender.People，whether male or female，laughed more readily in response to a male speaker.The researchers also observed that laughter rarely interrupted speech.Instead，laughter came at the end of a phrase，much like punctuation following a written sentence.
Humans may be "tuned（使協(xié)調(diào)）" for laughter much in the same way that songbirds are "tuned" for song — especially their own specific family song.Certain nerve cells （神經(jīng)細(xì)胞） in the songbird's brain "fire" in response to hearing his song.Perhaps humans have specialized nerve cells that respond to laughter.After all，laughter is a specialized vocalization，and we are "tuned" to respond to vocalizations in language.
（1）How did Bachorowski's team do their research？
A．By studying how people laugh globally.
B．By analyzing cultural influences on humans' laughter.
C．By observing everyday conversations in shopping malls.
D．By studying sounds made by volunteers in response to funny movies.
（2）What did Bachorowski's team find？
A．Men and women laugh differently.
B．Vowel sounds are rarely heard in laughter.
C．Cultural influences determine how people laugh.
D．People think jokes are funnier than comedy movies.
（3）Which of the following agrees with Provine's finding？
A．Men laugh more often than women.
B．Listeners laugh more often than speakers.
C．Laughter may easily interrupt a conversation.
D．Male speakers make people laugh more easily.
（4）Why does the author mention songbirds in the last paragraph？
A．To describe how birds laugh.
B．To praise the beautiful songs they sing.
C．To explain how humans' laughter works.
D．To show that laughter also exists among animals.
