A strong hit to the head will normally give you a concussion(脑震荡). Woodpeckers(啄木鸟), however, strike their beaks(喙) into trees thousands of times a day and are perfectly fine.
We used to think that a woodpecker’s skull(头骨) worked as a kind of safety helmet which absorbed the shocks. A new study by Sam Van Wassenbergh, a researcher at the University of Antwerp in Belgium, proved that this “common sense” was in fact false.
Van Wassenbergh and his colleagues argued that, if a woodpecker’s head absorbed the force, it would not be able to strike the tree with enough force.
“If the beak absorbed much of its own impact, the unlucky bird would have to pound even harder,” they said in their paper. In other words, if the theory were true, the woodpecker would have to peck even harder to compensate for both the shock-absorbing qualities of the sponge-like bone inside its skull as well as the density(密度) of the wood.
The scientists recorded four different kinds of woodpeckers in zoos as they were pecking. The team used data from their high-speed recordings to build digital models of the woodpeckers. Van Wassenbergh described the woodpeckers motion as “a hammer(锤子) hitting wood” since their movement appeared rigid and focused.
The research suggested that woodpeckers don’t have any shock-absorbing device or the ability to reduce the amount of force. Although they are without “helmets”, the team claimed that the woodpeckers’ tiny size and weight protect them.
A woodpecker’s brain is about 700 times smaller than that of a human. “Smaller animals can withstand higher deceleration(减速). Think about a fly that hits a window and then just flies back again,” Van Wassenbergh said. “So that is why even the hardest hits we observed are not expected to cause any concussion.
12. What did people use to believe about woodpeckers when they peck trees?
A.Their beaks could spread the shocks they produce. |
B.They could stand slight concussions. |
C.Their bodies were soft enough to absorb the force. |
D.Their heads were able to reduce the shocks. |
13. What does the underlined word “impact” in Paragraph 4 probably mean?
A.Influence. | B.Shock. | C.Limit. | D.Benefit. |
14. Which of the following statements about the experiment proves to be true?
A.Woodpeckers do not have special safety devices. |
B.How woodpeckers peck depends on their type. |
C.Density of the wood affects a woodpeckers pecking force. |
D.The shock absorber theory is mostly correct. |
15. Where is this text probably taken from?
A.A guidebook. | B.A medical report. | C.A science magazine. | D.An advertisement. |