Although the rooster's strident wake-up call just before
sunrise feels as regular as an alarm clock, the evidence that the
birds are somehow driven to herald the dawn has long been
anecdotal. After all, a rooster is rarely shy about making his
presence known regardless of the time of day. Now, Japanese
scientists have quite literally shed light on the phenomenon. To
see whether roosters simply crow in response to external stimuli or
according to a circadian rhythm—an internally driven, cyclical
pattern of behavior that occurs over a 24-hour period—the team put
one group of birds into a room with continuously dim lights and
tracked the birds' crowing over the course of a month. Even in the
absence of a daily cycle of light and dark, the authors report
today inCurrent
Biology,the
roosters continued to crow near dawn, suggesting that the birds' cacophonous racket is indeed
controlled by an internal circadian clock. However, over time their
crows became more scattered, suggesting that the rhythm eventually
faded as they adjusted to a new regime of perpetual
twilight.
青春就应该这样绽放 游戏测试：三国时期谁是你最好的兄弟！！ 你不得不信的星座秘密Image may be NSFW.
