The spring breeze happily blew a river green. Every sunny morning, I take paper to feed the ducks beside the daffodils. When all kinds of colorful ducks (or not ducks) gathered around me and pecked at the bread bit by bit, I wondered if anyone had started to do science by feeding ducks.
So when I saw Professor ReinholdNecker, a lovely German grandfather with a beard, who published a review paper in 2007, I couldn't help laughing. Chickens and ducklings also have big science. Grandpa Nike may be born to study neck, and he even wrote a wonderful popular science story, telling us the story of "nodding yes, shaking your head no"
Is the bird really nodding when it walks? The answer is no.
1930, neutrons have just been discovered, neutrinos and dark matter hypotheses are being put forward, and biologists Dunlap and O.H.Mowrer of johnhopkins University in the United States are feeding pigeons. They found a room, put some food at one end of the room, and then released pigeons at the other end to pursue food. At the same time, they took pictures of pigeons walking with a camera even worse than many mobile phones today. Teachers Deng and Mo told us through this simple experiment and fuzzy photos that when pigeons walk, their heads don't move back and forth regularly, but keep stretching forward. When walking, the pigeon has its neck forward and its head first. Then, the head is still in the previous position, waiting for the body and heel to enter. Just because the body moves forward and the position of the head relative to the body moves backward, it creates the illusion of nodding forward first and then necking back.
Why can't pigeons walk gracefully and quietly like swans, but they have to stretch their necks one by one? Teacher Deng put forward a hypothesis: at the stage of waiting for the body to follow up, the temporarily static head is conducive to the pigeons to obtain a stable vision and make them see things around them clearly. However, he did not provide evidence. For more than 40 years, scientists, like our readers today, have been deeply troubled by this problem and put forward different hypotheses.
Rivers and lakes are generally divided into three schools: balance theory, dynamic theory and visual theory. The heroes of balance theory believe that the change of body speed stimulates the vestibular organ in the inner ear that controls balance and causes nodding; Experts in sports theory emphasize that when a bird walks, each wing throws a foot, which may make the muscles of its neck and head reflect naturally, so its head keeps moving; Seeing heroes naturally hold high the banner of Mr. Deng and Mr. Mo and carry forward the theory that "nodding and seeing clearly is a good start".
After 45 years of quarreling, chickens and pigeons are still walking one by one. A hungry baby becomes a mother who nurtures her offspring, a lively girl becomes an old woman, and a high-spirited young man is tempered by life into a silent old man. But this problem has not been solved, and no one knows the answer.
In the journal Nature, 65438-0975, Professor MarkB. Friedman published a paper strongly supporting the "visual department". From the UniversityofEdinburgh in Scotland to Carnegie Mellon University in the United States, Mr. Fu has been studying the problem of visual control, which can be said to be a big cow of visual school.
Teacher Fu designed a set of exquisite experiments. He first challenged the balance school, designed a box with four sides closed, put pigeons in it, and pushed the box to imitate the walking speed of pigeons. At this time, the pigeon sitting quietly in the box did not step, and there was no musculoskeletal movement when walking; When the pigeon is pushed together with the cage, the pigeon can't see any changes in the surrounding environment, that is, there is no visual stimulation. But because the pigeon is pushed, the change of speed is enough to cause the reaction of vestibular organs. And this pigeon is motionless, with no intention of nodding at all (Figure A). This proves that the vestibular system is not enough to cause pigeons to nod.
The balance school was put down, and Teacher Fu then locked the sports school. He made a hole in the bottom of the box and put it on a portable skateboard. Pigeons stand in the hole at the bottom of the box and on the skateboard. When the pigeon moves freely in the box, the skateboard automatically slides back, keeping the relative position between the box and the pigeon unchanged. At this time, although the pigeon is walking, the world (box) it sees is no different (Figure B). Pigeons, unexpectedly, don't cran their necks!
Next, he put the box with the hole back on the fixed table, and the pigeon was still standing in the hole. Teacher Fu pushes the box slowly by himself. At this time, the pigeons on the stage did not leave, but the world (box) in front of them changed under the impetus of Teacher Fu (Figure C). At this time, the pigeon that can't walk, its head actually started to move again! Teacher Fu found that when the box was pushed more than 20 centimeters, the pigeon's head would stretch forward. In the process of pushing the box, the pigeon's head will move from time to time.
Teacher Fu made great efforts and gave a beautiful conclusion expected by the visual school: balance and walking are not enough to make pigeons nod, and the "nodding" of pigeons has a lot to do with maintaining visual stability. This experiment has not been overturned for more than 30 years since it came into being. Such an imaginative and rigorous experiment is still amazing today.
At about the same time, Professor B.J. Frost was doing the same thing at dairy queen University. Maybe this No.2 teacher likes fitness. He creatively put pigeons on the treadmill. The same conclusion is being born. When the speed of the track belt of the treadmill is fixed with the walking speed of the pigeon, although the pigeon is stepping, it does not change its position relative to the surrounding environment. At this time, the pigeon's head stopped moving.
Teacher Fu Er also described an oolong experiment in the paper published in 1978. At the end of an experiment, he suddenly found that the pigeon sitting on the treadmill had its neck stretched forward until it finally lost its balance and fell on the treadmill with a bang.
Teacher No.2 was surprised: Did pigeons walk too much and even their nerves were affected? In order not to be accused of cruelty to animals, he searched for the reason, and finally suddenly found that he forgot to turn off the treadmill, and the track belt was still moving at a very slow speed. Because the speed is not enough for pigeons to walk, in order to keep their vision stable, the pigeon's head does not move, its body moves backwards with the treadmill, and its neck is stretched longer and longer until it falls awkwardly and eats shit.
Bathed in the pleasant sunshine by the river, I suddenly read this paragraph and couldn't help laughing. The ducks quietly foraging around started up, nodded or spread their wings and jumped into the river, breaking the shining trees.
The story of time has entered 2 1 century. MasakiFujita, a student at the University of Tokyo in Japan, is studying why pigeons stretch their heads and feet almost at the same time when walking.
The Japanese do things very seriously. In order to find out where the center of gravity of the pigeon is, he caught seven pigeons, and each pigeon was hung by a rope fourteen times (is a multiple of seven his lucky number? ), recorded and calculated the average center of gravity, the distance from eyes to chest, the length of folded wings and so on. Then use a high-speed Sony camera (technology has finally improved) to record the steps of the pigeon, and then calculate the time difference between its head, feet and center of gravity.
He got the detailed process of pigeon movement. When the pigeon lifts its hind feet forward, its center of gravity moves forward with its body. The neck stretches forward, after a short pause, the hind foot touches the ground and becomes the front foot, and the neck is shortened, and a short rest is continued. Then start from the hind foot of the front foot, and the center of gravity of the body will also move, and repeat the above steps. No matter how the head and feet move, the center of gravity of the pigeon basically does not deviate from the body.