In order to beat its competitors, it grows fangs, antlers, or is very big; In order to attract females, it tries its best to show its beauty. Birds are friendly and harmonious, unlike wild animals, which are brave and belligerent. They are covered with "all kinds of bird crowns, pendants, protrusions, horns, airbags, feathers and bare feathers." Birds' feathers and elegant long feathers that grow all over the body are decorated. Beaks, bare skin and feathers on the head are often colorful. "This passage is Darwin's description that he marveled at these friends with gorgeous feathers and speculated that females are just like males. He also wrote: "Strong love for beauty, keen perception and taste" and "low-level rational thinking ability" are not contradictory.
Beauty is not the basis of reproduction, but it helps reproduction. Darwin said: "In the battle to survive and leave a large number of offspring, if males with better genetic quality are not present, those males without attack weapons, decorations and temptations will also win a total victory." But if the former is present, they will easily get rid of their opponents.
Female animals prefer flashy and gorgeous clothes to angular embellishment. Female swordfish like male fish with long sword tail (sword tail refers to long tail fins with different colors); Female swallows and widows prefer long-tailed males and so on. The male peacock laboriously drags a colorful long tail with eye spots composed of 150 to 200 feathers. As Helena Caroline wrote, "It has to feed not only his wife and children, but also a long tail!" " This kind of jewelry is not only easy to attract carnivores, but also consumes valuable metabolic energy and has to be carried with you.
However, gaining women's admiration is the compensation for these troubles. The male peacock with the most exquisite long tail (eye-lifting point) has a higher mating success rate than other peacocks. If Dapeng's mottled white tail feathers are painted with white dye, or the male swallows stick to the tail, their mating success rate is higher than that of other birds. This means that women prefer exaggerated and unconventional features.
Why do female animals like luxury? This has become a difficult problem. In 1930, geneticist Sir ronald fisher described an explosive and escalating process of "survival of the fittest" in heterosexual selection, which can explain this difficult problem. The process of "survival of the fittest" is as follows. When showing preference, for example, females like males with long tails, females will mate with males with relatively long tails, and hatched cubs will also grow tails. Once a preference is formed for some reason, there will be corresponding pressure to choose. Because only in this way, the female bird will give birth to the male bird that will be favored by the opposite sex in the future. This pattern is repeated, and females are no longer willing to mate with males with small tails. As this bias becomes stronger and stronger, the tail becomes longer and longer.
Exaggerated and conspicuous behavior is the product of evolution. In the past, the behavior adopted to adapt to survival experienced a long and tortuous development, which finally made animals far ahead in the competition. Now, just like bestsellers, best-selling records or fashions, they are preserved because of their popularity. However, most biologists believe that the irresistible beauty displayed in biological form has richer connotations than fashion; They believe that beauty is not arbitrary, but a form of communication.
According to a theory put forward by biologist Amenz Zahawi, showing off is a means of "setting unfavorable conditions to hinder opponents". Peacock proudly wagged his huge tail and said, how healthy and strong I am. I can grow a tail feather with a radius of 60 inches, I can absorb all kinds of nutrients to keep its gorgeous appearance, and I am not afraid of being easily attacked from behind. Only the best animals can grow up and show off like this. It must have strong immunity to parasites in order to keep the luster and fullness of its feathers. Because of the huge price to pay, the information conveyed by the gorgeous feather tail is true and credible.
Women are interested in rhythmic men. The motivation is to hope that the offspring born will have strong viability. So will a beautifully decorated male animal be the best father? There is no evidence that they will take better care of their offspring, but it seems that they will pass on stronger genes to their offspring. The offspring of male peacocks with delicate tail feathers have a better chance of survival than those of birds with gorgeous tail feathers. Compared with the short-tailed swallow, the long-tailed swallow not only has more chances of survival, but also has a longer life span for its offspring. Compared with its brown companion, the red-necked stickleback fish with three spines is more likely to hold its eggs in its nest in the face of attack and plunder. Red neck is a threat to other males and a temptation to females. This proves that some ostentatious features are very effective in courtship and fighting. Flies of the family Exophthalmus have eyes on their feathers. Their quills are sometimes longer than the whole body. Female flies like male flies with feathers. As it turns out, these male flies have a hidden advantage: in the whole group, the number of female flies accounts for the vast majority, and these male flies carry a strong "Y" chromosome, which increases the chances of giving birth to young male flies.
In most cases, the large decorations of male animals are often more symmetrical than the small decorations, and female animals just like symmetry. Symmetry is not easy to form, especially when the decoration is huge and subject to sexual selection. However, because large decorations are a magic weapon to defeat the enemy and a reliable propaganda of the owner's excellent genetic quality, symmetry is exactly what animals expect. Animals with big decorations can relieve the pressure of growth more. Because the hormones circulating in the body to maintain the second gender characteristics actually destroy the immune function of the body. Only the strongest animals can maintain their own growth and immune activity.
Under natural circumstances, the tail feather length of a male swallow is about 20% longer than that of a female swallow. The male swallow with the longest tail can attract more mates than other males. Their long-tailed feathers are also more symmetrical than short-tailed swallows. Anders Muller, a zoologist, proposed that tail length and symmetry should be viewed separately, and whether they can independently influence the choice of female animals. In order to find out, he did a little plastic surgery, cut off the tail feathers of the male bird and stuck them on other males to make the tail short or long and symmetrical. There is asymmetry. In order to ensure that there is no difference in the glued feathers, which leads to the loss of interest of females, Muller cut off the tails of other males and glued them without changing the size and symmetry of the tails. It turns out that females care about both body shape and symmetry: males with long but asymmetrical tails are not as popular as males with long and symmetrical tails.
Zoologists Eistan Markussen and Ivo Forsted found that the largest deer, the reindeer in estrus, has the most symmetrical antlers. Interestingly, this correlation between size and symmetry does not apply to other parts of the body. Markussen and Forsted also suggested that the condition of antlers clearly tells us about parasites in reindeer. This situation cannot be known from other parts of the body. The preference of sexual selection promotes the development of animal distinctive features. Because conspicuous features such as antlers can clearly show the animal's physical condition, for example, the obvious asymmetry of antlers indicates that the animal's immune system has been destroyed. Does the mate selection tendency of peacocks, swallows, geese and reindeer inspire human beauty?