According to a study published in the latest issue of American Journal of Endocrinology, the researchers found that there are gay rams in the flock, and the brain area of these gay sheep is smaller than that of heterosexual sheep. Does this mean that homosexual behavior of animals is innate?
Experts believe that homosexual behavior is common in the animal kingdom and can be said to be normal.
Austrian animal behaviorist Connard Lorenz once observed a flock of wild geese. Among wild geese, there are often two male geese who have a very good relationship. They often stay together, comb each other's hair, wrap their necks around each other and make a mouth (kiss), and eventually they will climb over each other. In the cage, a male turtledove will bow to another male turtledove and make a series of courtship behaviors.
Li Chunwang, who specializes in animal behavior research at the Institute of Zoology, Chinese Academy of Sciences, said that homosexual behavior has been found in the animal kingdom from birds to mammals. They generally call it "homosexual contact" or "homosexual crawling".
Li Chunwang believes that this "same-sex climbing" behavior of animals is influenced by innate factors. Animals generally have seasonal estrus. At this time, the animals have matured and the process of energy accumulation has been completed. Stimulated by sex hormones in the body, they will have impulses and show courtship and mating behavior.
However, in some populations with more females and fewer males, or in populations with very strict hierarchical sequence, excellent male animals often win the favor of female animals. For example, during the mating season, the stags in the herd will compare whose hooves are bigger and whose bodies are stronger; Pheasants will see whose feathers are more beautiful; Tits are more pleasant than others. ...
Female animals choose those excellent male individuals for mating, and the remaining "bachelors" are not qualified to participate in breeding groups if they can't find a spouse. They can only have the same-sex crawling behavior to release the accumulated energy in their bodies.
"Same-sex comparison" is also a social behavior, which is influenced by the acquired environment. As long as the right environment is created, homosexual behavior can often be induced.
Some researchers have done this experiment with turtledoves. When the male turtledove is in estrus, he will show his love to the female turtledove in the cage. If you take the female turtledove out and put it in the hen, it will soon woo the hen. If there were no hens, she would even woo a pile of rags. It can be seen that it is understandable that a male turtledove courted another male turtledove without a spouse.
Li Chunwang also mentioned that during the breeding season, ostriches kept artificially in zoos turn a blind eye to the ostriches around them, and instead regard breeders as courtship objects. All this shows that animal sexual behavior has obvious sociality, and animal homosexual behavior is not only innate, but also influenced by social environment.
Li Chunwang said that the homosexual choice of animals is mostly temporary. When individuals of the opposite sex appear around them, they will immediately abandon the same sex and pursue the opposite sex.
However, some animals will not change their original intention even if the opposite sex appears after forming same-sex couples.
In the School of Life Sciences of Nanjing University, there are two female red-billed lovebirds. Every day, they spend a lot of time combing each other's feathers carefully. When feeding Tenebrio molitor, one of them often flies to the trough first and pecks up the worm with its beak, but it is not in a hurry to eat. Instead, they cooed and greeted the other to enjoy it, just like a loving couple.
Later, in order to let them reproduce, a male red-billed lovebird was released. Unexpectedly, it was beaten by the two sisters, and it was beaten into the corner for mercy. Finally, it had to be deleted.
Animal homosexuality is not good for species reproduction, but its existence also has certain biological and animal sociological significance.
Li Chunwang explained that homosexual behavior of animals is sometimes just a learning behavior. For example, when young primates play games, they sometimes have some crawling behaviors. At this time, they are only sub-adults, immature, without mature sexual organs and adequate sex hormone stimulation. Crawling between them is not sexual behavior, but the behavior that small animals imitate between adult animals. But this kind of learning is very useful for the later reproductive behavior of animals.
Other same-sex behaviors are aimed at relieving the pressure of the community and expressing mutual friendship. Antagonistic conflicts often occur between individuals of social animals, especially between animals of the same sex. For example, bonobos are excitable animals, and they often fight over trifles. However, their fight seems to have subsided faster than it happened, and one way is through sex.
Two people of the same sex rub each other's genitals, while the opposite sex has real mating behavior. They use this behavior to show goodwill, calm down the fight, and thus reduce the losses of their families and themselves. It can be seen that homosexual sex has the function of maintaining the stability of animal population.
Homosexual behavior and its environmental induction
Homosexuality exists in the animal kingdom from birds to mammals. 5% female gulls in California will have an indissoluble bond. They will stay together for two nights to protect the appearance of a couple. Austrian animal behaviorist Connard Lorenz once observed a flock of wild geese. Among wild geese, there are often two male geese who have a very good relationship. They often stay together, comb each other's hair, wrap their necks around each other and make a mouth (kiss), and eventually they will climb over each other. In the cage, a male turtledove will bow to another male turtledove and make a series of courtship behaviors.
This phenomenon is more common in mammals. In estrus season, 65,438+00% male goats are particularly indifferent to gentle teasing from female goats, but show strong interest in other male goats. Homosexual behavior of bonobos is characterized by homosexual climbing.
These various homosexual acts in the animal kingdom seem very puzzling. In fact, as long as a suitable environment is created, homosexual behavior can often be induced. In the turtledove experiment, when the male turtledove is in estrus, he will show his love to the female turtledove in the cage. If you take the female turtledove out and put it in the hen, it will soon woo the hen. If there were no hens, she would even woo a pile of rags. In this way, it is understandable that a male turtledove courted another male turtledove without a spouse. At this time, hens, rags and another male turtledove became the replacement objects of this male turtledove. However, the object of this courtship behavior will be corrected. Often after the female turtledove reappears, the male turtledove will immediately throw down the rag to chase the female turtledove. After some animals form same-sex couples, even if the opposite sex appears, it will not change their original intention. In the School of Life Sciences of Nanjing University, there are two female red-billed lovebirds. They spend a lot of time grooming each other's feathers every day. Sometimes they whisper, sometimes they sing in chorus. When feeding Tenebrio molitor, one of them often flies to the trough first and pecks up the worm with a chirp, but he is not in a hurry to eat it. On the contrary, it will coo and greet the other one to come and enjoy it. Later, in order to let them reproduce, a male red-billed lovebird was released. Unexpectedly, it was beaten by the two sisters, and it was beaten into the corner for mercy. Finally, it had to be deleted.
The function of homosexual behavior
Life evolution is a long process of survival of the fittest, and all life forms that can be preserved to this day have their reasons for existence. It is generally believed that from the ultimate function of sexual behavior-reproduction, same-sex mating can not produce offspring, which is a wasteful behavior mode. However, this phenomenon is widespread in the animal kingdom so far, so it has certain biological and animal sociology significance. The following are some common biological functions of homosexual behavior:
The biological significance of length skill training of homosexual behavior among animals may lie in the training of sexual skills. Young primates sometimes have some crawling behaviors when playing games. Studies have shown that there are more homosexual crawling behaviors in childhood than in adulthood, which may be due to the immature larvae, immature sexual organs and insufficient sexual hormone stimulation. The crawling between them is not a sexual act, but just a "game". Are the little guys imitating the behavior between adult animals? Gay sex in childhood may be a training of sexual skills.
2. Antagonistic conflicts often occur between individuals in social animals, so natural selection retains the behavior of restraining conflicts, among which exchanging gifts (such as food or branches), singing folk songs, dancing in chorus, combing each other's hair (feathers), even hugging (primates) and making mouth (birds) are the most common manifestations. Fighting between animals is usually of the same sex. The essence of animal sexual behavior may not only be reproduction, but also a means of combining individuals. Bonobos are excitable animals, and they often fight for trifles. However, it seems that their fight subsided faster than it happened, and one of the ways was through sex. Two people of the same sex rub each other's genitals, while the opposite sex has real mating behavior. They use this behavior to show goodwill, calm down the fight, and thus reduce the losses of their families and themselves. It can be seen that homosexual sex has the function of maintaining the stability of animal population.
3. Be able to release (relieve tension) During the mating season, in some populations with more females and fewer males or populations with very strict hierarchical sequence, female animals will choose male individuals with excellent genes to mate with them, and the remaining bachelors will often have same-sex intercourse with each other because they can't find a spouse and are stimulated by heterosexual mating nearby, just like the male turtledove mentioned above will woo hens without females or even rags, and the existence of substitutes is the basis of same-sex intercourse. Animals can release the action-specific potential energy accumulated in their bodies (that is, the degree of internal standby state before an action) to their substitutes through courtship or sexual behavior, thus alleviating their nervousness.
4. Alliance effect In seasonal breeding species, during the mating period, male animals often fight symbolically or desperately to form a new rank sequence. Winners often climb over losers and "show strength" to the weak, which is a kind of sexual assault. This phenomenon often happens among monkeys, and those monkeys who are not strong enough often rely on each other to form alliances to increase their chances of mating with females. Because two bachelors together are likely to defeat an opponent who is stronger than either of them, when the strong one is exhausted by the "alliance", one of them will stall the strong one and let the other mate with the female; Next time, they can exchange roles to benefit both sides. This situation is not uncommon among birds.
Evolutionary mechanism of homosexuality
Sexual reproduction is not always there, but a product of evolution. Biological sexual reproduction is preceded by asexual reproduction. The simplest asexual reproduction is to divide cells into two parts. The disadvantage of asexual reproduction is that it does not change the genetic material and cannot adapt to the changing environment. The emergence of sexual reproduction successfully solved this problem, but sexual reproduction evolved from asexual reproduction. Will the transitional characters and behaviors in the long history of evolution give us some enlightenment?
Sexual reproduction refers to the way of reproduction in which zygotes are produced through the combination of gametes (combining the genetic material of two gametes), thus producing the next generation. The most primitive sexual reproduction is homogamy, that is, two germ cells with the same morphological structure and size (there is no gender difference here) combine to produce a fertilized egg. Does this remind us of homosexuality? After a period of evolution, larger gametes combine with smaller gametes, which reminds people of the combination of eggs and sperm. Here, the larger gametes are equivalent to egg cells, providing half of the genetic material for the production of zygotes and more nutrients for the growth of zygotes; Smaller gametes provide the other half of the genetic material and less nutrition for the growth of zygotes. When this smaller gamete meets a smaller gamete, it will show relative female behavior. Note that there is no gender difference between the two cells here, only the size difference, which is a relative gender phenomenon. In higher biological groups, there is no lack of relative sexual behavior, just like a weak male orangutan relatively behaves in front of another strong orangutan, willing to approach the strong orangutan, and even having homosexual sex. The evolution of life is really wonderful. The law of natural selection is always helping organisms to choose the most suitable way for their survival and development, so the highest form of sexual reproduction-egg mating reproduction has emerged. The two gametes of sexual reproduction exist in two highly specialized cell forms, namely, eggs and sperm. Sexual reproduction enables organisms to maintain a certain frequency of gene changes, adapt to the suddenly changing environment at the fastest speed, and show structural differentiation, functional division of labor and further improvement of reproductive efficiency in individuals.
The earth in the early stage of life development is a rapidly changing world, and the emergence of sexual reproduction is undoubtedly an important means for the reproduction and development of organisms so far. Advanced organisms have developed into a highly differentiated bisexual world, but there are still traces of asexual reproduction in some animals, which provides evidence for us to study the origin of homosexuality.
As we all know, human beings are the highest-ranking animals with high gender differentiation on earth. The difference of human chromosome 23 (sex chromosome) determines human sex. Men are xy chromosomes and women are x chromosomes. When the fertilized egg develops to a certain period, the fertilized egg with xr chromosome appears testicles, and some of them. The ovary appears on the chromosome of the fertilized egg developing individual. However, the ultimate sex of human beings is not only determined by chromosomes, but also depends on the secretion of some chemicals during embryonic development. There is always a structure called Miller's tube in the embryo before the sex differentiation in the embryonic development stage. Under normal circumstances, if it is. Chromosome, Miller tube develops into normal female organ; If the testis exists, it will secrete a chemical called Miller inhibin, which will inhibit the development of female organs and make individuals produce normal male organs. When Miller's inhibin can't be secreted normally, the individual will grow into a person with female appearance and xy chromosome. In other words, men have the potential to differentiate into two kinds of rolls for grain in the embryonic period. People are so advanced that they can still leave traces of bisexual organs in structure, not to mention other creatures, intangible personality development and unpredictable behavior development.
Even in many higher animal worlds with bisexual reproduction, there is more than one reproductive form, and some species also have special reproductive ways, which may also provide an inductive basis for the occurrence of homosexual behavior. If an individual can produce two kinds of gametes, this situation is called hermaphroditism, which is common in flatworms, oligochaeta of annelids, gastropods of mollusks and a few petaloid gills. In vertebrates, eggs often exist in the testis of fish, fresh fish and Pang Zhao, which is called accidental hermaphroditism. Except for a few hermaphrodites who can fertilize themselves, most of them need allogeneic fertilization.
However, some teleost fish produce eggs and sperm from different parts of the same gonad and can fertilize themselves. There are also some fish, which are one sex in the early life and become the opposite sex at another time. For example, a tropical jealous fish is female in the early stage and becomes male in the later stage. Monopterus albus cultured in fresh water is female from embryo to first mature egg laying. After laying eggs, the ovaries gradually transform into testicles, producing sperm, and they are male until they die of old age. This is the phenomenon of sexual inversion in the animal kingdom. Many scholars have put forward different views on the causes of gender change, some think that it is caused by humidity, some think that it is related to nutritional conditions, and some think that male germ cells are small and have a short development time, so the proportion of males is high, but the phenomenon of sex reversal of Monopterus albus refutes the hypothesis of male precocious puberty. These assumptions are not perfect, and it is difficult to fully explain the phenomenon of change.
Recently, some scientists have done experiments on gay mice. Scientists selected a female mouse with obvious homosexual tendency for testing. It was found that the reproductive endocrine disorder and estrogen were low. After injecting it with a certain amount of estradiol, the mice are willing to accept the closeness and sexual behavior of male mice. After scientists injected a female mouse with strong sexual desire, the female mouse gradually lost interest in the male mouse and became attached to the female mouse around her. Experiments have proved that hormonal imbalance is likely to lead to homosexual behavior.
The evolution of the animal world is very long and complicated. In this process, various physiological and subconscious behaviors of animals are still maintained. With the further development of conscious activities, this phenomenon will inevitably be introduced by many conscious factors, thus making homosexual behavior more chaotic.
The world is full of wonders, and the homosexual behavior of animals needs further study and discussion.