During the 300 years from17th century to the end of 20th century, it can be said that the world gradually moved from modern times to modern times. In these 300 years, human civilization has developed rapidly, the times are progressing, and the earth is being changed by us little by little. At the same time, in these 300 years, more than 300 beautiful animals on the earth have left us forever. Among them: the world's largest auk, unsuspecting Stella manatee, the largest lion on earth, the southernmost wolf in the world, the only bear living in Africa, the only tiger in West Asia and the only pure white pervert in the world.
Most of these 300 species of animals are closely related to human beings from endangered to extinct. Some of them lost their homes because their habitats and homes were destroyed by human development and activities. Some of them are because humans kill maliciously for their own interests or to satisfy their own extravagant purposes. ...
In any case, it is certain that many creatures have disappeared from the earth forever because of human development and activities, whether intentionally or unintentionally.
According to the World Red Book, 1 10 species and subspecies of mammals and 139 species and subspecies of birds disappeared from the earth in the 20th century. At present, 593 species of birds, more than 400 species of animals, 209 species of amphibians and reptiles and more than 20,000 species of higher plants are on the verge of extinction.
Due to the lack of proper environmental protection, more than 794 species of wild animals in the world are on the verge of extinction.
More than 300 species of plants belonging to 76 families are endangered.
At present, only humans know the above information, and I don't know how many unknown species are disappearing.
Since the birth of cloned sheep, scientists have been hoping to use this technology to clone endangered mammals, such as Baiji dolphin and giant panda, which are called living fossils of animals. However, using cloning technology to save endangered animals faces many problems.
First of all, the existing cloning technology often requires a large number of eggs of the animal, but paradoxically, the rarer the animal, the more difficult it is to obtain eggs. Dolly has three mothers: one provides breast cells, one provides unfertilized eggs, and the other is responsible for "raising" embryos into lambs. Although the United States has done a lot of work on heterogeneous cloning, it is impossible to infer whether satisfactory results can be obtained in the end from the smooth progress of the initial experiment, and animals have not been successfully cloned by this method so far. Even if the replication is successful, whether the cloned animals will be different from the protozoa because they use the eggs of different animals remains to be further confirmed by the experimental results.
Secondly, the number of endangered animals is not only small, but also the main reason for extinction is their reproduction, which is the key to the success of cloning technology. The number of giant pandas is very small. At present, there are still many unsolved mysteries about their reproductive process, such as how long it takes for fertilized eggs to be implanted into the uterus of giant pandas. At present, humans can't get these data through experiments. Another example is the baiji dolphin, which is not only less than the giant panda, but also an aquatic creature; The technical difficulty of implanting embryos into uterus is incomparable to terrestrial animals.
In addition, cloning will also lead to the decline of genetic diversity of endangered species, which may lead to their extinction.
According to the report of "Reference News" on August 25th 1998, five of the 10 cattle cloned in Japan have died, which shows that the cloning technology needs to be further improved. Today, when cloning technology is not mature enough, we can only think that cloning technology is one of the effective means to protect endangered animals, but it is unrealistic and theoretically impossible to expect cloning technology to completely get rid of endangered animals. The protection of endangered animals still has a long way to go.
What is lost cannot be redeemed. Cherish what you have.