Darwin once said, "We cannot see these slow evolutions until the hand of time marks the passage of time." What he may not have expected is that, after more than 100 years, man himself has turned the gears of animal evolution faster, So that the evolution of animals can be seen at any time.
Humans actively 'edit' the evolution of animals
How long does it take for a sheep to mutate spider DNA? If it were natural selection, then this might never have happened. But under human manipulation, in less than a year, a goat, or even a group of goats, containing spider DNA was born. Their appearance remains the same, they don't have eight legs and they don't spin webs, but their goat milk contains a lot of spider protein. These spider proteins are very similar to the proteins that spiders use to make webs, and that's what the scientists aimed to do - to extract large amounts of spider proteins from goat milk, and then use these proteins for spinning.
This is not the first time humans have actively manipulated mutations in animal genes. Humans did this as early as 40,000 years ago. Humans at that time began to domesticate various wild animals, including wolves. During 40,000 years of domestication, humans have intentionally or unintentionally altered the DNA of these wolves so that they become another animal, a dog. The DNA of a dog is only about 0.5% different from that of its ancestors. Therefore, the dog also retains some ancestral habits, such as howling when it hears the same kind of howl.
It took humans about 40,000 years to turn wolves into dogs, but during that time, humans devised another way of manipulating the evolution of animal DNA—hybridization. Crossbreeding can create new species, and this process does not take 40,000 years at all. The mule we are familiar with is the product of crossbreeding. The ancients bred horses and donkeys to create a new species, the mule. A mule is stronger and requires less food than a horse of the same size. In addition, the mule inherits the temperament and virtues of the donkey, such as tenacity, endurance and docility. Today, in addition to mules, humans can also hybridize ligers (the offspring of lions and tigers) and other animals.
Although hybridization can create new species, the failure rate of hybridization is too high (there are also ethical issues in animal hybridization experiments), and most of the hybridized species are difficult to reproduce, and the hybridized species are not necessarily what humans want, so humans have to find another way. Find new ways to create new species or to promote species evolution. At this time, a sufficiently mature cloning technology has entered the human field of vision.
Seeing this, you may think: "Isn't cloning gene replication?" Yes, cloning technology alone cannot achieve the two effects just mentioned, but if combined with other technologies, then cloning technology can not only promote Species evolve and new species can be created.
Cloning is primarily performed by a technique called "somatic cell nuclear transfer". What kind of technology is this? Simply put, scientists first select the animal to be cloned, then extract the animal's somatic cell nucleus, and then transfer it to the same type of egg cell that has been enucleated. After the egg cell divides, the scientist transfers it to the surrogate mother's. In the womb, finally, the surrogate mother gives birth to the cloned animal.
At present, scientists are combining cloning and gene editing technology, trying to create a whole new species, or save endangered animals, and gene editing technology is also the technology that human beings can most cause animal evolution (or even mutation) at present. The aforementioned spider goat is the product of gene editing technology. Currently, scientists are using both techniques to save endangered animals such as black-footed ferrets and kakapo.
The black-footed ferret is one of the ten most endangered species in the world, and is currently only found in North America. Even with the long-term help of humans, their current number has not reached 1,000. An important reason for this is that their genetic diversity is insufficient (most of them are inbreeding), which makes them highly susceptible to diseases . Now, with the help of gene editing technology, scientists can program the genes of other dead black-footed ferrets into these surviving ferrets, and even knock out genes that are susceptible to disease in surviving ferrets, thereby enriching the genetic diversity of surviving ferrets . These edited ferrets are then cloned and then bred to save the black-footed ferret. The kakapo situation is very similar to that of the black-footed ferret.
Animals Inadvertently Influenced by Humans
In addition to human beings actively promoting the evolution of animals through modern science and technology, normal human inadvertent activities will also change the process of animal evolution.
In 2006, an American hunter shot and killed a peculiar-looking bear in Canada's Northwest Territories. This bear has both white and brown fur, looks like a polar bear at first glance, and has a slender neck like a polar bear, but it has the same sharp claws as a grizzly (a subspecies of the brown bear), and thick Shoulder. After DNA identification, scientists found that the bear was a hybrid of a polar bear and a grizzly bear, and it is now named the grizzly polar bear.
According to the available data, scientists speculate that due to global warming, the polar ice melted, and then the polar bears drifted to the south with the ice floes, while the north became warmer. The grizzly bears that originally lived in the south could "go north", and then they were They meet and mate at a certain location, thus giving birth to a grizzly polar bear.
But the story isn't over yet.
In 2010, another grizzly polar bear was shot, this time in Canada near the Arctic. Scientists have found through DNA testing that this grizzly polar bear is actually a second-generation individual, which means that both its parents are grizzly polar bears. Generally speaking, hybrid species are difficult to reproduce, but the grizzly polar bear breaks this natural law! Scientists still don't know why.
In addition to grizzly polar bears, scientists have also discovered other "natural" hybrid species, with more than 30 species, including the hybrid offspring of narwhals and beluga whales, the white narwhal.
The emergence of human cities is also one of the factors leading to rapid biological evolution.
More than 100 years ago, when the subway was built in London, England, some Culex mosquitoes (a type of mosquito) were left in the ground. Recently, scientists have discovered that although the Culex mosquitoes under the subway are similar in appearance to those on the ground, their DNA is different from that of their counterparts on the ground, so that scientists are now debating whether these underground Culex mosquitoes should be classified as new. species.
Similar things have happened in cities in other countries. Scientists have discovered that white-footed mice living in New York's Central Park have evolved genes that match New York's diet, making them better at digesting fat and neutralizing poisonous fungi from moldy nuts. toxins, while their counterparts farther away from cities do not have these genes; in Nebraska, another U.S. state, American cliff swallows living in cities have evolved smaller wings, which make them more flexible and more flexible. Can dodge traffic and buildings in front of them; crested lizards that live in cities in Puerto Rico have evolved longer legs and stickier toes, which make them easier to crawl on buildings; Great tits in cities across the UK have evolved longer beaks to steal food from bird keepers.
Other human activities can also inadvertently affect animal evolution. For example, poaching elephants, humans hunt elephants mainly for ivory, so their targets are often elephants with tusks. Some elephants have had to remove the "big tusk gene" from their gene pools due to the pressures of survival. Today's elephants have evolved smaller tusks and even lost their own tusks. Over the past 20 years, the proportion of tuskless female elephants in the African nation of Zambia's South Luangwa National Park, a place where ivory poachers thrive, has risen from 10 percent to 40 percent.
Humans' influence on other life processes on Earth is now greater than ever. Humans can use science to satisfy their own selfish desires, but they can also be used to make up for their own faults or contribute to the healthy development of other lives. Like the kakapo above, this animal, due to habitat destruction and human hunting, had only 51 left in 1995, but with the help of cloning and gene editing technology, their number has now increased to 211, and They are also healthier. In this way, the quality of evolutionary gear changes depends largely on humans themselves.
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