Research achievements ring the alarm bell - multiple branches of the Tree of Life have been "cut down"
Scientists have sounded the alarm for the mass extinction events triggered by human activities.
On September 18th, a study published in the Proceedings of the National Academy of Sciences revealed a stark reality: human behavior is pushing the entire branch of the Tree of Life to the brink of extinction.
Researchers say that due to human activities, the rate of extinction of animal species is 35 times higher than the average. This further proves that the sixth mass extinction of species in Earth's history is ongoing and accelerating.
The first extinction caused by a single species
A study published in the journal Science suggests that humans may have been almost extinct 930000 years ago, with a world population of only a thousand people for a long time. According to an article published in the Spanish newspaper El Ni ñ o, although humans only account for 0.01% of the Earth's biomass, this species currently accounts for 36% of the total number of living mammals. Livestock raised by humans accounts for 60% of the total number of mammals, with only 4% remaining being wild mammals.
On our planet, 96% is human and human food. However, human progress is constantly squeezing the space of other animals.
On September 14, 2018, an editorial in Science magazine stated that due to human shortsightedness, the entire world was on the brink of the sixth mass extinction of species. If we want to prevent a catastrophic extinction crisis, humanity must take immediate action to make changes in the redistribution of space and resources on Earth.
The sixth mass extinction was the first extinction caused by a single species, which was entirely caused by humans. The previous few were caused by meteorites and extreme geological processes, and the impact was not limited to a single species.
Human causes species extinction to accelerate 35 times
Scientists have found that not only a single species, but also the entire "genus" - the classification level between species and families in the tree of life - is disappearing.
According to research, since 1500 AD, out of approximately 5400 genera and 34600 species, 73 genera of mammals, birds, reptiles, and amphibians have become extinct. Most of these extinctions occurred within the past two centuries. Overall, there are 44 genera of birds that have disappeared the most, including elephant birds in Madagascar, ostriches in New Zealand, and Mohawk honey birds in Hawaii. The number of extinct mammalian genera ranks second. In addition, the Earth has lost 10 families and two orders.
It is estimated that the current extinction rate of vertebrate species is 35 times higher than in the past 1 million years. If it weren't for human influence, it would have taken 18000 years for so many species to disappear.
The study also indicates that at least one-third of known vertebrate populations are declining and being squeezed into smaller ecosystems. For example, in the early 20th century, there were 10 million elephants, but today there are less than 500000, and they have disappeared from many countries.
In addition, there are also some little-known organisms among the disappearing species, such as the Australian stomach frog, which swallows fertilized eggs and hatches in the stomach. They became extinct in the mid-1980s. Gastric frogs must shut down gastric acid secretion after swallowing embryos. Researchers believe that this genus of animals could have helped people study gastric acid reflux and related cancers, but their extinction has put an end to this possibility.
Appeal to Save the Tree of Life
The disappearing genus represents a closed door. When they disappear, the unique evolutionary path will forever disappear, leaving the tree of life incomplete.
The loss of the entire genus may affect the functionality of the entire ecosystem. In the eastern United States, large predatory animals such as bears, cougars, and wolves have disappeared, while the numbers of white tailed deer and mice have increased significantly. And deer and mice are the hosts of Lyme disease spreading lice, which leads to millions of such cases occurring in the United States every year.
The loss of biodiversity and excessive exploitation of wild spaces have also accelerated the destruction of resources that could have been used to improve human health. For example, although the number of stomach frogs in Australia is small, animals like this may also play an important role in maintaining ecological balance.
As for the Tree of Life, if a smaller "branch" falls off, nearby branches can grow relatively quickly to fill the gap. In this situation, species diversity on Earth remains more or less stable. But when a large "branch" falls off, it leaves a huge hole in the crown - the loss of biodiversity, which may take 15-20 million years to "regenerate" through the evolutionary process of species formation, and humans cannot wait or wait that long.
In order to avoid or mitigate the impact of species extinction, researchers are calling for attention and protection of tropical rainforests, which have the highest biodiversity.
"The window of opportunity for action is rapidly disappearing." Researchers point out that what happens in the next 20 years is likely to determine biodiversity and the future of humanity.
