Tuwa Creative
"Where does life come from?"One of the ultimate issues, so far, we have no ability to answer this question well.However, we found that the key to answering this question, from single -cell bacteria, to the extremely long life, to the huge blue whale, and even our humans, all organisms actually have amazing similarity.As a result, Darwin proposed a famous concept in his book "Species Origin" in 1859 -that is, "homologous of all things", that is, all creatures that have survived on the earth have common ancestors.
In 1999, biologist Patrick Futail first combined the first letter of the words "last ancestors" to name this hypothesis ancestor creature as "Luka Kaka(Luca).As the root of the tree of life, Luka was later differentiated into a life system including bacteria, ancient bacteria and eukaryotes.Since then, countless scientists have embarked on the way to find Lucas "true body".
On July 12, 2024, a new study published in the magazine of "Nature-Ecology and Evolution" made scientists a step forward on this road.They discovered that "Luca" appeared earlier than before, and the structure was more complicated.
The members of the research team compared the genome of 350 groups of ancient bacteria and 350 groups of bacteria to find them in common to determine which features were the first to appear.They followed the evolutionary models of individual genes and gene families of these ancient bacteria and bacteria. Through comparing the evolutionary history of individual genes and species genes, they can better explore which genes are copied, lost or experienced horizontal gene transfer.
According to the above methods, the research team has obtained several important inferences about the origin of life.
First of all, the appearance time of the ancestor "Luca", the common ancestor of life, was about 4.2 billion years ago, which was much earlier than the previous thought of 3.8 billion years.We know that the earth was formed about 4.6 billion years ago, that is, the earliest form of life appeared shortly after the earth was formed.This shows that the origin of the origin of life may be simpler than what I thought before.
Follow, "Luca" has a huge genome.To what extent?Studies show that the genome of "Luca" contains at least 2.5 million base pairs and encodes 2,600 protein.This is much more complicated than the previous estimates, almost the same as the complexity of the existing primary creatures.
So how did Luca survive on the early earth?Scientists have found that Luca takes hydrogen and carbon dioxide as food.In the era of no evolutionary organs, hydrogen is equivalent to "chemical sunshine", providing endless energy for Lucas own metabolism, and its metabolism products (such as methane) can become the nutrients of other life.Therefore, scientists believe that this chemical hydrogen circulation system can support a simple ecosystem, and Luca was not the only form of life at that time, but other life bodies were extinct and did not leave offspring.
Research also shows that Lucas body exists in a gene to resist virus invasion, indicating that life may have the ability or potential to fight virus since its birth.
In the body of Lucas body, scientists have also discovered a gene that can protect it from ultraviolet damage, which indicates that Luka may not live in the hot spring spray mouth of the deep sea, but instead, but instead, but insteadIt may live in surface water, and they can capture carbon dioxide and hydrogen from the atmosphere to support themselves.On the other hand, there is also a kind of enzyme that is common in thermal bacteria -reverse rotation enzymes, which means that Luca may also break around at the bottom of the sea.
The results of the contradictory research like this are not uncommon in the exploration of early life.Other scientists believe that due to the role of gravity, a large number of surrounding asteroids and meteorites will occur 3.8 billion years ago. Therefore, this period is called the "heavy bombardment period".Under the severe and frequent impact, there is no liquid water on the surface of the earth, so early life cannot appear.
Because we cant go through the time to return to life from the time of life, we can see the scene at the time from scratch. Such contrary to research conclusions is not difficult to understand.Moreover, life like Luca with only tiny structures cannot form fossils in long geological activities, leaving conclusive evidence. We can only use existing biological and technical means to make as much as possible to be closer to the truth.The results of this research are just the beginning.Although it brings together data and methods of multiple disciplines, it seems that we only get a small piece of the huge puzzle of life origin.On the road to exploring the ultimate human question of "where life comes from", we are still in a long way to go.
This article is the support of the popular science China · Creative Cultivation Plan Author: Liu Sen
Review:Research librarian
Produced: The Department of Science and Technology of the Chinese Association of Science and Technology
Producer: China Science and Technology Publishing House Co., Ltd., Beijing Zhongke Xinghe Cultural MediaLimited
