Back in 1859, in the fundamental scientific work “The Origin of Species”, the English naturalist Charles Darwin wrote something interesting. In his opinion, billions of years ago an organism lived on Earth, which is the common ancestor of all life on our planet. Thanks to him, humans and even tiny microbes are very distant, but still relatives. At that time, this was just a guess, but modern scientists already have evidence that the common ancestor of all living organisms did exist. It was given the name LUCA (Last Universal Common Ancestor), and thanks to the study of a large amount of genetic data from microbes, scientists were able to learn a lot of interesting things about this creature.
This is what the common ancestor of all life on Earth looked like according to the neural network (of course, he couldn’t fly )
Common ancestor of animals and humans
All living things on our planet can be divided into two large groups: prokaryotes and eukaryotes. The first group includes organisms that do not have a nucleus (bacteria and archaea). The second group is represented by organisms whose cells contain nuclei (humans, plants, fungi, etc.).
Scientists already have evidence that LUCA really existed
It’s hard to believe that completely different living organisms like humans and microbes have a common ancestor. However, scientists have conducted a lot of research and are convinced that prokaryotes and eukaryotes have many common genes. They were transmitted by a single creature that lived billions of years ago. That is, we still have a common ancestor – the naturalist Charles Darwin was absolutely right.
Here is another article about the great naturalist:What Charles Darwin wrote in his notebooks and where they are stored?
Last Universal Common Ancestor
The Last Universal Common Ancestor is known by the acronym LUCA. Scientists believe that this is a single-celled organism that lived on our planet about 4 billion years ago. From a scientific point of view, he is the genetic parent of all living things on Earth – without him, no plants, no animals, no humans would exist.
LUCA lived long before the appearance of animals and plants familiar to us
To find out how and where the most ancient organism lived in world, German scientists have conducted a genetic analysis of more than 6 million genes. It turned out that only 355 of them were transmitted to modern organisms from a distant ancestor. Thanks to the discovery of these genes, scientists were able to find out that LUCA was a very resistant organism to extreme conditions.
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What was the common ancestor of all living organisms
He passed on genes to modern bacteria that allow them to survive in conditions without air. Also, the ancient creature was a thermophile, that is, it lived calmly at high temperatures. Based on all this, scientists concluded that LUCA lived in places where there was no access to oxygen, and the environment was heated to at least 42 degrees Celsius. He was neither a predator nor a herbivore – in those days such food sources did not yet exist. Scientists are inclined to believe that the ancient creature drew energy from inorganic substances.
Gene analysis also showed that in the modern world methanogens and acetogenic bacteria are most similar to LUCA. Methanogens are monocrete organisms that live in oxygen-free conditions and produce methane. Acetogenic organisms also live in conditions without oxygen and produce acetates – salts and esters of acetic acid. According to scientists, these are one of the most ancient living organisms in the world. For example, methanogens appeared on our planet approximately 2.2 billion years ago. Today, they and acetogenic bacteria can be found in hydrothermal conditions, which are rich in sulfur and other substances important for their life.
Billions of years ago, the Earth was an extremely unsuitable place for life – only LUCA could survive
Of course, everything written above is just the tip of the iceberg. If scientists manage to dig deeper, they will be able to learn a lot of interesting things about the main ancestor of all living organisms. Well, now we can say with great confidence that life on Earth originated in extreme conditions. And this is quite logical, considering that billions of years ago our planet was an extremely unpleasant place.
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Despite the fact that more than 8 billion people live on Earth, our planet cannot be called ideal. In some of its regions it is very hot, while in others there are frosts all year round. Also, do not forget about destructive earthquakes, hurricanes and other natural phenomena. At the beginning of 2024, we published an article about what air temperature is the most comfortable for human life. Can you guess the answer right now?