We explain what biological evolution is, its relation to natural selection and what are the evidences of the Theory of Evolution.
What is biological evolution?
When we talk about biological evolution or simply evolution , we refer to the series of bodily changes ( phenotype ), expressed in genetic information ( genotype ) and therefore transmissible to the offspring, that a population of living beings suffers from Over several generations.
In other words, evolution is the process of change and adaptation to the environment of living beings . It allows a series of significant bodily or physiological changes to be introduced into a species , which in the long run are also capable of giving rise to a totally new species .
To better understand this, let’s go back to the origin of life on Earth, billions of years ago. Although they did not resemble us, the first forms of microscopic life competed with each other for access to food and energy . Those that were more successful in that competition (that is, more fit for the environment) reproduced more than others.
This survival and transmission of genetics more adapted to the environment is called natural selection . In addition to the spontaneous mutations that occur during the genetic processes of reproduction , some of these beings were increasingly differentiated from the rest, thus forming new species.
The most suitable species reproduced more and conquered new food niches, while the less apt ones became extinct or were forced to change to survive.
This process extended over billions of years on our planet, thus giving rise to what we know today as species: groups of living beings genetically related and capable of reproducing each other.
Different species have genetic evidence that links them to common ancestors , as occurs between humans and our cousins, chimpanzees. It is estimated that our common ancestor with them, that is, the species that diversified and started both theirs and ours, about 13 million years ago.
What is more surprising is that the last common ancestor of all life on our planet lived 3.8 billion years ago . This unicellular organism is known as LUCA ( Last Common Universal Ancestor , that is, Last Universal Common Ancestor).
As will be seen, evolution is nothing other than the effect of the struggle between species to survive and adapt better to the environment, giving rise to new species as their physical and genetic differences become more and more pronounced.
Origin of the theory of evolution
Although it is called theory, evolution is a proven scientific fact , of which there is abundant evidence in the natural world, especially in the fossil record.
The idea of evolution arose in the nineteenth century, the result of various contributions in numerous sciences. However, the one who enunciated the Theory of Evolution was Charles Darwin (1809-1882), a British naturalist, by whose last name this theory is also known as Darwinism .
Darwin, in the midst of his travels around the globe, noted that many species of animals from faraway places were similar to each other , except for significant physical differences. He also noted that these differences were usually linked to some type of accident or geographical separation.
For example, the fauna of the Galapagos Islands, in Ecuador, was similar to that of the coast. Darwin realized that by being separated from it by several kilometers of ocean, he had taken a different historical (evolutionary) course. However, the current Theory of evolution is not exactly the same as Darwin published in his book The Origin of Species in 1859.
At the moment a synthesis of the Darwinian principles of the natural selection is sustained, next to those of Alfred Russel Wallace (who independently proposed the Theory of the evolution in 1858), the Laws of Gregor Mendel on the inheritance , and some other scientific advances similar. That is why it is known as modern evolutionary synthesis.
Evidence of biological evolution
The evidences of evolution are diverse and are in different fields of scientific knowledge . For example, paleontology has found numerous fossil evidence of extinct animals , but similar in some degree to the species we know today.
On the other hand, by the comparative study of the organs of the different known animals and even of the human being, anatomical similarities have been discovered that point to a common biological ancestor for different species , and even vestiges of ancient forms of the species, such as remains of front leg bones in the snake skeleton.
Similarly, embryology has discovered similar patterns of development in the early stages of life of different animals , including humans, that seem to confirm the presence of common ancestors.
For example, in some stages of the formation of birds and vertebrates , the embryo shows presence of gills, which matches them with fish. Something similar occurs with cellular biochemistry , which has almost identical processes in different organisms , or with recent advances in the reading of human DNA , 99% of which is identical to that of chimpanzees.