The Evidence of the evolution of living beings Demonstrate the genetic change in a population from one generation to another.
The speed and direction of change is variable with different species lines and at different times. Continuous evolution over many generations may result in the development of new varieties and species. Failure to evolve in response to environmental changes can lead to extinction .
When scientists speak of evolution as a theory, it does not mean that it is mere speculation. It is a theory in the same sense as propositions that the Earth is round rather than flat or that our bodies are made up of atoms.
Most people would consider these fundamental theories sufficiently proven by empirical evidence to conclude that they are actually facts. With the massive amount of evidence of biological evolution accumulated during the last two centuries, it can be ensured that evolution has occurred and continues to occur.
All life forms, including humans, evolved from earlier species, and all still living species of organisms continue to evolve today. They are not unalterable final products.
Many, if not most, biological scientists accept that primordial life on Earth began as a result of natural events 3.5-4 billion years ago.
However, it is not necessary to believe in this viewpoint to accept that living creatures evolved by natural means after the origin of life.
Charles Darwin Modified his religious beliefs, like many others, as a result of the discovery of a convincing proof of the evolution.
He came to believe that God created the order of the universe including the rules of nature that give rise to biological evolution.
Key Evidences of Evolution
1-Fossil remains
The remains of animals and plants found in the sediments give us an indisputable record of the changes suffered over large periods of time. This evidence proves that there was a tremendous variety of living beings.
Some extinct species had traits that were transient between major groups of organisms. Their existence confirms that the species are not fixed but can evolve to other species over time.
The evidence also shows that what appear to be gaps in the fossil record is due to incomplete data collection. The more we learn about the evolution of species, these gaps or"missing links in the chain of evolution"are filled with fossil specimens.
One of the first gaps to be filled was between small bipedal dinosaurs and birds. Just two years after Darwin published The origin of species , A fossil of 150-145 million years of Archeopteryx was found in southern Germany.
He had jaws with teeth and a long bony tail, wide wings and feathers like birds, and skeletal features of both. This finding verified the assumption that the birds had reptilian ancestors.
Since the discovery of Archeopteryx, there have been many other crucial evolutionary breccias that were filled in the fossil record. Perhaps the most important, from our human perspective, was that of the apes with our own species.
Since the 1920s, there have been literally hundreds of well-dated intermediate fossils found in Africa, which were transitional species that carried monkeys to humans during the last 6-7 million years. This evidence is presented in the last three tutorials of this series.
2- Chemical and anatomical similarities
Living things on Earth are fundamentally similar in the way they develop their basic anatomical structures and in their chemical compositions.
No matter whether they are single-celled protozoans or highly complex organisms with billions of cells, they all begin as single cells that reproduce by similar division processes. After a limited life span, everyone also ages and dies.
All living things on Earth share the ability to create complex carbon molecules and some other elements. In fact, 99% of the proteins, carbohydrates, fats and other molecules of living things are made up of only 6 of the 92 most common elements. This is not a mere coincidence.
All plants and animals receive their specific characteristics from their parents through the inheritance of certain combinations of genes. Molecular biologists have discovered that genes are, in fact, segments of DNA In our cells.
All the tens of thousands of types of proteins in living things are made mainly of only 20 types of amino acids.
Despite the great diversity of life on our planet, the simple language of the DNA code is the same for all living beings. This is proof of the fundamental molecular unity of life.
In addition to molecular similarities, most living things are equal in that they obtain the energy necessary for growth, repair and reproduction directly from sunlight by photosynthesis , Or get it indirectly by consuming plants and other organisms that eat plants.
Many groups of species share the same types of body structures because they inherited them from a common ancestor who had them. This is the case with vertebrates, which are animals that have internal skeletons.
The arms of humans, the front legs of dogs and cats, the wings of birds and the fins of whales and seals have the same types of bones (humerus, radius and ulna) because they have preserved these features of their ancestors in common.
All these important chemical and anatomical similarities between living beings can be explained more logically by assuming that either they share a common ancestry or that they arose as a result of similar natural processes. These facts make it difficult to accept a theory of special and independent creation of different species.
3- Geographical distribution of related species
Another clue to past evolution patterns lies in the natural geographic distribution of related species. It is clear that major isolated land areas and island groups often developed their own plant and animal communities.
For example, before humans arrived, 60-40,000 years ago, Australia had over 100 species of kangaroos, koalas and other marsupials, but none of the more advanced placental terrestrial mammals such as dogs, cats, bears, horses.
The terrestrial mammals were totally absent from the even more isolated islands that make up Hawaii and New Zealand. Each of these places had a large number of plants, insects and bird species that were not found anywhere else in the world.
The most likely explanation for the existence of unique biotic environments in Australia, New Zealand, and Hawaii is that life forms in these areas have been evolving isolated from the rest of the world for millions of years.
4- Genetic changes over generations
The environments of the Earth are constantly changing, usually in subtle and complex ways. When the changes are so large that they go beyond what most members of a population of organisms can tolerate, a generalized death occurs.
As Charles Darwin observed, not all individuals perish. Fortunately, natural populations have genetic diversity. Those individuals whose characteristics allow them to survive an environmental crisis will probably be the only ones able to reproduce.
Subsequently, its traits will be more common in the next generation, then the evolution of the population will have occurred.
This natural selection process that results in evolution can be easily demonstrated over a 24 hour period in a laboratory petri dish of bacteria living in a nutrient medium.
When a lethal dose of antibiotic is added, there will be a mass death. However, some of the bacteria are usually immune and survive. The next generation is mostly immune because they have inherited immunity from survivors.
This same phenomenon of the evolution of bacteria accelerated by human actions occurs in our own bodies at a time when an antibiotic drug is unable to completely eliminate a bacterial infection.
That is the reason why doctors are sometimes reluctant to recommend an antibiotic for their patients and insist that the full dose is used even if the symptoms of the disease go away. They do not want to allow any bacteria that are potentially resistant to antibiotics to survive.
References
- Evidence of Evolution (s.f.). Retrieved from boundless.com.
- Evidence for evolution (s.f.). Retrieved from khanacademy.org.
- Three Main Pieces of Evidence Supporting Evolution (s.f.). Retrieved from futurism.com.
- Lines of evidence: The science of evolution (s.f.). Retrieved from evolution.berkeley.edu.
- Rene Fester Kratz. WHAT EVIDENCE SUPPORTS THE THEORY OF EVOLUTION? (S.f.). Retrieved from dummies.com.
- Ker Than. What is Darwin's Theory of Evolution? (2015). Retrieved from livescience.com.