The biologist T. Dobzhansky once said, “Nothing in biology makes sense except in the light of evolution.” The interconnection between life and evolution remained a mystery until the radiance named Charles Darwin illuminated the scientific world with a novel piece of work titled “On the Origin of the Species using Natural Selection or the Preservation of Favoured Races in the Struggle for Life” published in 1859. It was a result of a voyage on HMS Beagle for more than five years, combined with great observations, tedious note-making, and extensive collaborations with field experts to understand the collected data. Darwin (1859) showed how species altered through a process of natural selection, and how all the life on earth evolved slowly over millions of years. The essay aims to outline and present evidence for biological evolution.
Logic and evidence of Biological Evolution. Biological evolution is the method of alteration in Organismal characteristics over time due to genetic variation and natural selection. The evidence for evolution can be from multiple sources- the fossil records, the chemical and anatomical similarities in organisms, the geographical distribution of related species, and recorded gene-based evidence. Fossil records are present in sedimentary rocks and there are gaps or ‘missing links’ due to incomplete data collection. Archaeopteryx, a fossil found in Germany, had toothed jaws and a bony tail like that of dinosaurs; broad wings and feathers like birds and was concluded as a missing link between the reptiles and birds. It may not be a coincidence that carbon and a few other elements form the basis of all life forms on earth. Molecular biologists discovered genes or chemically coded material to form proteins by central dogma mechanism. There are only 20 amino acids responsible for building protein blocks and diversity among life forms. The anatomical similarity is observed in the arms of humans, wings of the bird, and the flippers of a whale as they have some type of bone because of similar ancestry. Another clue is from biogeography. Isolated land masses like that of Australia and Madagascar have distinct flora and fauna. Kangaroos, Koalas, and marsupials are found in Australia while other placental mammals are missing. Genetic fitness in a changing environment allows an organism to survive. Thus not all individuals perish in the harshest conditions, a few endure as in the case of the evolution of antibiotic-resistant bacteria where a few immune bacteria survive the antibiotic treatment and flourish to produce an entirely new population. Using molecular biology techniques one may conclude, in genus Canis, the members’ wolves, dogs, and foxes have the same ancestor as they share more than 98% of genes. Scientists are able to gather more evidence in support of evolution with advancements nowadays.
Evolution is a scientific theory based on observations, experimentations, and explanations, different from a hypothesis which is simply a proposition to explain any phenomena. Evolutionary changes are heritable and natural selection is the process acting on populations with individuals having different genetic traits capable of transmitting to the subsequent generation. The accumulated variations lead to the formation as well as the extinction of species. Variations, are a result of mutations that arise in a population by chance but natural selection is the result of interactions between the populations with their environment. This variability accumulated over time leads to diversity. Biogeographical separation of flora and fauna presents evidence for diversity across the earth.
Reference
Darwin C. (1859). On Origin of Species by Means of Natural Selection or the Preservation of Favoured Races in the Struggle for Life. London: John Murray, Albemarle Street.