By Yervand Kondrahjian | Staff Writer
Evolution is a biological process by which the characteristics of a species change over multiple generations. The theory of evolution is based on the idea that all species are related and change gradually over time. Genetic variation within a population is key to evolution, affecting an organism’s physical characteristics or phenotype. If an individual has traits that give them an advantage over others in their environment, they can pass those traits on to their offspring.
Charles Darwin proposed the theory of evolution through natural selection, which states that variations in physical characteristics exist among members of a species. Those individuals that are better adapted to their environment have a higher likelihood of surviving, finding food, avoiding predators, and resisting disease. These individuals are also more likely to reproduce and pass on their genes to their offspring. Conversely, individuals that are poorly adapted to their environment are less likely to survive and reproduce, and their genes are less likely to be passed on.
Darwin’s influential work On the Origin of Species, published in the 1850s, proposed that all living things can be traced back to a common ancestor and that species undergo “descent with modification.” Natural selection is the mechanism by which evolution occurs, as populations acquire more heritable characteristics that aid in survival and reproduction over time.
At the genomic level, evolution operates through changes in DNA sequence. Our genes, which are the fundamental units of inheritance, are influenced by these changes. Understanding the evolution of various species requires examining their DNA sequences. Our own genome contains the history of our evolution, as genetic mutations that affected our ancestors have contributed to the appearance of the human genome. When two species share similar DNA, it is assumed that their DNA and genes share common ancestors. For example, humans and the fruit fly Drosophila melanogaster share much of their DNA, and the fruit fly contains 75% of the genes that cause diseases in humans.
Over time, changes accumulate in DNA, some of which may confer a selective advantage to an organism. Other changes may be detrimental if they affect important daily functions. Some genes remain relatively unchanged and are said to be conserved. Understanding the mechanisms of evolution requires examining the DNA sequences of different species, including our own.