Charles Darwin was a 19th century naturalist who has become the focal scientist for evolution. Though recent advances in science, particularly genetics, have found that he got a few things wrong, the great portion of what he concluded from his observations on the Galapagos Islands and years of thoughtful consideration that followed shaped current understanding of how populations change. Essentially, evolution is the change in a population over time, and Darwin was the man who saw adaptation from individual variation driving this population dynamic.
Field research and archeology
Field research and other physical investigations into species differences have confirmed Darwin’s original observations. Reproductively isolated populations of a species adapt to their new environments and, over time, become different. This is now known as adaptive radiation. The process is driven by natural selection, which involves “survival of the fittest”. Fittest refers to reproductive fitness. Individuals in a population who are better suited to survive due to their physical characteristics will survive to reproduce, passing along those characteristics. The population then becomes skewed towards those characteristics, altering the population with each generation.
Though the field of genetics has been able to fine tune Darwin’s conclusions and even show where he was wrong, genetic analysis has also been able to prove that he was on the right track when he concluded that variation within a population drives selection within a population. New mutations were not considered by Darwin, but they introduce new variability into a population that also drives the processes described by Darwin. Evolution at its most simple level is the genetic differences in a population when comparing its composition at two time points, which then translates into physical differences. The physical differences were what Darwin observed, as he recognized that the species on the Galapagos Islands were a later time point from the species on the mainland. It is also in this way that evolution leads to speciation.
Though Darwin was not entirely correct about the branching of the “tree of life”, his theories on a common ancestor have been shown to be accurate by both genetics and archaeology. As populations of a species become genetically isolated, they become new species, but it is not isolated to a single event. This causes multiple later species to be descendants of the same ancestral population.
This concept is important in vaccine development. Though evolution tends to be associated with more complex organisms, such as mammals, it occurs more quickly and readily in microbes. Every day the effects of mutation and variation in the physical characteristics of populations of microbes are observed and utilized to protect human populations against them. Making Darwin’s observations and theories about evolution valid today.
Darwin's theory of evolution by natural selection was just one point in the development of a scientific understanding of how populations change, a process now known as evolution. Using what Darwin got right about his observations more than 150 years ago, scientists continue to find evidence of variation and natural selection, increasing their understanding of how evolution shapes populations.