Modern evolutionary synthesis

The modern synthesis is the coalescing of Darwinian evolution and Mendelian genetics into a powerful theoretical framework. It is also commonly known as "neo-darwinism," "new synthesis," "synthetic theory," or the, "modern evolutionary synthesis."

History
Modern synthesis was subsequent to the publication of Darwin's theory on the origin of species by natural selection. As years passed, biological research illustrated a number of shortcomings with his theories. At the time Darwin wrote his manuscript, the scientific community knew nothing about genetics or how variation was generated within a population. Gregor Mendel, who is known as the father of modern genetics, published his research several years after Darwin's The Origin of Species. In time, the principles of genetics Mendel set forth established that variability was limited and passed to offspring in predictable patterns. Many decades later, after the structure of DNA was elucidated, and the source of variability was understood to be related to variations of genes (alleles), mutations were proposed as the source of variability driving the evolution of populations.

In United States the fundamental catalyzing work was the book released in 1937 by Theodosius Dobzhansky Genetic and the Origin of Species. In Britain an important work was the Julian Huxley's book Evolution: The Modern Synthesis. Other major contributors to the synthesis included Ernst Mayr, with his 1942's book Systematics and the Origin of Species and George Gaylord Simpson who wrote the book Tempo and Mode in Evolution in 1944, among others.

Biological evolution theory has therefore become an integration of Charles Darwin's theory of the evolution of species by natural selection, Gregor Mendel's theory of genetics as the basis for biological inheritance, random genetic mutation as the source of variation, and mathematical population genetics. This composite of mechanism is known as the modern evolutionary synthesis.

Criticism
According to Philip E. Johnson, the decisive disconfirmation of neo-Darwinism comes from the fossil record. Even granting the assumption that neo-Darwinism macroevolution is capable of producing basic changes, it does not appear to be the case. For Duane T. Gish, the fossil record should produce thousands and thousands of transitional forms. He argues that although only a small fraction of all plants and animals have been found, it is also a fact that it has already been excavated a good representative number of the fossils that exist. It seems clear that after 150 years of intense search, a large number of transitional fossils would have been found if this were the case. Francis Hitching states that when seeking the links between major groups of animals they simply do not exist, at least in sufficient numbers so that their status is beyond doubt. Another issue that challenges the model of the modern synthesis are mutations. Mutations are almost always harmful (99.99%), if not lethal, to the unfortunate body where they occur.