Why is modern synthesis important?
What is now known as the modern synthesis is the eventual marriage of neo-Darwinism, with its support of natural selection and rejection of the inheritance of acquired characteristics, to Mendelian genetics, with its particulate inheritance. The modern synthesis is the fundamental basis for all current work in evolutionary biology.
Modern synthesis is important because it is the union of ideas from various fields of biology. It bridged the gaps between geneticists, naturalists, and paleontologists. "The guiding theories of Modern Synthesis are that natural selection is the driving force of evolution and that evolution is understandable in terms of mutations in and recombinations of particulate genes."
It was very important to settle the dispute between 'geneticists' and 'biometrists/evolutionists', which divided Biology until at least 1930. The modern synthesis builds on population genetics to explain what happens to populations, as described by Charles Darwin, under natural selection.
However, it quickly became propaganda, and unsolved problems like the role of genetic variation in so-called macroevolution remain so partly because important aspects of Darwin's discourse, like developmental biology topics, were left out.