 With the newfound molecular understanding of inheritance came an explosion of research . A notable theory arose from Tomoko Ohta in 1973 with her amendment to the neutral theory of molecular evolution through publishing the nearly neutral theory of molecular evolution . In this theory , Ohta stressed the importance of natural selection and the environment to the rate at which genetic evolution occurs . One important development was chain @-@ termination DNA sequencing in 1977 by Frederick Sanger . This technology allows scientists to read the nucleotide sequence of a DNA molecule . In 1983 , Kary Banks Mullis developed the polymerase chain reaction , providing a quick way to isolate and amplify a specific section of DNA from a mixture . The efforts of the Human Genome Project , Department of Energy , NIH , and parallel private efforts by Celera Genomics led to the sequencing of the human genome in 2003 . 
