Final answer:
King and Wilson's discovery was in the field of Biology, highlighting the genetic similarities between humans and chimpanzees, which spurred further research in human evolution.
Step-by-step explanation:
King and Wilson made a striking discovery in the field of Biology, particularly in the genetics of human evolution. Their work contributed significantly to our understanding of human evolution by comparing human and chimpanzee DNA, thereby showing that humans and chimps share approximately 98-99% of their DNA. This challenged the notion of how physical differences could arise from such similar genetic sequences, leading to a deeper investigation into regulatory genes that control the expression of other genes.