On human DNA, it would not have worked because the oligonucleotide would not have specifically bound to a single site. On a DNA as complex as human DNA it would have bound to hundreds or thousands of sites depending on the sequence involved and the conditions used. What I needed to make this work was some method of raising the relative concentration of the specific site of interest. What I needed was PCR, but I had not considered that possibility. I knew the difference numerically between five thousand base pairs as in a plasmid and three billion base pairs as in the human genome, but somehow it didn't strike me as sharply as it should have. My ignorance served me well. I kept on thinking about my experiment without realizing that it would never work. And it turned into PCR.