In which decade did the application of molecular biology techniques to large populations become prominent?

• A. 1960s
• B. 1970s
• C. 1980s
• D. 1990s

Answer: (D)

The main idea is when molecular tools started to be used at population-wide scales rather than just in single samples. The 1990s brought a turning point because technologies for large-scale genetic analysis became practical and affordable. PCR and DNA sequencing advances continued, but what mattered for big studies was the rise of high-throughput genotyping methods and SNP panels that let researchers screen thousands of individuals efficiently. The Human Genome Project and related efforts during that decade also fostered the infrastructure, data sharing, and analytic approaches needed for population-level molecular studies. Before the 1990s, molecular work tended to focus on smaller samples or simpler markers, so the shift to studying genetic variation across large populations truly took off in that decade.