They may not have known why it was so, but Babylonian herdsmen and farmers knew that certain traits were passed down among animals. Clay tablets from the era show they also knew how to cross-pollinate date palm trees. The formal study of genetics did not begin until the mid-1800s. However, when Austrian botanist and monk Gregor Mendel experimented with pea plants in a monastery garden.
‘Meticulously cross-pollinating peas with different traits, such as seed color, he discovered that first-generation offspring didn’t mix the characteristics of the two-parent samples but displayed discrete traits of one or the other.
Mixing a red-flowered pea with a white-flowered pea, for example, would produce not pink-flowered offspring, but rather red-flowered ones. Moreover, whiteness recurred in successive generations, meaning that the trait had not been lost but was being passed along in latent form. Ignored at the time, Mendel’s work described the basic laws of heredity.
It was not until the early 20th century that experiments, particularly with the cells of fruit flies, confirmed the existence of chromosomes as carriers of genetic information. Then, in 1941, geneticist George Beadle and biochemist Edward Tatum showed that genes were not simply passive carriers of information; they also functioned at a cellular level as a code for the production of proteins.
Three years later, a team including bacteriologist Oswald Avery, geneticist Colin M. MacLeod, and biologist Maclyn McCarty began unlocking the composition of genes, determining that they were made of deoxyribonucleic acid or DNA.
The pace of discovery since then has been furious. In 1953, biophysicists James D. Watson and Francis Crick proposed the double-helix structure of DNA—two strands of the material, knit together by four base chemicals. Since then scientists have identified specific genes within a DNA strand, connected those genes to character
traits, spliced genes, and cloned or replicated them. These successes have
led to new treatments for cancer, allowed doctors to address certain birth
defects through gene therapy. Given biotechnologists the tools to grow new medicines. And made it possible for forensic scientists to confirm individual identities with biological evidence.