Delbrück's experiment

Delbrück's experiment demonstrated the randomness of mutations in bacteria, particularly in the context of antibiotic resistance. In the 1940s, biologist Max Delbrück and his colleagues exposed bacterial cultures to phages, viruses that infect bacteria. They found that mutations in the bacteria, allowing them to survive the phage attack, occurred spontaneously before exposure, rather than as a reaction to the phage itself. This challenged the prevailing idea that mutations were adaptive responses to environmental pressures, suggesting instead that genetic variation exists independently of environmental challenges. Delbrück’s work laid the groundwork for modern genetics and evolution studies.