We are a mashup of our parents. Their genetic material mixes together to form the unique DNA combinations in each of us that produce the rich variety of human life. In contrast, bacteria – microscopic beings found in every nook of our planet – typically reproduce simply by dividing, meaning that successive individuals are all identical clones. We didn’t know of any way for bacteria to swap genetic information, until Joshua Lederberg (pictured, right) – born on this day in 1925 – found them exchanging little DNA loops (plasmids) along temporary connecting bridges in 1946. A few years later he showed they can also share genes without even touching, via a virus courier (bacteriophage). These mechanisms became core tools in the fledgling field of molecular biology, and the discoveries won Lederberg a share of the 1958 Nobel Prize. Appreciating the value of variety, he went on to pioneer the study of artificial intelligence and biology in outer space.
Written by Anthony Lewis
BPoD stands for Biomedical Picture of the Day. Managed by the MRC London Institute of Medical Sciences the website aims to engage everyone, young and old, in the wonders of biomedicine. Images are kindly provided for inclusion on this website through the generosity of scientists across the globe.