UN International Day of Women and Girls in Science.

This is Barbara McClintock, a botanist. In her work on maize she made fundamental contributions to our understanding of genetics, which have applications far wider than just plant science.

Barabara McClintock. Image courtesy of the Smithsonian Institution Archive

 She was the first person to describe a phenomenon called 'chromosome crossover'. This is a mechanism in which bits of parent chromosomes are swapped during sexual reproduction, allowing inheritance of new combinations of alleles (versions of genes). This discovery was key to understanding how different traits are inherited between generations and is thought to be crucial to the success of sexually reproductive organisms.

She was the first person to describe transposons or 'jumping genes'. These are elements of DNA that can move within the genome, causing mutations. This work also showed that genes could actually be switched on or off, a fundamental concept to understanding how organisms actually work.

She won the 1983 Nobel Prize for Physiology or Medicine for her work on transposons, the only time it's been awarded to a lone woman. Both of these discoveries occur in a wide range of organisms, from mosses to humans, and they have greatly increased our knowledge of the natural world.

Her mother tried to prevent her going to University fearing it would make her 'unmarriageable'. Fortunately her father disagreed, but antiquated ideas about women's role in society almost prevented one histories greatest geneticists in reaching her potential. Things have improved but I still see sexism in science and relatively few women make it to top academic posts. We as a society need to change the way that science works, to allow equal access and opportunity within the field.