Evolution is not only about competition: the cellular origins of a very big idea

If the competitive nature of existence ever gets you down, you might want to consider one leading theory of how complex life came to emerge in the first place. The endosymbiotic theory of mitochondrial origin (also known as symbiogenesis) is one of the leading theories for the development of eukaryotes – the nucleus-containing cells that are the building blocks of all multicellular organisms. According to the theory, narrated here by the biologist Rob Lue of Harvard University, it was a symbiotic partnership between two primitive cells that allowed them to thrive, develop organelles for specialised tasks, and eventually give rise to complex new lifeforms. In other words, cooperation was key – and it remains so today.