How Simple Can Life Get? It’s Complicated

In the pageant of life, we are genetically bloated. The human genome contains around 20,000 protein-coding genes. Many other species get by with a lot less. The gut microbe Escherichia coli, for example, has just 4,100 genes.

Scientists have long wondered how much further life can be stripped down and still remain alive. Is there a genetic essence of life? The answer seems to be that the true essence of life is not some handful of genes, but coexistence.