Bacteria

Bacteria are a singled-celled life form. Along with archea, bacteria are prokaryotic, meaning their cells do not have a distinct nucleus with a membrane. Bacteria reproduce uniparentally (from just one parent), when a cell divides into two, or when a small bud leaves the cell and eventually becomes the size of its parent. Due to global bacteria's extensive cooperation and gene-sharing, scientists and scholars have sometimes referred to bacteria as an example of "decentralized democracy."

Through a process known as horizontal gene transfer, bacteria cells around the world so extensively swap genes with other that the biologists Sorin Sonea and Maurice Panisset referred to the world's bacteria as a giant superorganism. The swapping of genes has allowed bacteria to survive in a variety of extreme climates for billions of years. A team led by Bill Martin found that some 80 percent of genes in the bacteria genome had at some point arrived through horizontal gene transfer.

Examining this gene swapping, Margulis and Sagan stress that bacteria function as "a sort of worldwide decentralized democracy." Graham Purchase comments, "This vision has much in common with that of many prominent 19th century anarchist thinkers, notably Elisee Reclus and Peter Kropotkin."

Bacteria have played a number of beneficial roles for other life-forms. They invented photosynthesis. They are crucial for humans' digestive systems, and for soil maintenance in forests and on farms. Many antibiotics come from bacteria. Reportedly, "Life on Earth would die out faster if organisms in the Superkingdom Prokarya [Bacteria] became extinct than if any of the other life-forms disappeared." According to widely accepted scientific theory, bacterial cells have entered, through horizontal gene transfer over the course of roughly two billion years, into the genomes of all animal cells including human cells."