ABSTRACT
Arguably, the emergence of higher levels of organization is a rare event in the history of life. Two billion years ago some prokaryotic cells joined to form the first eukaryotic cell, and then around seven hundred million years ago, give or take, some clones of eukaryotic cells joined to form the first multicellular organisms. It is not clear that very much has happened—hierarchically speaking—since then. We have had a few cases of multicellulars getting together to form (near) superorganisms: some insect colonies, some colonial, marine invertebrates, and perhaps some highly social vertebrate groups. But these are not as integrated at the superorganism level as the multicellulars are at theirs, and anyway a few bee hives, the Portuguese Man of War, and the United Nations is not much to show for seven hundred million years. So, apparently, this emergence of higher levels doesn’t happen very easily. And maybe that’s what makes it so interesting when it does happen.
