Virtually every definition of the word “life” includes the capability to undergo Darwinian evolution as a necessary characteristic. This is true of life on Earth and of thinking about what would constitute life beyond Earth. If it can’t change, the thinking goes, then it cannot be truly alive.
In addition, evolutionary selection and change occurs within the context of broad planetary systems — the chemical makeup of the atmosphere, the climactic conditions, the geochemistry and more. If an environment is changing, then the lifeforms that can best adapt to the new conditions are the ones that will survive and prosper.
So evolution is very much part of the landscape that Many Worlds explores — the search for life beyond Earth and effort to understand how life emerged on Earth. Evolution happens in the context of broad conditions on Earth (and perhaps elsewhere), and finding potential life elsewhere involves understanding the conditions on distant planets and determining if they are compatible with life.
This all came to mind as I read about the discovery of a remarkable collection of fossils alongside a river in China, fossils of soft-bodied creatures that lived a half billion years ago in the later phase of what is termed the the Cambrian explosion. They are of being compared already with the iconic “Burgess Shale” fossil find in Canada of decades ago, and may well shed equally revelatory light on a crucial time in the evolution of life on Earth.
The new discovery is reported in the journal Science in a paper authored by Dongjing Fu and a team largely from the Northwest University in Xi’an. The paper reports on a zoo of Cambrian-era creatures, with more than half of them never identified before in the rock record.
The animals are soft-bodied — making it all the more remarkable that they were preserved — and some bear little resemblance to anything that followed. Like the Burgess Shale fossils, the Qingjiang discovery is of an entire ecosystem that largely disappeared as more fit (and predatory) animals emerged.… Read more