Lake Life

Researchers working on some of the oldest fossils in the world suggest that multicellular animals, as opposed to single cell life, may have arisen in lake environments, not in the deep ocean as most biologists assume. Further, studying the fossils in a South China geologic strata implies that animal life diversified quickly after its appearance.

SPECULATION: Lakes provide a more dynamic environment than the deep ocean. Energy from the sun could penetrate deep into most lakes. Energy, water, abundant but limited food, and competition for that food may have led to cooperation among single cell organisms that led quickly to permanent associations. Since lakes are much smaller than oceans, interaction among cells would almost necessarily have been greater than they would have been in the open ocean. Interaction is the first step towards multicellular life forms.

Such a line of reasoning has clear implications for the search for life beyond Earth. We have good indications that Mars once had lakes of water (probably not oceans), and we know that Saturn's extraordinary moon Titan has lakes of methane, plus an energetic environment, plus organic compounds everywhere. Finding animal fossils on Mars, therefore, and at least that on Titan, may be more likely than previously thought.