By “macro-life” I just mean large, complex life such as are we humans or is the oak in my backyard.
A recent interest in landing on other planets has led researchers in many different fields to try to physically simulate extra-Earth conditions in Earthly spots; such as, Antarctica, icy mountain tundras and boiling springs.
Most of the search for extra-Terrestrial life is centered on microbe-sized life, such as bacteria. This process has led to the following extract from a JPL/California Institute of Technology report:
Almost everyone believes that our great, great, great…great grand-ancestors were bacteria. If the surface bacterial life evolved into multi-celled, complex forms such as we humans and other plants and animals, is it possible that the deep subsurface bacteria also might have evolved into large, complex forms?
Rephrased: Is it possible that a few miles beneath the surface, Earth has an structure of large, complex lifeforms, living and evolving in the darkness of their cavern homes?
And if this evolutionary process is possible, what might be the implications of co-equal or even superior civilizations existing, growing, and evolving under our very feet?