ABSTRACT
The idea of light as necessary to life is so powerful that it is often assumed that all organisms depend on it. Light is not merely a matter of life and death in the longer term of biological evolution, but a critical factor in a shorter timetable of cultural evolution, in which humans had every reason to be afraid of the dark. Using sunlight is literally like tapping into a nuclear reactor over which the organism has very little control, and certainly none that can be exerted quickly. The evolution of the eukaryote microalgae stems from organisms that acquired a photosynthetic capability by stealing photosystems from their prey. As well as relying upon photosynthesis to manufacture glucose and energy, plants are responsive to patterns of movement in light. The presence or absence of light has been critical, as illustrated by marine biologist Kevin Flynn's exploration of the intricate relationship that phytoplankton have with light.
