Study Suggests Earth was Purple

The earliest life on Earth might have been just as purple as it is green today, a scientist claims. Ancient microbes might have used a molecule other than chlorophyll to harness the Sun’s rays, one that gave the organisms a violet hue.

Chlorophyll, the main photosynthetic pigment of plants, absorbs mainly blue and red wavelengths from the Sun and reflects green ones, and it is this reflected light that gives plants their leafy color.

According to the scientist, chlorophyll appeared after another light-sensitive molecule called retinal was already present on early Earth. Retinal, today found in the plum-colored membrane of a photosynthetic microbe called halobacteria, absorbs green light and reflects back red and violet light, the combination of which appears purple.

Primitive microbes that used retinal to harness the sun’s energy might have dominated early Earth, thus tinting some of the first biological hotspots on the planet a distinctive purple color.