Billions of years ago, Earth was a different place. Intense volcanism, meteorite impacts, and toxic gases like methane made it hostile to modern life. Most notably, it lacked the oxygen-rich environment that makes our planet as luscious and green as it is today. Within it, photosynthetic bacteria, such as purple (PSB) and green (GSB) sulfur bacteria, thrived, playing a vital role in producing organic matter through photosynthesis.
