Once, over 2.5 billion years ago, Earth’s oceans were teeming with microscopic life. Among them were cyanobacteria, tiny organisms that discovered a way to harness the sun’s energy—photosynthesis. With each breath of sunlight, they exhaled something new into the world: oxygen.
At first, this oxygen was harmless. It dissolved into the oceans, reacting with iron to paint the seabed in bands of rust—the very iron formations we mine today. But cyanobacteria were relentless, churning out more and more oxygen until, one day, the ocean could hold no more. Oxygen spilled into the atmosphere, changing the planet forever.
What should have been their greatest achievement became their undoing. Most life at the time couldn’t survive in oxygen, a gas that was, ironically, a lethal poison to them. As the air turned toxic, entire species perished, including many of the cyanobacteria themselves. Their own success had nearly wiped them out.
And yet, some survived. A few had adapted, learning to tolerate oxygen, even to thrive in it. These resilient microbes would go on to shape the world as we know it, paving the way for complex life, animals, and eventually humans.
Sometimes, what we create—our own success, our own actions—can turn against us. But history teaches us this: adaptation is survival. The ones who endure are not always the strongest, but the ones who learn, evolve, and turn their challenges into stepping stones for the future.
So when life changes in ways you never expected, remember the cyanobacteria: what nearly destroyed them became the very thing that built a world.
Engineer's Log 