Cyanobacteria appeared on Earth 3.5-2.4 billion years ago, initiating photosynthesis and releasing the oxygen they produced into seawater, forming large amounts of oxygen on the planet.

The emergence of living organisms, the production of organic matter mainly through photosynthesis, the accompanying release of oxygen, and the formation of limestone derived from living organisms led to the formation of the oxygen-rich, nitrogen-dominated atmosphere that we see today.

The oxygen-rich atmosphere also formed an ozone layer that blocked cosmic rays and ultraviolet rays, which are harmful to living organisms, allowing them to expand on land.

It is believed that all living organisms on earth share a common ancestor, and that evolution occurred as their descendants multiplied and reproduced, causing various mutations in their genes.

As a result, today's biodiversity has emerged, forming a biosphere linked by complex relationships with one another.