Why Humans Would Not Enjoy a Planetary Surface Only for Bacteria

It is often wondered why humans would not enjoy living on a planet where the only organisms left are bacteria. To indulge in such a scenario, we must delve into the fascinating and complex world of biology, evolution, and human adaptation.

Understanding Bacteria

Bacteria are incredibly versatile microorganisms that have been thriving on Earth for billions of years. They are single-cell organisms capable of surviving in diverse environments, some of which might not be suitable for more complex life forms. Bacteria do not possess the complex nervous systems necessary for experiencing emotions or enjoying life as we know it.

Planetary Habitability and Human Needs

For humans to survive on a planet inhabited only by bacteria, the environment would need to meet certain criteria. However, the presence of only bacterial life does not guarantee a habitable environment for humans. The evolution of human life has depended on a complex ecosystem and the availability of diverse resources. If Earth were to revert to a state where only bacteria existed, several key issues would arise:

Lack of Free Oxygen: Prior to the Great Oxygenation Event, which began around 800 million years ago, the atmosphere lacked free oxygen. This would immediately render a human visit to such a planet fatal. Oxygen is crucial for human respiration and the metabolic processes that power our bodies. Unfamiliar Ecosystem: Before the rise of plants, the environment would be devoid of the greenery, trees, and diverse plant life that provide us with food, oxygen, and a balanced ecosystem. The lack of plants would mean an absence of animal life that relies on them, greatly limiting our resources. Predation and Predators: Even if we were to assume a world where human-sized creatures could survive by preying on bacteria, the presence of predators larger and more dangerous than much of today's fauna would make survival a constant struggle. The last ice age, though brutal, left us with relatively smaller and less threatening predators compared to what might prevail in a post-bacterial world. Limited Resources: The availability of food would be severely limited. The supermarket produce we enjoy today is a relatively recent development in evolutionary terms. Without plants or animals, we would have to rely on finding and eating smaller organisms, a lifestyle far removed from our current pursuits of agriculture, trade, and industry.

Human Evolution and Multicellular Life

The evolutionary journey from single-celled organisms to multicellular life forms, as seen in humans, is a monumental achievement. It is based on the complex interdependencies of various biological systems that support life as we experience it. While bacteria are essential in many aspects of our current environment, the intricate balance required for human survival would be lost in a planet solely populated by them.

For humans or any multicellular life form, a world only populated by bacteria would be a stark and inhospitable one. The presence of emotions, awareness, and the ability to appreciate the beauty and intricacy of the world, let alone the enjoyment of simple pleasures like eating steak or bacon and enjoying the lush greenery of trees, would be entirely dependent on the existence of a complex web of life that supports and nourishes us.

If we were to imagine a scenario where humans lived alongside bacteria, we must recognize that our survival would be precarious, our living conditions harsh, and our enjoyment of life as we know it significantly diminished. The world we once knew, built on the foundations of a diverse and evolving ecosystem, would be replaced by a monotonous and uncomplicated existence, devoid of the rich array of experiences that make our lives meaningful.