Bacteria and Homo Sapiens, a Tale of Oxygen and CO2
Homo sapiens’ ancestor tree goes back to about 4 billion years ago when our oldest relatives, bacteria, and archaea started their journey. These two, were hard at work for two billion years as tiny biochemists, developing myriads of metabolic tricks with organic compounds, laying the foundation for the workings of our cells. Even though they didn’t even have a nucleus in their cell, they already had the basics for life: RNA, DNA, and respiration.
There is scientific consensus about the creation of the first complex cell by a daring act of a first endosymbiosis, in which a bacterium went inside an archaeon. This serendipitous leap allowed the development of the mitochondria, the energy center of the cell, and the further leap to a nucleus that holds and protects the genetic information. After the appearance of these complex cells called eukaryotes (with a nucleus) the cells quickly acquired a variety of organelles to turn the cell into a very chic and high tech lab that was able to make multi-cellular beings and evolve to culminate in Homo sapiens.
Bacteria and Homo sapiens, what a story in between! And yet, these are the only species that can share the prize for their ability to dramatically change the whole Earth’s environment, oceans, and atmosphere. It sounds impossible, how could unconscious beings manage a power that rivals our own? Their unicellular being doesn’t even have a nucleus, much less a sophisticated cerebral cortex to propel the species to the heights of progress and technology.
The evolutionary trek from bacteria to Homo sapiens has happened thanks to the Earth’s ability to sustain its flourishing. The early planet in which life started didn’t look very different from now, except it had a higher proportion of oceans. The atmosphere was dominated by oxidized gases spewed by volcanoes, mostly CO2, water vapor, nitrogen gas, and sulfur dioxide, but very little oxygen. Since CO2 was so abundant, the Earth was much warmer and the sea had absorbed a lot of it, increasing its acidity.
Bacteria were one of the single-celled pioneers who embarked on a gradual metabolic testing and invention journey that allowed them to colonize every ecological niche while changing the appearance of the world while even depositing rocks and minerals at a gigantic scale.
Bacterial processes that strip electrons from the iron dissolved in the oceans created iron formations that can still be seen; these give evidence of the first type of photosynthesis practiced by bacteria. This primitive photosynthesis didn’t produce oxygen, but according to recent studies by researcher Dr. Tanai Cardona, leader of the Molecular Evolution Lab at the Imperial College of London, the bacterial move to oxygen-producing photosynthesis evolved much earlier than thought. According to his research, oxygen production started about 3.4 billion years ago, not much after the beginning of life.
This gradual and long-term production of oxygen by many bacteria was enhanced by the arrival of the cyanobacteria, a more efficient oxygen producer. This led to what is called the Great Oxygenation event, 2,4 billion years ago, in which the oxygen levels in our atmosphere and ocean finally rose to allow the evolution of life that relies on this oxidative process as the basis for their metabolism. Since then, most species have met their cell’s energy requirements by oxidizing resources, in our case, food with oxygen. Once plants evolved, there was a second oxygenation event around 600 billion years ago.
The bacterial activity changed our planet’s atmosphere and oceans dramatically, but since it was very gradual, they didn’t destroy the existing anaerobic life. These organisms could still thrive, using the oxygen to oxidize minerals and solutes in the ocean to feed them.
The main effect of this great oxygenation of our planet caused mostly by bacteria was a dramatic climate change. By increasing oxygen concentration in the atmosphere, bacteria transformed the Earth’s climate, in what is called the great snowball effect, a very deep ice age. As oxygen went up, the relative concentration of CO2 and other greenhouse gases diminished and the systems of the Earth responded according to the laws of physics by cooling down dramatically.
Homo sapiens has been on the scene for about 300 thousand years and during most of that time, the species only had the power to affect their local environment but was never able to outdo bacteria by reaching all of the Earth’s systems. This feat was only possible with the start of the Industrial Revolution, about 250 years ago, when the extreme use of fossil fuels and natural resources became a must for a civilized society. Since then, humans have produced more and more greenhouse gases, busy in their purposeful agenda of progress and technology, but just as unaware as bacteria of the effect it would have on the composition of their oceans and atmosphere.
Homo sapiens’ enchantment with progress quickly led to a belief in eternal growth based on the false premise that a finite planet was not a problem for a top species with the ingenuity to figure out how to substitute all the finite resources. A good example was the finite quality of the supply of Guano, the natural resource that provided the nitrogen required for the manufacturing of gunpowder, explosives, plastics, and fertilizer for industrial agriculture. The solution to the scarcity problem arrived with the invention of the Haber-Bosch process for creating artificial nitrogen. The Green Revolution in industrial agriculture was a nitrogen feast and this, summed to the nitrous oxide that is emitted when we burn fossil fuels, caused the disturbance of the whole Earth’s nitrogen cycle. Our emissions of this gas have sharply increased and the effect of this potent greenhouse gas is being felt in the atmosphere, adding to our climate woes.
This is but one example of how the belief in our capacity to create artificial resources makes us forget that we live in a universe ruled by the 2nd law of thermodynamics. We need energy to do work, but it is impossible to use all of it. Life manages to get the maximum of energy with clever metabolic tricks that evolved over eons, but our machines continue to be highly inefficient, getting little energy that is useful for work, while dissipating a lot of it in heat. If the cells weren’t very energy efficient, there would have never been enough energy for the growth of complex organisms like us. Our machines have been growing to suit our technological needs thanks to the availability of densely energetic fossil fuels, but their inefficiency implies that we had to use too much and too quickly, affecting the environmental balance.
This law of thermodynamics implies that all energy creation implies waste, but we seem quite ignorant of its universal rules since we insist on building infrastructure and growing our machine arsenal, forgetting that the more energy we use, the more waste we create. We have been piling waste in our atmosphere, rivers, oceans, and soil, thinking it is not a problem since most of the time we can’t even see it. The 2021 Great Reset, the New Deal for Nature, politicians from Biden to Macron, influencers like Greta Thunberg and Naomi Klein, are all promising to “build back better”. They insist that just by doing some carbon capture at a large scale (very low chances) and building energy-efficient buildings, it is possible to undo the damage.
Unlike bacteria, which didn’t have a way to measure the changes in gas concentrations that their activities were causing to the atmosphere and the ocean, our ingenuity has made it possible to measure the cumulative effects of our waste on the planet. It is easy to see just by looking at gas concentration charts that the levels of greenhouse gases in our atmosphere have already crossed a dangerous limit. Carbon dioxide concentration went up to its all time high on February 5 2021, 419.5 ppm. This implies that the whole Earth has been perturbed, so proposals for fast and easy solutions to the problem are not only pretentious but misguided. We know that the feedback mechanisms from these changes are ominous: the Arctic is melting and warming up faster than we thought, causing further emissions of methane; Antarctica is also in trouble, its glaciers and the rest around the world are melting too; the ocean is becoming more acid and changing its salinity and the atmospheric and oceanic currents are disturbed, creating a future of climate unpredictability.
We have the intellectual capacity to measure all these things and put all these variables in context to create a realistic picture of extreme climate and environmental disaster, but we try our best to ignore it, we don’t like this picture, it is not optimistic; our leaders oblige us by proclaiming that all we need is to “build back better”. This is not a time to build back better, this is a time to choose our priorities carefully, taking into account the fact that the dense energy is finite and that any economic growth, even so-called ‘sustainable’ will only aggravate the problem. This is a time to think about how we are going to cope with an increasingly disturbed climate that is going to endanger food production and create increasingly frequent and stronger natural disasters, droughts, and floods that will render more areas uninhabitable.
People talk about saving the planet, but the planet doesn’t need to be saved; it will continue for a long time until an asteroid damages it irreparably, or the sun creates problems. It is Homo sapiens and most of the complex life on Earth that needs to be saved because it is in great danger of extinction. Extinctions have happened before, the most notable was the one caused by the asteroid that hit the Yucatan in Mexico about 65 million years ago. The initial catastrophe caused the release of huge amounts of soot and dust that clouded the sun creating a cooling effect that caused part of the extinction. But once the sky cleared, the huge release of CO2 created by the impact heated up the planet completing the extinction of the dinosaurs and many more animals.
Just like the dinosaurs, we are now the top predator on Earth, the most powerful, but also the most vulnerable once the food chain is disturbed by extinction and habitat loss. We are the first top predator that is willfully causing its demise by insisting on its ability to fix everything with more technology while choosing to ignore that this technology will only compound our problem. The good news is that life on Earth will continue, bacteria, microorganisms, and a few other species will remain and will quickly devise ways of surviving within the new parameters creating new evolutionary avenues that will probably open a future for new types of life.
