When we consider living organisms, we see many different forms such as bacteria, fungi, plants, and animals. As scientists study each field, we start to understand the world that we live in better and better. As we understand our world, the earth, better and better, we start to wonder what would be the fundamental basic rules that regulate the relationships among these life forms and non-living forms. There are many different forms of life along with their geophysical differences. For example, some life forms are well adapted to live in deserts while other life forms are well adapted to live in the freezing weather. From the studies on evolution that has started with Darwin, we understand that adaptation is the key concept to this theory. Some life forms fit to a given environment and thus can survive while some life forms would not be able to adapt to a given environment thus being removed from nature. Thus, adaptation is the key to evolution. However, there are a few questions that are not easy to answer. They are; ‘Why evolution happens?’, ‘Does evolution have direction toward something?’, or ‘What would determine the timeline for a species to evolve?’ In this article, we will explore these questions so that we expand our understanding of evolution further.
The goals of evolution
Evolution is a widely accepted theory that explains how life forms change over time. It is also well understood that evolution is based on the processes in which life forms adapt to a given environment. As a result, we find that some life forms have evolved relatively rapidly and some life forms haven’t evolved much and are thus called ‘living fossils’. Some important questions to ask at this point are ‘why evolution happens?’ and ‘what is the goals of evolution?’
As mentioned above, evolution happens when life forms adapt to a given environment. Adaptation means survival. When a life form adapts to a given environment, the life form has increased its chance to survive. On the other hand, when a life form cannot adapt to a given environment well, the chances of survival drop. Environmental factors do not mean only weather or conditions of the area. They also include abundance of food. This implies that if there is plenty of food and if there is no significant change in the environment, the life forms in that specific region don’t have to evolve. On the other hand, whenever there is decrease in food resources or changes in the environment, the life forms should evolve to fit to the changes. For example, let’s assume that there are birds that eat seeds from plant A. As time passes, the plant A population starts to drop and there is a new plant type (plant B) that starts to grow, but the seeds of plant B have different shape from those of plant A. In this case, the birds should adapt to these changes and have to evolve to fit to the new environment. The beak sizes and shapes of the birds should change. Whichever finds a good fit to pick up the seeds from plant B now have an increased chance to survive as plant B replaces plant A. Thus, the population of the birds with proper size and shape of their beak will be able to survive better and dominate after changes of plant type complete. This explanation seems to be good enough for evolution theory and we find similar expression from our biology related books. However, there is still a question that remains to be answered – ‘What made the changes in the environment that triggered life forms to evolve?’
What are the driving forces of environmental changes? – Continental drift!
From the example above, it is clear that the birds that adapted to the environmental changes would survive better and thus evolution happens. During the adaptation, there would be trials and errors as well. However, there is one important consideration missing from this example. It is clear that changes in food type due to environmental factors forced the birds to evolve. Then the question is ‘what are the driving forces for the environmental changes that affecting the source of the food for birds?’ When there are changes in plant types, it means there are changes in temperature, humidity, precipitation patterns, or other factors. This implies that changes in plant types derive plant evolution. This also means that environmental changes force the plants to evolve to fit to the changed environment and the plant evolution forces animals to evolve. Thus, the most important factor for evolution are environmental changes. Here we ask another important question – ‘what makes the environment change?’
Based on the ‘continental drift’ theory, the continents we are standing on were once one piece. This one piece of land was broken and each piece has been moving away from each other and they are still moving. Because of this movement of the broken pieces, we find some regions of earth have frequent earthquakes. This explains why we see changes in climate over time. However, the climate changes made in this case are very slow and gradual – millions of millions of years. This means that life forms have time to adjust little by little to the changes. Gradual changes in climate force life forms to adapt over time. Thus, evolution occurs gradually and slowly. This also indicates that nature allowed individual species to have time for trials and errors for the species to acquire its suitable fit to the changes. Here we ask the next question – Is there any goals set for evolution?
Toward the balanced world
As mentioned above, evolution happens when life forms adapt to the changing environment. It seems that it is just matter of survival for the life forms to the changing environment. Evolve to fit to the changing environment, and thus species can continue to exist. This seems to make perfect sense until we think about ‘what is the meaning of survival?’ and ‘why survival of life forms is important for nature?’ To answer these questions, we need to explore how nature is designed. Plants are important for animals because they provide oxygen to breath and food to feed on. Animals, on the other hand, consume oxygen and release carbon dioxide, which is food for plants. When an animal dies, bacteria and fungi will decompose the body and break them down to forms that plants can absorb. Thus, animals are food for plants and bacteria and fungi do their work to bridge these two different worlds. As we explore the animal kingdom, we find plant eaters, meat eaters, and combinations of the two. Meat eaters have an important role in controlling the population of plant eaters. But any animal bodies would go back to the soil and become nutrients for plants eventually. This shows that survival of plants, animals, and bacteria and fungi is interdependent. Plants need animals to control their population and circulation of nutrients and in some cases, to spread the next generation and animals need plants to survive. We can refer to these relationships among life forms as balanced world. Whenever there are environmental changes, plants and animals evolve not just to survive but keep the balance. Thus, the evolution is balance directed.
What happens if the natural balance is changed too quickly?
As we explored above, nature is designed to keep its balance. With the gradual changes in the environment, all life forms start to adapt. However, from the earth’s history, we find cases when the balance was changed quickly by some natural activities. Many volcanoes that erupted at the short period of time or huge asteroids that hit earth a long time ago would be good examples. Whenever sudden changes in balance happened, they caused mass extinction of life forms. Since each level in the food pyramid depends on each other, these types of mass extinctions would force the life forms to start from the beginning – the very bottom of the food pyramid which are producers (plants). These are good examples that are known from history of the earth. In recent years, however, we hear about the sixth extinction. This is not because of natural activities but human activities. As we produce green house gases more and as we cut down the trees more, we are unbalancing the gas ratio as discussed in the article ‘Global warming – is it real or a hoax?’ With the increase of green house gases, we now started to see the changes in climate such as severe storms. Even though many people understand the severe weather and the global warming are closely related, some people claim that there is not enough scientific evidence that can prove the relationship. But to understand the relationship between global warming and climate changes, we don’t have to wait for the scientists to provide us with series of solid evidence. We can simply think logically about the phenomenon. For example, let’s assume that we are boiling water to cook pasta for diner. As the water gets hotter and hotter, we can find the water movement is getting more violent. Air is lighter than water and easier to be affected by temperature changes. As the earth temperature gets warmer, we will find some regions of earth that have higher temperature than average compared to other regions of earth. This means movement of the air should get stronger than before. As the earth gets warmer and warmer, there will be many different places that have increased in temperature. This means not only that there will be stronger storms but also that they will increase in number. This is why we started to have more severe weather conditions in these days. There is one more very important fact to remember in addition to climate change – that is acceleration of the changes. Climate change looks very slow and does not seem to making immediate impact. This is because the characteristics of nature. The changes from physically balanced state would need higher inputs to begin with. This means that the changes made over initial period of time wouldn’t be easy to notice. However, we should remember that the changes will accelerate once it passes a certain point. This implies that as we ignore the possible impact longer and longer, the damage we will suffer from gets more severe. This also implies that later we start working to reverse these changes, the longer it takes to recover from the damage. Thus, here we ask one last question that is very important – ‘Should we keep breaking the natural balance?