From the moment that you are born, your clock starts ticking till you die. Death is one of the fundamental rules of life. Your average life expectancy depends on various factors; your level of exercise, diet, environment, and even happiness. Even though hypothetically, you can improve your chances of not dying due to accidents or diseases by improving your lifestyle and avoiding risks, but you cannot stop it. From plants to animals to even the strongest man in the world, every single living being has to die certainly.
Some scientists suggest that your DNA contains the information regarding how many times your cells can divide, and you will die eventually. After thousands of years of evolution and natural selection, why are we not immortal, and why do we die?
You have a variety of cells for different body functions. You have skin cells for your skin, nerve cells that function in your nervous system, and cells that make up your glands and produce hormones in your body. The origin of all these cells is the stem cell; this specific cell type does not have one destined function. Instead, it can form into any cell as needed by your body. Stem cells are undifferentiated cells that set the foundation for several cell types. Each day millions of cells die and are replaced by new ones. Since stem cells can form into any cell type, they can also regenerate lost or damaged cells. They are only present in the first few days of your embryonic life; that is, during fetus formation. One interesting organism, the hydra, has stem cells throughout its life cycle. This means that it can continuously regenerate the injured cells and continue to live on forever ideally. But that does not happen, and they do die due to diseases or some other unnatural causes.
Scientists have studied the life cycles of various plants and animals; some die due to accidents or diseases, whereas others die as an effect of old age. The life cycles vary between the species, but all have a common pathway: birth, growth years, peak, and eventually natural decline.
Senescence is the phenomenon of cell aging and its deterioration due to old age. When we say that someone died because of natural causes, that isn’t technically true. When people say that we die because our cells age or get diseased and start to malfunction as years pass by, that is true. But that is an effect, not the cause of death.
There were thousands of theories presented to find out why humans die, and researchers debunked many. Cell division Is an ongoing process in your body. The more the cells divide, the risk of faulty cells increases with every division. Most of the time, these impaired cells die by a process called apoptosis, where your body destroys the damaged cell. But in other instances, due to some mutations, these cells can continue to survive and eventually form a mass of faulty, rapidly multiplying cells that we know as cancer.
Due to natural selection, the risk of such incidents was reduced by cells only dividing a certain number of times before it dies. A part of your chromosome called telomeres determines this. Chromosomes are present in the form of strands in every cell of your body and contain your genetic makeup. Telomeres are present on the ends of these strands and are shortened with every cell division. This is how your body is constantly multiplying cells, and the protection wears down due to telomere shortening leading to mutations and eventually death.
But the question remains, why do we die? What is the role that evolution plays in this limited time that we have in this world? The problem of cellular mutations could have been tackled through evolution then why is death still inevitable? Humans are a collection of genes. An early theory was that we die to make space for our younger generations, but this did not make sense as the chances of gene transfer are only 50% in the next generation. Accidents, plagues, and diseases happen that cause widespread death. So, we cannot blame the genes entirely for death. No matter how hard they try to keep us alive, the supposedly unnatural factors are always in play. This means that our genes have no way to survive forever other than passing it on to our offspring.
Evolution Favours the process of reproduction rather than preservation. The priority being the long-term survival and health of the species. So, the genes that help further the long-term survival of the species will remain, and those who don’t will eventually die out.
In early development, multiple cellular divisions are needed for growth and development. In comparison, such rapid divisions in late adulthood could lead to cancer. Hence there is an intricate balance to be maintained between when you’re young to when you get old. So, your genes in this situation favor the survival of the younger version as it has better chances.
According to theories, at some point, as you age, your genes stop caring about your survival. Hundreds of years ago, the average expectancy of human beings was much shorter and till 30. You were much more likely to die of infections, injury, or contagious diseases than of old age. But it is in recent years, due to medical advancements, the average life expectancy has increased to around 70 years. With advances in age, your genes assume the increased likelihood of you being dead and the less they care about you. If your genes stop trying to help you survive, it is more likely that you will die since your body is not working efficiently to defend itself from diseases and cellular mutations. But remember! Age is not the cause of death. It is a risk factor involved that makes people succumb to the conditions related to aging. Scientists and coroners are getting better at pinpointing the cause of death in cases when someone dies in their sleep peacefully and is assumed to die of old age.
The leading causes of death nowadays include cardiovascular diseases, stroke, cancer, and respiratory infections. These diseases can affect you at any age, but they are more likely to as you get older and your body starts giving up on you.
Until Next Time,
Team Doctor ASKY!