Scientifically, how is a person considered dead? Do we have a soul?
What Defines Death?
Death occurs when certain parts of the body cease to function: specifically, the cardiovascular system, the lungs, and the brain. From a medical perspective, there are different states of death.
“Clinical death” is defined as the cessation of cardiovascular and respiratory functions, where the body no longer receives oxygen and nutrients. However, individuals in clinical death can often be resuscitated using cardiopulmonary resuscitation (CPR), which frequently yields positive outcomes.
In the case of “brain death”, the cerebellum, cerebrum, and brainstem have all ceased functioning, although some deep brain cells may still be active. Nevertheless, the individual has completely lost consciousness.
Even if the brain is “dead,” a person diagnosed with brain death can still be artificially maintained for a considerable time. For instance, a pregnant woman who is brain dead may remain alive until her child is delivered. Some brain-dead patients may still respond to external stimuli, such as during surgeries. However, from a medical viewpoint, these responses are merely reflexes and not indicative of pain perception.
In some countries, the definition of brain death remains contentious.
Death is an Unpreventable State
The human body is composed of trillions of cells. Cells continuously divide to ensure growth, with old cells being replaced by new, identical ones. However, at some point, this cell division slows down and eventually halts.
It is highly likely that the rate of cell division—whether fast, slow, or stopped—depends on the ends of the chromosomes. If cell division causes these ends, considered the protectors of chromosomes, to shorten, then eventually no cells will divide anymore.
At this point, there will be no new cells while old ones die off. Thus, a living body will ultimately perish.
Biologically, the human body can live a maximum of 150 years. This conclusion comes from a study published in the journal Nature Communications in 2021. In reality, the longest-living person recorded was 122 years old. That was Jeanne Calment, a French woman, who passed away in 1997.
In the picture, Jeanne Calment is joyfully smoking and drinking wine on her 117th birthday. She died in 1997 at the age of 122 and still holds the record for the longest-lived person (Photo: Jean-Piere Fizet/ Getty Images).
What happens to the body during the transition from life to death?
Initially, body parts continue to live in a state of oxygen and nutrient deprivation. However, gradually, as cell division ceases completely, cells begin to die. If too many cells die, the organs will stop functioning.
The earliest reactions occur in the brain, where brain cells die within 3 to 5 minutes. The heart may continue to beat for up to half an hour to an hour afterward. Once blood circulation stops, the blood clots and forms “dead spots”. These spots help forensic doctors determine the cause and time of death.
After 2 hours, the body stiffens due to a lack of adenosine triphosphate (ATP). ATP is essential energy for cells; without ATP, muscles will stiffen. After a few days, this rigidity lessens. It is only at this point that the digestive system dies, with bacteria in the digestive tract beginning to decompose and decay the body.
However, pathogens in the body can still pose a threat for a long time. For example, hepatitis pathogens can survive for several days, and tuberculosis bacteria can remain for many years. The entire process of body decomposition after death can take up to 30 years.
