The existence of each individual is, in truth, an extraordinary and highly improbable phenomenon. Every being that breathes in this vast universe is the outcome of a chain of events so remarkably fortuitous that the mere possibility of their occurrence borders on the implausible.
To begin, consider the simple fact that our parents met. Think of their individual life stories, of the everyday decisions that led them to coincide at a specific time and place. Each of those moments was shaped by countless variables: the choice of a career, a change of residence, shared friendships, even the mere fact of being in a particular place at a precise moment. Had any of these factors been different, they might never have crossed paths.
Take, for example, two people meeting at a university. For both to be in that space, they must have decided to study at that institution, in that city, at that particular time. Their families’ choices, economic opportunities, and even their academic interests and aptitudes played a crucial role in steering them toward that common destination. A minimal variation in any of these aspects—given the sheer number of decisions and circumstances that must align perfectly—could have sent them along divergent paths, and consequently, our existence would never have materialized.
Now consider the instant of conception. Each male ejaculation contains roughly between 40 and 600 million spermatozoa, each competing to fertilize an ovum. The probability that a specific sperm cell, carrying half of our genetic material, will be the one to succeed is infinitesimal. Yet the improbability does not end there. The ovum itself is a single cell, selected from among thousands of oocytes present in the mother’s ovaries. The exact timing of ovulation, the viability of the sperm, and the physiological conditions of the maternal body—all must coincide precisely for conception to occur.
We must also consider previous generations. Each of our ancestors had to survive their own challenges and vicissitudes to reach reproductive age and procreate. From disease and famine to wars and natural disasters, the odds that each of them survived and left descendants are also extremely low. Any change in this ancestral chain would have altered the course of the genetic history that culminates in us.
Moreover, genetic recombination during meiosis ensures that every individual is unique. This process, in which chromosomes exchange fragments of DNA, generates immense genetic diversity. Thus, it is not only improbable that one is conceived at all, but the specific combination of genes that defines us is singular. The probability of an identical combination repeating is practically nil.
Science also allows us to understand the complexity of embryonic and fetal development. From the implantation of the embryo in the uterus to the countless processes of cellular differentiation that lead to the formation of organs and systems, every stage of human development is rife with potential contingencies. Maternal health and well being, nutrition, and the absence of factors capable of causing congenital defects are essential for normal development. Any disturbance in this delicate balance could result in complications that prevent the birth of a viable human being.
Sociology and psychology likewise play a role in our existence. Family dynamics, cultural influences, and socioeconomic conditions affect our parents’ decisions and, consequently, our chance of being born. In societies with high infant mortality or in contexts of intense migration, the variables that determine procreation become even more complex.
Furthermore, human existence does not depend solely on biology and family history. It is also influenced by the stability of our planet and its capacity to sustain life. Earth lies within the “habitable zone” of our solar system, at a distance from the Sun that allows liquid water to exist. Were we slightly closer or farther away, conditions would be too extreme for life as we know it.
The existence of each individual is a phenomenon of mathematical and biological improbability, framed by a series of extraordinary coincidences and circumstances. From the meeting of our parents, through the process of conception and embryonic development, to sociocultural influences, everything converges in a unique way for us to be born. Each life is, therefore, an unrepeatable combination of events that highlights the wonder and mystery of existence. Reflecting on this improbability not only invites us to appreciate life more intensely, but also to value each moment and to recognize the fragility and identity of our own being.
Nullius in verba