BY AFSHAN NABI (MBG/III)
afshan.nabi@ug.bilkent.edu.tr
“Forming an embryo is the hardest thing you will ever do. To become an embryo, you had to build yourself from a single cell. You had to respire before you had lungs, digest before you had a gut, build bones when you were pulpy, and form orderly arrays of neurons before you knew how to think.” – Scott F. Gilbert
Human life begins when two “half-cells” called gametes fuse together to form an extraordinary new cell. Each half-cell comes from one of the parents: the mother provides an egg (the female gamete), and the father provides the sperm (the male gamete). I call the gametes half-cells because, unlike any other cell in our body, gametes contain only half the genetic information needed to construct a human being. But when the male and female gametes come together, they generate a new cell, with a complete set of genetic material. This new cell, called the zygote, is, arguably, the most potent cell known to humankind. It seems a mundane thing, but then it starts to divide and re-divide; over the course of nine months, it creates a new human being. When you pause to think about it, this cell is an unrivaled source of amazement. Yet, it so commonplace – every human you have ever seen is the end product of this cell.
One of the first events that occurs in the mass of cells the zygote gives rise to is the separation of those cells into two kinds: cells devoted to making up this particular individual (the somatic cells) and cells devoted to creating the next generation (the germ cells). In other words, one of the earliest things that happens to you inside the womb is that the cells that will have the potential to create all your possible children are set aside. They do not contribute to your creation. Some scientists think that the ultimate aim of every embryo is to facilitate the conception of a new one. So, it sets aside some cells from the very start to ensure it fulfills that aim. You yourself just fill the role of a sort of vehicle to carry the germ cells that will give rise to gametes into the future and ensure that some of those gametes fuse with gametes from other vehicles to create new embryos.
Going on the assumption that animals are only vehicles for their germ cells, it follows that as soon as they have children, they have arrived at the end of their usefulness. Thus, their bodies no longer need to be maintained, and so, eventually, they die. Such a view seems preposterous when applied to humans; we live on well after we have children. But this is only to ensure that our children can learn to survive – human babies are notoriously unprepared for survival compared to other animal babies. For animals whose children do not need them to survive, fate is harsher.
Consider the silkworm moth. The larva that feeds on mulberry leaves and forms a cocoon is the sexually immature form. From the cocoon emerges the mature moth. It has no mouthparts; it cannot eat. The only energy it has access to is the energy stored in its body from the food eaten by the larva. This energy is sufficient to mate and to use its wings to fly once – for the purpose of laying its eggs. Then the moth dies.
Next, consider the more morbid case of the Australian crab spider mother. She lays about forty eggs in a nest of eucalyptus leaves and gorges on insects, often ones bigger than herself. Then, she allows her babies to feed on her: they attach themselves to thinner parts of her leg joints and suck her to death. She allows this because it prevents the spider babies from eating each other. Her death as a source of food is a delaying tactic; it increases the chance that more of her offspring will survive. Since she has already played her role in carrying life into the future, there is no reason for her to survive any longer.
Though we humans may suffer in other ways, nothing as dramatic as what occurs in the cases above happens to us. But, to reiterate, our bodies separate the cells that make us from the cells that will make our children very early on. Genetically, we are primed to ensure that our life is successful in creating more life. But it does not end there. Psychologically, too, we are wired to ensure that we take life into the future that we ourselves will never experience. Think of the gravity with which most of us pursue our love affairs. Philosopher Arthur Schopenhauer had this to say about our obsession with our love lives: “The ultimate aim of all love affairs … is more important than all other aims in man’s life, and therefore it is quite worthy of the profound seriousness with which everyone pursues it.” Even before birth, the aim of our life is to create more life. And once we have done so, we try to ensure that the new life will survive long enough to produce yet more life. Once that happens, life, as a whole, gains more by our death.
So, if life is the ultimate aim of life, why do we have death? Why not everlasting life?
Consider this: at some point or other, you have heard complaints about how kids these days always have a gadget in their hands and know nothing of games like cops-and-robbers that we used to play as kids. Exposure to technology is fundamentally changing their brain structure and abilities. Pediatric therapist Cris Rowan writes that lengthy daily exposure to technology has been linked to disorders in children that include diabetes, obesity, ADHD, autism, anxiety, depression and sleep disorders. However, even children who are physically healthy, and spend enough time playing imaginary games and being around other people, but also receive a limited, sensible exposure to technology, will have brains different from those of us who grew up without any technology at all. And in the future, if we ever become spacefarers or find ourselves facing killer machines, younger generations may be better equipped than we are to survive by virtue of their different brains.
This leads to contemplation of an unavoidable fact: our environment is continuously changing. A single, unchanging organism with a fixed genetic code would not be able to survive far into the future. But the way our germ cells are made ensures that the genome of every individual is at once similar enough to that of the parents that they are still human and yet different enough that they can possess new features their parents do not have. Add to these small genetic changes the environmental alterations that shape the new group, and you obtain a generation fundamentally different from the one before it. Newer generations can become better suited for coping with the changing environment than their parents, and this ensures their better survival. Insisting on eternal organisms means asking for stagnation and death. It is like demanding to maintain the oldest, slowest operating system when more robust ones are available.
It may feel like death is a huge waste of life, but in our world, life without death is impossible, since in such case all life would soon sputter and crash, into death.