BreathlessAnt's Blog

What is growth? Nothing but the natural outcome of an increase in cell mass, cell length, and, most importantly, cell number - the latter happening subsequent to cell division.

Another form of growth occurs following differentiation, when a pleuripotent (capable of forming any cell lineage) cell finally achieves one of its end phenotypes. For example, we have stem cells in our body which grow and divide unequally - giving rise to one daughter stem cell and another daughter cell that has acquired some new characteristics and is more ‘advanced’ in its skill sets. This process occurs over and over again until such time as we have a cell that is say a Kupfer cell of the liver (of macrophage lineage - its function is to phagocytose or eat other dead/ foreign cells) or say an erythrocyte or red blood corpuscle (its function is to carry oxygen through its hemoglobin pigment - it doesn’t even need its nucleus and so the nucleus is shed along the way!)

Sometimes death also plays a big role in growth (shades of ‘kuchh pane ke liye, kuchh khona padta hai‘!). The foetal palm is an irregular webbed appendage. As the foetus grows, digitation occurs - i.e., the cells present in areas between the future fingers actively commit suicide (programmed cell death or apoptosis) in response to a command from their genes! The gap formed where these cells existed leads to separation of the fingers! Voila!

In fact, within all living beings there is an active process of death called apoptosis (akin to the shedding of leaves in autumn) that occurs in tissues and organs in which some cells are ‘fated’ to die. Components of the apoptosis process are sets of genes called caspases and an interestingly named gene ‘Yama’ (yes, named by its Indian discoverers after the Hindu god of death) whose activation sets up a cascade of events leading to cell death.

An aside: Why is growth of fetuses termed growth - and not growing up? I guess because until they are out into the big bad world, they do not have their own identity, ergo no growing up.

Growing up is what happens to new borns, to children, to teens, to sub-adults and to youth. The newborn infant is totally dependent on others for everything - his body has not completed developing yet, he doesn’t have teeth, he can’t walk, he can’t talk - in fact he is totally at the mercy of the big bad world, were it not for his mother, carer and nurturer! With the passage of time, the baby grows, learns and develops new skills and, over a period of time, he becomes an independent person.

By his early 20s, like the majority of humans, he would have stopped growing (in height for one). He would have his full set of permanent teeth, his voice would have ‘broken’ long back, and his primary sexual organs and secondary sexual features would have matured. He would by then be ready to procreate and soon find a mate. A process that happens very ‘naturally’ - in fact it is nature’s way to ensure that genes are passed along to the next generation at a time when the parents are young, active and capable of caring and nurturing a child.

In the decade that follows, his growth would already have peaked and would be in the plateau phase of growth. He would be actively using all his acquired skill sets to get ahead in life, learning all the time, making mistakes, learning from them and hopefully not making the same mistakes again! He would be wiser than say a sub adult. Sometime around this time, he would grow ‘wisdom’ teeth - such apt terminologies of the good old days! Usually it would be around this time that he would be peaking in his career, negotiating terms to his advantage.

In the years to come, he would turn around the next corner, and enter into the slouching 40s. He may find that his near vision has weakened and he needs a pair of reading glasses (’chalishi’ - another quaint yet apt term that describes the slowing down of life processes). The muscular tone of his body - all over, not just the optic muscles, starts going slack; he would have developed a paunch, perhaps even a double chin. The hair loss would have started earlier, and by this age it would peak and he would get self conscious and start back combing his hair in that weird and laughable manner. And the graying of this hair too would be peaking thereabouts. All these processes are signs of growing old.

As in all biological systems, there is a very fine line between growing up and growing old. So, when did growing up halt and growing old begin? Theoretically aging - a progression in age, is also a kind of growth. But it is the active process of growing OLD that is termed aging.

So what all would happen to this human during aging? His metabolism would slow down, the activity and levels of many of his body’s enzymes would go down, he would not be able to easily digest all the good foods he used to merrily plough through in his youth. Perhaps he would fall ill more frequently - small illnesses, an outcome of the weakening of his immune system. Perhaps there would be the onset of chronic illnesses like diabetes, hypertension, arthritis, heart disease. Due to wear and tear, inadequate replenishment, increased stress, his joints, his organs, even his bones would start weakening.

All these conditions would signal inadequacy of the body’s component sysems to cope with changing circumstances. Not only would his muscle tone become poorer, the collagen (bundles of fibers that r fixed underneath his skin and provide it a supporting scaffold) would start getting degraded and so his skin would go slack - and he would see the appearance of fine wrinkles that would deepen with time. Yes, what better sign of aging than this! With time, all his systems slow down, his requirement and expenditure of energy too would go down.

What we know today about life and death is that at birth itself each of our component cells have been programmed to perform a certain number of cell divisions and then stop dividing. Also, within our nucleus, the ends of the chromosomes called telomeres need to have their ends replenished regularly to stop them from being sticky. Once that replenishment stops, the ends get shorter and stickier - a sure fire indicator of aging. The ability of our body to counter oxidative stress would be severely hampered. There would come a time when the multi system aging would lead to death of the organism, i.e. the human.

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