How long does an average human live? In 1900 the average life expectancy of humans across the world was 31 years, and today it is about 68. This improvement is largely due to the fact that death-causing infection can now be won over by medicines that did not exist back then. Health practices help in increasing our life span. Proper nutrition, exercise and “good habits” (what they are depends on whom you believe or follow) are known to do so. Ayurveda, Yoga, natural medicines and tonics are some of the “classical” methods in this context. The more we learn about each of these, the more we understand the basis behind how they help (or hinder) the body in keeping fit.
As the body ages, it becomes less and less efficient. Senescence sets in, and we try to find methods to fight it. The body of a youth is fitter, in general, than that of a senior citizen. It was here that Markandeya in Hindu mythology won over Tithonus is Greek mythology. Markandeya wanted to be sixteen for ever while Tithonus was given eternal life, not eternal youth. The former realised that a youthful body is fitter.
What then happens to the body as we age? The body has several parts, most of them dependant on, and interacting with, one another. If one of them weakens, it tells on the others and, thus, the whole body. The more we understand the anatomy and physiology, the better we are in attempting to keep the overall body fit and working well. Too much consumption of sugar, for example, tends to affect the physiology and function of the blood, kidney, the nerves and the eye. Smoking affects the lungs and several other parts of the body. Too much food and little exercise bloats up the body and weakens its efficiency. Inefficiency in one component or part of the body tells on our overall health. If the heart does not pump blood efficiently, it tells on our overall metabolism. Cardiologists attempt to correct this pump (and often succeed). They may do so by putting in stents which restore proper blood flow. They may even remove the “bad” heart and replace it by transplanting a healthy one.
Transplantations of cells (such as in blood transfusions), tissues (such as the cornea of the eye) or even a whole organ (heart, kidney) have now become standard methods of repairing body parts. Advances in cell biology today have made researchers attempt to “build” such body parts - cells, tissues and organs. Cells of various types can be, and are now being, made in the lab using stem cell-based methods, though not tissues yet. But in the not-too-far future, tissues and simple organs are on the cards. This needs biologists working with engineers in the nascent fields of design and engineering. For example, our own researchers in the defence sector, led earlier by Dr A P J Abdul Kalam, had made metallic stents to insert in the blood vessels and light weight metallic alloys to replace the bones in the legs of polio patients. Getting closer to using biological materials themselves, a group in the U.S. had already engineered a human bladder over 20 years ago and inserted it in the body of a young man. He is doing well. Likewise, bioengineering a human ear is on its way. Collaboration between scientists at the IIT Hyderabad and the L V Prasad Eye Institute aims at “bioprinting” a cornea of the eye by successively printing actual cells layer on layer. (This is somewhat similar to the ‘inkjet’ mode of printing used in earlier generation printers). Biosynthetic organ regeneration is the new goal.
One such ‘audacious’ goal is to build a whole human eye from scratch. The researcher asked: “if a lizard can rebuild its cut-off tail, or a salamander its lost eye, why can we not awaken the hidden salamander in us”? What he means is: let us look at the genes in the amphibians, and their counterparts in us humans, look for how its genes go on to build its eyes, and attempt to do similar with our genetic counterparts”. Biomedical sciences are moving into an era where poorly performing (or non-performing) body parts can be made in the lab and inserted in humans. This is the audacious goal of one Dr Aubrey de Grey of California, who has founded what is called SENS (or strategies for engineered negligible senescence) and says: “The man who will live up to 150 years is already with us” and “who knows, we may soon live up to 1000”.
Reminds me of an old 1946 Ford Prefect car that we had in the 1970s. We first changed its tyres, then its carburetor, then got its engine re-bored and valves changed, changed its radiator, spark plugs, and wipers, repainted it and then sold it before leaving Kanpur. It must surely be chugging away somewhere, reminding one of what General McArthur once said of old soldiers: they never die, they just fade away! But Dr. Aubrey de Grey says, old bodies may never die; they just get redone.