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grandpa & grandson When it comes to acknowledging your age, nothing comes close as to putting a grandson on your shoulders. Not even your mirror image. The first thing you must do is to dispose of the idea that your physical fitness is anything like it seems. Then you must fight off the thoughts on evolution and its logic (invincibleness, that is), like ageing and death do hold meaning, they evolved. On the bright side, you don’t fool yourself with afterlife accommodations - the life after you is on your shoulders. To cool down even more, when you are by yourself, take the book Life Ascending by Nick Lane (Norton, 2009) and read about the ten great inventions of evolution - death is one of them. Below is an excerpt from that book. And because the text might scare away you with some terms from bioscien- ces, I’ve included a small, handy glossary; the selection of terms is, actually, from another Lane’s book, Oxygen, The Molecule that made the World (Oxford, 2002). And yes, my brain cells are not replaceable. That much I can remember If you would like to learn more about the park and zoo I walked with my grandson on shoulders, click here. |
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from Life ascending by Nick Lane (Norton, 2009) The chances are we will never live forever, nor would many wish to. The problem is implicit in the make-up of the first colonies, the distinction between the sex cells and the body. Once cells began to differentiate, the disposable soma become subservient to the germ-line. The more that cells become specialized, the greater the benefits to the body as a whole, and so the germ-line in particular. The most specialized cells of all are the neurons of the human brain. Unlike more mundane cells, neurons are practically irreplaceable, each one wired up with as many as ten thousand synaptic connections, each synapse founded in our own unique experience. Our brains are not replaceable. When one neuron die, there is usually no pool of stem cells to replace them; and if one day we succeed in engineering a pool of neuronal stem cells, we must surely replace our own experience in the bargain. And so the price of immortality is our humanity. |
amino acids: the building blocks that are linked in chains to form proteins in all living things. Twenty different types are found in proteins; the order in which they are linked together is specified by the DNA code. DNA (deoxyribonucleic acid): genetic material of all cells, twisted into double helix. The sequence of four ‘letters’, A (adenine), T (thymine), C (cytosine), and G (guanine) encodes the order of amino-acid building blocks in proteins. eukaryote: organism with cells having a ‘true nucleus’. Eukaryotes comprise one of the three domains of life. Animals, plants, fungi, algae and protozoa are eukaryotes. germ line: the cells responsible for passing genes on to the next generation. gene: unit of DNA comprising the coding sequence for a single protein ( or RNA molecule) mitosis: type of cell division in eukaryotic cells in which the chromosomes are doubled and then separated to produce two daughter cells genetically identical to the parent cell. nucleus: central ‘control centre’ of eukaryotic cells, containing genetic material (DNA) combined with proteins, separated from the rest of the cell by a double membrane. protein: large molecule made of a long chain of amino acids folded into a three-dimensional shape that dictates its function. Cells make many different kinds of proteins, which make up most of cell’s structure and carry out all its functions. The amino acid sequence of proteins are encoded in the genes. RNA (ribonucleic acid): single-stranded thread of nucleic acids, which resembles DNA in its sequence of ‘letters’. There are various types of RNA (messenger RNA, ribosomal RNA, and transfer RNA), which are all essential to cells. soma: the body, as opposed to the germ line (the sex cells) stem cell: unspecialized progenitor cell, which divides by mitosis to replenish population of specialized (differentiated) cells. synapse: a region where nerve cells join, a region where nerve impulses are transmitted and received. |
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