The Immortals and the Hidden Species
Scientifically, the study has two major conclusions: On the one hand it confirms that the FoxO gene plays a decisive role in the maintenance of stem cells.
It thus determines the life span of animals -- from cnidarians to humans. On the other hand, the study shows that aging and longevity of organisms really depend on two factors: the maintenance of stem cells and the maintenance of a functioning immune system. Materials provided by Christian-Albrechts-Universitaet zu Kiel. Note: Content may be edited for style and length. Science News. Hydra -- mysteriously immortal The tiny freshwater polyp Hydra does not show any signs of aging and is potentially immortal. Aging in humans When people get older, more and more of their stem cells lose the ability to proliferate and thus to form new cells.
ScienceDaily, 13 November Christian-Albrechts-Universitaet zu Kiel. Solving the mystery of aging: Longevity gene makes Hydra immortal and humans grow older. Retrieved September 28, from www. Active aging refers to having initiative and doing things the aging person considers important. The indicator consists of a Researchers have now discovered that the protein Gcn4 decreases protein synthesis and extends the life of yeast cells.
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Even anti-aging creams can't stop Old Father Time. But new research reveals you may be able to slow Now, a group of researchers has discovered that an existing drug reduces body fat and appetite in older rats, Below are relevant articles that may interest you. ScienceDaily shares links with scholarly publications in the TrendMD network and earns revenue from third-party advertisers, where indicated. On the Keto Diet?
Ditch the Cheat Day Boy or Girl? Living Well. A monkey is a machine that preserves genes that enable it to go up trees, a fish is a machine that preserves genes so that it can live in water; there is even a small worm that preserves genes in German beer mats. DNA works in mysterious ways. For simplicity I have given the impression that modern genes, made of DNA, are much the same as the first replicators in the primeval soup.
It does not matter for the argument, but this may not really be true. The original replicators may have been a related kind of molecule to DNA, or they may have been totally different. In the latter case we might say that their survival machines must have been seized at a later stage by DNA. If so, the original replicators were utterly destroyed, for no trace of them remains in modern survival machines.
Along these lines, A. Cairns-Smith has made the intriguing suggestion that our ancestors, the first replicators, may have not been organic molecules at all, but inorganic crystals of minerals, little bits of clay. Usurper or not, DNA is in undisputed charge of all living forms of life today, unless, as I tentatively suggest in Chapter 11, a new seizure of power is now just beginning memes.
See also, The beginning of life on earth by de Duve; an article that originally appeared in the September-October issue of American Scientist. A DNA molecule is a long chain of building blocks, small molecules called nucleotides. Just as protein molecules are chains of amino acids, so DNA molecules are chains of nucleotides.
A DNA molecule is too small to be seen, but its exact shape has been ingeniously worked out by indirect means. It consists of a pair of nucleotide chains twisted together in an elegant spiral; the 'double helix'; the 'immortal coil'. The nucleotide building blocks come in only four different kinds, whose names may be shortened to A, T, C and G Adenine, Thymine, Cytosine and Guanine.
These are the same in all animals and plants. What differs is the order in which they are strung together. A G building block from a man is identical to a G building block from a snail. But the sequence of building blocks in a man is not only different from that in a snail. It is also different, though less so, from the sequence in every other man except in the special case of identical twins.
Our DNA lives inside our bodies. It is not concentrated in a particular part of the body, but it is distributed in all of our cells. There are about a thousand million million cells a thousand billion making up an average human body, and, with some exceptions which we can ignore, every one of those cells contains a complete copy of that body's DNA.
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It is as though, in every room of a gigantic building, there was a book-case containing the architect's plans for the entire building. The 'book-case' in a cell is called the nucleus. The architect's plans run to 46 volumes in man, the number is different in other species. The 'volumes' are called chromosomes.
They are visible under a microscope as long threads, and the genes are strung out along them in order. It is not easy, indeed it may not even be meaningful, to decide where one gene starts and ends and the next one begins. Fortunately, as this chapter will show, this does not matter for our purposes. I shall make use of the metaphor of the architect's plans, freely mixing the language of the metaphor with the language of the real thing. Page will provisionally be used interchangeably with gene, although the division between genes is less clear-cut than the division between the pages of a book.
This metaphor will take us quite a long way. When it finally breaks down I shall introduce other metaphors. Incidentally, there is of course no 'architect' or rather the architect is "natural selection". The DNA instructions have been assembled by natural selection. DNA molecules do two important things. Firstly they replicate, that is to say they make copies of themselves. This has gone on non stop ever since the beginning of life, and the DNA molecules are now very good at it indeed.
As an adult, you consist of a thousand million million cells, but when you were first conceived you were just a single cell, endowed with one master copy of all the architect's plans. This cell divided into two, and each of the two cells received its own copy of the plans, so that each of them could replicate themselves. Successive divisions took the number of cells up to 4 2 2 , 8 2 3 , 16 2 4 , 32 2 5 , 64 2 6 , and so on into the thousand of billions 2 At every division, the DNA plans were faithfully copied, with scarcely any mistakes.
It is one thing to speak of the duplication of DNA. But if the DNA is really a set of plans for building a body, how are the plans put into practice? How are they translated into the fabric of the body? This brings me to the second important thing DNA does. It indirectly supervises the manufacture of the different kinds of molecules of proteins that make up the organs of the body and the building of all these organs with their functions.
Thus as the cells divide and multiply, the different organs of the body appear and build-up. As we know, it takes years to build a human capable of reproducing itself in its turn. The haemoglobin which was mentioned in the last chapter is just one example of the enormous range of protein molecules. See animation on hemoglobin. The coded message of the DNA, written in the four-letter nucleotide alphabet ATCG, is translated in a simple mechanical way into another alphabet.
This is the alphabet of amino acids which spells out protein molecules. Making proteins may seem a far cry from making a body, but it is the first very small step in that direction. Proteins not only constitute much of the physical fabric of the body; they also exert sensitive control over all the chemical processes inside the cell, selectively turning them on and off at precise times and in precise places. Exactly how this eventually leads to the development of a baby is a story which it will take decades, perhaps centuries, for embryologists to work out.
But it is a fact that it does. Genes do indirectly control the manufacture of bodies, and the influence is strictly one way: characteristics acquired after birth are not inherited.
Futurologist Dr Ian Pearson says technology is causing humans to 'evolve'
No matter how much knowledge and wisdom you acquire during your lifetime, not one jot will be passed on to your children by genetic means. Each new generation starts from scratch.
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A body is the genes' way of preserving the genes unaltered. The evolutionary importance of the fact that genes control embryonic development is this: it means that genes are at least partly responsible for their own survival in the future, because their survival depends on the efficiency of the bodies in which they live and which they helped to build. Once upon a time, natural selection consisted of the differential survival of replicators floating free in the primeval soup. Now, natural selection favours replicators that are good at building survival machines, genes that are skilled in the art of controlling embryonic development.
In this, the replicators are no more conscious or purposeful than they ever were. The same old processes of automatic selection between rival molecules by reason of their longevity, fecundity, and copying-fidelity, still go on as blindly and as inevitably as they did in the far-off days. Genes have no foresight. They do not plan ahead. Genes just are, some genes more so than others, and that is all there is to it. But the qualities that determine a gene's longevity and fecundity are not so simple as they were.
Not by a long way.
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In recent years, the last six hundred million or so, the replicators have achieved notable triumphs of survival-machine technology such as the muscle, the heart, and the eye evolved several times independently. Before that, they radically altered fundamental features of their way of life as replicators, which must be understood if we are to proceed with the argument. The first thing to grasp about a modern replicator is that it is highly gregarious.