| DeathDeath. Why it happens? Why do we
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| | evolution. Any new animal, be it a mouse
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| die? Why do animals die? Why do plants
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| | or a human, starts life as a single cell.
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| die? What is the need of this? In my
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| | That cell differentiates and develops
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| opinion mechanism of death was selected
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| | into the complete animal. It assures that
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| during Evolution.From the position of
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| | a rare advantageous variant sequence of
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| Darwin's theory of Natural Selection
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| | DNA will be rapidly propagated by natural
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| everything, that benefits survival of
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| | selection. It is much easier to reproduce
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| species and gives advantage in Natural
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| | and maybe get some new genes or
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| Selection, is preserved in following
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| | favourable mutations starting from a
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| generations.Improvements were often left
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| | single cell than starting from a whole
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| unchanged from the moment of life
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| | multicellular organism. Functions of most
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| appearance. Though there could be other
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| | genes will have been optimized by random
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| ways, certain mechanisms were
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| | point mutation and selection in any given
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| accidentally selected. These improvements
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| | species. Signalling between cells during
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| are reproduced in the genome of more
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| | the development process ensure that
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| complex species. Billions of years ago,
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| | everything ends up in the right place.
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| according to the theory of evolution,
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| | Tiny changes in these Signalling
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| chemicals randomly organized themselves
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| | processes can have very large effects on
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| into a self-replicating
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| | the resulting animal. Genome, with at
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| molecule.Lightings and UV-radiation
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| | most forty-sixty thousands genes, is able
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| helped to create first organic molecules.
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| | to specify the creation of a human body
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| This phenomenon is reproducible in a lab.
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| | containing trillions of cells, billions
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| The experiments were described in
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| | of carefully wired neurons and hundreds
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| 1950-60.First self-replicating molecules
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| | of different cell types all amazingly
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| were probably RNA. First enzymes were
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| | sculpted into organs as diverse as the
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| probably RNA - enzymes. Then proteins,
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| | liver and the brain. This is why
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| DNA and more complex lipid molecules and
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| | mechanism of proliferation of fertilized
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| polysaccharide came to the scene.Death as
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| | oocytes was selected.Hence, having
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| it is did not exist at the stage of
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| | younger (smaller) and older (bigger)
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| Primeval Soup . Sure some organic
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| | animals make sense.But there is the
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| molecules were destroyed , some new
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| | problem: adult animals (or plants)
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| created. But in general it was still that
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| | consume all the nutrition around and
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| swirling and bubbling primary broth -
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| | there is not much left for next
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| quasi alive in our understanding as a
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| | generation.Then it is why mechanism of
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| mixture of biochemical
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| | Death was selected as a mean for next
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| reactions.Everything in the evolution was
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| | generation to establish.Imagine the
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| build from the previous blocks selected
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| | following:First, mechanism of
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| sometime by accident.Appearance of lipid
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| | proliferation was selected . If
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| membranes allows to compartmentalize the
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| | mono-cellular organism does not have
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| primary broth and create first cells.At
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| | mechanism of reproduction it does not
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| the cellular stage we could already talk
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| | produce offspring with possible
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| about the Death. Cell is destroyed,
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| | favourable mutations. Let say there are
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| membrane is broken, everything leaked
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| | primitive bacteria spontaneously created
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| out. This is the Death.Content of cell
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| | in primeval soup. Just few of them. They
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| inside lipid membrane is irradiated.
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| | consume nutrition, they live happily,
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| Process of crazy molecular swirling is
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| | practically immortal but they do not
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| messed up by free radicals irreversibly.
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| | divide. Then set of enzymes appeared
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| This is also signs of Death.Yet at the
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| | during mutations. The set allows bacteria
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| cellular stage we cannot talk about
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| | to split. Synthesis of the new set is
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| Aging. Death at this stage is accidental,
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| | disadvantageous. It requires additional
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| not programed.Organic molecules may age
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| | energy and nutrition. But advantage of
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| (oxidation, conjugation, etc.) and cell
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| | splitting allows new mutants immediately
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| would die. But damaged molecule are
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| | overgrow non-proliferating cells.
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| repaired or synthesized fresh usually.
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| | Selection is really cutthroat.Bacteria
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| Hence, no good reason for a single cell
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| | growing in a tube represent mini
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| organism to age. Irreparable damage from
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| | evolution. Any bacteria that fit for the
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| external cause leads to Death, not Aging.
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| | environment are also selected on the
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| This is accidental death. For
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| | ground of simplicity. In a toxic
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| multicellular organisms, there is a
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| | environment (antibiotics) mutant bacteria
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| parental organism that ages and
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| | having a new mechanism of neutralisation
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| eventually dies after next generation is
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| | would survive. But the more simple
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| born. For mono-cellular organism, there
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| | bacteria will eventually overgrow
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| is parental organism that divides and
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| | complicated ones. Unless complication
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| becomes the next generation. There is no
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| | gives big advantage that outweigh the
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| Aging leading to death of parental
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| | benefits of simplicity. Another example:
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| organism.Mono-cellular organisms are
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| | HIV virus is very complex compare to some
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| practically immortal in a right
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| | other viruses. But because of the
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| environment.Mechanism of division was
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| | complexity it evades immune response.
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| selected during evolution. Cell has
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| | This is why it is so successful. For
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| volume (3-D). Surface membrane is
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| | humans there was some discussion that
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| measured in square units (2-D). Growing
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| | hernias are direct problem of erect
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| beyond limits cause inadequate supply of
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| | posture. So erect posture leads to
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| nutrition from environment. Division
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| | disadvantage. From the other hand erect
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| solves the problem.Microbes, bacteria are
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| | posture frees the hand, that allows to
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| immortal. Some divide every 20 minutes.
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| | produce the tools and this gives huge
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| In a an hour they multiply 8 times.Tumour
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| | advantage in the survival in natural
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| cells divide slower. They are eukaryote.
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| | world by creating possibility to adapt to
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| Most aggressive divide once a day. There
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| | virtually any condition.All high animals
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| is no need for Aging.They would die if
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| | have just 4 extremities. Obviously it is
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| you do not feed them. They die when you
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| | enough in cutthroat environment. Growing
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| kill them with undiluted bleach in a
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| | additional couple of extremities will
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| flask. Otherwise they grow unstoppable.
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| | consume much more resources and take much
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| No aging.Multicellular organism
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| | more time, not giving big advantage in
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| supposedly has several control mechanisms
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| | speed or protection of an animal. Thus,
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| to prevent excessive growth and division,
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| | danger of losing one of the limb is not
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| to kill an extra cell. Apoptosis,
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| | so big as the danger to not proliferate
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| programmed death, is used.Cancer cells
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| | fast enough.Bilateral design of majority
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| often loose the control mechanisms.A
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| | of animals was chosen at the level of
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| scientist from Yale once pointed out to
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| | primitive species. Though lower
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| me that we can not say these cells are
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| | multicellular organisms may have 3-side
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| immortal. Maybe they divide and parental
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| | symmetry or 5-side symmetry like sea
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| cell dies. Indeed. We do not follow the
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| | stars. Often something chosen in the
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| fate of every individual cell during
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| | selection becomes building blocks for
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| experiments. They should give more
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| | higher species. Maybe 5-side symmetrical
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| children cells than parental cells die.
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| | tiger would be possible but it requires
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| Otherwise there would not be the
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| | intermediate chain.The same is true for
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| multiplication. It is a possible
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| | the mechanism of Death. Once chosen, it
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| scenario. We do not follow the fate of
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| | is replicated in all higher organisms. It
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| individual bacteria as well. Maybe they
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| | should give an advantage in ultimate
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| actually undergo aging.From the other
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| | species survival. Otherwise it loses
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| hand some experiments suggest that new
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| | sense and species would be wiped out.So,
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| cells contain roughly half of the parent
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| | what is advantage for Death?Immortal and
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| cell after division. So it is not Death
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| | childless animals are growing and
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| or Aging. Next generations contain 1/4, 1
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| | growing. Mutations lead to species
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| 8, 1/16 and so on of the parent cell. Any
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| | producing offsprings. They have
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| mechanism that is more complex than
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| | disadvantage of been more complex. But
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| simple division would cause disadvantage
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| | advantage of proliferating animals is
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| in evolution and would be quickly
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| | occupation of vaster areas. They displace
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| eliminated. On the level of mono-cellular
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| | immortal and childless species. Now, if
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| organism neither Aging nor Apoptosis make
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| | proliferating animals are immortal they
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| a lot of sense. Though Nature often have
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| | do not give offsprings enough space or
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| hidden reasons.Flick's phenomenon and
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| | food. Next steps of mutation brought
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| telomeres shortening make sense for a
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| | mechanism of programmed death at certain
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| multicellular organism. Cells of
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| | age.Let consider situation when out of
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| multicellular organism do age. They stop
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| | two species one is immortal and producing
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| dividing after 70 divisions or so.A
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| | offsprings, other is mortal with
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| multi-cell organism has clear cut
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| | offspring production as well. Mortality
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| advantage over a mono-cell.Why would
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| | looks like an obvious disadvantage in
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| mechanism of Death selected for
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| | stable environment. Adult organism are
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| multicellular organisms? Scenario could
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| | more powerful and more protected compare
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| be the following.Big organism have more
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| | to juvenile.However, next catastrophe
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| advantages compare to smaller one -
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| | will wipe out all the species altogether.
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| stability, protection, etc. There are not
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| | Only some mutants can adopt to new
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| so many natural enemies for whale or
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| | environment. But "mutant" for a
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| elephant because of their size. Large
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| | multicellular organism imply that the
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| animals could be brought down by
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| | mutation happened when the organism had
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| bacteria, viruses, small parasites, and
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| | only one cell (the stage of fertilized
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| lack of available food. Rare predator
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| | oocyte for example). Otherwise it needs
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| attack whale or elephant.No wonder that
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| | precisely the same mutations on the level
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| evolution was going into the direction of
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| | of several cells - infinitely impossible
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| bigger animals - just look at giant bones
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| | event.Thus, any species that had the
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| of dinosaurs and you will feel some
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| | mechanism to allow next generation to
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| appreciation.Millions years ago not only
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| | flourish (mechanism of programmed Death)
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| Dinosaurs but also insects or crustacean
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| | will have advantage. They produce more
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| were enormous. Cockroaches, spiders or
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| | offspring than immortal species. Death of
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| dragon flies with size of one metre (3
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| | parents spares the space and nutrition.
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| feet). Going back in time we find shells
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| | Immortals can die form accidents only. It
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| of enormous molluscs. Many things imply
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| | is too long for children to expect a
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| that bigger animal with unstoppable
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| | vacancy.Then, having more offspring
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| growth have a lot of advantages compare
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| | automatically means having more mutations
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| to small ones. New species often evolve
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| | (by mere number of events). Having more
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| in their size. An example is growth
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| | mutations means more probability for
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| acceleration in humans. Females prefer
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| | adaptation to the new
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| taller mates that lead to taller
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| | environment.Immortal multicellular
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| children. Shorter plants usually cannot
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| | organisms, even if they existed in the
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| compete with the taller forms in the
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| | past, were quickly wiped out by accidents
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| wild. A short mutant in a patch of tall
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| | and overgrown by mortal multicellular
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| plants would be shaded outMechanism of
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| | organisms.Again all this is just a
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| reproduction was also selected during the
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| | hypothesis.
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