Death  

redmustang91 57M  
8821 posts
6/28/2006 8:28 am
Death


I am always surprised at how many people fear death. Why? Oblivion is something people crave. We love to sleep and love to kill time. Many suffer serious pain and anguish in this all too imperfect world. so here is to oblivion!

Not that I am in a rush to quit the place. But in good time, exiting seems perfectly natural and reasonable. Let the next group worry about the mess created so far. Due to the continued effects of Global Warming, which I seriously doubt will be stopped, "After me the deluge!" supposedly said by King Louis the 14th, was just a little premature!

Here are some interesting meditations on death by the smart, lovely and interesting Olivia Judson, biologist:

Ashes to Ashes, Dust to Dust

Yesterday, I discussed how natural selection can sometimes drive populations extinct. Today, I want to present a series of short meditations on the evolution of death. As you read these, you might reflect on two questions: Why do we grow old and die? And what is the role that death plays in evolution?

Meditation One: Death Sustains Life

We tend to think of death as the end of life – and indeed, for every individual, it is. But it is also essential for life. Without death, there would be no evolution (or at least, it would have to proceed rather differently from the way it does today). More important still, without death, there would be little life.

Death for one organism means life for another. This is obviously true for animals – they eat other organisms to live. Less obviously, it is also true for plants. Plants appear passive and pacific, standing there with leaves spread, collecting light from the sun. But appearances can be deceptive. Some plants have evolved to poison the ground to stop other plants growing near. Others evolve to grow fast, so they don’t risk living in someone else’s shade: if they fail to get enough light and space, they will die.

Meditation Two: On the Scale of Death in Nature

Behind the apparent harmony of nature, it’s carnage – and on an unimaginable scale. Let me give you some examples. First: great tits. These are small songbirds – adults weigh less than an ounce – that live in the Old World. A single brood of nine chicks (a typical family size) will eat 120,000 caterpillars while they are in the nest. In summer, Britain is home to 2.1 million pairs of adult great tits. Think how many caterpillars there must be.

Another example: gannets. These are seabirds that hunt fish such as pilchards and mackerel by plunging into the sea from a great height. (It’s dramatic: they look like miniature kamikaze fighter planes, and if you’ve never seen them dive, I urge you to do so at the earliest opportunity.) An adult needs to consume around 1,100 kilocalories (or calories, as you Americans call them) a day. (I could live on that – I’d be a bit hungry, but otherwise I’d be fine.)

A spotted hyena can eat a young Thomson’s gazelle in under two minutes, bones and all. An aardwolf – a small black-and-yellowish-white relative of the hyena – eats 200,000 termites a night. Two hundred thousand termites – imagine if there were a predator of humans that killed on that scale.

The next time you talk of someone dying a “natural death,” pause to consider that for many creatures, the most natural death is to be gobbled up and swallowed.

Meditation Three: On the Disposal of Corpses

One reason nature generally looks harmonious to us is that we rarely see an animal being killed, nor do we often see bodies lying about. But the rarity of corpses is easily explained: they are quickly disposed of. Those organisms that are not killed by predators, but die of something else – disease, say – provide sustenance for a feasting horde of other animals, from beetles and butterflies (some butterflies eat carrion) to vultures and lions (despite their respective reputations, lions scavenge more than hyenas do). Within 10 days, the corpse of an adult male gorilla – which weighs about 330 pounds – will be reduced to nothing but a pile of bones and hair. And this is in a tropical forest, where the carrion eaters are mostly maggots and mongooses.

Meditation Four: On Early Death.

Few creatures besides us can aspire to die in their beds at age 95 (or equivalent). Most organisms die young.

Consider this report on Belding’s ground squirrels written in 1981 by the biologist Paul Sherman:

Of the estimated 308 young born to 72 study females in 1974-1977, 89 (29 percent) are known to have died before weaning. Most of these were killed by coyotes, badgers, and conspecifics [that is, other Beldings ground squirrels]. Several were killed by weasels and hawks, a few drowned in torrential rainstorms, one was killed by hail, one died following convulsions and paralysis, I accidentally stepped on one, and five others died of unknown causes. Conspecifics cause more deaths than any other predator species.
An infant mortality rate of 29 percent! And infanticide a substantial component of that! Horrific. For comparison, among humans, the worst place in the world to be born is presently Angola – where infant mortality is 18 percent.

In fact, in many species, the norm is not to reach adulthood. In one study of palm trees, out of 170,000 seeds that were scattered in a tropical grassland, just one third became seedlings – and only 15 grew into trees.

Early death and massive death together fuel evolution. The greater the carnage, the more efficient natural selection becomes. This is easy to see: if only a tiny fraction of the population survives to reproduce, then natural selection can more easily winnow the genes that make it to the next generation.

Meditation Five: On Lifespan

Death shapes the trajectory of life: life span is as much subject to natural selection as anything else. Organisms evolve to not repair their bodies for any longer than they usually live: there’s no point in building to last for 1000 years if you’re only likely to survive for an afternoon. And so, some organisms have evolved vanishingly short lives: if nothing else kills them by their evolved time, they just sort of fall apart. animals that live in places where there are lots of predators – where being killed early on is likely – evolve to reproduce younger and more often than animals from safer places. You can watch this happen: if you move guppies from streams where there are lots of predators into streams where there are few, they evolve to reach sexual maturity later, and have fewer young at a time. So you might predict that animals such as tortoises that are well protected and can’t easily be killed might evolve to have extremely long lives – and you’d be right.

Meditation Six: On Sex and Death.

In general, sex shortens your life. Sometimes, this can be rather dramatic. In some species of marsupial mouse, for example, the males live for just one breeding season: at the end of it, they keel over, their bodies ravaged. Castrate the males early in their lives, and they’ll live for a couple of years. (Indeed, testosterone is bad for life expectancy: castration generally increases male life span.) In general, a short life span is associated with bacchanalia; a long life span is associated with a leisurely pace of reproduction. (There are exceptions; some plants will live for many decades before flowering just once. Then they die.)

Meditation Seven: On Old Age

Natural selection is good at getting rid of mutations that kill you before you can reproduce. It is much less good at getting rid of mutations that kill you later on – for they will not stop you reproducing. This is one reason there are so many diseases of old age.

Meditation Eight: On Immortality.

Immortality is something most of us equate with gods. But you could also equate it with cancers. For just as we get old and die, so do cells of our bodies. Most of our cells can divide only a certain number of times. After their quota, they stop. “Immortal cells” ignore the usual signals that tell a cell: “You’ve had your time. No more dividing for you.” Immortal cell lines can be made in the laboratory, where they are useful for research. When cells in your body go immortal spontaneously, though, it’s usually bad news: cells dividing indefinitely is one of the attributes of cancer.

Meditation Nine: On the Afterlife.

W. D. Hamilton, one of the great evolutionary biologists of the 20th century (we met him last week), wrote in an article called “My intended burial and why”:

…this great Coprophanaeus beetle will bury me. They will enter, will bury, will live on my flesh; and in the shape of their children and mine, I will escape. No worm for me nor sordid fly, I will buzz in the dusk like a huge bumble bee. I will be many, buzz even as motorbikes, be borne, body by flying body out into the great Brazilian wilderness beneath the stars, lofted under those beautiful and un-fused elytra which we will all hold over our backs. So, finally, I too will shine like a violet ground beetle under a stone.

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