Science Forums 2

[Michaelangelica]

Why should anyone—person, ungulate, or bird—eat soil? And how do dirt eaters choose which soil to consume?
Why do plant-eating animals and pregnant or nursing women particularly hunger for soil? You might suppose the easiest way to get answers would be to ask people, since animals can’t tell us.
But if you quiz soil-eating people about their motives, they just give unhelpful replies like I feel good when I eat it or I like the taste.
If you press them, they say they think it cures stomach problems or worms or diarrhea or aids, or that it is good for them during pregnancy, or that it adds a good taste to food or masks bitter tastes, or that it is useful as a pacifier in a baby’s mouth.
These varied answers don’t identify precise physiological explanations for geophagy, but they suggest several possible benefits.
The six explanations most discussed among zoologists, anthropologists, and doctors are to assuage hunger, to provide grit for grinding food in the stomach, to buffer stomach contents, to cure diarrhea, to serve as a mineral supplement, and to adsorb toxins.

Eat Dirt | Environment | DISCOVER Magazine
Lot of theories in this fascinating article on the huge prevalence of soil eating among humans, animals and birds.
no one has pointed out that eating soil ivolves eating 90% critters and wee beasties.
Whole Lotta Bugs

Whole Lotta Bugs
An estimated 5 million trillion trillion bacteria live on Earth (and they have a combined weight roughly equal to that of the top three feet of France).
94 percent of them live in the top 1,300 feet of Earth's surface.
The bacteria inside animals and us account for just a fraction of 1 percent. (*90% of 'human' is a bug of some kind) Whitman's estimate reemphasizes the enormous genetic diversity of bacterial life.

Within the multitude of oceanic bacteria alone, he calculated, any given gene is struck by four mutations every 20 minutes. Though most mutations are detrimental for the bugs, he says, "this gives you a tremendous opportunity for change and adaptation to a new environment."

An alternative to pyrolysis??
Certainly our present method of disposing of human bodies is not ecologically sound or even probably sustainable.

From Bodies to Rosebushes
by Josie Glausiusz
For the environmentally aware, death is the final indignity. A cemetery burial can take 50 years to decompose and can contaminate groundwater. Cremation pollutes the atmosphere with heavy metals and noxious gases. Biologist Susanne Wiigh-MŠsak has another way: Freeze-dry the body and turn it into fertilizer.

From Bodies to Rosebushes | Environment | DISCOVER Magazine

How to Make a Desert
You don't need to destroy all the plant life you see--just rearrange it a little. Then let nature do the rest.
Schlesinger knows that the tablespoons of soil he and Raikes are collecting may help reveal a profound secret of the desert. If Raikes and Schlesinger had come to this spot 150 years ago, they would have been surrounded by almost uninterrupted grasslands stretching across the basin. Somehow the Jornada has since changed, and Schlesinger, Raikes, and the other researchers who work here think they know why.
In many cases, they believe, a desert is like a living organism. Like a cactus or a sidewinder, it needs parents to give it birth, but once kicked into the world it can grow and thrive on its own. Deserts aren’t necessarily the product of outside forces like decreasing rainfall, they say. Rather, it’s the internal ecology of the desert itself--its web of plants, animals, and soil--that drives its growth to maturity and stability. Nor does the transformation of a grassland to a desert necessarily mean the creation of a place where life is more scarce--only one where life is rearranged.

How to Make a Desert | Environment | DISCOVER Magazine
I wonder what the role of soil microbiology was/is here and how cow poo changed all that?

Are We Ready for Alien Bugs?
In a dozen years, NASA plans to bring Mars soil samples to Earth. No one is quite certain what to do with them when they get here

Are We Ready for Alien Bugs? | Space | DISCOVER Magazine
A good question, Safely locked up I would hope.

Altruistic bacteria?

Death and the Microbe
Most people think of bacteria as selfish individualists. But in many microbial colonies, some bugs gladly sacrifice themselves for the greater good of bugkind.
by Lori Oliwenstein
When times get tough, bacillus gets pregnant. Normally the common soil bacterium divides by binary fission; it doubles its chromosomes and builds a septum--a wall--right down its center, dividing itself in half and producing two identical twin cells. But when food starts to run out, and survival becomes paramount, such equality is the first thing to go. Binary fission is still the order of the day, but the precursor cell now places the septum closer to one pole than another, producing two unequal cells-- only one of which will survive.

Death and the Microbe | Environment | DISCOVER Magazine

Prokaryotes at the Gate
Bacteria, ancient members of the prokaryotic world, are striking back with a vengeance and we are running out of weapons to fight them.
. . .

Tomasz, however, argues that we need to rethink our whole approach to treating infectious diseases. Despite its intuitive appeal, Tomasz believes the scorched-earth, take-no-captives approach to bacteria may have backfired.

"Bombing everybody who resembles a prokaryote at the gate is probably a mistake," he says.

That indiscriminate practice just incites every industrious germ in the vicinity to develop and share resistance strategies.
Drugs designed to combat a broad spectrum of bacteria may be cleaning out your respiratory system, but they're also furnishing the hardiest bugs a lab for experimenting with resistance

Prokaryotes at the Gate | Health & Medicine | DISCOVER Magazine
Why arn't there more dead gardeners? If they muck around with bacteria all day?

Not long after Viking landed on Mars, the Friedmanns published a paper describing microorganisms living in the Ross Desert of Antarctica, in mountain ranges so cold and dry they were thought to be devoid of life. NASA had sent researchers to test soil there, in fact, as a trial run for Viking; they found nothing persuasive.

But the Friedmanns did, without leaving Tallahassee. Not in the soil, but in a rock shipped to their lab-- a small but perfect specimen of Beacon sandstone, as Friedmann described it.
The rock was colonized by bacteria that led a miserable existence. All through the dark polar winter, they would barely hold on, at 50 below.
Not until summer could they thaw, rehydrate, and photosynthesize, and then only when midday temperatures were sufficiently high--and only if, at the same time, water from melted snow still lingered. The Friedmanns called these creatures cryptoendoliths: crypto for hidden, endolith, meaning inside rocks.
. . .
Friedmann keeps a large collection of such death-defying organisms in his lab and studies them between treks to exotic environments.
. . .
Among the denizens of the extreme are thermophiles that love water so hot it would kill us, psychrophiles that thrive in places so cold, halophiles in salt brine so strong, and barophiles under pressure so high that we’d expire. Together, such microbes are sometimes called extremophiles, as opposed to mesophiles--creatures, like us, that prefer medium conditions. Of course, from an extremophile’s point of view, we are the ones who live at extremes. It is a very subjective measure of things, Friedmann says.
. . .
Friedmann has traveled the world looking for them, but the wretched of Earth do not congregate in places that humans find comfortable. So Friedmann has searched in deserts from the Gobi in Mongolia to the Atacama in Chile, and in frozen lands from pole to pole. He has looked high on mountains, and deep in the sea. And along the way, he has wondered: If microbes colonize such miserable habitats on Earth, where else beyond Earth might similar life-forms exist?
. . .
Endoliths have been joined in recent years by a number of other impossible life-forms, microbes that might also be models of life on other planets and moons. Earth is infected with bacteria more than a mile below its surface--the current record for deep-dwelling life is 9,600 feet. Microbes may live deeper, but drilling to find them is too difficult

Looking for Life in All the Wrong Places | Space | DISCOVER Magazine
A fascinating article. well worth some study
How are we going to protect all this life/diversity from us?

Lichens, Plants and Snail Poo

The harsh Negev Desert in Israel is strewn with limestone boulders, which have nitrogen-fixing lichens growing on them. Various species of land snails feed on the lichens during the night.
Once the sun comes up the snails retreat to the sheltered areas under the boulders and release their faeces down there. Research has shown that about 11% of total soil nitrogen inputs in the Central Negev Highlands of Israel come from the snail poo!

Nitrogen Fixation