This passage is taken from a book entitled Water: The Fate of Our Most Precious Resource by Marq De Villiers (© 1999 by Marq de Villiers).
- Where did water come from? The
- most common assumption is that
- the earth itself is around 4.6 billion
- years old, formed by gravity from
- cosmic junk, clouds of ionized
- particles around the sun, debris
- left over from the somewhere-
- sometime explosion called the Big
- Bang. This cosmic garbage dump
- coalesced to form a protoplanet,
- which grew by gravitational attraction
- of even more junk (what the
- cosmologists call “particulates”).
- This was the Hadeon Eon: a sort-of
- Earth existed, but there was no
- atmosphere, no ozone layer, no
- continents, and no oceans – and
- most definitely no life.
- Around half a billion years later,
- give or take an eon or two, things
- had settled down enough to
- precipitate rocks; the oldest known
- rocks are in Greenland, and have
- just celebrated their 3.9 billionth
- birthday. The earth was still aflame
- with volcanoes and bombarded by
- asteroids, meteorites, and whatever
- else was floating in the interstellar
- void and intersecting with our nascent
- planet, but those oldest rocks show
- signs of having been deposited in
- an environment that already
- contained water. There is no direct
- evidence for water for the period
- between 4.6 and 3.8 billions years
- ago. But suddenly, there it is.
- The prevailing theory is that the
- atmosphere was created from the
- release of gases from volcanic eruptions.
- As the eons passed, the first lightweight
- silica and aluminum rocks, which are
- typical of continental land masses,
- formed. The surface of the earth
- cooled, and water vapor in this spanking
- new atmosphere condensed to form the
- water of the oceans. Which begs the
- question: Where did the water vapor in
- the atmosphere come from in the first
- place? What was it in the volcanism
- that was our first “weather” that
- produced water? Or perhaps it was
- already present in all that cosmic
- junk – comets, after all, are sometimes
- little more than frozen lakes of water –
- and it came from space, an alien and
- infinitely curious little molecule. For
- water is curious, much more curious
- than it might at first sight appear,
- and is actually little understood. Why
- is it, for instance, that water is the
- only substance whose solid form is
- less dense that its liquid one (a
- phenomenon that has profound
- implications for aquatic life)?
- Scientists have discovered that water
- is made up of hexagons of hydrogen
- atoms arranged in what is called a
- “cage” structure, and that the
- smallest theoretical drop of water
- is made up of six molecules arranged
- as a cage. Which means what? No
- one really knows.
- In any case, water appeared,
- precipitated from what were not
- yet called the heavens. Then, around
- 2.5 billion years ago, life on earth
- began. And it almost certainly began
- in water.
- Darwin and the early evolutionists
- imagined life evolving in a pool of
- soupy, chemical- and nutrient-rich
- water, an idea still pretty much
- accepted today, although there is a
- small but influential scientific subset
- that believes that life, too, might have
- come to us from space, ready formed,
- cosmic nuggets among the infinite
- dross.
- “Runoff collected in a small volume
- is the most likely means of achieving
- the necessary concentration of
- ingredients,” says Gustaf Arrhenius,
- a geochemist at the Scripps Institute
- of Oceanography. In the dry language
- of chemists he writes: “Ponds may
- have further concentrated
- compounds on the internal
- surfaces of sheet-like minerals,
- which attract certain molecules
- and act as a catalyst in the
- subsequent reactions. Two
- aldehyde phosphate molecules
- thus united form a sugar phosphate,
- a possible precursor to organic life”
- – as though that explained anything
- at all.