|What characteristics of living things does a
river have? Is a river alive?
A River is not alive in the usually sense of the
word which is properly restricted to bonafide
"living" systems. Poetically however it is
sometimes useful to use a metaphor and think of an
inanimate but complex system as being 'alive'.
This is useful analogy because some natural
systems are very complex and so are living
systems. A river is a complex system because it
responds to external perturbations (minor upsets)
in complex ways. For example, if one dumps a lot
of sand into a river, the river will change its
course over time in such a way as to come back to
an equilibrium (stable) configuration. This is
similar to for example the way the internal
processes within your body regulate the
temperature: when its hot out you sweat and
evaporation of sweat tends to cool you. If its
cold out you get goose bumps and your blood
circulation slows down to conserve your body heat.
This sort of SELF-REGULATION is common in COMPLEX
A river is a geological entity
but it also hosts many life forms all of which are
Defining life is not an easy, but generally, most
biologists would say "no", a river is not alive.
Like living things, rivers represent a flow of
material, in this case water, through them, just
as much of the matter in living organisms flows
through them. Rivers also tend to concentrate
matter that had been widely distributed into a
more narrow place, thus (locally) destroying
entropy and creating order (although, like life,
they need an external source of energy and
externally created entropy, namely the Sun's light
and the Earth's gravity, to do this). However,
this really isn't a quintessential aspect of life;
wood, for example, is made up of toxins created by
a plant's metabolism that have been sequestered
where they cannot do it any harm, and provide
support on the side. The material in wood doesn't
leave normally until after the plant is
Moreover, rivers (1) do not
reproduce, (2) do not store information of the
design of their form within them, and (3) possess
no internal organization and form except that
which gravity and the laws of fluid mechanics
dictate. Life forms, while they conform to the
laws of physics, they store information which
physics then regulates by means of differential
reproduction of different packages of stored
information, i.e. evolution by natural selection.
They change over time as a
result of changes in climate, changes in the
geology/topography from uplift of mountains, they
change from presence and absence of
Rivers also grow:
They start as
a small stream, and grow, cutting through the soil
and rocks, growing until they ultimately reach
the ocean at the height of their maturity.
Do you think a river is alive? Why or why not?
Do you think living things live in rivers? I'm
guessing your answer is: yes, because fish live in
Where exactly does a river begin
and end? Where exactly are the sides of a river?
Do you know of any living thing that doesn't have
clear borders and some kind of skin or shell that
keeps some things in and some things out? Does a
river have this?
Sometimes people talk
about "living water" because water gives life to
every living thing. But a river is not alive,
scientifically. Some words have special meanings
in science. For example scientists call some
vegetables "fruits" because they have seeds. So
scientists say tomatoes and squash are fruits.
Scientists (and actually, everyone) have struggled
since the dawn of history trying to pin down
exactly what "life" is, and where to put the line
between life and non-life. There's still no
perfect answer, since things like complex viruses
or specialized computer programs still tend to
muddy the waters. In any case, there are some
fairly rigorous definitions that exist, which
define life as something that possesses the
following six traits:
Maintaining a consistent internal state (like
sweating to maintain our temperature)
Metabolism: Require energy and gain it by
utilization of compounds in the environment
3. Growth (not simply the addition of random
matter, but extension of the organized form)
4. Response to the environment (like a plant
turning to face a light)
5. Adaptation: The
ability to change
behavior or activity in
response to signals and stimuli.
Under these rough definitions,
a river does not satisfy 1-- its level may rise
and fall over the year, and it does not maintain
in level or temperature. It doesn't fulfill 2
either. It does fulfill 3-- a river can get
bigger over time, reaching new areas and splitting
into new tributaries. It also fulfills 4, since
it can bend around a boulder in its path over
time. You might argue that it fulfills as well,
since in curving around the path, it etches out a
new path which it will stay with, even if the
boulder is removed. It fails 6 as well, since
rivers don't make new rivers.
noting that some books will list very specific
traits (such as being made of cells) as
characteristics of life-- but those definitions
have gotten too narrow. If we tomorrow discovered
a form of life based on, say, complex clay-mineral
substrates- either deep underground or on another
planet, they would exclude it as life by an
arbitrary claim that all life is cellular life.
As I stated at the beginning-- pinning down life
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