Hi all you in search of a definition of life!
Life is not divided into five or six kingdoms. However man, in
his desperate urge to bring order into things, has divided
biological lifeforms - as defined by man and limited to findings
on this planet - into six kingdoms. At present...
We can deal with this in different ways:
We can accept that life is what we define it to be, and then
different schools can argue to include or exclude viruses, prions
and other simple replicating structures into the definition.
We can choose a more philosophic or even religious approach to
the definition of life.
Or we can have a more physiochemical definition, e.g. that life
is any force that increase entropy and concentrate materia, on
earth mainly in the form of complex organic compounds rich in
carbon, nitrogen, etc.
But life can also be defined as communication and interaction. By
reducing the freedom of molecules, cells, multicellular organisms
or communities, freedom on a higher level of complexity can be
The lipid bilayer membrane locks molecules on the inside of a
liposome. But inside, they can be concentrated and protected.
The nucleus gives molecules even less degrees of freedom and a
higher degree of specialisation, but also allow for a higher
degree of complexity and adaptation of that colony of molecules.
With the appearance of multicellular organisms, even idividual
cells can have different specialised functions. Less freedom,
loss of omnipotency, but room for more complex and diverse
organisms to form.
Communication, chemical signals, becomes more and more complex
and more and more necessary.
Later on comes nervous systems and immune systems (are they not
just different aspects of the same thing? Isn't the immune system
just a floating brain, attempting to continously re-define
Organisms form colonies, groups, packs, communities
Different groups of organisms form echo-systems
Communication, exchange of information, interaction,
interpretation and adaptive behaviour becomes the essence of
Less freedom but more advantages...
Then cultures, religions, civilisations. (OK, I admit that this
may be interpreted as a homocentric perspective. Maybe the tick
is the top of the evolution, if there is such a thing. But in
terms of continous increase of complexity, cultures and religions
are good examplpes.)
Less freedom for the individual, still more specialised
functions, less omnipotency but more advantages, more chances of
survival and prosperity.
And what's life?
Maybe life is all that communication that happens between cell
divisions, between the formation of haploid cells and
reproduction? Maybe life is not so much in the gene as
I am writing this, partly inspired by a Danish biologist, Jesper
Hoffmeyer, whom I do not know much about, but he has written a
book on this issue which provoked my thoughts quite a lot.
Unfortunately for most of you, the book is in Danish with the
title "En snegl p} vejen" ("A snail on the road"), 1993.
Late Monday evening
Ingvar Eliasson, M.D., Ph.D.
Ingvar Eliasson, M.D., Ph.D.
S-392 36 Kalmar, Sweden
Ingvar.Eliasson at alinks.se
Website: http://www.alinks.se/ (in Swedish only)