a reply to: AlienView
Why is Evolution happening?
Still, I've yet to see an explanation as to why in an inorganic universe a biological experiment is
There's a whole lot to unpack in the first bits. First off, you don't need to know why
something is happening to know that it is
happening. Secondly, calling life an "experiment" presumes an experimenter. Thirdly, you're misusing terms like "anomaly" and "inorganic."
I think what you're basically getting at is why did life arise from an inanimate universe?
. (aka the origin of life aka abiogenesis)
The first thing to ask yourself is what is life? What distinguishes living things from the inanimate stuff? After all, they're composed of the same
There have been all sorts of attempts at defining what constitutes life. I would say that among the most fundamental traits of living organisms are
that they're composed of cells (or self-contained units) which sustain biochemical reactions and are capable of reproduction (or at least of being
Although not everything that reproduces is alive, everything that is alive reproduces. In this way, evolution and life are inextricable. In fact,
evolution predates life. Evolution can be thought of as change over time resulting from the effects of selection on a thing that reproduces — but
not just any reproduction, for selection to occur, the reproduction must be such that there are variations between generations.
After all, if the reproduction is exact, there's no change.
So if we assume that evolution began with some sort of prebiotic replicators, the next question is what is the minimal replicator? There's nothing
definitive as far as the precise chemical pathway but a very popular hypothesis is that all life on Earth probably originated with self-replicating
RNA (the RNA World hypothesis). That's not to say that there weren't stages in evolution before "RNA world" but rather that all life as we know it is
a result of an evolutionary history in which this was a stage.
Recent research has demonstrated that RNA can assemble from precursors under certain geochemical conditions
) and scientists have also synthesized RNA enzymes capable of replication
). Interestingly, those replicating RNA enzymes are a pair that
reproduces one another (cross-replication):
The replicating system actually involves two enzymes, each composed of two subunits and each functioning as a catalyst that assembles the other.
The replication process is cyclic, in that the first enzyme binds the two subunits that comprise the second enzyme and joins them to make a new copy
of the second enzyme; while the second enzyme similarly binds and joins the two subunits that comprise the first enzyme. In this way the two enzymes
assemble each other — what is termed cross-replication. To make the process proceed indefinitely requires only a small starting amount of the two
enzymes and a steady supply of the subunits.
Notice that none of this requires any "why."
(continued in next post)