| Like particle cosmology,
biology
has a big bang with associated parts like quarks
and leptons.
Life on the earth
may have originated from a soup of natural organic molecules including
amino
acids. In one picture something happened and RNA formed. DNA evolved out of the RNA world .
Complex life arose out of DNA. This process is the Big Bang
part.
The linked action of DNA and RNA propagates the genetic code very well
and also generates the proteins needed for life. It is as though one
had a computer
code capable of producing central processors as needed. A word of caution is in order here. This is not your granddaddy’s biology. The tree of life at the start of our hundred years is only a small part of what is now recognized. New arrivals include the archaea with the halophiles, biota that flourish in salty environments, and thermophiles. |
? The origin
of life is not understood.
An interesting
place to read about this is de Duve’s 2002 book "Life
Evolving". De Duve argues that getting RNA by chance is
implausible. A complex
chemical environment is needed. Catalysts may or may not be required.
Clays
might help. Perhaps there is a natural selection for molecules. One
interesting
clue may be chirality,
handedness in molecules. The history of
the first
billion years on earth also should offer hints. For the first 0.1
Gyr there was
a hot
atmosphere of water, carbon dioxide, carbon monoxide, nitrogen and
oxygen. Then
the rain came and a rocky crust appeared in the 0.2 to 0.4 Gyr period.
Biologically processed carbon appeared at 1 Gyr generated from
self-replicating, carbon-based microbial life. This was anaerobic life
without
much free oxygen around. Then photosynthesis began to produce oxygen.
One point
is that life started relatively early! |