First of all - Researchers have synthesized ribonucleotides, the constituent components of RNA, for the first time in a laboratory. Here's a "ghetto" primer for the origin of life - goes something like this
- BIG BANG ==> QUARKS
- QUARKS ==> ATOMS
- ATOMS ==> MOLECULES
- COMETS WITH MOLECULES SMASH EARTH
- GOOEY PONDS ==> RIBONUCLEOTIDES
- RIBONUCLEOTIDES ==> RNA
- RNA ===> DNA
- DNA ===> SINGLE CELL WALL (w/DNA)
- SINGLE CELL WALL w/DNA ==> MULTICELLULAR
- MULTICELLULAR ===> ME
- ME ===> ???
GOOEY PONDS - RIBONUCLEOTIDES
Comets and meteors full of organic precursor molecules smashed the Early Earth for the first billion or so years of its existence. In some areas, these molecules accumulated into ponds and heated up, got rained on, evaporated, heated up, got rained on, evaporated..... you get the picture. After a while this "stew" of chemicals became more complex and turned into ribonucleotides. Also, a bunch of other molecules - precursors to proteins, such as amino acids and their precursors were all in the "stew" too.
Ribonucleotides have been shown to assemble into RNA. An "RNA world" is hypothesized to have existed in the early Earth. RNA are very crafty molecules that we currently use in each cell to take information from our DNA to our protein making factories in our cells. RNA probably catalyzed reactions and started error-prone replication at this point - a sort of primitive life - this is sometimes categorized as the RNA WORLD hypothesis
Chemically, DNA is very close to RNA with slight but significant structural differences. DNA coils around in a beautiful double helix structure (like a twisted rope ladder) whereas RNA is just a single strand - kinda like a spiral staircase. DNA is also a more stable chemical molecule compared to RNA. DNA mostly likely evolved from RNA - probably in a similar way that simple organic molecules turned into ribonucleic acids - via alternating cycles of heat, radiation, rain and evaporation.
The rest of the story is pretty straight forward (spotty in direct evidence but somewhat strong in circumstantial evidence & lab studies ) -- Somehow DNA found a way inside of a cell - or some type of primitive phosphate based lipid membrane -- which provided a protected and enclosed environment to create proteins from more primitive amino acids and to protect itself (DNA). These cells over time competed and only the strongest and most efficient replicaters and resource managers survived and dominated their local environment. Before you know it - a sexy mitochondria primitive cell decided to colocate within the same cell boundary - and VOILA - the perfect union - Energy, Replication, Information Storage -- Life.
GREAT, GREAT, GREAT GRANNY
Now, the second story is an impressive fossil find named Ida that shows a 47 million year old animal that seems to be the precursor to the current line of monkeys, apes and humans (if u believe in this Evolution stuff).
This fossil is way cool since it has very specific features known only to humans, monkeys or apes including opposable thumbs, 5-digits in hands & feet, small incisors along with canine teeth, etc.
Read more about this find in the original PLoS article publication.
Life is sexy, Natural Selection is sexy.
REFERENCES / LINKS
PLoS ARTICLE - Darwinius masillae
TIME MAG: Stanley Miller Experiment
WIRED SCIENCE: Life's First Spark Re-Created ...
ScienceDaily: IDA Discovery
REVEALING THE LINK: IDA Website