Origin of Life
For many years scientist have puzzled over how organisms on earth came to be. Paleontologist, or scientist who study fossils, can find out much about how life started and the appearance of organisms in ancient life. The information that paleontologists use to classify their findings is know as the fossil record. The fossil record shows the change of organisms over time and history of life on earth.

Geologic evidence found by paeontologists show that earth is approximately 4.6 billion years old. They believe pieces of cosmic debris were attracted to each other over the course of about 100 million years. According to the theory the planet was struck by large planet sized objects that caused enough heat to melt the globe. When the elements rearraged, they did so according to density. The most dense particles formed the earth's core, while the somewhat dense particles floated to the top to form the outer layers of earth.
Scientist believe that early earth's atmosphere was much different from the way it is now. They believe that the early atmoshpere consisted of; hydrogen, cyanide, carbon dioxide, carbon monoxide, nitrogen, hydrogen, sulfide, and water. This would have made an environment that is not suitable for humans.

Geological evidence suggest that 200-300 million years after earth cooled enough to carry water in the liquid form, cells that resemble modern bacteria formed. Another new formation in early earth was microspheres. Microspheres were organisms with selectively permeable membranes that can allow water molecules to pass through them. Evidence suggest that these microspheres might have gained the characteristics of living cells over time.

Another question that has puzzled scientist is the evolution of DNA and RNA. One hypothesis scientist have come up with is: an abiotic stew of matter formed simple organic molecules. In time, RNA nucleotided formed from the simple organic matter. The RNA was able to replicate itself, synthesize protein, and funtion in information storage. From that the Proteins build cell stuctures and catalyze chemical reactions. The RNA helps in protein synthesis and finally, the DNA funtions in information storage and retrieval.

external image 61px-Dna-split.pngImage shows DNA splitting. How did RNA play a role in the orgin of life? How did RNA play a role in the orgin of DNA?