how we developed over time into this complex organism?
first, i'd like to thank you for this opportunity but there is something i don't understand about evolution. how we humans developed from a single cell organism in the ocean of the earth into this complex organism, i mean information had to be added to the DNA of the single-celled organism in the ocean of the earth for it to produce a more complex organism, right?
where did the information come from?or has it always been there but no expressed?
You're absolutely correct that information had to be added to the DNA of a single-celled organism. The DNA did not have that information to begin with. In fact, DNA grows in a very slow, but measurable way. Usually this is in the form of either (1) junk, harmless additional nucleotides, (2) deleterious, harmful additional nucleotides (which either kill the orgamism or render it unable to reproduce), (3) beneficial additional nucleotides, which (rarely) code for new, helpful traits, and (4) the wholesale duplication of genes or portions of DNA, usually through unplanned chemical processes.
Situations #3 and #4 are more rate than #1 and #2, but all four have been documented under laboratory settings and in nature. I even mention situation #4 on the FAQ here: http://www.evolutionfaq.com/faq/how-does-evolution-cause-increases-genetic-information-required-go-single-celled-life-complex-an
I should point out something very important: once the leap to multi-cellular life occurred, DNA did not need to make very many dramatic additions to create wildly different species we see today-- just changes in current genes. And changing a gene is must easier and faster than waiting for DNA to slowly grow in size.
To prove my point, we know that Earth only hosted single-celled life for 3 *billion* years, before it finally made the jump to multi-cellular life. All of the amazing biodiversity we see today-- plants, animals, etc, all occurred in only the last 500 million years.
As for the journey itself, I usually recommend people watch a short animation from the TV series Cosmos. It's a little cheesy, but it does an excellent job in summarizing the evolution of human beings from single-celled life: