Chicken Bone

A very quick google found this online developmental biology textbook.You might want to take a look at that text and try to refine your question, e.g. did you mean from birth or from conception?And as for your OP ... Why don't you dial back the snark and take a look at this.You'll notice that there are several fields of study: protein evolution, biochemistry, genetics, evolutionary biology, molecular biology. To answer your question, one would need more than a passing familiarity with each of these disciplines.It's no surprise that an encyclopedia couldn't answer all of your questions.Have you done any other research?Edited by molbiogirl, : typo and more info

The origin of the universe is off topic here. Please address that topic on the appropriate thread.Have you had a chance to read the forum guidelines? If not, I suggest you take the time to do so.Whomever it was you were quoting was simply saying that s/he couldn't fully answer the question. (Please try to become familiar with the dBcodes link ... they will allow you to use quote boxes. If you have any questions, the FAQ can help.)Why do you assume, after having looked at one encyclopedia, that the question can't be answered? Please refer to my prior post that I've recently edited to include a couple useful links.Edited by molbiogirl, : No reason given.