Sci-Ed Fact: The
book of life is very rich; a typical chromosomal DNA molecule
in a human being is composed of about five billion pairs of nucleotides.
The genetic instructions of all other life on Earth are written
in the same language with the same code book. -This shared genetic
language is one line of evidence that all the organisms on Earth
are descended from a single ancestor, a single instance of the
origin of life some four billion years ago. (Carl Sagan) |