Every cell in our bodies contains the evidence of our evolutionary origins.  The basic process of life on Earth is so common that we share about 50% of our genes with carrots, and about 99% of our genes with chimpanzees (but, that's a difference of 15 million to 30 million genes and gene switches).  In fact, humans are genetically closer to chimps than mice are to rats.  Here are some useful biological facts:

• We get an exact copy of the mitochondria in each cell from our mother, almost every time.
• Every male gets an exact copy of his Y chromosome from his father, almost every time.
• Both mitochondria and Y chromosomes slowly mutate over time at known rates.

With this knowledge, geneticists can estimate how recently any two of us shared a common female ancestor, or any two males shared a common male ancestor.  Using this information and other data, the evidence strongly points to the claim that most or all of us are descended from a group of Africans that started migrating about 100,000 years ago.

We share about 99% of our genes with chimps, but we have 23 pairs of chromosomes while chimps and other great apes have 24.  A close examination of the chromosomes shows that one pair of our chromosomes is made of two from the other primates.  Our combined chromosome even shows the evidence of where the two chromosomes joined, with the ends of the old chromosomes in the middle of the joined chromosome.  For more, see Evidence of Common Descent between Man and Other Primates.

Most animals have the capability to synthesize vitamin C, but in humans and other primates the gene for this is broken and doesn't function.  The differences in the DNA sequences for this broken gene (called a pseudogene) correlate to the genetic drift that is predicted by evolutionary theory, with chimpanzees being the most similar to humans — followed by orangutans and macaques.