We Dogs have been man's best friend for quite a while. It may have been as long as 100,000 years. By comparing these cells in dogs today and similar cells in Wolves we can estimate the approximate time wolves joined people by the fireside. But dog breeds as you know them today are really only very recent. Ever wondered why old pictures of dogs don't quite look like dogs do today, well its not that they couldn't draw a hundred years ago.
Genes are the chemical instruction codes that are inside every cell.