Ok! How many cells before we have a human? You make the call!
1,2,4,8,16,32,64,128,256,512,1024,2048......2^x-power?
All the instructions are in the first cell.
I heard a French cellular biologist on the radio one time. I can't recall his name. He was an atheist but believed that life began at conception. He told the interviewer that cells in an embryo don't go 1-2-4-8-16-... but 1-2-3-4-8-16... He could not explain why the 3, but it is always there.
He then went on to explain that if he caught the embryo (zygote?) at only two cells, he could remove one cell, replace it with a cell from another embryo, and the two cells would continue to grow as one organism. However, once the embryo had achieved the three cell stage this was no longer possible. The embryo would die if he removed one of the three cells and replaced it with a cell from another embryo.
From that he concluded that the embryo was a living being from the 3 cell stage.
Shalom.