That would be a perfectly reasonable answer if we agreed on what a heartbeat was, and when it starts. So far, you have refused to directly define what you consider to be a heartbeat. Do you consider a few fluctuating cells to be a heartbeat, or does it also require a developed heart with muscle, and valves, and all the other parts that most consider to be the heart? You are certainly free to weasel out of answering that question. but I have no desire to continue the discusson until you do. Goodby.A heart starts beating when there's a heart to beat. I don't know why you think that's some kind of gotcha question because it's what I've been saying all this time. Haven't you been paying attention?