For about how many years of geological time have humans existed on earth?

I think that it is 4.5 million years. It does not end there though because other people would just say it and go. The reason we know this is because there is some people who lose teeth in those areas when mankind started then they took it to a lab and they found their results after continuous testing.

What is the difference between cytokinesis in plant and animal cells? animal cells dived by a cleavage furrow. plant cells divide by a cell plate that eventually becomes the cell wall. cytoplasm and cell membranes are necessary for cytokinesis in both plant and animals.