The myosin in our own skeletal muscles is more closely related to the myosin driving the flight muscles of that irritating housefly buzzing around your head than it is to the myosin in the muscles of your own sphincters
Evolution, Biology
It seems that all eukaryotic cells either have, or once had (and then lost) mitochondria. In other words, possession of mitochondria is a sine qua non of the eukaryotic condition
Biology