There are 2 functions for cell surface markers. The first is to recognize the outside cell. The second is to allow the cell to bind to substances outside the cell.
Cell surface markers are proteins expressed on the surface of cells that often conveniently serve as markers of specific cell types. There are different types of cell surface markers. These markers are vital for the human body to function. These markers also vitally affect the functions of other biological systems of other organisms and creatures such as animals.
Maybe because food was here before the population even started to grow?♀️
The invention of the microscope allowed the first view of cells. English physicist and microscopist Robert Hooke (1635–1702) first described cells in 1665. He made thin slices of cork and likened the boxy partitions he observed to the cells (small rooms) in a monastery.