At the top of the list are I and we , which apparently date back tens of thousands of years. I don’t know about the way the researchers came to their conclusioncomputer analysis of “the rate of change of words in English and the languages that share a common heritage”but, humans being communal creatures, I and we seems to make a lot of sense.
The scientists argue that one , two , three , and five are only slightly older. Maybe we had to first figure out how many I s and We s there actually were.