Listed by the number of language families in which they have cognates. 
7 - thou
6 - I
5 - not, that, we, to give, who
4 - this, what, man/male, ye, old, mother, to hear, hand, fire ,to pull, black, to flow, bark, ashes, to spit, worm

Linguists identify 15,000-year-old ‘ultra-conserved words.' To hear the words, click here.