Origins
The word 'me' — the first-person singular oblique pronoun — is a strong candidate for the most ancient recognizable word in continuous use in the English language. It descends from Old English 'me' (me, to me, for me), from Proto-Germanic *miz, from PIE *h₁me- (me), the oblique (non-nominative) form of the first-person singular pronoun.
The reflexes across the Indo-European family are remarkably uniform: Latin 'me' (me, accusative), Greek 'me' (με, me), Sanskrit 'ma' (me), Old Irish 'me' (me), Lithuanian 'mane' (me, accusative), Old Church Slavonic 'me' (me), Persian 'man' (I/me), Armenian 'mez' (us), Tocharian 'mi' (me). The consistency is striking — this single syllable has remained recognizable across every major branch of the family for over six thousand years.
The reason for this stability is the same as for 'we': extreme frequency, early acquisition, and semantic irreplaceability. Children acquire first-person reference earlier than any other pronoun function, and they hear and produce 'me' thousands of times daily. There is no metaphor, circumlocution, or synonym that can replace the concept of self-reference. These factors create enormous conservative pressure that protects the word from sound change, semantic drift, and lexical replacement.
Proto-Indo-European Roots
The relationship between 'me' (oblique) and 'I' (nominative) is suppletive — the two forms come from different PIE roots. 'I' comes from PIE *h₁eg (I), while 'me' comes from *h₁me- (me). This suppletive pattern is inherited from PIE itself and is maintained across the family: Latin 'ego' vs. 'me,' Greek 'ego' vs. 'me,' Sanskrit 'aham' vs. 'ma.' The nominative and oblique forms of the first person have been etymologically distinct for as long as we can reconstruct.
In Modern English, 'me' has expanded beyond its historical oblique role. In informal speech, 'me' is increasingly used as a subject pronoun ('Me and John went to the store'), a development that alarms prescriptivists but follows a natural tendency: since 'me' is the more frequent form (the object case is used more often than the subject case in running speech), it tends to generalize. The construction 'It is me' (rather than formal 'It is I') has been standard in spoken English for centuries and was already established by Shakespeare's time.
The possessive forms 'my' and 'mine' derive from the genitive of the same pronoun: Old English 'min' (my, mine), from Proto-Germanic *minaz, from PIE *h₁mene- (of me). 'My' is the unstressed form (used before nouns: 'my book') and 'mine' the stressed form (used predicatively: 'it is mine'), a stress-based split parallel to 'of/off' and 'to/too.'