I am fascinated by the evolution of language but had never given much thought to punctuation. If I gave it any consideration at all, I tended to think of punctuation marks such as the period, the comma, and the apostrophe as somehow having been there from the beginning of writing, appearing somewhat organically along with writing. But according to Florence Hazrat at the University of Sheffield, the origin of punctuation marks can be dated quite precisely.

In the broad sense, punctuation is any glyph or sign in a text that isn’t an alphabet letter. This includes spaces, whose inclusion wasn’t always a given: in classical times stone inscriptions as well as handwritten texts WOULDLOOKLIKETHIS – written on scrolls, potentially unrolling forever. Reasons for continuous script aren’t entirely clear, but might be connected to a conception of writing as record of speech rather than a practice in itself, and since we’re hardly aware of the minuscule pauses we make between words when speaking, it isn’t obvious to register something we do and perceive unconsciously with a designated sign that is a non-sign: blank space.

Writing without punctuation lasted for many hundreds of years, in spite of individual efforts such as those of Aristophanes, the librarian at Alexandria. Around 200 BCE, Aristophanes of Alexandria wished to ease pronunciation of Greek for foreigners by suggesting small circles at different levels of the line for pauses of different lengths, emphasising the rhythm of the sentence though not yet its grammatical shape.

It appears that muchof the punctuation we are familiar with actually owes its origins to one person, the 7th-century churchman and encyclopaedist Isidore of Seville.

Isidore invented the period, comma and colon. He rethought Aristophanes’ punctuation, based on pauses when reading aloud, in terms of grammatical parts of the sentence: an utterance whose sense and grammar were complete would receive a dot at the top of the line, which would eventually migrate down to the bottom and become the full stop or period we know today. An utterance whose sense and grammar were complete but accommodated expansion would get a dot in the centre: the future colon. Lastly, an utterance that was neither complete in sense nor in grammar would be marked off with a dot at the bottom, evolving into the comma. Where previously only the full sentence received a boundary sign, it was now also possible to distinguish the constituents within. Isidore’s ideas circulated widely and, by the end of the same century, Irish monks had added spaces between words to his system of dots. These changes attest to a shift in the perception of writing from record of speech to record of information. Meaning no longer needed to pass from eye to mind via voice and ear, but was directly – silently – apprehended.
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By the late Middle Ages, the comma, the colon and the full stop had established themselves. The exclamation and the question mark joined their ranks, attesting to a need for emotional emphasis and clarification of intonation. What is perfectly clear in speech can become doubtful in its written form, in spite of question words and interrogative grammatical constructions.
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Writers from the end of the 17th century onwards had various marks at their disposal, including question and exclamation marks, brackets and semicolons for pausing and adding, dashes for interruptions and unfinished business, and dot dot dots to signal hesitation or uncertainty, not to speak of hyphens, commas, asterisks, ampersands, footnotes, the humble full stop and space, and countless other marks of punctuation and typographical signs. None of these enjoyed hard-and-fast rules, and all of them were still in the making. Writing had come to touch all areas of private and public life, and with that came a desire to represent through inky marks the vagaries of the mind, the inflections of the voice, and the intensity of feeling.

Not all proposals for punctuation marks caught on.

Frustrated by the misunderstandings arising from a failure to catch tone in writing, the English printer Henry Denham invented a mark denoting sarcasm. Denham offered his sign in 1575. A mirrored question mark, he hoped, would flag up a rhetorical question, making it easier to get the drift of the writer’s intention. But it never caught on.

The article has all manner of additional interesting little details from the history of punctuation.

Of course, we now live in an age when to convey nuance (or to hit people over the head with obviousness) we use the # symbol followed by a word (“#sarcasm’ etc.) and also have a bewilderingly large array of emoticons. They are not universally adopted. I, for one, never use emoticons. This is partly because I think words can more accurately capture my meaning and partly because I am apprehensive that I may accidentally send the wrong emoji, such as replying with a thumbs up or happy face when someone gives me tragic news.

I also never use popular common abbreviations like lol and ttyl even in text messages, and always punctuate any message if they are more than a few words long. I still feel spasms of discomfort to send a text without a salutation such as ‘Hi [name]’ or not end with my name, although that reveals me to be a a weirdo in the text world. I find it easier to carry out my preferences by using my computer with its full keyboard to compose and send text messages, since I find typing on the phone keyboard awkward. I will also sometimes write out longer messages on a word processor, paragraphs and all, so that I can edit them easily, before cutting and pasting it into the text box. What can I say? I am definitely old school.