Tech watchers tell us that the earliest adopter of any innovation is invariably the porn industry. But the steadicam auteurs and their upholstered stars have failed to get much purchase on emojis. True, the blameless aubergine has been co-opted for purposes undreamed of even in Heston Blumenthal’s Frankenkitchen. I might be more unworldly than most, but it strikes me that few other emojis are likely to frighten the horses. 

Keith Houston’s history of emojis reveals that explicit images as well as political provocations, flagrant brand advertisements and other undesirables fall foul of something called the Unicode Consortium, a group of online elders that sets the standard for digital symbols. They are to online communications what the august Académie Française is to the French language: guardians of unimpeachable detachment, grave and discouraging of change. They have the last word on all pictographs, admitting a select few to the emoji lexicon and rejecting a great many more – including those that the porn barons yearn to see adopted.

Your own emoji habit might not extend beyond the occasional text message: a thumbs-up saves time and offers a verisimilitude of warmth. But anyone who’s ever caught a whiff of the teen spirit surrounding, say, the ‘drop’ of an exclusive trainer won’t need much persuading that the debut of an emoji is met with near hysteria in some quarters. There’s even something called ‘emoji day’, an annual event at which the priestly overseers of Unicode reveal which squiggles and blobs have made the grade. This fixture of the coding calendar is Christmas, New Year’s Eve and an Apple upgrade rolled into one. The big reveal happens before a tough crowd, or perhaps merely an overstimulated one. Fans still swoon with disbelief at the shocking solecism of sanctioning a cheeseburger emoji in which the sliver of Day-Glo orange representing the slice of cheese appeared beneath the toothsome patty.

We’ve been condensing information into pictorial form ever since the caveman left a note to himself to get more bison. Houston says the antecedents of emojis range from Egyptian hieroglyphics to the graphics at the Olympic Games that signpost events to competitors and fans of many tongues. But the emoji as we know it began to emerge at the turn of the millennium, in the unthinkable time before we all had mobile phones, when a Japanese pager operator introduced heart-shaped characters to jazz up its messages. These embryo emojis broke out of their home market and went global after Google took a shine to them, though not before an awkward culture clash over an anthropomorphic turd. The Japanese were very attached to it; the Silicon Valley bros, for all their chutzpah, were fastidious mummy’s boys who proved more squeamish.

Houston chronicles the awakening of emojis to questions of diversity. The original default skin tone, school custard – the pigmentation of the Simpsons and other natives of Springfield – was replaced by a broader palette. The characters representing people in occupations – mechanics and nurses, for example – have been tweaked to address gender issues. There has been fierce lobbying from the red-headed community.

I expected to learn about titchy pictures from Houston’s book, but it also taught me a surprising amount about words. ‘Face with tears of joy’, the name of a set of features as internationally recognisable as those of Taylor Swift, was solemnised as word of the year by the Oxford English Dictionary in 2015. ‘Rubricators’ were the scribes who added images to scrolls in antiquity; ‘manicules’ are motifs of disembodied hands pointing in one direction, a reinvention of the fingerposts still sometimes seen at crossroads.

The historians are all over emojis now. It’s hard to think of anything more artificial as a subject, so it’s waggish of Houston to bill his survey as a natural history. But this is also a kind of promise to the reader of a close study, and I’m not convinced that it has been entirely fulfilled. The author, who describes himself as ‘a moderately obsessive observer’ of emojis, is an affable companion and is diligent in running down academic studies and trade journal commentaries. But his survey might have been improved had he spent more time with flesh-and-blood characters as well as computer-generated ones and exhausted some shoe leather (sweat emoji, boot-with-toe-poking-out emoji). He might have sought out emoji enthusiasts in the wild, or at least their bedrooms, and joined them for the pant-wetting countdown to emoji day. It wouldn’t have hurt him to have blagged a ringside seat at the deliberations of the frowning Unicode Consortium. In emoji terms, it’s not a thumbs down from me for Face with Tears of Joy, but it’s the sign of one hand clapping.