“The first time ever I saw your face,” crooned Roberta Flack, “I thought the sun rose in your eyes and the moon and the stars were the gifts you gave.”

That was in 1969 when a face was still the preserve of poets, photographers and portrait artists. Back in the 20th century, faces were keenly interpreted through the arts of their time, with the precious reputations of those studied often entirely dependent on the outcome.

Today our reputations are mediated through new technology. Our fingerprints, gestures, voice and gait can be monitored and analysed by cameras and sensors, often resulting in computers making judgments about who we are, how we are and what we might do next.

Of all the biometric data sources that feed these machines, the face is still the most precious. A face tells a story. It conveys information, publicly communicating so much personal data that faces are indeed the most valuable resource for any technology company wanting to understand not only who somebody is, but what they might be thinking or feeling at any given time.

For many years technologists had tried to crack this code. Around the time of Roberta Flack’s hit song, the CIA were funding an engineer using early computers in California to attempt facial recognition. Success did not come until the general public helped enormously by plastering their own faces, and those of others, all over the internet.

Then a company called Clearview AI wanted to make money out of facial data, so it set out to scrape the internet for billions of images of faces without people’s consent. Clearview now has 30 billion faces stored in its database, thought to be used by the police in the United States to conduct nearly one million face searches.

The story of Clearview is told in Your Face Belongs To Us, a new book by the New York Times technology reporter, Kashmir Hill. She investigates the company as they try to build their idea of “Google for faces”, scraping public photos from the internet and making them easier to search through and find.

The question that occurs to me about companies exploiting our facial images like this is, haven’t we only got ourselves to blame?

If only we were a bit more circumspect about posting selfies online, or tagging in all our friends on social media posts, this would be much harder for them to achieve. We have to start thinking of our face as the most precious of all our biometrics. In the same way we wouldn’t put up with companies taking our fingerprints or scanning our iris every five minutes, we should not assume it is okay to automatically give away the image of our face.

Will facial recognition technology be more or less judgemental?

It’s a quaint twist that the human face is an expression of both personal feelings as well as public information. In speaking with Greg Rowland, one of the UK’s foremost semioticians, he expressed the deep abiding fixation with faces: “It is demonstrated by our desire to see them everywhere and anywhere, perhaps in a simple circle of dots for eyes, in the expressions we ascribe to car grills, or onto abstract patterns of all kinds. If paranoia is the tendency to coral disparate signifiers towards a singular signified then facial recognition is the paranoia that we all, quite happily, share.”

There is no denying the power of the face. With power comes responsibility, and there are already examples of our faces getting caught up in the most absurd of circumstances. In China police are using it to identify those wearing pyjamas in public and to prevent people from stealing. Hill told me about a public restroom in Beijing requiring you to look at the facial recognition camera to trigger the deployment of the toilet paper. We have our own absurdities in the UK, most notably when North Ayrshire Council used facial recognition cameras to identify which school children in the canteen queue were entitled to free school meals.

The question now arises, will facial recognition technology be more or less judgemental about our faces? On the one hand, artificial intelligence and algorithms could be said to be more objective. If beauty is in the eye of the beholder, perhaps machine readability will be kinder to those of us not hitherto categorised as classic beauties. Alternatively, as we give up our faces to technology companies, will a brand new form of discrimination emerge?

The cover of Hill’s book is made of shiny metallic material that, much like a mirror, reflects the reader’s face. Over the top lies the zig-zag design of multiple mapping points that trace the distance between both eyes, the nose and mouth, the shape of the cheekbones and the contour of the lips. If you raise your own face into the mirrored cover, you might see the grace and beauty of your own reflection staring back at you. Alternatively you may see beyond that, into the ugly future of facial recognition and the associated attributes of untrustworthiness, cruelty and bias.