WE'RE not alone. In April, scientists searching in the Philippines found something more romantic and tangible than a quantum wrinkle in the gravitational time-soup, or whatever they're searching for in the far reaches of space at the moment.

They found the bones of a previously unknown human species.

Homo luzonensis, named for the island of Luzon where they were found, lived about 50,000 years ago. According to the BBC, their physical features would have been "a mixture of those found in very ancient human ancestors, and in more recent people." Think Prince Philip crossed with Ariana Grande.

That Homo sapiens was just one of many human species will, of course, not be news to most. Anyone who read Yuval Noah Harari's brilliant, blockbusting and perspective-changing book 'Sapiens' will be aware that once upon a time there were quite a few human species hanging about, living out our lives, counting down the millennia until Playstation 4s were invented.

Before reading it myself, I was vaguely aware of some of the others. Homo neanderthalensis, primarily, Homo erectus and Homo denisova. But Harari's brief and accessible (to simpletons like me) account of the history of human life was a revelation, and, to be honest, has since assumed the significance of a near-religious text in my (atheistic and heathenous) thinking.

As origin stories go, I find it mysterious and exciting. One human species for example, Homo floresiensis, was a diminutive sort, just three-and-a-half feet tall, who lived in what is now Indonesia. Harari explained they would have hunted elephants; a feat less impressive when he admits the elephants would also have grown to a miniature, island-stunted scale.

And Harari even managed to make the lives of hunter-gatherers - before agriculture came along 12,000 years ago - sound pretty great in many respects. They only did around 20 hours of what might be termed ‘work’ a week, for example, leaving plenty of time to sit around, learn an instrument or train for a marathon.

Thinking about the other ancient human species - many of which Homo sapiens may have killed or bred out of existence - prompted me to think: how would we modern and sophisticated sapiens treat another human species if they were alive now?

And surely the unhappy answer is that it is doubtful they would be considered 'persons', and more likely that they would be persecuted or exploited as a resource. You just have to look at how we treat other sapiens, never mind the way we are wiping out non-human species, from the tiniest invertebrates to our nearest relatives, Ponginae - the orang utans.

Without delving into the subject of animal rights, and the many valiant battles that have been fought in recent decades in an attempt to accord basic legal rights to species like chimpanzees, it would be fair to say that even modern western society's most ambitious definitions of 'equality' extend only as far as Homo sapiens.

We are steadfastly sapien-centric. Our laws (which of course, as Harari points out, only exist in our collective imagination anyway) are built around sapiens and their property. We fret about petty nonsense and obsess over our own, tedious, self-defined subdivisions – never mind that these divisions pale into insignificance against our daily eradication of other species' natural habitat, extermination of their populations, and the psychological harm inherent in, say, highly-intensive animal farming systems (a key part of the sapiens story).

Since the days when we shared the planet with the likes of Homo luzonensis, Homo floresiensis and the rest, sapiens have become extraordinarily successful and mind-bogglingly numerous. The dark, ancient forests of the planet where once we may have heard the echoing calls of our ancestors are now more likely to ring to the sound of chainsaws. We’ve brought a large number of animals to extinction, from woolly mammoths and sabre-toothed tigers to the dodo – and there’s much more to come in that regard. And all this in a mere 200,000 years. The blink of an eye.

It makes you wonder about the next 200,000 though. Perhaps one day some as-yet-unevolved species will dig up the bones of Homo sapiens, dotted among the thick strata of iron which will encircle the Earth, and wonder why, on a planet so bountiful, with a climate so conducive to life, we were all but alone on it at the end.