Humans (Homo sapiens) are a species of upright apes that first began to split off from other primates around 2.8 million years ago. That's a long time on a human timescale; on a geological scale, it’s not very long at all. Humans aren’t rocks, though, so all we really have is our own time scale. We are unique among the animals, we think. A lot of people have a lot of opinions on what makes the difference. Intelligence. Curiosity. Organisation. They’re all compelling arguments. I’ve just never quite been convinced by them. An animal is an animal; no matter its details, it will always be most significantly informed by being a creature, with a body and evolutionary traits.

Homo sapiens are not the only human animal. Human, homo, is a genus, not a species, albeit a genus of which we are the only surviving member. We’re a monotypic taxon: we have no extant cousins from the same branch as us. You have to go further back to find our fellows—apes and monkeys. Other monotypic taxons are platypuses, narwhals, dugongs and aye-ayes. There’s no word yet on whether any of those think of themselves as the main character of the universe. Maybe all animals do.

A quick note here: I’m going to be using “human” to describe Homo sapiens, terminology that is controversial among paleoanthropologists. Many consider Neanderthals (neanderthalensis), and some other Homo species, to also be varying species of humans under the prescribed definitions. I agree; however, this is a fun little blog post that I’m writing, and for the sake of readability, Homo sapiens are humans, and Neanderthals are Neanderthals. I also already wrote a bunch of it before realising this problem. Sorry, okay? I’m so fucking sorry.

Evolution happens unbelievably slowly. Mammals emerged about 220 million years ago. It took another 150 million years for primates to fumble their way into existence. 40 million years after that, the Hominidae family finally shows up. When did humans become humans, you ask? I have no clue. We diverged from chimps about 15 million years ago. The Homonini sub-family first figured out tools about 2.5 million years ago. These innovators weren’t Homo sapiens, but Australopithecus garhi, probably somewhere around modern-day Ethiopia. The Homo genus hadn’t yet evolved. I have a passionate but recreational interest in evolution, and my lack of formal training is really on show as I try to sift through the map of early human evolution. It’s complicated and messy, and really we don’t know enough to draw clear lines between species. Australopithecus were bipedal, something we consider very significant to human evolution; but they also had notably small brains, disrupting another element we consider crucial. Evolution is not an arrow.

To call the Neanderthal an animal feels strange, even though I hold no issues with calling humans animals. In a way, it feels impossible that Neanderthals ever really existed on an ecological level. Humans are used to being distinct as a species. Even among our fellow primates we are unique. Neanderthals blur that line more than even chimps and gorillas. They were so like us that the reality never quite settles.

We’d prefer for human evolution to be simple. We want a grand moment of difference, when the human species tore itself from the confines of nature and became what we now know ourselves to be. Evolution isn’t a matter of grand moments, though. Humans developed in fits and starts, growing and regressing over and over before the sapiens even emerged. We don’t even have a name for the first known species in the Homo genus. We just call them LD 350-1. It’s impossible to know when upright apes began complex conversations. I wish, desperately, I could tell you what LD 350-1 called themselves. If they called themselves anything at all. We’ll never know. All we can know is that over a very long time, a category of upright ape emerged with brains that became gradually larger. And slowly, evolutionary pressures culled the number of distinct species.

And then there were two.

Not really, actually. Unfortunately, evolution doesn’t neatly fit into the narrative of an essay either. There’s good evidence that other Homo species lasted longer than Neanderthals. Homo floresiensis lived in Indonesia until 50,000 years ago. Neanderthals died out around 40,000 years ago. We didn't get that much time alone together.

I don't know what the relationship between humans and Neanderthals was like. No one will ever know. Thousands of years ago, it was already lost. All we have is our imaginations, and how you imagine that relationship will inevitably tell us something about how you think about humanity. If the put the entire human species into one body and left it in a room with a Neanderthal and a gun, what would it do?

We don’t know why exactly Neanderthals went extinct. There’s a tendency to centre humans in theories, which is not necessarily here, but still worth considering. We crave narrative in our own history, including triumph; or, depending on your perspective, horrific violence. It seems likely that humans did contribute significantly to the extinction of Neanderthals, but not actively. We didn’t all suddenly cooperate to become the dominant primate species on the planet. It would have been much more passive, more coincidental. Humans happened to be better adapted to our shared environment. So much of evolution is about luck. That’s what “survival of the fittest” means. No matter which genomes we sequence now, we can’t erase from our history how much coincidence was necessary for humans to have outlived our cousins. We want the triumph. We want a cohesive narrative in which we have existential agency. The way we think about Neanderthals is invariably coloured by hindsight: the knowledge that we lived and they did not. We can only ever tell this story in reverse.

A significant factor was probably sheer population size. There were far more humans than Neanderthals. Recent estimates put the effective population of Neanderthals at around 10,000 individuals, compared to (the difficult quantity to estimate of) around 50,000 for humans at approximately the same time. The most recent census data from Sydney’s inner west puts the population at 182,000 people. Numbers can play a game in evolution, especially between competing species. I don’t mean that humans and Neanderthals were individually in competition with one another; rather, we filled the same ecological niche, and in close quarters only one species tends to survive.

I suppose I can’t talk about other people's projections onto Neanderthals without revealing my own. I don’t think the human species can be generalised into a single set of behaviours, and I know very little about the behaviours of the Neanderthal. I imagine we were suspicious of one another, and that we went to war, and we did the worst things imaginable to one another, because of our differences. We also sat by the same fire that we harnessed together, and we were moved by the company. I think there were times when the line between species was unclear and unnecessary; and that sometimes the line was very, very present. In 2010, genomic sequencing confirmed that humans interbred with Neanderthals with some frequency. Any love you could possibly experience existed between a human and a Neanderthal at some point. The same is true for any kind of cruelty. All I can do is speak in hypotheticals. I don’t know. That’s the whole point.

I don’t know why we survived and they didn’t. It’s ultimately arbitrary, isn’t it? Ecological niches aren’t exactly roomy. When push comes to shove in evolution, someone has to go eventually. Like so many species it was a slow decline. The only reason we’re so interested in the why of this one is comparison. It needs justifying. What makes humans so special? If we’re the fittest and the best and at the very top of the food chain, then why do we do what we do? That’s not what Darwin meant by “fittest,” anyway. It's adaptation, not virtue.

We want to find meaning in our species’ survival. And you can if you like. God knows it’s hard enough to get up in the morning, we all need something. For me, the arbitrary nature is the meaning. It could have been anyone, but it’s us, all here together. We have all, against the odds, tumbled through time and space to stand here on our little blue home at the same time. So much of survival is luck.

When I write about animals, I invariably end up writing about humans. This makes sense: everything we know about animals is about animals as observed by humans and in relation to our own behaviours. Every species has a distinct lens with which it views the world. That humans’ lens is seemingly impossibly advanced doesn't speak to omniscience, but the skill of abstraction. We are still just one species in over a million. All ecology is comparative ecology.

For many people, this causes an existential spiral. Humans do not want to be animals. To me, though, that we can only ever observe through the prism of our own ecological context is an immense comfort. What a burden it would be to know everything, to have the one perspective that contains absolutely everything under the sun! What a horrific responsibility that would be. Yet it’s a responsibility many seem to crave. The more desperate and less intelligent have convinced themselves that there might be a new species in the machine, that the rocks we jolt with electric shocks until they move ones and zeros back and forth are in some way alive. Ontological arrogance is another common trait of the human animal. We’ve achieved a lot, but we can’t make rocks come alive. That stuff is best left to experts like snails.

There’s a lot we’ll never know about Neanderthals, which means that there’s a whole lot we’ll never know about ourselves. Regardless of the cause, something was lost to us forever when Neanderthals disappeared. We catch glimpses of it in the great apes. It’s lonely to be the only survivor in a genus. Monotypic organisms aren’t the ultimate goal of evolution; if anything, it puts the genus at greater risk. We’re the only ones left. That doesn’t necessarily mean that we’re superior. All it means is that we survived. That’s just how nature goes sometimes.

The most extraordinary thing is that we know about them at all. A dove in a park doesn’t know about passenger pigeons.  A quoll has never heard of a thylacine. But we know about Neanderthals, and because we know, we care. We care enough to want to resurrect them, and we misunderstand them enough to try. What would happen to a Neanderthal clone awakening to find their entire sister species staring at them with bated breath?

Maybe they’d like it. Maybe all Neanderthals spent their lives dreaming of being on stage. I couldn’t tell you. I’m just a human.