The John the Baptist hypothesis, they had eventually called it, following discussions going on across Earth and transmitted out to them.

  Zaimu went on, ‘Remember, I was with Salma when we found her. Salma and I, down on Nine. And I thought we could recognise her emotions at least, pretty clearly, with or without signs, language, even her songs. Right from the beginning. She was scared. Bewildered. Whatever. It was obvious. But when we brought her back to the Shadow and took care of her – OK, especially Salma – she opened up. Her body language stopped being so defensive – and then the songs. She was always being social, or trying to be, is what I think of that. Not delivering some awful warning encoded in her genome. Or whatever.’

  Salma grinned. ‘She’s done even better since we learned to whistle song fragments back. We are lousy at it, but we keep trying. Yes, that’s my theory too. Her songs are all about being social. Not awful warnings, or sermons. That’s all. Isn’t that enough?’

  ‘Hell, no, kid,’ Boyd said gruffly. ‘Because why the hell, in that case, has she been thrust through some kind of portal from another universe to here? Just to say “hi”? I mean, what we thought was a black hole unfolded – a black hole – and there she was. The whole set-up needed intelligent, technological parties – like us, but more powerful – to make it work. But out came – this. Why would you do that, why send her, if we were not to take away some kind of meaning – some kind of data, a complex message? That’s what I’ve always believed. She must have some kind of message from ET somewhere, even if it’s encoded in her DNA or her neurones—’

  ‘She doesn’t have DNA,’ Meriel said, ‘not quite, and not quite analogous structures to neurones.’

  ‘Yeah, yeah. But all I’m saying is that I still believe some day she’s going to open up and deliver The True Message. Hell, I don’t know. Maybe she’ll just sing it. Or fart it out.’

  Zaimu leaned forward again, Salma saw, grabbing the initiative. ‘Whereas I don’t believe she has a “message” of that kind at all. As I keep saying, I was there from the beginning, with Salma.’ He glanced around. ‘None of you lot were there, at that moment. Everything you got was second-hand, our reports at the time, verbal and images, all before you got to see the reality. Everything was – filtered – for you, by our first reaction to her, and by her first reaction to us, I suppose. She had already adapted. And so our experience of that moment of first contact was the most authentic it could possibly be.’

  Boyd snorted. ‘OK, wise guy. How jealous I am. So before you write your autobiography, what did you take away from that precious, unrepeatable first contact?’

  ‘That I don’t think she has a message,’ Zaimu said. ‘As I just said. Not as you mean. Her songs are just – social, I think. And no, I don’t believe there’s anything clever like inscriptions in her DNA. Nothing so literal.’

  ‘Then what’s the point? Where’s the message? If there’s no – signal—’

  Zaimu shook his head. ‘I believe her presence is the message. Her very existence. Her nature. Here, in our universe – separated from whatever lies on the other side of Planet Nine, if it really is a portal from someplace else. All we have to do is figure out what that means.’ He glanced at Hild. ‘And, Captain, I remember saying you something like that on the very day we found her. That the very fact that she looks quasi-human is itself a message.’

  Hild smiled. ‘Thanks for that. But we never followed up that thought, did we?’ She stood up. ‘OK. Well, we’ve had the years we’ve been stuck here to figure it out – or at least to observe. Maybe we can beat up that idea a little more for a while?’

  Meriel snorted. ‘And before the Cronus and its boatload of eggheads shows up to tell us we got it all wrong.’

  ‘You got it. Five minutes. Bathroom breaks only. I’m looking at you, Boyd. Then, back here and we push it until it cracks, or we do.’

  When they got back, Meriel, a little grumpily Salma thought, grabbed the floor, and started to summarise key points of Feathers’ anatomy.

  ‘If there’s anything in the notion that Feather is the message, well, let’s look at her. Salma, maybe you could help keep her calm and happy in the meantime …’

  After the first discovery, it had taken a while for Salma to persuade Meriel that she shouldn’t use Feathers as a specimen: no pointing or jabbing or handling. Feathers was always visibly unhappy to be the centre of that kind of attention. Maybe some kind of prey reflex, they had speculated. All those predatory human eyes fixed on her, human claws grasping.

  So, as Meriel spoke, Salma was careful to make eye contact with Feathers, to smile, to stroke her back, downwards the way the feathers fell – a gesture she had relished from the start.

  ‘As you all know,’ Meriel went on, ‘she’s essentially, well, bird-like in many ways. There’s the basic body structure, more or less like ours – the skeleton, the soft tissues, the outer skin – with, in her case, feathers. She has a lightweight skull and skeleton – and light bones generally are typical of birds. Strong but not massive, full of struts and cavities – evolved for flight. This is even though Feathers herself is flightless, her wings having evidently devolved back into arms, or hands.’

  Zaimu put in, ‘So, if you think about that, she’s the product of a lot of evolutionary change, of time. To grow wings and then lose them. She comes from an old biosphere – older than ours, perhaps.’

  Meriel nodded grudgingly. ‘Good point. Back to her anatomy.

  ‘She’s strong, especially her upper body, with big muscles evidently evolved for flight anchored to her breastbone. Her arms are winglike still, especially when she spreads them – you can see the feathers, rooted in what must have been an aerodynamically efficient way, once. By now the flight feathers, and others, have evidently evolved into a kind of down – but still tough, resilient. As Joe suggested, they serve as a decent radiation shield for parts of the body. And there’s very complex chemistry in there, the feathers’ layers. I’m still trying to determine if she actually photosynthesises … I mean, if her outer skin and feathers are full of something like chlorophyll, that can take energy direct from sunlight.’

  Boyd looked sceptical, but intrigued. ‘A photosynthesising animal. In terms of exploiting the sunlight energy, a very efficient arrangement, if you cut out the middle man – or the middle vegetation. Even if it means a lot of sunbathing. I could get used to that.’

  Zaimu went on, ‘And look at her frame. She’s very muscular, and very smart, with a brain as large as ours – in fact, more convoluted, more structured. Oxygen breather, of course, with big lungs behind that breast bone, and a big brain to support … Her heart – or the analogue, it’s a series of pumps rather than just one, like ours – circulates blood very efficiently, and that bloodstream is also more efficient at carrying oxygen than ours is, into the bargain.’

  Hild said, ‘All good points. But what about the real basics, though? The four limbs. What can we infer from that? I mean, on Earth the basic tetrapodal body plan goes back to the first ancestral amphibian that crawled out of the ocean onto dry land, doesn’t it? Four limbs, a head. And out of that came the dinosaurs, the birds, the mammals … What if those common ancestors had had six legs, or eight? Or two? Did it have to be four? Why should Feathers be like us in that way, two legs to stand on, manipulator arms, a head—’

  Meriel shrugged. ‘Maybe the upright four-limbed design is optimal for intelligence in some way. Two manipulator arms, two legs to run away, and to stand you up tall so you can see far with the optical gear in your head. Maybe you don’t need more limbs than four.’

  Boyd snorted. ‘You’re trying to say the human body plan is inevitable if you want smartness? Tell that to the octopuses.’

  Hild nodded. ‘OK. Keep speculating, keep picking holes. We’re trying to figure out why this being, with this body design, has been – presented – to us. Maybe nothing about our evolution was necessary, even if it had to deliver smart tool-making creatures. There’s something about her anatomy, her deeper nature, that – well, maybe that is the message we’re supposed to get. Boyd made a good point. Why is she a bird and not an octopus?’

  Meriel nodded. ‘Good. So let’s follow that line.’

  ‘How could our evolution have been different?’ Meriel asked. ‘If we can map that out we might get some idea of how – unusual – it is that Feathers here is so like us. Even if not identical.

  ‘And we probably have to go back through the history of life on Earth to figure that.’ She sighed. ‘On which I’m the nearest to an expert, so I’ll keep talking.

  ‘You know that our genetic code is run on DNA, a big molecule which in turn is assembled from a set of amino acids.

  ‘And as you know, Feathers’ biochemistry is also built on amino acids, but a different set. There are a lot of aminos to choose from, but presumably only some large but finite group of those sets that will work to support life. But we do know of lots of theoretically possible variants on our own system – stuff that could potentially support some form of life. The biochemists call it “protein space”, I believe.

  ‘Anyhow, if you want to base natural evolution in some environment on any selection of those complex carbon molecules, you have to have some kind of medium, like water, and some process, to deliver those big molecules into a place where a genetic system could self-assemble.

  ‘Imagine the young Earth, still roiling from the big final bombardments as the planets formed. There would have been a murk of carbon and nitrogen chemistry delivered by comets and such – ammonia, carbon dioxide and water. And we know that amino acids – even RNA, the first replicator molecule – can form by chance, for example if a warm puddle, or even a mist, is hit by lightning strikes …

  ‘Then you have to have it all stirred up or forced into contact, maybe through being trapped on clay surfaces, or concentrated in a drying-out tidal pool. And then, presumably if you are lucky enough, all this concentrated sludge starts to self-assemble into structural units, proteins, alongside some kind of information-retaining structure like DNA, which is itself an assemblage of amino acids. The components of the machine and the blueprint.

  ‘And then, when you have a structure that is capable of self-replicating – even if slowly and clumsily in the beginning – you have the beginnings of life. Natural selection gets to work right from the off, as the marginally better replicators out-breed the lesser.

  ‘Nobody knows if this had to have happened at all. Was it inevitable? If so there could be life everywhere there’s a world even remotely like Earth: heat, carbon, water, nitrogen. This is still speculative, after centuries of study.

  ‘But surely, however life came about, you have to have some process like that, you see – mesobiosis, they call it, chemistry becoming life, life from lifelessness – or at least the components of life.

  ‘But,’ she said heavily, ‘it doesn’t seem to be the case that our specific kind of coding and reproduction system, our DNA design, is the only one that could prevail. Protein space, remember?

  ‘Look, you need around twenty amino acids to make a protein, and there are a hundred different proteins in nature – our nature. But there are a lot of different combinations of acids you could pick out, one by one, until you get to twenty – always supposing you have to stop at twenty.’ She thought that over. ‘I suppose in principle you could have a hundred to power twenty different protein designs – umm, that’s ten thousand trillion trillion trillion.’

  ‘A lot,’ said Boyd.

  ‘A lot. Of course they wouldn’t all be functional … Hmm … Just thinking that through. How many stars in our universe?’

  Zaimu checked. ‘A mere ten billion trillion.’

  Boyd snorted. ‘Wimpish. So there are more types of protein than there are individual stars in our universe, many orders of magnitude more. So there’s no need to imagine that every possible combination of twenty-fold protein sets has been tried out, anywhere in our universe – no need to imagine our particular set of proteins and aminos and DNA types is in any way optimal, the best. Our set has emerged from natural selection, so it does its job pretty well, but there must be many other designs that would work still better, out in chemistry-set space. And Feathers’ DNA? Or whatever she has?’

  Meriel shrugged. ‘Similar to ours, broadly. A subtly different corner of DNA space, and I haven’t figured it all out—’

  Boyd said, ‘Good job. You’ve got to leave something for the geniuses on the Cronus to work out.’

  The rest chuckled.

  Salma joined in, but didn’t really get the joke. Billions and trillions …

  She often felt more than a little out of her depth in fast, high-information conversations like this, even when the others made an effort to include her. Sometimes she was very aware of her lack of any kind of formal schooling, which she knew, because they told her, all the rest had had. Still, she could joke, join in their laughter.

  And Feathers stirred, hearing Salma’s voice, the chuckles, and made the soft clucking sound that Salma had come to associate with pleasure. Salma grinned and rubbed her back.

  Boyd leaned forward now, took more coffee.

  ‘Maybe we’re looking at this the wrong way up. It’s easy to concentrate on the differences. So she has a different genetic-chemistry makeup. So what? Maybe that doesn’t matter so much. In what ways is Feathers like us?’

  Meriel shrugged. ‘OK, another good question. Well, she’s an evidently intelligent creature, who has evidently emerged from an evolutionary process. Natural selection, like ours in some way.

  ‘To evolve at all, you have to have some equivalent of DNA, a record that defines how to build another little Feathers. As you say, Boyd, the precise medium may not matter. ‘But you have to give the DNA-analogue room to play, to pass on traits to offspring. You have to be a creature that has offspring …’

  And she glanced over at Feathers. Salma knew everybody would be thinking about the sad little eggs she frequently laid now, unfertilised, pointlessly hidden in improvised nests throughout the habitat.

  Meriel said, ‘But that offspring has to have differential levels of fitness. Meaning, fit to the environment you find yourself in. And you need some kind of selection process to weed out that fitness – like our natural selection, evolution. So, just by chance variations of the genes, you get a bunch of little Feathers, of whom some are a little better at flying, say, than their siblings. And maybe that enables them to do just that bit better at surviving than the groundhogs, and so their genes survive a bit better, proportionately. And the same process occurs in the next generation – fly better, you have more kids. Pretty soon everybody’s flying around like nobody’s business—’

  ‘Until the hawk comes along to take out the chicks,’ Boyd growled. ‘But why get smart?’

  Meriel said, ‘Fair question again.’

  ‘On a roll,’ Boyd murmured.

  ‘There’s a huge cost. I mean, to become smarter, in our kind of body plan anyhow, you need a bigger brain, and supporting networks – senses, nervous systems, stuff that allows the brain to take in information and then act on it by giving the body orders. But all that is expensive, in terms of energy. So, yes – why get smart at all?’

  ‘You can make better weapons,’ Joe suggested. ‘Better than the claws nature gave you. Better tools all round. Your chances of survival must be better.’

  Meriel pressed on. ‘OK. But it’s more fundamental, more powerful than that. The smarter you are, the more you learn and remember, the more you can predict the future – you can guess where the food is – and ultimately even control your food supply, by becoming some kind of cultivator. A farmer. Like humans, and some ants by the way. And with language, when you get around to inventing that, you can pool your intellects, and achieve stuff no one could achieve alone, or even with a few immediate family, like a chimp pack. All of which gives your genes a still better chance of propagating than the other guy’s.’

  Boyd said, ‘But then you have to go and spoil it all and invent stuff like intensive farming—’

  ‘Right. You win until you get to the point where you are despoiling your environment, and even then if you’re smart enough you stop …’

  ‘Hm,’ said Hild. ‘It does make you wonder why intelligence isn’t even more widespread than it is. In Earth’s biosphere, I mean.’

  Meriel shrugged. ‘I’m no expert, remember. But there is plenty of intelligence rattling around on Earth – the birds, for example. Their song is pretty elaborate, their flocking, their nesting behaviour pretty intricate. You ever try to make a bird’s nest as a kid? … I guess most of you never got the chance. Anyhow, you end up with a handful of straw. The cephalopods, like the octopuses, tend to be solitary, so they put together fantastic gardens of stuff that does nobody else any damn good at all. And there are lots of collective intelligences, without any single over-brain, or consciousness, at all. Like the ants, with hives like intricate, self-assembling machines. They do pretty well—’

  ‘OK, OK,’ Boyd said. ‘But look, with all due respect to the octopuses, we aren’t just smart. As we said before. We are the only intelligent species to have deliberately, if dumbly, screwed up the whole planet – and then, maybe more significantly, rebuilt it again. The climate-recovery decades, all those heroic stories we heard at school … And after that we have been the only species to get off the Earth – aside from a few bugs that may have hitched a ride to Mars on splashed-off meteorite debris.’ He waved a hand. ‘We are the only species to have built spacecraft, to come out to places like this …

  ‘But now, evidently, here’s Feathers and her folk. And they have evidently done something similar. Broken out of their world. Gone to the stars. Gone even further, if that black hole is any clue …’

  Hild asked, ‘So what are you getting at, Boyd?’

  ‘What are the odds? What are the odds of another tool-wielding, world-shaping intelligence showing up in this galaxy of ours? And on top of that, what are the odds of it looking even remotely like us, as Feathers does? And what are the odds of it showing up here? And what does it mean …’ He ran down. ‘Ah, hell. I think I’m getting out of my depth here.’