Anthology 2. Luminous [1998, 2010]

by Greg Egan

  In the foyer, a holographic bust of Mitochondrial Eve herself, mounted on a marble pedestal, gazed proudly over our heads. The artist had rendered our hypothetical ten-thousand-times-great grandmother as a strikingly beautiful woman. A subjective judgement, certainly, but her lean, symmetrical features, her radiant health, her purposeful stare, didn’t really strike me as amenable to subtleties of interpretation. The aesthetic buttons being pushed were labelled, unmistakably: warrior, queen, goddess. And I had to admit that I felt a certain bizarre, involuntary swelling of pride at the sight of her … as if her regal bearing and fierce eyes somehow ‘ennobled’ me and all her descendants … as if the ‘character’ of the entire species, our potential for virtue, somehow depended on having at least one ancestor who could have starred in a Leni Riefenstahl documentary.

  This Eve was black, of course, having lived in sub-Saharan Africa some 200,000 years ago, but almost everything else about her was guesswork. I’d heard palaeontologists quibble about the too-modern features, not really compatible with any of the sparse fossil evidence for her contemporaries’ appearance. Still, if the Children had chosen as their symbol of universal humanity a few fissured brown skull fragments from the Omo River in Ethiopia, the movement would surely have vanished without a trace. And perhaps it was simply mean-spirited of me to think of their Eve’s beauty as a sign of fascism. The Children had already persuaded over two million people to acknowledge, explicitly, a common ancestry which transcended their own superficial differences in appearance; this all-inclusive ethos seemed to undercut any argument linking their obsession with pedigree to anything unsavoury.

  I turned to Lena. ‘You know the Mormons baptised her posthumously, last year?’

  She shrugged the appropriation off lightly. ‘Who cares? This Eve belongs to everyone, equally. Every culture, every religion, every philosophy. Anyone can claim her as their own; it doesn’t diminish her at all.’ She regarded the bust admiringly, almost reverently.

  I thought: She sat through four hours of Marx Brothers films with me last week – bored witless, but uncomplaining. So I can do this for her, can’t I? It seemed like a simple matter of give-and-take – and it wasn’t as if I was being pressured into an embarrassing haircut, or a tattoo.

  We walked through into the sequencing lounge.

  We were alone, but a disembodied voice broke through the ambience of endangered amphibians and asked us to wait. The room was plushly carpeted, with a circular sofa in the middle. Artwork from around the world decorated the walls, from an uncredited Arnhem Land dot painting to a Francis Bacon print. The explanatory text below was a worry: dire Jungian psychobabble about ‘universal primal imagery’ and ‘the collective unconscious’. I groaned aloud, but when Lena asked what was wrong I just shook my head innocently.

  A man in white trousers and a short white tunic emerged from a camouflaged door, wheeling a trolley packed with impressively minimalist equipment, reminiscent of expensive Scandinavian audio gear. He greeted us both as ‘cousin’, and I struggled to keep a straight face. The badge on his tunic bore his name, Cousin André, a small reflection hologram of Eve, and a sequence of letters and numbers which identified his mitotype. Lena took charge, explaining that she was a member, and she’d brought me along to be sequenced.

  After paying the fee – a hundred dollars, blowing my recreation budget for the next three months – I let Cousin André prick my thumb and squeeze a drop of blood onto a white absorbent pad, which he fed into one of the machines on the trolley. A sequence of delicate whirring sounds ensued, conveying a reassuring sense of precision engineering at work. Which was odd, because I’d seen ads for similar devices in Nature which boasted of no moving parts at all.

  While we waited for the results, the room dimmed and a large hologram appeared, projected from the wall in front of us: a micrograph of a single living cell. From my own blood? More likely, not from anyone’s – just a convincing photorealist animation.

  ‘Every cell in your body,’ Cousin André explained, ‘contains hundreds or thousands of mitochondria: tiny power plants which extract energy from carbohydrates.’ The image zoomed in on a translucent organelle, rod-shaped with rounded ends, rather like a drug capsule. ‘The majority of the DNA in any cell is in the nucleus, and comes from both parents, but there’s also DNA in the mitochondria, inherited from the mother alone. So it’s easier to use mitochondrial DNA to trace your ancestry.’

  He didn’t elaborate, but I’d heard the theory in full several times, starting with high-school biology. Thanks to recombination – the random interchange of stretches of DNA between paired chromosomes, in the lead-up to the creation of sperm or ova – every chromosome carried genes from tens of thousands of different ancestors, stitched together seamlessly. From a palaeogenetic perspective, analysing nuclear DNA was like trying to make sense of ‘fossils’ which had been forged by cementing together assorted bone fragments from ten thousand different individuals.

  Mitochondrial DNA came, not in paired chromosomes, but in tiny loops called plasmids. There were hundreds of plasmids in every cell, but they were all identical, and they all derived from the ovum alone. Mutations aside – one every 4,000 years or so – your mitochondrial DNA was exactly the same as that of your mother, your maternal grandmother, great-grandmother, and so on. It was also exactly the same as that of your siblings, your maternal first cousins, second cousins, third cousins … until different mutations striking the plasmid on its way down through something like 200 generations finally imposed some variation. But with 16,000 DNA base pairs in the plasmid, even the fifty or so point mutations since Eve herself didn’t amount to much.

  The hologram dissolved from the micrograph into a multicoloured diagram of branching lines, a giant family tree starting from a single apex labelled with the ubiquitous image of Eve. Each fork in the tree marked a mutation, splitting Eve’s inheritance into two slightly different versions. At the bottom, the tips of the hundreds of branches showed a variety of faces, some men, some women – individuals or composites, I couldn’t say, but each one presumably represented a different group of (roughly) 200th maternal cousins, all sharing a mitotype: their own modest variation on the common 200,000-year-old theme.

  ‘And here you are,’ said Cousin André. A stylised magnifying glass materialised in the foreground of the hologram, enlarging one of the tiny faces at the bottom of the tree. The uncanny resemblance to my own features was almost certainly due to a snapshot taken by a hidden camera; mitochondrial DNA had no effect whatsoever on appearance.

  Lena reached into the hologram and began to trace my descent with one fingertip. ‘You’re a Child of Eve, Paul. You know who you are, now. And no one can ever take that away from you.’ I stared at the luminous tree, and felt a chill at the base of my spine, though it had more to do with the Children’s proprietary claim over the entire species than any kind of awe in the presence of my ancestors.

  Eve had been nothing special, no watershed in evolution; she was simply defined as the most recent common ancestor, by an unbroken female line, of every single living human. And no doubt she’d had thousands of female contemporaries, but time and chance – the random death of daughterless women, catastrophes of disease and climate – had eliminated every mitochondrial trace of them. There was no need to assume that her mitotype had conferred any special advantages (most variation was in junk DNA, anyway); statistical fluctuations alone meant that one maternal lineage would replace all the others, eventually.

  Eve’s existence was a logical necessity: some human (or hominid) of one era or another had to fit the bill. It was only the timing which was contentious.

  The timing, and its implications.

  A world globe some two metres wide appeared beside the Great Tree; it had a distinctive Earth-from-space look, with heavy white cumulus swirling over the oceans, but the sky above the continents was uniformly cloudless. The Tree quivered and began to rearrange itself, converting its original rectilinear form into something much more
misshapen and organic, but flexing its geometry without altering any of the relationships it embodied. Then it draped itself over the surface of the globe. Lines of descent became migratory routes. Between eastern Africa and the Levant, the tracks were tightly bunched and parallel, like the lanes of some palaeolithic freeway; elsewhere, less constrained by the geography, they radiated out in all directions.

  A recent Eve favoured the ‘Out of Africa’ hypothesis: modern Homo sapiens had evolved from the earlier Homo erectus in one place only, and had then migrated throughout the world, out-competing and replacing the local Homo erectus everywhere they went – and developing localised racial characteristics only within the last 200,000 years. The single birthplace of the species was most likely Africa, because Africans showed the greatest (and hence oldest) mitochondrial variation; all other groups seemed to have diversified more recently from relatively small ‘founder’ populations.

  There were rival theories, of course. More than a million years before Homo sapiens even existed, Homo erectus itself had spread as far as Java, acquiring its own regional differences in appearance – and Homo erectus fossils in Asia and Europe seemed to share at least some of the distinguishing characteristics of living Asians and Europeans. But ‘Out of Africa’ put that down to convergent evolution, not ancestry. If Homo erectus had turned into Homo sapiens independently in several places, then the mitochondrial difference between, say, modern Ethiopians and Javanese should have been five or ten times as great, marking their long separation since a much earlier Eve. And even if the scattered Homo erectus communities had not been totally isolated, but had interbred with successive waves of migrants over the past one or two million years – hybridising with them to create modern humans, and yet somehow retaining their distinctive differences – then distinct mitochondrial lineages much older than 200,000 years probably should have survived too.

  One route on the globe flashed brighter than the rest. Cousin André explained, ‘This is the path your own ancestors took. They left Ethiopia – or maybe Kenya or Tanzania – heading north, about 150,000 years ago. They spread slowly up through Sudan, Egypt, Israel, Palestine, Syria and Turkey while the interglacial stretched on. By the start of the last Ice Age, the eastern shore of the Black Sea was their home …’ As he spoke, tiny pairs of footprints materialised along the route.

  He traced the hypothetical migration through the Caucasus Mountains, and all the way to northern Europe – where the limits of the technique finally cut the story dead: some four millennia ago (give or take three), when my Germanic two-hundredish-great grandmother had given birth to a daughter with a single change in her mitochondrial junk DNA: the last recorded tick of the molecular clock.

  Cousin André wasn’t finished with me, though. ‘As your ancestors moved into Europe, their relative genetic isolation, and the demands of the local climate, gradually led them to acquire the characteristics which are known as Caucasian. But the same route was travelled many times, by wave after wave of migrants, sometimes separated by thousands of years. And though, at every step along the way, the new travellers interbred with those who’d gone before, and came to resemble them … dozens of separate maternal lines can still be traced back along the route – and then down through history again, along different paths.’

  My very closest maternal cousins, he explained – those with exactly the same mitotype – were, not surprisingly, mostly Caucasians. And expanding the circle to include up to thirty base pair differences brought in about 5 per cent of all Caucasians – the 5 per cent with whom I shared a common maternal ancestor who’d lived some 120,000 years ago, probably in the Levant.

  But a number of that woman’s own cousins had apparently headed east, not north. Eventually, their descendants had made it all the way across Asia, down through Indochina, and then south through the archipelagos, travelling across land bridges exposed by the low ocean levels of the Ice Age, or making short sea voyages from island to island. They’d stopped just short of Australia.

  So I was more closely related, maternally, to a small group of New Guinean highlanders than I was to 95 per cent of Caucasians. The magnifying glass reappeared beside the globe, and showed me the face of one of my living 6000th cousins. The two of us were about as dissimilar to the naked eye as any two people on Earth; of the handful of nuclear genes which coded for attributes like pigmentation and facial bone structure, one set had been favoured in frozen northern Europe, and another in this equatorial jungle. But enough mitochondrial evidence had survived in both places to reveal that the local homogenisation of appearance was just a veneer, a recent gloss over an ancient network of invisible family connections.

  Lena turned to me triumphantly. ‘You see? All the old myths about race, culture, and kinship – instantly refuted! These people’s immediate ancestors lived in isolation for thousands of years, and didn’t set eyes on a single white face until the twentieth century. Yet they’re nearer to you than I am!’

  I nodded, smiling, trying to share her enthusiasm. It was fascinating to see the whole naı¨ve concept of ‘race’ turned inside out like this – and I had to admire the Children’s sheer audacity at claiming to be able to map hundred-thousand-year-old relationships with such precision. But I couldn’t honestly say that my life had been transformed by the revelation that certain white total strangers were more distant cousins to me than certain black ones. Maybe there were die-hard racists who would have been shaken to the core by news like this … but it was hard to imagine them rushing along to the Children of Eve to be mitotyped.

  The far end of the trolley beeped, and ejected a badge just like Cousin André’s. He offered it to me; when I hesitated, Lena took it and pinned it proudly to my shirt.

  Out on the street, Lena announced soberly, ‘Eve is going to change the world. We’re lucky; we’ll live to see it happen. We’ve had a century of people being slaughtered for belonging to the wrong kinship groups – but soon everyone will understand that there are older, deeper blood ties which confound all their shallow historical prejudices.’

  You mean … like the biblical Eve confounded all the prejudices of fundamentalist Christians? Or like the image of the Earth from space put an end to war and pollution? I tried diplomatic silence; Lena regarded me with consternation, as if she couldn’t quite believe that I could harbour any doubts after my own unexpected blood ties had been revealed.

  I said, ‘Do you remember the Rwandan massacres?’

  ‘Of course.’

  ‘Weren’t they more to do with a class system – which the Belgian colonists exacerbated for the sake of administrative convenience – than anything you could describe as enmity between kinship groups? And in the Balkans—’

  Lena cut me off. ‘Look, sure, any incident you can point to will have a convoluted history. I’m not denying that. But it doesn’t mean that the solution has to be impossibly complicated, too. And if everyone involved had known what we know, had felt what we’ve felt—’ she closed her eyes and smiled radiantly, an expression of pure contentment and tranquillity ‘—that deep sense of belonging, through Eve, to a single family which encompasses all of humanity … do you honestly imagine that they could have turned on each other like that?’

  I should have protested, in tones of bewilderment: What ‘deep sense of belonging’? I felt nothing. And the only thing the Children of Eve are doing is preaching to the converted.

  What was the worst that could have happened? If we’d broken up, right there and then, over the political significance of palaeogenetics, then the relationship was obviously doomed from the start. And however much I hated confrontation, it was a fine line between tact and dishonesty, between accommodating our differences and concealing them.

  And yet. The issue seemed far too arcane to be worth fighting over – and though Lena clearly held some passionate views on it, I couldn’t really see the topic arising again if I kept my big mouth shut, just this once.

  I said, ‘Maybe you’re right.’ I slipped an arm around he
r, and she turned and kissed me. It began to rain again, heavily, the downpour strangely calm in the still air. We ended up back at Lena’s flat, saying very little for the rest of the night.

  I was a coward and a fool, of course – but I had no way of knowing, then, just how much it would cost me.

  * * *

  A few weeks later, I found myself showing Lena around the basement of the UNSW physics department, where my own research equipment was crammed into one corner. It was late at night (again), and we were alone in the building; variously coloured fluorescent display screens hovered in the darkness, like distant icons for the other post-doctoral projects in some chilly academic cyberspace.

  I couldn’t find the chair I’d bought for myself (despite security measures escalating from a simple name tag to increasingly sophisticated computerised alarms, it was always being borrowed), so we stood on the cold bare concrete beside the apparatus, lit by a single fading ceiling panel, and I conjured up sequences of zeros and ones which echoed the strangeness of the quantum world.

  The infamous Einstein–Podolosky–Rosen correlation – the entanglement of two microscopic particles into a single quantum system – had been investigated experimentally for over twenty years, but it had only recently become possible to explore the effect with anything more complicated than pairs of photons or electrons. I was working with hydrogen atoms, produced when a single hydrogen molecule was dissociated with a pulse from an ultraviolet laser. Certain measurements carried out on the separated atoms showed statistical correlations which only made sense if a single wave function encompassing the two responded to the measurement process instantaneously – regardless of how far apart the individual atoms had travelled since their tangible molecular bonds were broken: metres, kilometres, light-years.