"Greg Egan - Mitochondrial Eve" - читать интересную книгу автора (Egan Greg)

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