Beginnings, it’s said, are apt to be shadowy.
So it is with this story, which starts with the emergence of a new species maybe two hundred
thousand years ago.
The species does not yet have a name—nothing does—but it has the capacity to name things.
As with any young species, this one’s position is precarious.
Its numbers are small, and its range restricted to a slice of eastern Africa.
Slowly its population grows, but quite possibly then it contracts again—some would claim
nearly fatally—to just a few thousand pairs.
The members of the species are not particularly swift or strong or fertile.
They are, however, singularly resourceful.
Gradually they push into regions with different climates, different predators, and different
prey.
None of the usual constraints of habitat or geography seem to check them.
They cross rivers, plateaus, mountain ranges.
In coastal regions, they gather shellfish; farther inland, they hunt mammals.
Everywhere they settle, they adapt and innovate.
On reaching Europe, they encounter creatures very much like themselves, but stockier and
probably brawnier, who have been living on the continent far longer.
They interbreed with these creatures and then, by one means or another, kill them off.
The end of this affair will turn out to be exemplary.
As the species expands its range, it crosses paths with animals twice, ten, and even twenty
times its size: huge cats, towering bears, turtles as big as elephants, sloths that stand
fifteen feet tall.
These species are more powerful and often fiercer.
But they are slow to breed and are wiped out.
Although a land animal, our species—ever inventive—crosses the sea.
It reaches islands inhabited by evolution’s outliers: birds that lay foot-long eggs, pig-sized
hippos, giant skinks.
Accustomed to isolation, these creatures are ill-equipped to deal with the new-comers or
their fellow travelers (mostly rats).
Many of them, too, succumb.
The process continues, in fits and starts, for thousands of years, until the species,
no longer so new, has spread to practically every corner of the globe.
At this point, several things happen more or less at once that allow Homo sapiens, as
it has come to call itself, to reproduce at an unprecedented rate.
In a single century the population doubles, then it doubles again, and then again.
Vast forests are razed.
Humans do this deliberately, in order to feed themselves.
Less deliberately, they shift organisms from one continent to another, reassembling the
biosphere.
Meanwhile, an even stranger and more radical transformation is underway.
Having discovered subterranean reserves of energy, humans begin to change the composition
of the atmosphere.
This, in turn, alters the climate and the chemistry of the oceans.
Some plants and animals adjust by moving.
They climb mountains and migrate toward the poles.
But a great many—at first hundreds, then thousands, and finally perhaps millions—find
themselves marooned.
Extinction rates soar, and the texture of life changes.
No creature has ever altered life on the planet in this way before, and yet other, comparable
events have occurred.
Very, very occasionally in the distant past, the planet has undergone change so wrenching
that the diversity of life has plummeted.
Five of these ancient events were catastrophic enough that they’re put in their own category:
the so-called Big Five.
In what seems like a fantastic coincidence, but is probably no coincidence at all, the
history of these events is recovered just as people come to realize that they are causing
another one.
When it is still too early to say whether it will reach the proportions of the Big Five,
it becomes known as the Sixth Extinction.
This beautifully simple tale of how humans came to dominate our planet is from the book
The Sixth Extinction by Elizabeth Kolbert.
You can download and listen to the audiobook version of this book for free through the
link below with a one-month free trial of Audible.com.
For TDC, I’m Bryce Plank.
Thanks for watching.