What's that in the mirror, or the corner of your eye?
What's the footstep following, but never passing by?
Perhaps they're all just waiting, perhaps when we're all dead.
Out they'll come a-slithering, from underneath the bed.

     In a dream, you walk outside to find your familiar landscape swarming with fantastic beings. Depending on where you live, there might be deer with antlers thick as tree boughs, or something resembling a live armoured tank. There's a herd of what look like camels - except they have trunks. Furry rhinoceroses, big hairy elephants, and even bigger sloths - sloths?? Wild horses of all sizes and stripe. Panthers with seven-inch fangs and alarmingly tall cheetahs. Wolves, bears, and lions so huge, this must be a nightmare.

     A dream, or a congenital memory? This was precisely the world that Homo sapiens stepped into as we spread beyond Africa, all the way to America. Had we never appeared, would those now-missing mammals still be here? If we go, will they be back?

...

     Mammoths were grazing animals, evolved to steppes, grassland, and tundra, unlike their much older relatives, the mastodons, which browsed in woods and forests. Mastodons had been around for 30 million years, and ranged from Mexico to Alaska to Florida - but suddenly they, too, were go. Three genera of American horses: gone. Multiple varieties of North American camels, tapirs, numerous antlered creatures ranging from dainty pronghorns to the stag moose, which resembled a cross between a moose and an elk but was larger than either, all gone, along with the sabre-toothed tiger and the American cheetah (the reason why the sole remaining pronghorn species of antelope is so fleet). All gone. And all pretty much at once? What, Paul Martin wondered, could possibly have caused that?

...

     Martin mourned, but by then he had been setting blazes of his own in the palaeontology world with his theory of what had wiped out millions of ground sloths, wild pigs, camels, Proboscidea, multiple species of horses - at least 70 entire genera of large mammals throughout the New World, all vanished in a geologic twinkling of about 1000 years:

"It's pretty simple. When people got out of Africa and Asia and reached other parts of the world, all hell broke loose."

...

     [The International Wildlife Museum]'s centrepiece is the faithfully reproduced 2500-square-foot trophy room of McElroy's Tucson mansion, which bears the taxidermised spoils of a lifelong obsession with killing large mammals. Locally often derided as the "dead animal museum", for Martin on this night, it's perfect.

     The occasion is the launch of his 2005 book, Twilight of the Mammoths. Just behind his audience rises a phalanx of grizzly and polar bears, frozen forever in mid-attack. Above the podium, its ears extended like grey spinnakers, is the trophy head of an adult African elephant. To either side, every breed of spiral horns found on five continents is represented. Pulling himself from his wheelchair, Martin slowly scans the hundreds of stuffed heads: bongo, nyala, bushbuck, sitatunga, greater and lesser kudu, eland, ibex, Barbary sheep, chamois, impala, gazelle, dik-dik, musk ox, cape buffalo, sable, roan, oryx, waterbuck, and gnu. Hundreds of pairs of glass eyes fail to return his moist blue gaze.

     "I can't imagine a more appropriate setting," he says, "to describe what amounts to genocide. In my lifetime, millions of people slaughtered in death camps, from Europe's Holocaust to Darfur, are proof of what our species is capable of. My 50-year career has been absorbed by the extraordinary loss of huge animals whose heads don't appear on these walls. They were all exterminated, simply because it could be done. The person who put this collection together could have walked straight out of the Pleistocene."

     He and his book conclude with a plea that his accounting of the Pleistocene mega-massacre be a cautionary lesson that stops us from perpetrating another that would be far more devastating. The matter is more complicated than a killer instinct that never relents until another species is gone. It involves acquisitive instincts that also can't tell when to stop, until something we never intended to harm is fatally deprived of something it needs. We don't actually have to shoot songbirds to remove them from the sky. Take away enough of their home or sustenance, and they fall dead on their own.

Listen! Question: Why do we talk out loud when we know we're alone? Conjecture: because we know we are not. Evolution perfects survival skills. There are perfect hunters. There is perfect defense. Question: Why is there no such thing as perfect hiding? Answer: How would you know? Logically, if evolution were to perfect a creature whose primary skill were to hide from view, how could you know it existed? It could be with us every second and we would never know. How would you detect it? Even sense it? Except in those moments when, for no clear reason, you choose to speak aloud. What would such a creature want? What would it do?

You know sometimes when you talk to yourself? What if you're not? What if it's not you you're talking to? Proposition: What if no one is ever really alone? What if every single living being has a... companion. A silent passenger. A shadow. What if the prickle on the back of your neck is the breath of something close behind you?

Das Firmament blaut ewig, und die ErdeWird lange fest steh'n und aufblüh'n im Lenz.Du aber, Mensch, wie lange lebst denn du?
The firmament is blue forever, and the Earth
WIll long stand firm and bloom in spring.
But, man, how long will you live?