As I write this in my basement office, a
sticky trap lies beneath my desk catching
whatever insects wander by. Its current
haul is pretty typical: a cricket, a spider
and some small flies. But as Rob Dunn
writes in his intriguing new book, Never
Home Alone, I’m missing a lot if I think
that’s all that lurks beneath my slippers.
Dunn has carved out an unusual niche as an ecologist,
studying the myriad fauna that inhabits houses. These creatures are mostly small, such as microbes and insects, but
that’s only one reason they’ve gone largely undocumented.
There’s also a bias worth noting. “As ecologists, we’re
trained to study life in ‘nature,’ which we have come to
believe means the absence of humans,” Dunn writes. But it’s
impossible to know what harmful or helpful species might
live alongside us, he argues, if no one ever looks. So as Dunn
relates in this backstage pass to his work, he and a team of
fellow renegades set out to catalog life in unnatural spaces.
The team immediately found surprises. In their first look
at house dust, Dunn and colleagues identified almost 8,000
bacterial species, including many new to science. What’s
more, an average home had about 100 species of arthropods
(SN: 9/3/16, p. 15). The team also revealed that a giant species of Japanese camel cricket had invaded American homes
without anyone noticing. And that was just the beginning.
In shower heads, Dunn’s group discovered an entire ecosys-
tem. There were dozens of species of Mycobacteria, some of
which can cause diseases including tuberculosis and some of
which might impart health benefits. Alongside these microbes
live predatory swimming bacteria, multicelled protists that
eat the swimmers, and tiny worms that eat the protists. “This
is the food web that falls upon you as you bathe,” Dunn writes.
In their searches over the last several years, Dunn and col-
leagues have found about 200,000 different species in homes.
If your skin is starting to crawl at the thought of all these
uninvited houseguests, don’t despair. Most are harmless,
or even helpful, Dunn has found. To that end, he’s not only
identifying who’s there, but also asking what they’re doing
there, and if they might be useful in some way.
Some have potential, he’s learned — even the camel
cricket. By considering the insect’s ecology — camel crickets
typically live in caves, where food is scarce and difficult to
digest — Dunn reasoned that bacteria in the cricket’s gut may
help it break down scraps of detritus. And in fact, he and colleagues have identified bacteria from the camel crickets that
could perhaps break down industrial waste. Who knows what
talents may lie in silverfish or drain flies?
Seen through Dunn’s curious eyes, a house becomes not
just a set of rooms, but a series of habitats to be explored.
His writing and research lend a new appreciation of what
many of us consider pests.
For the most part, it’s our fight to sterilize our homes that’s
actually harmful, Dunn argues. Chlorinating tap water kills
off many “good” bacteria to the benefit of harmful ones,
and our efforts to exterminate the German cockroach have
served only to create ones that are harder to kill.
Rather than trying to seal everything out, Dunn says, we
should welcome a little bit of nature into our homes. Open a
window and enjoy the abundance of life. — Erika Engelhaupt
Never Home Alone
BASIC BOOKS, $28
There’s a hidden world
living in your house
What wiped out the behemoths?
Today’s land animals are a bunch of runts compared with creatures from
the not-too-distant past. Beasts as big as elephants, gorillas and bears were
once much more common around the world. Then, seemingly suddenly,
hundreds of big species, including the woolly mammoth, the giant ground
sloth and a lizard weighing as much as half a ton, disappeared. In End of
the Megafauna, paleomammalogist Ross MacPhee makes one thing clear:
The science on what caused the extinctions of these megafauna — animals
larger than 44 kilograms, or about 100 pounds — is far from settled.
MacPhee dissects the evidence behind two main ideas: that as humans
moved into new parts of the world over the last 50,000 years, people
hunted the critters into oblivion, or that changes in climate left the animals
too vulnerable to survive. As MacPhee shows, neither scenario matches all of the available data.
Throughout, Peter Schouten’s illustrations, reminiscent of paintings that enliven natural
history museums, bring the behemoths back to life (such as the elephant bird of Madagascar,
right, shown with modern lemurs for scale). At times, MacPhee slips in too many technical
terms. But overall, he offers readers an informative, up-to-date overview of a fascinating
period in Earth’s history. — Erin Wayman
End of the
Ross D. E. MacPhee
and Peter Schouten
W. W. NORTON & CO.,