Illustration by Matt Collins February 2019, ScientificAmerican.com 75ANTI GRAVITY
S A
A A A SSteve Mirsky has been writing the Anti Gravity column since
a typical tectonic plate was about 36 inches from its current location.
He also hosts the IY_[dj_ÒY7c[h_YWdpodcast Science Talk.What
the Deuce
A number of studies
about number two
By Steve Mirsky ere een a t f cra in the news lately, and for a
change I mean that literally. Let’s start with the study
presented last November 18 at the annual meeting of the
American Physical Society’s Division of Fluid Dynamics
entitled “How Do Wombats Make Cubed Poo?” Yes,
wombats produce dicelike discharges. The marsupial’s
unique ability attracted the attention of researchers who
looked at the innards recovered from two wombats lost
in the everyday carnage of roadways around the world.
“In the final 8 percent of the intestine,” the dung
detectives wrote, “feces changed from a liquid-like
state into a solid state composed of separated cubes of
length 2 cm. This shape change was due to the azi-
muthally varying elastic properties of the in test in al
wall.” After that inspection, they emptied the intes-
tines and inflated them, presumably not by mouth.
“We found,” they wrote, “that the local strain varies
from 20 percent at the cube’s corners to 75 percent at its edges.
Thus, the intestine stretches preferentially at the walls to facili-
tate cube formation. This study addresses the long-standing
mystery of cubic scat formation and provides insight into new
manufacturing techniques for non-axisymmetric structures
using soft tissues.” At long last, 3M meets BM.
Back in March 2018, Israeli researchers published a study in
the journal Applied Energy stating that poultry expulsions could
be pressure-cooked into a burnable powder that might replace
some coal in electricity production. Or even be pressed into bri-
quettes for cooking. Just before Thanksgiving, NPR did a story
about this research and pointed out that someone could theoreti-
cally collect a turkey’s droppings over its lifetime, turn that mess
into fuel and then use it to cook the very same turkey. Perhaps
selective breeding could even get the hapless bird to go pluck itself.
In the December 20th edition of the Journal of Cleaner Pro-
duction, the same Israeli group published a similar study with
human excreta. To quote: “It is postulated that hydrothermal car-
bonization of hu man excreta could potentially serve as a sustain-
able sanitation technology.” Perhaps your future energy-efficient
home will be able to connect the toilet directly to the furnace.
Last November, Tech Insider dredged up and tweeted video
related to a story first reported in 2015 about Antarctica’s Gen-
too penguins getting together to relieve themselves en masse.
Their warm guano helps to melt the snow and ice. Having thus
cleared the field, the birds can build nests on beaches or small
patches of vegetation.In the same month the news site Crosscut ran a piece about
the University of Washington’s Conservation Canines program.
Reporter Hannah Weinberger wrote that “a rotating cast of 17
lucky dogs ... [are] taught to approach scent detection as a game,
where they are rewarded for learning how to track the scents of
dozens of species’ feces.”
The samples that the dogs then locate in the field give re -
searchers valuable information about local animal populations—
more data than could be generated by camera traps or hair
snares. So what’s it like to sniff out scat for a living? One dog
allegedly de scribed it as “rough.”
Also in November the Journal of Paediatrics and Child Health
ran a study entitled “Everything Is Awesome: Don’t Forget the
Lego.” Six pediatric health care professionals swallowed a plas-
tic Lego minifigure head, representing the myriad small objects
little kids swallow, and then pawed through their own stool to
see how long it took for the head to emerge. The time between
ingestion and elimination was dubbed the Found and Retrieved
Time (FART), which averaged 1.71 days.
The authors noted that “it is likely that objects would pass
faster in a more immature gut.” Therefore, they “advocate that
no parent should be expected to search through their child’s fae-
ces to prove object retrieval.” In other words, trust the process—
these things have a way of working themselves out. SA
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