The EconomistFebruary 22nd 2020 Science & technology 772 this triple alliance is that, acting together,
the three organisms create a biofilm which
can move about as a single entity. This pre-
sumably assists their feeding by allowing
them to travel collectively to pastures new.
None of this information would have
emerged by studying the organisms in iso-
lation, or even by pairwise comparison.
Even a triangle, however, is probably
too much of a simplification. A typical soil
sample contains hundreds or thousands of
bacteria and fungi. A number of workers in
the field think, though, that it is possible to
strip things down to viable communities
with a couple of dozen members.
One of these optimists is Kirsten Hof-
mockel of the Pacific Northwestern Na-
tional Laboratory, in Richland, Washing-
ton. She has created simplified microbe
communities by selecting for those depen-
dent ultimately on a single food stuff. She
started with chitin, the second most abun-
dant carbohydrate polymer after cellulose.
She mixed this material with sterile soil
and then added an inoculum of organisms
from natural soil, to see what survived.
What emerged was a mixture of 20 organ-
isms that subsequent experiments have
shown live well together as a community.
Having proved her method, she then re-
peated the process with five other complex
carbohydrates. The result is a set of eco-
logical “cassettes” that can be used for ex-
periments that do things like varying soil
acidity and chemical composition, to see
what thrives in which conditions.
Dr Hofmockel’s simplified communi-
ties are a step forward because they provide
a basis for standardisation. This allows ex-
periments to be repeated in different lab-
oratories and the results compared mean-
ingfully. Standard organisms make it
easier for researchers to build on each oth-
ers’ work. This is why fruit flies, small
nematode worms, cress plants and mice
are used so often in biology labs.
Standardised procedures are equally
important. And, to that end, Trent Northen
of Lawrence Berkeley National Laboratory
described his ecofabto the meeting. This
is a transparent silicone apparatus in
which soil microbes can be brought into
contact with plant roots in controlled con-
ditions. Dr Northen hopes it will become
ubiquitous, in the way that things like Petri
dishes have, and has designed software
that will direct a 3dprinter to make plastic
moulds from which the ecofab can be
created by anyone who chooses to down-
load the program.
The fruit of all this effort, researchers
hope, will be ways to make soil healthier.
There is already a market for so-called bio-
fertilisers, which are enriched in micro-or-
ganisms reckoned to be good for the soil.
But these products are like herbal medi-
cines: sometimes they work and some-
times they don’t. And nobody really knows
why. Dr Handelsman, Dr Hofmockel, Dr
Northen and their numerous colleagues
intend to bring rigour to the subject, just as
chemists once turned willows, poppies
and foxgloves into aspirin, morphine and
digitalis. Then, by direct inoculation, or by
the use of suitable chemicals to encourage
some microbe species and discourage oth-
ers, soils can be kept healthy and suitable
for the crops growing in them. 7A
ristotle reckoned the face was a
window onto a person’s mind. Cicero
agreed. Two millennia on, facial expres-
sions are still commonly thought to be a
universally valid way to gauge other peo-
ple’s feelings, irrespective of age, sex and
culture. A raised eyebrow suggests confu-
sion. A smile denotes happiness. A frown
indicates sadness.
Or do they? An analysis of hundreds of
research papers that examined the rela-
tionship between facial expressions and
underlying emotions has uncovered a sur-
prising conclusion: there is no good scien-
tific evidence to suggest that there are such
things as recognisable facial expressions
for basic emotions which are universal
across cultures. Just because a person is
not smiling, the researchers found, does
not mean that person is unhappy.
As Lisa Feldman Barrett, one of the au-
thors of the study, published in Psycholog-
ical Science in the Public Interest, told theaaas meeting in Seattle, “We surprised
ourselves”. Dr Feldman Barrett is a psychol-
ogist at Northeastern University in Boston,
Massachusetts, and along with her col-
leagues she found that, on average, adults
in urban cultures scowled when they were
angry 30% of the time. Which meant that
some 70% of the time they did not scowl
when angry. Instead, they did something
else with their faces. People also scowled
when they were not angry. “They scowl
when they’re concentrating, they scowl
when someone tells them a bad joke, they
scowl when they have gas, they scowl for
lots of reasons,” says Dr Feldman Barrett.
A scowl, the researchers concluded, is
certainly one expression of anger. But it is
not the only way people express that emo-
tion. The ambiguous nature of facial ex-
pressions was not restricted to anger, but
seemed valid for all six of the emotional
categories that they examined: anger, dis-
gust, fear, happiness, sadness and surprise.
All this raises questions about the ef-
forts of information-technology compa-
nies to develop artificial-intelligence algo-
rithms which can recognise facial
expressions and work out a person’s un-
derlying emotional state. Microsoft, for ex-
ample, claims its “Emotion api” is able to
detect what people are feeling by examin-
ing video footage of them. Another of the
study’s authors, however, expressed scep-
ticism. Aleix Martinez, a computer engi-
neer at Ohio State University, said that
companies attempting to extract emotions
from images of faces have failed to under-
stand the importance of context.
For a start, facial expression is but one
of a number of non-verbal cues, such as
body posture, that people use to communi-
cate with each other. Machine recognition
of emotion needs to take account of these
as well. But context can reach further than
that. Dr Martinez cited an experiment in
which participants were shown a close-up
picture of a man’s face, which was bright
red with his mouth open in a scream.
Based on this alone, most participants
said the man was extremely angry. Then
the view zoomed out to show a football
player with his arms outstretched, cele-
brating a goal. His angry-looking face was,
in fact, a show of pure joy.
Given that people cannot guess each
other’s emotional states most of the time,
Dr Martinez sees no reason computers
would be able to. “There are companies
right now claiming to be able to do that and
apply this to places I find really scary and
dangerous, for example, in hiring people,”
he says. “Some companies require you to
submit a video cv, and then this is analysed
by a machine-learning system. And de-
pending on your facial expressions, they
hire you or not, which I find really stun-
ning and not only based on the wrong hy-
pothesis, but a dangerous hypothesis.” 7SEATTLE
Facial expressions are not usually a
reliable guide to how people feelPsychologyFace blind