Like hunter-gatherers in the jungle, modern humans are still
experts at spotting predators and prey, despite the developed
world's safe suburbs and indoor lifestyle, a new study
The research, published online this week in the Proceedings
of the National Academy of Sciences, reveals that humans
today are hard-wired to pay attention to other people and
animals much more so than non-living things, even if inanimate
objects are the primary hazards for modern, urbanized folks.
The researchers say the finding supports the idea that natural
selection molded mechanisms into our ancestors' brains
that were specialized for paying attention to humans and other
animals. These adaptive traits were then passed on to us.
"We're assuming that natural selection takes a
long time to build anything anew and that's why this is
left over from our past," said study team member Leda
Cosmides, an evolutionary psychologist at the University of
California, Santa Barbara (UCSB).
Immersed in a rich, biotic environment, it would have been
imperative for our ancestors to monitor both humans and non-human
animals. Predators and prey took many different forms—lions,
tigers and bears—and they changed often, so constant
eyeballing was critical.
While the environment has changed since then, with high-rises
emerging where forests once took root and pampered pets taking
the place of stalking beasts, our instinct-driven attention
has not followed suit.
"Having this pop-out attentional bias for animals is
sort of a vestigial behavior," said study team member
Joshua New of Yale University's Perception and Cognition
In the study, groups of undergraduate students from UCSB,
watched images displayed on computer monitors. The flashing
images alternated between pairs of various outdoor scenes,
with the first image showing one scene and the next an alternate
version of that scene with one change. Participants indicated
each time whether they detected a change.
The photographs included animate categories, such as people
and other animals, as well as inanimate ones, such as plants,
artifacts that can be manipulated (stapler or wheelbarrow)
and fixed artifacts, such as landmarks (windmill or house).
Overall, the subjects were faster and more accurate at detecting
changes involving all animals compared with inanimate objects.
They correctly detected nearly 90 percent of the changes to
"living" targets compared with 66 percent for inanimate
In particular, the students spotted changes in elephant
and human scenes 100 percent of the time, while they had a
success rate of just over 75 percent for photos showing a
silo and 67 percent for those with a coffee mug.
Though we are more likely to meet death via an SUV than
a charging wildebeest, the results indicated subjects were
slower and less successful at detecting changes to vehicles
than to animals.
The researchers compare our attentional bias toward animals
to the appendix, an organ present in modern humans because
it was useful for our ancestors, but useless now.
These results have implications for phobias and other behaviors
that involve focus toward specific categories of objects over
"People develop phobias for spiders and snakes and
things that were ancestral threats. It's very infrequent
to have somebody afraid of cars or electrical outlets,"
New told LiveScience. "Those statistically pose
much more of a threat to us than a tiger. That makes it an
interesting test case as to why do tigers still capture attention."