Reading Passage 1
Pheidole dentata, a native ant of the south-eastern U.S., isn't immortal. But scientists have
found that it doesn't seem to show any signs of aging. Old worker ants can do everything
just as well as the youngsters, and their brains appear just as sharp. 'We get a picture that
these ants really don't decline,' says Ysabel Giraldo, who studied the ants for her doctoral
thesis at Boston University.
Such age-defying feats are rare in the animal kingdom. Naked mole rats can live for almost
30 years and stay fit for nearly their entire lives. They can still reproduce even when old,
and they never get cancer. But the vast majority of animals deteriorate with age just like
people do. Like the naked mole rat, ants are social creatures that usually live in highly
organised colonies. 'It's this social complexity that makes P. dentata useful for studying
aging in people,' says Giraldo, now at the California Institute of Technology. Humans are
also highly social, a trait that has been connected to healthier aging. By contrast, most
animal studies of aging use mice, worms or fruit flies, which all lead much more isolated
lives.
In the lab, P. dentata worker ants typically live for around 140 days. Giraldo focused on ants
at four age ranges: 20 to 22 days, 45 to 47 days, 95 to 97 days and 120 to 122 days. Unlike
all previous studies, which only estimated how old the ants were, her work tracked the ants
from the time the pupae became adults, so she knew their exact ages. Then she put them
through a range of tests.
Giraldo watched how well the ants took care of the young of the colony, recording how
often each ant attended to, carried and fed them. She compared how well 20-day-old and
95-day-old ants followed the telltale scent that the insects usually leave to mark a trail to
food. She tested how ants responded to light and also measured how active they were by
counting how often ants in a small dish walked across a line. And she experimented with
how ants react to live prey: a tethered fruit fly. Giraldo expected the older ants to perform
poorly in all these tasks. But the elderly insects were all good caretakers and trail-
followers-the 95-day-old ants could track the scent even longer than their younger
counterparts. They all responded to light well, and the older ants were more active. And
when it came to reacting to prey, the older ants attacked the poor fruit fly just as
aggressively as the young ones did, flaring their mandibles or pulling at the fly's legs.
Then Giraldo compared the brains of 20-day-old and 95-day-old ants, identifying any cells that were close to death. She saw no major differences with age, nor was there any
difference in the location of the dying cells, showing that age didn't seem to affect specific
brain functions. Ants and other insects have structures in their brains called mushroom
bodies, which are important for 82 processing information, learning and memory. She also
wanted to see if aging affects the density of synaptic complexes within these structures-
regions where neurons come together. Again, the answer was no. What was more, the old
ants didn't experience any drop in the levels of either serotonin or dopamine-brain
chemicals whose decline often coincides with aging. In humans, for example, a decrease
in serotonin has been linked to Alzheimer's disease.
'This is the first time anyone has looked at both behavioral and neural changes in these
ants so thoroughly,' says Giraldo, who recently published the findings in the Proceedings
of the Royal Society B. Scientists have looked at some similar aspects in bees, but the
results of recent bee studies were mixed-some studies showed age-related declines,
which biologists call senescence, and others didn't. 'For now, the study raises more
questions than it answers,' Giraldo says, 'including how P. dentata stays in such good
shape.'
Also, if the ants don't deteriorate with age, why do they die at all? Out in the wild, the ants
probably don't live for a full 140 days thanks to predators, disease and just being in an
environment that's much harsher than the comforts of the lab. 'The lucky ants that do live
into old age may suffer a steep decline just before dying,' Giraldo says, but she can't say
for sure because her study wasn't designed to follow an ant's final moments.
'It will be important to extend these findings to other species of social insects,' says Gene
E. Robinson, an entomologist at the University of Illinois at Urbana-Champaign. This ant
might be unique, or it might represent a broader pattern among other social bugs with
possible clues to the science of aging in larger animals. Either way, it seems that for these
ants, age really doesn't matter.

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Questions 1-8
Complete the notes below.
Choose ONE WORD ONLY from the passage for each answer.
Write your answer in boxes 1 - 8 on your answer sheet.
Ysabel Giraldo's research
Focused on a total of 1................................ different age groups of ants, analyzing
Behaviour:
• how well ants looked after their 2 ................................
• their ability to locate 3.............................. using a scent trail
• the effect that 4................................ had on them
• how 5............................... They attacked prey
Brains:
• comparison between age and the 6................................. of dying cells in the brains of ants
• condition of synaptic complexes (areas in which 7................................. meet) in the brain's
'mushroom bodies'
• level of two 8................................ in the brain associated with ageing

Questions 9-13
Do the following statements agree with the information give in Reading Passage 1?
In boxes 9-13 on your answer sheet, write
TRUE if the statement agrees with the information
FALSE if the statement contradicts the information
NOT GIVEN if there is no information on this
9 Pheidole dentata ants are the only known animals which remain active for almost their
whole lives.
10 Ysabel Giraldo was the first person to study Pheidole dentata ants using precise data
about the insects' ages.
11 The ants in Giraldo's experiments behaved as she had predicted that they would.
12 The recent studies of bees used different methods of measuring age-related decline.
13 Pheidole dentata ants kept in laboratory conditions tend to live longer lives.