Buzz
Such remarkable feats of defying aging are uncommon in the animal kingdom. Naked mole rats can live for nearly 30 years and remain healthy for most of their lives. They can reproduce even in old age and are resistant to cancer. However, the majority of animals, like humans, experience age-related deterioration. Like naked mole rats, ants are social creatures that live in highly organized colonies. 'It is this social complexity that makes P. dentata an ideal subject for studying aging in humans,' explains Giraldo, now at the California Institute of Technology. Humans, too, are highly social beings, a trait linked to healthier aging. In contrast, most animal studies on aging use mice, worms, or fruit flies, which lead more solitary lives.
In laboratory settings, P. dentata worker ants typically live for about 140 days. Giraldo focused on ants across four age groups: 20-22 days, 45-47 days, 95-97 days, and 120-122 days. Unlike previous studies that estimated ant ages, Giraldo tracked them from the pupae stage to adulthood, ensuring precise age determination. She then subjected them to various tests.
Giraldo observed the ants' caregiving behaviors towards the colony's young, documenting their frequency of attending, carrying, and feeding. She compared the abilities of 20-day-old and 95-day-old ants to follow the scent trails typically left by insects to mark food sources. She assessed their responsiveness to light and measured their activity levels by counting their movements across a defined line in a small dish. Additionally, she tested their reactions to live prey, such as tethered fruit flies. Giraldo anticipated that older ants would perform poorly in these tasks. However, the elderly ants proved adept at caregiving and following trails, with 95-day-old ants tracking scents longer than their younger counterparts. They exhibited robust responses to light stimuli, were highly active, and displayed aggressive behaviors towards prey, such as gripping the fly's legs or flaring their mandibles, much like their younger counterparts.
Next, Giraldo compared the brains of 20-day-old and 95-day-old ants, identifying any cells nearing death. She found no significant differences due to age, nor were there variations in the location of dying cells, indicating that specific brain functions were unaffected by age. Ants and other insects possess brain structures known as mushroom bodies, crucial for information processing, learning, and memory. Additionally, she investigated whether aging affected the density of synaptic complexes within these structures – regions where neurons connect. Once again, the answer was negative. Furthermore, older ants did not experience a decrease in serotonin or dopamine levels – brain chemicals whose decline often correlates with aging in humans, potentially linked to conditions like Alzheimer’s disease.
‘This is the most comprehensive study to date examining both behavioral and neural changes in these ants,’ remarked Giraldo, who recently published her findings in the Proceedings of the Royal Society B. While scientists have explored similar aspects in bees, recent bee studies have yielded mixed results – some indicated age-related declines, termed senescence by biologists, while others did not. 'Currently, the study raises more questions than answers,' says Giraldo, 'including how P. dentata manages to maintain such remarkable health.'
Moreover, if these ants do not deteriorate with age, why do they eventually die? In the wild, predators, diseases, and the harsh natural environment likely prevent ants from reaching their full 140-day lifespan observed in laboratory conditions. ‘Those fortunate enough to survive to old age may experience a sudden decline just before death,’ suggests Giraldo, though her study was not designed to track the ants' final moments.
‘It will be crucial to extend these findings to other species of social insects,’ emphasizes Gene E. Robinson, an entomologist at the University of Illinois at Urbana-Champaign. P. dentata may represent either a unique case or a broader pattern among other social insects, potentially offering insights into the science of aging in larger animals. Regardless, it appears that age truly does not matter for these ants.
Questions 1-8
Conclude 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 statements below agree with the information provided 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.
Response
1. four/4
2. youthful
3. cuisine
4. bright
5. assertively
6. place
7. nerve cells
8. substances
9. not true
10. accurate
11. not accurate
12. NOT STATED
13. CORRECTIELTS Exam Preparation
