Harvester-ant colonies live for fifteen to twenty years, though individual worker ants live only a year. The way a colony...
GMAT Critical Reasoning : (CR) Questions
Harvester-ant colonies live for fifteen to twenty years, though individual worker ants live only a year. The way a colony behaves changes steadily in a predictable pattern as the colony grows older and larger. For the first few years, the foragers behave quite aggressively, searching out and vigorously defending new food sources, but once a colony has reached a certain size, its foragers become considerably less aggressive.
If the statements above are true, which of the following can most properly be concluded on the basis of them?
Passage Visualization
| Passage Statement | Visualization and Linkage |
|---|---|
| Harvester-ant colonies live for fifteen to twenty years, though individual worker ants live only a year. | Establishes: Temporal framework and generational turnover
|
| The way a colony behaves changes steadily in a predictable pattern as the colony grows older and larger. | Establishes: Behavioral evolution follows age/size correlation
|
| For the first few years, the foragers behave quite aggressively, searching out and vigorously defending new food sources, but once a colony has reached a certain size, its foragers become considerably less aggressive. | Establishes: Specific behavioral pattern - aggression decreases with maturity
|
| Overall Implication | CORE PATTERN REVEALED: Despite complete worker turnover every year, colony behavior follows predictable age-based patterns. This creates a paradox: individual experience cannot explain behavioral changes since no worker lives long enough to learn colony-wide patterns, yet collective behavior evolves systematically over the 15-20 year lifespan. The behavioral programming must be transmitted through mechanisms beyond individual ant learning. |
Valid Inferences
Inference: Colony behavior patterns are maintained and transmitted through mechanisms that operate independently of individual worker ant experience or learning.
Supporting Logic: Since individual worker ants live only one year while colonies exhibit predictable behavioral changes over 15-20 years, and since these behavioral changes follow consistent patterns (from aggressive to less aggressive foraging), the behavioral evolution cannot be explained by individual ant learning or experience. Therefore, the colony must have systematic ways of transmitting behavioral information that transcend the lifespan of any individual worker.
Clarification Note: The passage supports that behavior changes occur independently of individual worker experience, but does not specify the actual mechanisms (genetic, chemical, structural, etc.) responsible for this behavioral transmission across generations of workers.
This talks about colonies not growing larger due to pressure from neighbors. However, the passage doesn't mention anything about neighbor pressure or factors that might prevent colony growth. This introduces new information not supported by the passage and doesn't follow from what we're told about the predictable behavioral patterns.
This discusses unpredictable environmental changes affecting colony tasks. The passage actually emphasizes that behavioral changes follow a 'predictable pattern' as colonies age, and doesn't mention unpredictable environmental factors or task changes. This contradicts the predictable nature described in the passage.
This suggests mature colonies go extinct because younger, more aggressive colonies outcompete them for food. The passage tells us colonies live 15-20 years and become less aggressive over time, but it doesn't explain why they eventually die or mention competition between colonies as a cause of death. This goes beyond what we can conclude from the given information.
This states that the behavioral pattern doesn't arise from changes in individual worker ant behavior. This is exactly what we can conclude! Since individual workers live only one year but the colony shows behavioral changes over 15-20 years, and since the colony goes through complete worker turnover annually, the long-term behavioral patterns cannot be explained by any individual worker's behavior or experience. The pattern must emerge from colony-level factors independent of individual workers.
This describes how new colonies form through young workers leaving mature colonies. The passage doesn't provide any information about how new colonies are established or mention workers leaving to form new colonies. This introduces completely new information not supported by the passage.