Background: A dilution effect is seen when animals living in a group "dilute" their risk of attack, each individual being just one of many in the group. George C. Williams and W.D. Hamilton proposed that group living evolved because it provides benefits to the individual rather than to the group as a whole, which becomes more conspicuous as it becomes larger. One common example is the shoaling of fish. Experiments provide direct evidence for the decrease in individual attack rate seen with group living, for example in Camargue horses in Southern France. The horse-fly often attacks these horses, sucking blood and carrying diseases. When the flies are most numerous, the horses gather in large groups, and individuals are indeed attacked less frequently. Water striders are insects that live on the surface of fresh water, and are attacked from beneath by predatory fish. Experiments varying the group size of the water striders showed that the attack rate per individual water strider decreases as group size increases.

Situation: Kenya's Masai Mara wildebeest migration is one of the greatest spectacles in the natural world. Every year thousands of wildebeests cross the Mara river. John went to see the migration last year. He noticed that the wildebeests crossed the the river in a very large group. He noted that as case A. His guide told him that is not the case in other times of the year. The wildebeests cross the river in smaller groups in other times. John noted that as case B. The guide added that in both cases on thing is constant, they are attacked by the lions.

Question: In which case wildebeests would have lower risk of attack from the lions, case A or case B?
Answer: case A

Situation: Kenya's Masai Mara wildebeest migration is one of the greatest spectacles in the natural world. Every year thousands of wildebeests cross the Mara river. John went to see the migration last year. He noticed that the wildebeests crossed the the river in a very large group. He noted that as case A. His guide told him that is not the case in other times of the year. The wildebeests cross the river in smaller groups in other times. John noted that as case B. The guide added that in both cases on thing is constant, they are attacked by the lions.

Question: In which case wildebeests would have higher risk of attack from the lions, case A or case B?
Answer: case B

Situation: Kenya's Masai Mara wildebeest migration is one of the greatest spectacles in the natural world. Every year thousands of wildebeests cross the Mara river. John went to see the migration last year. He noticed that the wildebeests crossed the the river in a very large group. He noted that as case A. His guide told him that is not the case in other times of the year. The wildebeests cross the river in smaller groups in other times. John noted that as case B. The guide added that in both cases on thing is constant, they are attacked by the lions.

Question: In case A would the wildebeests have lower or higher risk of attack from the lions than in case B?
Answer: lower

Situation: Kenya's Masai Mara wildebeest migration is one of the greatest spectacles in the natural world. Every year thousands of wildebeests cross the Mara river. John went to see the migration last year. He noticed that the wildebeests crossed the the river in a very large group. He noted that as case A. His guide told him that is not the case in other times of the year. The wildebeests cross the river in smaller groups in other times. John noted that as case B. The guide added that in both cases on thing is constant, they are attacked by the lions.

Question: In case B would the wildebeests have lower or higher risk of attack from the lions than in case A?
Answer: higher

Situation: Kenya's Masai Mara wildebeest migration is one of the greatest spectacles in the natural world. Every year thousands of wildebeests cross the Mara river. John went to see the migration last year. He noticed that the wildebeests crossed the the river in a very large group. He noted that as case A. His guide told him that is not the case in other times of the year. The wildebeests cross the river in smaller groups in other times. John noted that as case B. The guide added that in both cases on thing is constant, they are attacked by the lions.

Question: In which case an individual wildebeest would get more benfit, case A or case B?
Answer: case A

Situation: Kenya's Masai Mara wildebeest migration is one of the greatest spectacles in the natural world. Every year thousands of wildebeests cross the Mara river. John went to see the migration last year. He noticed that the wildebeests crossed the the river in a very large group. He noted that as case A. His guide told him that is not the case in other times of the year. The wildebeests cross the river in smaller groups in other times. John noted that as case B. The guide added that in both cases on thing is constant, they are attacked by the lions.

Question: In which case an individual wildebeest would get less benfit, case A or case B?
Answer: case B

Situation: Kenya's Masai Mara wildebeest migration is one of the greatest spectacles in the natural world. Every year thousands of wildebeests cross the Mara river. John went to see the migration last year. He noticed that the wildebeests crossed the the river in a very large group. He noted that as case A. His guide told him that is not the case in other times of the year. The wildebeests cross the river in smaller groups in other times. John noted that as case B. The guide added that in both cases on thing is constant, they are attacked by the lions.

Question: In case A, would an individual wildebeest get less or more benfit than in case B?
Answer: more

Situation: Kenya's Masai Mara wildebeest migration is one of the greatest spectacles in the natural world. Every year thousands of wildebeests cross the Mara river. John went to see the migration last year. He noticed that the wildebeests crossed the the river in a very large group. He noted that as case A. His guide told him that is not the case in other times of the year. The wildebeests cross the river in smaller groups in other times. John noted that as case B. The guide added that in both cases on thing is constant, they are attacked by the lions.

Question: In case B, would an individual wildebeest get less or more benfit than in case A?
Answer: less

Situation: Kenya's Masai Mara wildebeest migration is one of the greatest spectacles in the natural world. Every year thousands of wildebeests cross the Mara river. John went to see the migration last year. He noticed that the wildebeests crossed the the river in a very large group. He noted that as case A. His guide told him that is not the case in other times of the year. The wildebeests cross the river in smaller groups in other times. John noted that as case B. The guide added that in both cases on thing is constant, they are attacked by the lions.

Question: Which case would see the dilution effect working better, case A or case B?
Answer: case A

Situation: Kenya's Masai Mara wildebeest migration is one of the greatest spectacles in the natural world. Every year thousands of wildebeests cross the Mara river. John went to see the migration last year. He noticed that the wildebeests crossed the the river in a very large group. He noted that as case A. His guide told him that is not the case in other times of the year. The wildebeests cross the river in smaller groups in other times. John noted that as case B. The guide added that in both cases on thing is constant, they are attacked by the lions.

Question: Which case would see the dilution effect not working better, case A or case B?
Answer: case B

Situation: Mike was visiting the African Savannah. One animal that interested him most was the African Buffalo. He noticed that the buffaloes would usually live in a large herd, often exceeding few hundreds. He noted that as case A. But sometimes the buffaloes would live in a small herd. He noted that as case B. Interestingly, there are incidents when an aggressive male buffalo would live by itself. He noted that as case C.

Question: In which case an individual buffalo would have higher risk of attack, case A or case B?
Answer: case B

Situation: Mike was visiting the African Savannah. One animal that interested him most was the African Buffalo. He noticed that the buffaloes would usually live in a large herd, often exceeding few hundreds. He noted that as case A. But sometimes the buffaloes would live in a small herd. He noted that as case B. Interestingly, there are incidents when an aggressive male buffalo would live by itself. He noted that as case C.

Question: In which case an individual buffalo would have lower risk of attack, case A or case B?
Answer: case A

Situation: Mike was visiting the African Savannah. One animal that interested him most was the African Buffalo. He noticed that the buffaloes would usually live in a large herd, often exceeding few hundreds. He noted that as case A. But sometimes the buffaloes would live in a small herd. He noted that as case B. Interestingly, there are incidents when an aggressive male buffalo would live by itself. He noted that as case C.

Question: In case A, would an individual buffalo have lower or higher risk of attack than in case B?
Answer: lower

Situation: Mike was visiting the African Savannah. One animal that interested him most was the African Buffalo. He noticed that the buffaloes would usually live in a large herd, often exceeding few hundreds. He noted that as case A. But sometimes the buffaloes would live in a small herd. He noted that as case B. Interestingly, there are incidents when an aggressive male buffalo would live by itself. He noted that as case C.

Question: In case B, would an individual buffalo have lower or higher risk of attack than in case A?
Answer: higher

Situation: Mike was visiting the African Savannah. One animal that interested him most was the African Buffalo. He noticed that the buffaloes would usually live in a large herd, often exceeding few hundreds. He noted that as case A. But sometimes the buffaloes would live in a small herd. He noted that as case B. Interestingly, there are incidents when an aggressive male buffalo would live by itself. He noted that as case C.

Question: In which case the group would get more benefit as a whole, case A or case B?
Answer: case B

Situation: Mike was visiting the African Savannah. One animal that interested him most was the African Buffalo. He noticed that the buffaloes would usually live in a large herd, often exceeding few hundreds. He noted that as case A. But sometimes the buffaloes would live in a small herd. He noted that as case B. Interestingly, there are incidents when an aggressive male buffalo would live by itself. He noted that as case C.

Question: In which case the group would get less benefit as a whole, case A or case B?
Answer: case A

Situation: Mike was visiting the African Savannah. One animal that interested him most was the African Buffalo. He noticed that the buffaloes would usually live in a large herd, often exceeding few hundreds. He noted that as case A. But sometimes the buffaloes would live in a small herd. He noted that as case B. Interestingly, there are incidents when an aggressive male buffalo would live by itself. He noted that as case C.

Question: In case A, would the group get less or more benefit as a whole than in case B?
Answer: less

Situation: Mike was visiting the African Savannah. One animal that interested him most was the African Buffalo. He noticed that the buffaloes would usually live in a large herd, often exceeding few hundreds. He noted that as case A. But sometimes the buffaloes would live in a small herd. He noted that as case B. Interestingly, there are incidents when an aggressive male buffalo would live by itself. He noted that as case C.

Question: In case B, would the group get less or more benefit as a whole than in case A?
Answer: more

Situation: Mike was visiting the African Savannah. One animal that interested him most was the African Buffalo. He noticed that the buffaloes would usually live in a large herd, often exceeding few hundreds. He noted that as case A. But sometimes the buffaloes would live in a small herd. He noted that as case B. Interestingly, there are incidents when an aggressive male buffalo would live by itself. He noted that as case C.

Question: In which case the dilution effect would not work, case B or case C?
Answer: case C

Situation: Mike was visiting the African Savannah. One animal that interested him most was the African Buffalo. He noticed that the buffaloes would usually live in a large herd, often exceeding few hundreds. He noted that as case A. But sometimes the buffaloes would live in a small herd. He noted that as case B. Interestingly, there are incidents when an aggressive male buffalo would live by itself. He noted that as case C.

Question: In which case the dilution effect would work, case B or case C?
Answer: case B