Answer:
1, Being hungry and thirsty tend to made the boys in poor nations become extremely aggressive toward one another.
This type of situation tend to be caused when resources are scarce. This caused a heavy competition among the boys to obtain the small amount of food available for them. This competition tend to make them become aggressive toward one another, and make them have higher tendencies to conduct violence.
2. Changes in behavior tend to be caused by either of these components : Biological (if it's caused by our bodily function) or Environmental (if it's caused by external factors surrounding us)
These changes tend to be unpredictable and occurs without people realizing it.
When people are forced to live under an extremely limited resources (this is considered as environmental factors that can change people's behavior) Their survival instincts will kick in. Under such circumstances, most people are willing to take extreme measures to ensure that the basic need of themselves and their loved ones are taken care of. Even if it has to happen on the expense of other.