Animals having grown accustomed to lives of easy food, water and (sometimes) shelter are having a difficult time adjusting to the life that they were born to lead.
The articles notes;
"The animals were also more susceptible to starvation and disease than their wild animal counterparts and less able to form successful social groups."
"Their lack of hunting skills and their lack of fear towards humans, for example, are major disadvantages."
Most people have seen the movie Trading Places.
In the movie, Dan Akroid's character ultimately surrenders to his new condition and learns to adapt from there.
He has to learn lessons that his social groups failed to teach.
Mortimer and Randolf have became so fat and comfortable that they forgot how to hunt.
In the movie Coming To America, we see them in a pitiful state - begging for crumbs.
Their "knowledge" of the workings of the world seems to have failed them in a new social structure.
Since the financial bubble burst - why are many having problems coping with a life without pampering?
Why the suicides and killings?
Maybe, they too - forgot how to hunt.