In an African reservation for orphaned elephants, the young (<21 yrs old) males grew aggressive, even killing rhinoceros at the waterhole.
Until two much older, senior, still strong, male elephants have been brought there, on purpose.
Aggressivity stopped. Do you wonder why?
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http://www.youtube.com/watch?v=cX6iEBvDd_Q
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In Louisiana, if I remember correctly a radio program, 85% of the prison population grew up without the [biological] father, and most of them without any father whatsoever.
