You forget that with most other animal species the young mature very fast.  You also forget, even though you quoted the line, that the article states, "engage in oral sex with each other."  It said nothing about sex with adults.  You also may not be aware that sexual experimentation is quite common among human prepubescents, though as a society we attempt to curb that behavior.  You didn't comment on this but you may also want to consider that in most other animal species their isn't a "weaker sex" so rape is usually not a consideration since the would-be rapist might just as likely get their ass whooped if their intended is not amenable.