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People tend to categorize snakes as either venomous or harmless , but , as colubrids demonstrate , the reality is a continuum , from completely harmless , to mildly venomous , to deadly . The case has already been made for endangered languages as a subject worth linguistic attention in recent works such as Crystal ( 2000 ) and Nettle and Romaine ( 2000 ) , as well as the seminal Krauss ( 1992 ) . By age 13 , a dramatic shift occurs , and more than twice as many girls as boys are depressed , a proportion that persists into adulthood.1 This two-to-one ratio exists regardless of racial or ethnic background and has been reported in other countries . As a result they fail to recognize the warning signs . Fortunately , professional societies such as SBL , AAR , ASOR , APA , MLA , and others have made various attempts to expose their memberships to these developments to some degree , although perhaps not always as consistently as might be wished . The bulk of his discussion centers on pre - and post-Jihad factors leading to this language shift , such as ethnic hostility , natural catastrophe , conversion to Islam , intermarriage , diminished language loyalty , government policy , etc. On the positive side , educated Gurdung people have developed a Gurdung language association , the language is being taught formally , and Haruna himself is publishing a grammar of Gurdung he hopes will contribute to its preservation . He discusses Gurdung 's basic classification as well as historical migrations such as those forced by the Hausa / Fulani Jihad in the 18th century . However , there are entire endangered families such as Khoe and Kordofanian , as well as 8 endangered isolates . Medications such as monoamine oxidase inhibitors , tricyclic anti-depressants and SSRI 's ( Selective Serotonin Reuptake Inhibitors ) have been utilized successfully , particularly with adolescents with a family history of depression .