[1967 R50/2]

I speak German, Mandarin and English...the first two learned as adults.

Scientifically, languages are easier to learn when you are a child. Your brain is somehow geared for it. Once you hit puberty, this ability almost disappears.

With that said, in the the western hemisphere, you really only need two languages: English and Spanish. Sure, you will run into Portugese, French and Quecha in spots, but really you could travel from the Terra del Fuego to the Bering Sea and only speak English and Spanish. Nowhere else in the world could you travel such a distance and rely only on one or two languages.