Through the language glass

is an excellent book edited by Guy Deutscher (isbn 978-0-8050-8195-4). As usual I'm going to quote from a few pages:
In the meantime, The Origin of Species had appeared and Darwinism had conquered the collective psyche. As George Bernard Shaw later wrote, "Everyone who had a mind to change changed it."
The Lamarckian nature of Magnus's model now emerged as just one of the gaping holes in his Emmental of a theory.
People find names for the things they feel the need to talk about.
In a large society of strangers there will be many more occasions where elaborate information has to be conveyed without reliance on shared background and knowledge.
"What fetters the mind and benumbs the spirit… the dogged acceptance of absolutes." [Edward Sapir]
Languages differ essentially in what they must convey and not in what they may convey.
The Matses… have to be master epistemologists. There are separate verbal forms depending on whether you are reporting direct experience (you saw someone passing by with your own eyes), something inferred from evidence (you saw footprints on the sand), conjecture (people always pass by at that time of day), or hearsay (your neighbour told you he had seen someone passing by).
Guugu Yimithirr… does not make any use of egocentric coordinates [eg left, right] at all! … Whenever we would use the egocentric system, the Guugu Yimithirr use the four cardinal directions: gungga (North), jiba (South), guwa (West), and naga (East. … They maintain their orientation with respect to the fixed cardinal directions at all times. Regardless of visibility conditions, regardless of whether they are in a thick forest or on an open plain, whether indoors or outside, whether stationary or moving, they have a spot-on sense of direction.
John Haviland estimates that as many as one word in ten (!) in a normal Guugu Yimithirr conversation is north, south, west, or east, often accompanied by very precise hand gestures. … Everyday communication in Guuga Yimithirr provides the most intense drilling in geographic orientation from the earliest imaginable age.
The conventional predictions are that within two or three generations at least half the world's six thousand languages will have disappeared.
Each step in this chain was natural and made perfect sense in its own local context. But the end result seems entirely arbitrary.
The worst thing about this loss of transparency is that it is a self propelling process: the less consistent the system becomes, the easier it is to mess it up even further.
Until the eleventh century, English had a full-blown three-gender system just like German.