Why topics are called cancer copics capricorn

E Tropic of Capricorn or Southern tropic is one of the five major circles of latitude that mark maps of the Earth. It is the parallel of latitude at 23° 26′ 22″ south of the Equator, and is the farthest southern latitude that the sun can appear directly overhead, occurring on the December solstice. Its northern hemisphere equivalent is the Tropic of Cancer. Latitudes south of the Tropic of Capricorn are in the Southern Temperate Zone. North of this line are the Tropics. 

The Tropic of Capricorn is so named because about 2000 years ago the sun was entering the constellation Capricornus on the December solstice. In modern times the sun appears in the constellation Sagittarius during this time. The change is due to precession of the equinoxes. 

The Tropic of Cancer (cancer is Latin for crab), or Northern tropic is one of the five major circles of latitude that mark maps of the Earth. It is the parallel of latitude that lies currently 23° 26′ 22″ north of the Equator. 

Ithink its deforestation.