A human being should be able to change a diaper, plan an invasion, butcher a hog, conn a ship, design a building, write a sonnet, balance accounts, build a wall, set a bone, comfort the dying, take orders, give orders, cooperate, act alone, solve equations, analyze a new problem, pitch manure, program a computer, cook a tasty meal, fight efficiently, die gallantly.
Specialization is for insects.
T hose pictures are perfect for backgrounds because they are rather dark or uniform. They don't mess your desktop very much. Read the copyright notice . And try to understand it, too. All the pictures are in 16 million colors and should show well on 65536 colors monitors.