Origins: The Mid Finger

According to Darwinian theory, in the course of the evolution of the homo sapien, the opposable thumb initially developed for the sole purpose of grasping tree branches. As the mind functionality evolved in the segue from homo erectus to sapien the use of the thumb was extended to holding tools and eventually wielding weapons.
As the social interaction between the sapien and neanderthals developed, the populations increased and the competition between them for food and mammoth skins also increased. At a disadvantage and with the impending threat of extinction from the ice age due to their unusual lack of body hair, the sapiens knew things had to change. They realized that by extending the arm and straightening the thumb with varying degrees in relation to the ground, it could act as a signal of sorts. Lacking a use or meaning attached to the signal, it was left to the members of the younger generation to experiment with.
Speculation among the archaeological community about use of this symbol indicates that the sapiens started a sport called "scalp the neanderthal" where after successful capture the hunters would stand in a semi circle around the unfortunate neanderthal. The leader would stride over the body with his arm outstretched in the thumb neutral position. He would close his eyes turn then stop. Then he'd open his eyes and rotate the hand. Whoever he was facing when the thumb became upright would have the pleasure of scalping the neandathal. It is widely accepted that this led to the extinction of the neanderthal as well as the development of the infamous thumbs-down signature of Caesar at coloseums after gladiator combat, and the much loved spin the bottle.
In addition the loved game of football/soccer was born after a sapien stumbled over the severed head of a fallen enemy. Trying to keep the head from rolling away a second sapien kicked it back to the first sapien, now lovingly known as "Clumsy" by the group of archaeologists who found his bones. This sport was refined by the Vikings and eventually developed to football as we know it.
At the same time, the seemingly useless mid metacarpal appendage adapted lengthwise, for the sole purpose of repelling annoyant green eyed variations of the homo sapien, who with the development of verbal communication came to be known as 'haters'.
An that is the murky past of the thumbs down and mid finger greeting. Next we'll cover the origin of the phrase "Give head"...