[angkor]

traits which can NOT be explained as being a result of selective evolutionary pressures, as language can.

Expand on that statement when you have a moment.

[RightWingAtheist]

All humans have the same brain structure, but reading and writing are not found across all cultures the way spoken and gesutral languages are, nor is there any satisfactory explanation as to account for how reading, writing and drawing might have evolved through selective pressure. They are exaptated, as opposed to evolved traits, which arise through the co-option of one feature for a purpose other than the evolved one. A good example of an exaptated feature are the hammer, anvil and stirrup bones in the inner ear, which are found in all mammals. These were originally part of the jawbones of our reptilian ancestors, and wound being pushed in to the ear as the jaw evolved into a more efficent single-boned structure for chewing. You can feel this evolutionary legacy every time you sit down to a meal-the reason you can't follow a conversation while chewin and swallowing is because your jaw keeps jutting upwards into the ear canal.