Feathers are outgrowths of the skin characteristic of birds, which are generally believed to have evolved from reptilian scales in the Mesozoic era. The structures are primarily composed of the fibrous protein keratin and are flexible, lightweight, and durable.

Beautiful and functional, feathers develop from tiny papillae embedded in follicles and receive nourishment from the blood vessels in the dermis. When a feather achieves its full size, the blood supply is discontinued and the central shaft of the structure becomes hollow. If a feather is lost through molting or pulling, the thyroid gland of the bird secretes a chemical that provokes the appropriate papilla to form a new feather.

Down feathers are the soft, fluffy feathers that first appear on young birds and that also form the protective undercoat of many avian adults. Slightly different in structure, down feathers do not feature the interlocking barbs that help give other types of feathers their strength. However, since their primary function is to provide warmth and insulation, their relative weakness is inconsequential. In fact, down feathers are so well-suited to their role as insulators, humans often utilize them to stuff winter coats and bedding, such as comforters and sleeping bags.

Perhaps due to the long held human dream of flight, humans have historically held feathers in an almost supernatural light. In ancient Egypt, for instance, feathers were representative of truth, and it was believed that the winged goddess Ma’at weighed the souls of the dead against a feather in order to determine their fate. If the deceased proved to be light as a feather, he or she was granted passage into the afterlife. Feathers were also venerated by many Native American tribes, who particularly revered those that once belonged to bald eagles due to their admiration of the birds’ strength and courage. Bald eagle feathers were awarded as symbols of great deeds and to warriors who performed heroic acts.

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