A skull appears white due to the natural color of bone, which is yellowish-white or beige, combined with taphonomic processes that can lighten the bone's color over time.
Natural Bone Color
- Composition: Fresh bone contains lipids and other organic components that give it a yellowish-white to beige hue (Dupras & Schultz 2014, Schafer 2001).
- Not Pure White: Bone is not naturally a stark white color when it's fresh.
Taphonomic Processes and Color Change
- Weathering: When a skull is exposed to the elements (sun, rain, soil), various taphonomic processes cause it to lighten and often appear whiter (Dupras & Schultz 2014, Pollock 2017, Pollock et al.22-Oct-2024).
- Bleaching: Sunlight bleaches the bone, reducing the intensity of the original yellowish or beige color.
- Mineral Changes: Mineral alterations within the bone structure, due to environmental interaction, can also contribute to a lighter, whiter appearance.
- Staining: Note that staining from soil or other substances can also affect bone color, sometimes darkening it rather than lightening it. However, the idealized "white skull" is usually the result of bleaching and weathering.
In Summary
The white color of a skull is a result of its natural yellowish-white bone composition being further lightened by environmental factors like sunlight and weathering, which bleach the bone and alter its mineral structure over time.
