Bones are biological structural materials made of dynamically adaptable tissues. They can be considered as complex natural composite materials with load bearing constituents such as osteons and interstitial lamellae cemented with weak bonding materials. In addition, they contain Haversian and Volkmann canals that are functionally needed but are structurally weak. Because of large variation in microstructure, the strength of a bone varies from bone to bone and animal to animal. In this study the applicability of Weibull statistics to fracture strength of bones has been evaluated. The statistics is based on the weakest link theory and has been used successfully for probabilistic design of critical engineering structural components. The analysis shows that the statistics is valid when applied to each type of bone and it differentiates data from different types of bones. The analysis provides an insight in terms of how nature designs its load bearing structures by the process of natural selection.