At what developmental stage do males and females show different patterns of iliac crest fusion?

The differentiation in patterns of iliac crest fusion between males and females typically occurs during adolescence. This stage is characterized by significant growth and developmental changes, where sexual dimorphism becomes increasingly evident. In males, the iliac crest tends to fuse later than in females due to differences in hormonal influences and growth patterns.

During adolescence, estrogen in females contributes to earlier closure of growth plates, while testosterone in males allows for prolonged growth and delayed fusion. As a result, the timing of iliac crest fusion can be used in forensic contexts to assess the biological sex of skeletal remains, as these fusions present distinct timelines that correlate with gender.

In other developmental stages like middle childhood and late childhood, the anatomical features and growth patterns have not yet diverged sufficiently to exhibit clear differences in iliac crest fusion. Early adulthood, while also a time for fusion, is not when the primary differentiation is first observed. Therefore, adolescence is the key period when males and females start showing distinct patterns in this regard.