Paranthropus boisei and Paranthropus robustus are remarkably similar in cranial and dentognathic features, yet their distinct microwearMicrowear features and carbon isotopeIsotopes (Stable)carbon compositions suggest strong ecological distinctions. To compare ecological niches in more detail using concepts from isotopic ecologyEcology theory, we use published isotope data to explore their patterns of inter-individual variabilityInter-individual variability along with those of other Plio-Pleistocene hominins. We address niche breadthNichebreadth by quantifying inter-individual isotopic variability using the following approaches: Inter-Quartile Range (δ13C), Standard Ellipse Area calculated using SIBER (δ13C, δ18O), Kernel Utilization Density using rKIN (δ13C, δ18O), and probabilistic niche region using nicheROVER (δ13C, δ18O and 44Ca/42Ca). All approaches suggest variability among Pliocene-Pleistocene hominins that includes relatively high niche breadthNichebreadth for mid-Pliocene australopiths from the Turkana BasinTurkana Basin, Paranthropus aethiopicus and most prominently, early Homo, while Paranthropus robustus and later Paranthropus boisei show relatively narrower niches and appear ecologically and adaptively distinct from other African early hominins.