It is important to note that variations in size, not just an increase in size over that of earlier hominins, is characteristic of H. erectus, much like living humans.
One of the traits most commonly associated with Homo erectus is an increase in body size. The Nariokotome specimen, an adolescent male individual, was over five feet tall at the time of his death (Walker & Leakey 1993; Figures 3 & 4). Estimates of his adult stature, had he continued to live to adulthood, differ depending on how researchers estimate his age at death based on his teeth and bones (for more see Smith & Alemseged NKP article LINK HERE) and the amount of growth he had left. Living humans generally experience a marked increase in growth during early adolescence (i.e., a ‘growth spurt'), a growth pattern that some researchers say distinguishes us from other apes. If early H. erectus had a human-like growth spurt, Nariokotome likely had a lot of growing left to do. Even if H. erectus did not have such a modern human-like pattern of growth, the specimen was clearly a tall individual relative to earlier hominins. Not all H. erectus were tall, however, as earlier fossils remains from sites like Olduvai Gorge in Tanzania and Dmanisi, Georgia, attest. It is important to note that variations in size, not just an increase in size over that of earlier hominins, is characteristic of H. erectus, much like living humans.