How much more would KNM-WT 15000 have grown?

Area of Science:

• Paleoanthropology
• Human Evolution
• Skeletal Biology

Background:

• The exceptionally complete juvenile Homo ergaster/erectus fossil, KNM-WT 15000, is crucial for understanding human evolution.
• Previous adult size estimations for KNM-WT 15000 relied on modern human growth models.
• Newer evidence suggests KNM-WT 15000 may have followed a more chimpanzee-like growth trajectory.

Purpose of the Study:

• To re-estimate the adult stature and body mass of Homo ergaster/erectus KNM-WT 15000.
• To utilize ontogenetic data from African apes to inform growth trajectory models.
• To compare estimated adult size with known Early Pleistocene hominin body sizes.

Main Methods:

• Collected ontogenetic data from four African ape taxa (chimpanzees and gorillas).
• Measured changes in femoral length, tibial length, and femoral head breadth from juvenile to adult stages.
• Applied ape growth models to KNM-WT 15000's developmental stage (M2 eruption, M3 not erupted).

Main Results:

• Estimated adult stature for KNM-WT 15000 ranges from 176-180 cm.
• Estimated adult body mass for KNM-WT 15000 ranges from 80-83 kg.
• These estimates align with chimpanzee growth patterns and indicate KNM-WT 15000 was not unusually large for his time.

Conclusions:

• Homo ergaster/erectus KNM-WT 15000 likely reached an adult stature near 180 cm and body mass around 80 kg.
• African ape growth models provide a more accurate framework for estimating KNM-WT 15000's adult size.
• The estimated size of KNM-WT 15000 is consistent with other Early Pleistocene East African hominins.