which may be related to how H. antecessor walked. The long trochlea caused a short neck of the talus, which bridges the head of the talus connecting to the toes, and the body of the talus connecting to the leg. This somewhat converges with the condition exhibited in Neanderthals, which is generally explained as a response to a heavy and robust body, to alleviate the consequently higher stress to the articular cartilage in the ankle joint. This would also have permitted greater flexion. Growth rate In 2010 Castro and colleagues estimated that ATD6-112, represented by a permanent upper and lower first molar, died between 5.3 and 6.6 years of age based on the tooth formation rates in chimpanzees (lower estimate) and modern humans (upper). The molars are hardly worn at all, which means the individual died soon after the tooth erupted, and that first molar eruption occurred at roughly this age. The age is within the range of variation of modern humans, and this developmental landmark can debatably be correlated with life history. If the relation is true, H. antecessor had a prolonged childhood, a characteristic of modern humans in which significant cognitive development takes place. Pathology The partial face ATD6-69 has an ectopic M3 (upper left third molar), where it erupted improperly, and this caused the impaction of M2, where it was blocked from erupting at all. Although impaction of M3 is rather common in modern humans, as high as fifty percent in some populations, impaction of M2 is rare, as little as 0.08 to 2.3%. Impaction can lead to secondary lesions, such as dental cavities, root resorption, or dentigerous or keratocysts. The mandible ATE9-1 exhibits severe dental attrition and abrasion of the tooth crowns and bone resorption at the root, so much so that the root canals (the sensitive interior) of the canines are exposed. The trauma is consistent with gum disease due to overloading the teeth, such as by using the mouth as a third hand to carry around items. A similar condition was also reported for the later Sima de los Huesos remains also at the Sierra de Atapuerca site. The left knee bone ATD6-56 has a height x breadth osteophyte (bone spur) on the inferior (lower) margin. Osteophytes normally form as a response to stress due to osteoarthritis, which can result from old age or improper loading of the joint as a consequence of bone