A new analysis of a well-preserved Neandertal child's skeleton reveals that Neandertals may have had extended period of brain growth compared to modern humans. An understanding of our Neandertal cousins can provide important insights into our own biology. Of particular interest are differences in brain size. Some studies have proposed that a larger brain in Neandertals can be explained by a faster rate of early postnatal growth, yet others have proposed a longer growth rate instead. Here, Antonio Rosas and colleagues describe a juvenile Neandertal skeleton from the 49,000-year-old site of El Sidrón, in Spain. The specimen, dubbed El Sidrón J1, exhibits an exceptionally well-preserved mix of baby and adult teeth, providing a rare opportunity to estimate an age at death from daily dental incremental markings preserved in teeth -- leading the team to estimate that the child died at 7.69 years of age. Analysis of El Sidrón J1 reveals that some vertebrae had still not fused in the 7-year-old Neandertal, yet these same vertebrae tend to fuse in modern day humans around the ages of 4 to 6. Interestingly, the brain of El Sidrón J1 was roughly 87.5% of the size of an average adult Neandertal brain upon death, whereas modern humans tend to have on average 95% of adult brain weight by that same age. The authors suggest that the unique pattern of vertebral maturation and extended brain growth might reflect the broad Neandertal body form and physiology, rather than a fundamental difference in the overall pace of growth in Neandertals.