An extended period of childhood evolved [in] people at least 160,000 years ago, according to a new analysis of a fossil child's teeth. That's the earliest evidence to date of a modern-human life history requiring intensive parental care and a wide range of early-life learning opportunities, the researchers say.
<...>
Tanya Smith's team examined an erupted molar, an incisor in the process of erupting, and a canine that had yet to erupt in the jaw of the Jebel Irhoud child. Tallies of enamel layers that typically form every 7 to 9 days as teeth develop, as well as counts of daily growth bands in the enamel, enabled the scientists to estimate that the child died at age 7 years, 10 months.
From
here.