29 – Beginning of slow human growth and extended development
300,000 years ago
The human growth pattern is unique among all mammals on the planet, including our primate cousins. Compared to our closest living relatives, the chimpanzees, our offspring have a longer juvenile period as part of an overall growth timeline that is very prolonged. However, we know that by around 300,000 years ago, human growth first started following the same basic trajectory that it does today. We can study this growth rate through the patterns of tooth formation, in particular, by investigating a tooth’s hard, outer coating of enamel, which grows in increments, leaving growth lines, similar to rings within a tree. By studying the rate of growth from these enamel growth lines, scientists determined that around 300,000-year-old Homo sapiens individual had the same exact pattern of prolonged tooth development and eruption times as in modern human children.
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Environmental and Climate Changes
Earth’s climate remains relatively stable with alternating glacial and interglacial periods