28 – Oldest human fossils discovered
300,000 years ago
In the fossil record, it can be a daunting task to identify exactly when a fossil species appeared. Often, evolution is a gradual process, and determining when exactly a species is so different from its ancestors that it now warrants a new name is challenging. For humans, we have only a single anatomical feature which differentiates us from all other hominins: the bony chin. No other hominin species has a chin that juts forward as ours does. So, when fossils were found at the site Jebel Irhoud in Morocco dating to 300,000 years ago that possessed bony chins, this unique feature helped scientists determine that these fossils are the oldest Homo sapiens fossils known.
Image credit https://www.nature.com/articles/nature.2017.22114
Environmental and Climate Changes
Earth’s climate remains relatively stable with alternating glacial and interglacial periods