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NOVA: Becoming Human | Diatoms Measure Climate Change

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Learn how scientists used the fossils of one-celled aquatic organisms, called diatoms, to understand ancient climate conditions in eastern Africa, in this video from NOVA: Becoming Human. White layers of a rock formation consist of deep-water diatoms and darker layers consist of shallow-water diatoms; the scientists interpreted the alternating layers in the formation to mean that a massive lake appeared and disappeared many times in their study area. If this part of Africa indeed experienced wet and dry periods over time, this supports a new idea that suggests climatic variability may have shaped human evolution.

This video is available in both English and Spanish audio, along with corresponding closed captions.

When Did the First Americans Arrive?

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Who were the first Americans, when did they arrive, and from where did they come? With limited evidence, scientists have long proposed a hypothesis that linked the migration route and the timing of the migration these ancient people to the end of the last ice age. However, new evidence suggests that this widely accepted hypothesis needs revision. This video segment adapted from NOVA describes how archaeologists are using this new evidence to develop a better understanding of the founding of the Americas.