For a period of 2 million years, ending with the last ice age around 10,000 B.C.,
the Earth experienced a series of convulsive glacial events. This
rapid-fire climate change meant that humans couldn’t rely on consistent
patterns to know which animals to hunt, which plants to gather, or even
which predators might be waiting around the corner.

How did we cope? By getting smarter. The neuro­physi­ol­ogist
William Calvin argues persuasively that modern human
cognition–including sophisticated language and the capacity to plan
ahead–evolved in response to the demands of this long age of
turbulence. According to Calvin, the reason we survived is that our
brains changed to meet the challenge: we transformed the ability to
target a moving animal with a thrown rock into a capability for
foresight and long-term planning. In the process, we may have developed
syntax and formal structure from our simple language. — Jamais Cascio, The Atlantic