Answer:
It says cross-breeding with other ancient hominids gave some subsets of human population the genes to contend and thrive in colder and harsher climates and behavioral/dietary changes also helped humans adapt to cold climates.
Explanation:
Hunter-Gatherers were individuals who get their sustenance from the abundance of nature, chasing creatures and assembling wild plants.
I'm pretty confident the answer to your question is drought.
Hope this helps!
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