سر نیزه های باستانی نشان می دهد که چگونه انسان های عصر یخبندان زمین را یاد گرفتند

Ancient spearheads reveal how Ice Age humans learned the land

At the end of the last ice age, early humans crisscrossed the Americas following seasons, rivers and game, often with a trusty spear in hand. Nearly 13,000 years later, archaeologists are using those spearheads to study how America's first inhabitants understood risk.