SCIENCE

Until recently, it was widely thought that the first humans arrived in North America via a land bridge between what is now Russia and Alaska. Now, anthropologists think America’s earliest humans didn’t arrive by land at all. (Science)

Why did humans migrate to the Americas? Use our activity to explore ancient push-pull factors.

Teachers, scroll down for a quick list of key resources in our Teachers Toolkit.

Discussion Ideas

• The “kelp highway” theory has nearly displaced the “Clovis-first” theory about how the Americas were populated. What is the Clovis-first theory?
  • As its name implies, the Clovis-first theory suggests that the ancient Clovis people were the first humans to settle in North America (and, later, South America).
    • The Clovis people, named after the town in New Mexico where their characteristic tools were first identified (take a look at those here), were nomadic hunter-gatherers who arrived in North America by crossing the Beringia land bridge about 13,500 years ago. (Learn more about Beringia here.) There, Clovis people and their descendants hunted large game and spread rapidly through the New World.

• What is the “kelp highway” theory?
  • The kelp highway theory suggests that the first Americans arrived not by land, but by sea, following the coastline of the Pacific Rim of northeastern Asia and Beringia to as far south as South America. Learn more about the kelp highway theory here.

• Why do anthropologists call this coastal route the “kelp highway”?
  • Incredibly rich kelp forest ecosystems trace nearly the entire route, and could have supported seafaring peoples. “Kelp resources extended as far south as Baja California, and then—after a gap in Central America, where productive mangrove and other aquatic habitats were available—picked up again in northern Peru, where the cold, nutrient-rich waters from the Humboldt Current supported kelp forests as far south as Tierra del Fuego.”
    • Kelp forests support not only their namesake algae (learn more about kelp here!) which can be an excellent source of nutrients itself, but fishes, marine mammals, sea urchins, sea stars, crustaceans, and mollusks.
      • Kelp forests and mangrove swamps are still important fisheries today.

• Why is the kelp highway theory more accepted than the Clovis-first theory at this point?
  • Archaeologists and anthropologists have identified several pre-Clovis sites in both North and South America. In particular, scientists point to the Monte Verde site on central Chile’s coast, which was occupied as early as 18,000 years ago. (Interestingly, the Monte Verde site is marked by the presence of kelp in the hearths of dwellings.)

• If most anthropologists agree, why hasn’t there been abundant evidence for the kelp highway theory?
  • Sea level rise! “Testing the kelp highway hypothesis is challenging because much of the archaeological evidence would have been submerged by rising seas since the last glacial maximum about 26,500 years ago.” The most promising sites may still be underwater and under meters of seafloor silt.
  • Anthropologists aren’t quite sure what they’re looking for, as pre-Clovis sites lack the signature cultural artifacts (those gorgeous projectile points!) that define Clovis. “The small sample of pre-Clovis sites has yet to produce a coherent technological signature with the broad geographic patterning that characterizes Clovis.”
  • Lesson: We need more underwater archaeologists!

TEACHERS TOOLKIT

Science: Finding the first Americans

Nat Geo: Exploring Ancient Human Migrations

University of Oregon Museum of Natural and Cultural History: Kelp Highway Hypothesis