11/1 lecture

radiocarbon dating

• need calibration (“adjustment”) for more precise identification of the specimen’s age

  • it’s bc the rate of C14 in the atmosphere has a slight variation

  • results in plus minor factor following the year number

• carbon absorption/dissipation isn’t completely uniform

  • solar radiation increases/decreases in slight ways over time

    • how to account for this?

      • check for radiocarbon date alongside dendeochronology

        • tree rings

          • exact and precise: one ring/year

• radiocarbon dating precision

  • calibrated is reported “cal.”

  • calibrated is significantly more precise (think stats normal distribution)

migrations as a human activity

• push factors or pull factors

• why migrate?

  • climate change

  • new opportunities

    • ex. australia variety of climate and temperature

      • homo sapiens arrived in Australia by 50,000 years ago - required boats

      • Australian megafauna start to disappear around this time

        • adaptations

          • fishing, etc

          • humans have used fire a lot to manage the landscape

            • “firestick farming”

    • tasmania

      • inhabited ~35000 ya

    • New Zealand

      • inhabited ~1200 CE

        • Moa (large flightless bird) becomes extinct around this time

the Americas

• being straight/beringia

• ancestral populations

  • early siberian sites ~48000 ya

    • siberian ppl were highly adapted

reading

• the Bering transitory archipelago

  • bering land is now underwater

• humans arrived in NA ~18k ya and used hunting, fishing, gathering as subsistence

• Haul-outs!

  • can get back on land when done

  • humans don’t belong in the water!

  • this also helps sea animals like seals, etc

  • birds also lay eggs here

• erosion

  • removes shoreline sites

what happens after initial settlement at Alaska?

• people go down the coast

  • “kelp highways”

  • basically they followed resources (ex, birds)

• tech

  • stone tools

    • crescents (channel islands)

      • hunting tool

      • found in sites associated with water +bird diet

  • extinct animals due to hunting

    • flightless duck

  • clovis point

    • found all over NA

    • not just a spearpoint, but also a social calling card of how ppl thought of tools

• birds

  • there were intact raven skeletons from Charlie Lake Cave in Canada.

  • ppl eat birds but also use feathers (clothing, etc)

• some of the earliest sites are far from Alaska

north American megafauna start to disappear around 10,000 years ago

• coincidence?

  • probably couples with the climate change (especially affects slow-reproducing animals) and human hunting

implications

• extinction of megafauna was a long process

• “further research is needed to fully disentangle the relative influences of climate, vegetation, and human activities…” (Vachuleta et al. 2019).