Hominins before humans

Fossils

• Mineralized bones or rocks

How to become a fossil

• Die
• Organism's body must be neglected
• Skelton must be buried (in rlly dry or rlly wet conditions)
  • You must be underground and STAY underground
• Fossilization phase
  • Chemical changing
  • Voids are filled with minerals
  • Teeth are preserved because they have minerals in them
    • Pancreas too
• Hardest part: discovery

  • Covered by a lot of rock, so this can be hard

    

    • Fossil evidence must be taken with a grain of salt, very rare that the oldest + youngest fossils are the oldest + youngest species

    Dating fossils

    • Radiometric dating
      • Slow decay: K-Ar dating
        • Wouldn't use this that often
      • Fast decay: C14 dating
        • Used often
        • Anything younger than 40 thousand years
      • In between: Thermoluminescence dating (TL), Electron spin-resonance dating
    • Magnetic dating
      • Earth's magnetic field reverses itself (N is S, S is N)
      • When rocks formed, record the direction of the earth's magnetic field at the time
      • We know when these reversal events happened
    • Relative dating
      • Association with other known species (extinct or appear by certain age)

    Assembling the data

    <aside> 💡 How do the fossilization process, modern dating methods, and the vagaries of discovery shape the narrative of human origins we tell today?

    </aside>

    • Our origin stories aren't 100% accurate and are instead a combination of assumptions and estimations
    • Discovery is not simply the chance of finding something, but support is also need (monetarily)
    • The narrative that we tell often ignores the indigenous perspective (WHICH IS IRONIC AS FUCK LOL)
    • The evolution of primates...that began in the America
    • Bias of environmental preservation
    • Fossils might not have preserved in certain locations

    

    Focusing on the last 20 million years

    • 20 mya: Wet, grassy, green areas

    • 10 mya: subtropical and tropical forests

    • 5 mya: becomes cooler and drier

      • Forests → open space (deserts)

    • 2 mya: glaciation + hot, dry dessert areas (period of extremes)

    • East Africa: Forests → open grass lands & savannas

• Our line comes from the ancestors of modern chimps + gorillas
• We are all the changes versions of our ancestors
• Hominid: Hominidae
• Hominin: prior to Homo

<aside> 💡 What distinguishes hominin from other hominids?

</aside>

• We habitually walk bipedally
• Our dentition and jaw musculature are different
• We have larger brains relative to our body size