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Soil Horizons and Profiles

The three major soil horizons include topsoil, subsoil and the C-horizon.

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Human Evolution

Human Evolution


Credit: ?????? ?.?.
Source: http://en.wikipedia.org/wiki/File:Craniums_of_Homo.svg
License: CC BY-NC 3.0

The crania of different hominids show the evolution of the brain case that indicates an increase in brain size. These skulls belong to 1) gorilla, 2) Australopithecine, 3) Homo erectus, 4) Neanderthal, 5) Homo sapiens or Homo heidelbergensis, 6) Modern human.

Why It Matters

  • Evolution does not proceed in a straight line, and human evolution is no exception to that rule.
  • One species does not turn into another. Similarly, a tree trunk has many branches. Each branch is different, but they have common roots. The model of the tree has been used in many different theories of evolution. Today, it is still beneficial for providing a basic understanding of eovlution. However, with all the scientific information we have aquired up until today, the tree doesn't fully grasp the complexity of evolution.
  • Credit: Ernst Haeckel
    Source: http://en.wikipedia.org/wiki/File:Age-of-Man-wiki.jpg
    License: CC BY-NC 3.0

    The evolutionary tree of species - Haeckel's Paleontological Tree of Vertebrates (c. 1879) [Figure2]

  • Organisms that seemed to be important in human evolution in the 1960s turned out not to be so important.
  • Some organisms that hadn’t even been discovered yet turned out to be direct human ancestors.
  • Modern humans did not evolve from Neanderthal. The two types shared a common ancestor.

Can You Apply It?

With the link below, learn more about human evolution. Then answer the following questions.

  1. Why is a chart that shows human evolution with only males not representative?
  2. What happened to Neanderthals when modern humans came into contact with them?
  3. What does it mean to be evolutionarily successful?
  4. What does human evolution really look like?

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Image Attributions

  1. [1]^ Credit: ?????? ?.?.; Source: http://en.wikipedia.org/wiki/File:Craniums_of_Homo.svg; License: CC BY-NC 3.0
  2. [2]^ Credit: Ernst Haeckel; Source: http://en.wikipedia.org/wiki/File:Age-of-Man-wiki.jpg; License: CC BY-NC 3.0

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