• The video above is from the January 2013 iPad edition of National Geographic magazine. Find more interactive content, photos, and videos in the iPad version of National Geographic magazine.


    Modern humans—Homo sapiens—began their migration out of Africa some 60,000 years ago. Our early ancestors kept exploring until they spread to all corners of the Earth. How far and fast they went depended on climate, the pressures of population, and the invention of boats and other technologies. Less tangible qualities also sped their footsteps: imagination, adaptability, and an innate curiosity about what lay over the next hill.

     

    Today, geneticists are doing their own exploring. Their studies have led them to a gene variation that might point to our propensity for risk-taking, movement, change, and adventure. This gene variant, known as DRD4-7R, is carried by approximately 20 percent of the human population. Several studies tie 7R (and other variants of the DRD4 gene) to migration. (Genetics is complex, however. Different groups of genes interact and yield diverse results in different individuals. DRD4-7R probably influences, not causes, our tendency toward “restlessness.”)

     

    Teaching Strategies

    Review “The Global Human Journey” video, then discuss geography and genetics as posed by queries in the “Questions” tab. 


    1. Follow the arrows and describe the path of early human migration across the world. Where are the oldest human settlements outside Africa?  Why do you think these areas were settled first?

      The oldest human settlements outside Africa are in Asia and the Middle East. These regions were probably the first to be settled because they are so close to Africa, and could be reached by foot over several generations.

    2. Consider the physical geography encountered by our ancient ancestors. Do you think early humans followed any geographic patterns in their migration out of Africa?

      Answers will vary! Human migration seems to follow coastlines. Early routes followed the coasts of the Red Sea, the Mediterranean Sea, and the Indian Ocean. Thousands of years later, human populations migrated along the west coast of North and South America. 

    3. Migration to remote island groups, such as the Philippines or the islands of Polynesia, appears to have been one of the final stages of global human migration. Can you think of any reasons for this?

      Answers will vary! People needed boats to efficiently migrate to isolated islands. Boat-building technology was a later development in human history.

    4. The so-called "restless gene," DRD4-7R, has been linked to the human tendency toward risk-taking, including migration. Can you think of other adventurous behaviors that may be influenced by "the restless gene"?

      Answers will vary, and research is inconclusive and ongoing! DRD4-7R has been consistently associated with attention-deficit/hyperactivity disorder (ADHD), which is itself associated with curiosity and novelty-seeking.

       

      DRD4-7R has also been associated with financial risk-taking: men with the DRD4-7R gene have been found to be more willing to invest in unproven (risky) economic ventures.

       

      People with DRD4-7R have a higher frequency of multi-racial ancestry, perhaps hinting at a willingness to embrace a different sort of change.

  • Term Part of Speech Definition Encyclopedic Entry
    ancestor Noun

    organism from whom one is descended.

    climate Noun

    all weather conditions for a given location over a period of time.

    Encyclopedic Entry: climate
    gene Noun

    part of DNA that is the basic unit of heredity.

    geneticist Noun

    scientist who studies the chemistry, behavior, and purposes of DNA, genes, and chromosomes.

    Homo sapiens Noun

    (200,000 years ago-present) species of primates (hominid) that only includes modern human beings.

    migration Noun

    movement of a group of people or animals from one place to another.

    population Noun

    total number of people or organisms in a particular area.

    technology Noun

    the science of using tools and complex machines to make human life easier or more profitable.

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