Seminar 4 2011 Discussion Page Challenge 3

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The Evolving Brain Challenge Question 2



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The Evolving Brain: social interaction and complexity - Discussion Page

Challenge Question 3


The human population has risen exponentially over the past 2000 years. Fogel (see figure on student chellenge questions) suggests that there is a link between human population growth rates and cultural evolution. The figure indicates that the point at which the rate of population growth changed dramatically coincides with the beginning of the second agricultural revolution. Discuss how population growth rates in humans have changed in the past 2000 years, outlining your view on the potential reasons for this change in rate.


Andrew M- Sacred Heart College Auckland

Over the last 2000 years, the growth rate of the human population has increased exponentially. In my opinion, this increase can be attributed to the increase in the size of the groups in which members of the human population lived. As group size increased, the evolutionary benifits of living in a group, such as the ability to gather more food, and increased protection against predators also increased. This led to a chain reation, where an increase in group size led to lower mortality rates and higher natality rates within the group, therefore further increasing the group's size.


However, to maintain order in a large group, complex reasoning is required to maintain relationships between group members, and to uphold the society. This requried an increased human brain capacity, and so increased brain capacity became a driver in the process of evoultionary selection. The evidence for this can been seen in the diagram provided in Fogel's "The Escape from Hunger and Premature Death" as the exponetial increase in the size of the human population is clearly accompanied by a similarly exponential increase in the rate of human scientific achievements. This indicates an increased brain capacity and ability for logical and precise thought, and so backs up the theory that there has been a great increase in human brain capacity, which in turn validates the idea that larger group size is the determining factor in the rapid increase of the human population.


However, increased human brain capacity has also contributed to the increase in the population size. What began as an evolutionary necesity for the maintanimce of a social structure has become a usefull tool for increasing human evolutionary fitness, and broadend the human ecological niche, as humans were now capable of changing the environment aroud them to suit their needs. 

LENScience

Thank you for your contribution. In your second paragraph you say increased brain size is a driver for the evolutionary process. Brain size is a feature of the organism, rather than a driver. In this example increased demand for group living, an environmental variable, would be the driver selecting for a larger more capable brain. Other potential reasons for this change in rate that could be considered would be cultural evolution as with more people there are more interactions.