Expert: John Shea - 11/29/2003

Question
What do archaeologists think happened to cause the transition between hunting and gathering societies to simple horticulture.  What developments happened in the world to cause subsitence level production to turn into surplus production and what are the demographical consequences for this

Answer
Dear Fliss,
Many archaeologists believe that the ecological "trigger" for horticulture among hunter-gatherers was a reduction in residential mobility.  Residential mobility varies widely among hunter-gatherers.  Some move often, others very infrequently.  Among the latter groups, there was probably a lot of pressure to prolong residence in better habitats, and thus, among such groups there would have been much experimentation with plant domestication.  Some crops, like cereal grasses and maize, grow spectacularly well if they are planted in areas other than those in which they ordinarily grow.  For example, wheat is sparse on the rocky crags where it grows naturally, but it is very adaptible and thrives (vastly more productive) if you plant it on alluvial fans.
Two of the demographic consequences of reduced mobility is increased adult survivorship (less loss of productive personnel) and decreased infant mortality.  Both these factors probably led to rapid increases in population size and density.
Sincerely,
John Shea