Humans viewed in the aggregate, face the same limitations on the use of Earth resources as other life forms. At the same time, individual humans can learn that careful modesty by many individuals in the taking of Earth resources leaves more resources for the present and future generations. Most important, humans can understand and communicate the advantages of modest taking for the aggregate of humans. Humans can consider and discuss their own sustainability.

How much Earth resources must each human take and how much may each human take? "Must take" is simple---enough to survive. "May take" is dependent on how many humans "must take". (enough)  Applying learned technology, humans may increase the amounts of resources available to them. Both the must and may take may be incorporated into a question answerable within the Kerala phenomena.  In Kerala we may ask: What is the smallest per capita use of Earth resources necessary to create a level of well-being high enough to motivate family size choices downward to zero population growth?

Zero population growth in any society depends on a steady total fertility rate of 2.1 or less. The total fertility rate in Kerala has held at a steady 1.8 for more than ten years. The measurable cause of the low birth rates in Kerala is the high well-being measures of Kerala.

Human sustainability requires both modest taking of Earth resources and zero population growth family sizes. We have searched and have not yet located a large society (ten million or more) which has both of these sustainability requirements at levels of Earth resource taking per capita lower than Kerala. Measured amounts of Earth resources used per capita in Kerala thus sets a standard for the low end of the "must take" by humans which is sustainable. We may call this low level of necessary taking of Earth resources a Kerala benchmark.

This Kerala benchmark may be used in comparisons with other societies which have achieved zero population growth. Measurements of the Earth resources per capita in these societies may be applied in calculations of the efficiency of the human processes creating well-being high enough to meet the sustainability condition of zero population growth.

(Directory)  March 20, 2000