 Yet data on the body mass index of hunter-gatherer and subsistence agriculturalists clearly show that between famines they do not deposit large fat stores

As a response to such criticisms, a modified "thrifty" gene hypothesis is that the famines and seasonal shortages of food that occurred only during the agricultural period may have exerted enough pressure to select for "thrifty" genes.The thrifty phenotype hypothesis arose from challenges posed to the thrifty gene hypothesis.The thrifty phenotype hypothesis theorizes that instead of arising genetically, the "thrifty factors" developed as a direct result of the environment within the womb during development.