Speakman's critique of the thrifty gene hypothesis is based on an analysis of the pattern and level of mortality during famines. Despite much anecdotal evidence used to suggest that famines cause substantial mortality, Speakman suggests that where real data are available famines actually involve rather low levels of mortality and there is no evidence that fat people survive famines better than lean people. In fact mortality actually falls mostly on groups such as the very young and very old where differential mortality in relation to body composition is highly unlikely. Speakman, J.R. (2006) The genetics of obesity: five fundamental problems with the famine hypothesis. In G. Fantuzzi, and T. Mazzone, (Eds) Adipose tissue and adipokines in health and disease Humana Press New YorkSpeakman, J.R. (2007) A novel non-adaptive scenario explaining the genetic pre-disposition to obesity: the ?predation release? hypothesis. CELL metabolism 6: 5-11 The drifty gene hypothesis was presented as part of a presidential debate at the 2007 Obesity Society meeting in New Orleans, with the counter-arguments favoring the thrifty gene hypothesis presented by British nutritionist Andrew Prentice. The main thrust of Prentice's argument against the drifty gene idea is that Speakman's critique of the thrifty gene hypothesis ignores the huge impact that famines have on fertility. It is argued by Prentice that while famine may actually have only been a force driving evolution of thrifty genes for the past 15,000 years or so, because famines exert effects on both survival and fertility the selection pressure may have been sufficient even over such a short timescale to generate the current phenotype distribution of BMI. This critique was published back-to-back with the original 'drifty gene' paper in the International Journal of Obesity in November 2008. Prentice AM, Hennig BJ, Fulford AJ. Evolutionary origins of the obesity epidemic: natural selection of thrifty genes or genetic drift following predation release? Int J Obes (Lond). 32: 1606-1610 Prentice et al predicted that the emerging molecular genetics field would ultimately provide a way to test between the adaptive 'thrifty gene' idea and the non-adaptive 'drifty gene' idea because it would be possible to find signatures of positive selection in the human genome, at genes that are linked to both obesity and type 2 diabetes, if the 'thrifty gene' hypothesis is correct. Two comprehensive studies have been performed seeking such signatures of selection. Ayub et al (2015) searched for signatures of positive selection at 65 genes linked to type 2 diabetes, and Wang and Speakman (2016) searched for signatures of selection at 115 genes linked to obesity. In both cases there was no evidence for such selection signatures at a higher rate than in random genes selected for matched GC content and recombination rate. These two papers provide strong evidence against the thrifty gene idea, and indeed against any adapative explanation which relies on selection during our recent evolutionary history, but instead provide strong support the 'drifty gene' interpretation.
Speakman's critique of the thrifty gene hypothesis is based on an analysis of the pattern and level of mortality during famines. Despite much anecdotal evidence used to suggest that famines cause substantial mortality, Speakman suggests that where real data are available famines actually involve rather low levels of mortality and there is no evidence that fat people survive famines better than lean people. In fact mortality actually falls mostly on groups such as the very young and very old where differential mortality in relation to body composition is highly unlikely. The drifty gene hypothesis was presented as part of a presidential debate at the 2007 Obesity Society meeting in New Orleans, with the counter-arguments favoring the thrifty gene hypothesis presented by British nutritionist Andrew Prentice. The main thrust of Prentice's argument against the drifty gene idea is that Speakman's critique of the thrifty gene hypothesis ignores the huge impact that famines have on fertility. It is argued by Prentice that while famine may actually have only been a force driving evolution of thrifty genes for the past 15,000 years or so, because famines exert effects on both survival and fertility the selection pressure may have been sufficient even over such a short timescale to generate the current phenotype distribution of BMI. This critique was published back-to-back with the original 'drifty gene' paper in the International Journal of Obesity in November 2008. Prentice et al predicted that the emerging molecular genetics field would ultimately provide a way to test between the adaptive 'thrifty gene' idea and the non-adaptive 'drifty gene' idea because it would be possible to find signatures of positive selection in the human genome, at genes that are linked to both obesity and type 2 diabetes, if the 'thrifty gene' hypothesis is correct. Two comprehensive studies have been performed seeking such signatures of selection. Ayub et al (2015) searched for signatures of positive selection at 65 genes linked to type 2 diabetes, and Wang and Speakman (2016) searched for signatures of selection at 115 genes linked to obesity. In both cases there was no evidence for such selection signatures at a higher rate than in random genes selected for matched GC content and recombination rate. These two papers provide strong evidence against the thrifty gene idea, and indeed against any adaptive explanation which relies on selection during our recent evolutionary history, but instead provide strong support the 'drifty gene' interpretation.
D
Speakman, J.R. (2006) The genetics of obesity: five fundamental problems with the famine hypothesis. In G. Fantuzzi, and T. Mazzone, (Eds) Adipose tissue and adipokines in health and disease Humana Press New YorkSpeakman, J.R. (2007) A novel non-adaptive scenario explaining the genetic pre-disposition to obesity: the ?predation release? hypothesis. CELL metabolism 6: 5-11
D
Prentice AM, Hennig BJ, Fulford AJ. Evolutionary origins of the obesity epidemic: natural selection of thrifty genes or genetic drift following predation release? Int J Obes (Lond). 32: 1606-1610
R
adapative
adaptive