User:Jmwils/sandbox

Evolution of Gestational Diabetes:

Evolutionary biologists suggest that ancient interbreeding may have increased the vulnerability of certain sub-populations to diabetes (3). Higher frequencies of specific Neanderthal alleles in Native and Latin American populations leaves them at higher risk for diabetes (3). European and African sub-populations lack these alleles and have a lower prevalence of gestational diabetes (3). Individuals that are at risk for diabetes have higher rates of gestational diabetes.

Dietary factors may have also played a role in the evolution of gestational diabetes. Historically, European diets were grain based and highly glycemic. High glycemic intake provides a more adequate glucose supply to the fetus. These European diets may have relaxed selective pressures that favored fetal demand for higher blood glucose (1). Alternatively, Southern Asian diets have historically had low-glycemic content. These diets may have supported a lower baseline blood glucose supply in the mother and favored the evolution of increased fetal demand (1). This dietary difference provides a possible evolutionary explanation as to why Asian populations report higher rates of gestational diabetes. This discrepancy between a pregnant mother's baseline blood glucose levels and fetal demand for more sugar are epistatic interactions that may increase the risk for gestational diabetes (2).

Evolutionary biologists predict that interactions between certain genes of the mother and fetus have undergone evolutionary selection. This mother-fetus evolutionary conflict selects for fetal genes that maximize nutrient transfer from the mother, and mother's genes that limit nutrient transfer to the fetus. In balance, mother and fetal genes work in tandem to provide both with adequate nutrient intake. However, if natural selection favors the fetus over the mother, it can pose a serious threat. Fetal exposure to more nutrients allows the placenta to release hormones directly into the mother’s blood (4). These hormones, such as human chorionic gonadotropin and human placental lactogen, can increase insulin resistance in the mother (4). This increase in insulin resistance causes blood glucose levels to rise and if the mother’s body cannot counteract this change, then gestational diabetes can develop (4). This concept follows the notion that, offspring's genes demand higher levels of investment than the optimal amount of investment beneficial to the mother (2).

(1) Brown, Elizabeth A., Maryellen Ruvolo, and Pardis Sabeti. "Many Ways to Die, One Way to Arrive: How Selection Acts through Pregnancy." Trends in Genetics. Elsevier, 8 Apr. 2013. Web. 01 Mar. 2016.

(2) Haig, David. "Altercation of generations: genetic conflicts of pregnancy." American Journal of Reproductive Immunology 35.3 (1996): 226-232.

(3) "The Deep Roots of Diabetes." Understanding Evolution. University of California, Berkeley, Feb. 2014. Web. 10 Mar. 2016.

(4) Haig, David. "Genetic Conflicts in Human Pregnancy." The Quarterly Review of Biology 68.4 (1993): 495-532. Web. 14 Mar. 2016.