GENETICS. Strength in small numbers.
Complex traits such as height and weight are influenced by multiple genes and by environmental factors. Because of this complexity, genetic studies of these traits often involve hundreds of thousands of individuals. These studies typically focus on urban populations, for which large sample sizes are readily available. For example, the GIANT consortium recently reported 697 genetic variants that explain 20% of the heritability of adult height (Wood et al. 2014), and 97 loci that account for just 2.7% of phenotypic variation in body mass index (BMI) (Locke et al. 2015). These discoveries required a staggering 250,000 to 300,000 individuals in total. And yet, on page 1343 of this issue, Fumagalli et al. report the identification of genetic variants influencing height and BMI based on data from just a few thousand Inuit individuals (Fumagalli et al 2015). These results exemplify how modern humans have adapted to diverse climates and diets.
