Summary
The influences of the microbiota on host physiology are so pervasive that the microbiota has been hypothesized to play a critical role in host evolution by shaping key host phenotypes (1). However, to contribute to host evolution, traits must be transmitted across generations. One way to assess whether some or all microbes are influenced by the genetic composition of the host, and therefore conserved across generations, is by measuring heritability. Host species–specific patterns in the composition of the microbiome—the genetic content of the microbiota—suggest there is some degree of heritability in the microbiota (2). However, studies evaluating variation in the microbiota and host genetics within a single host species have generally reported low heritability for a small proportion of microbial taxa (3). On page 181 of this issue, Grieneisen et al. (4) reject this common conclusion by demonstrating that most gut microbiota traits in wild baboons exhibit some degree of heritability.
