ouch is software for phylogenetic comparative analysis. It allows one to evaluate hypotheses of evolution of multivariate quantitative characters under selection. It is fully explained in

M.A. Butler and A.A. King (2004). Phylogenetic comparative analysis: a modeling approach for adaptive evolution. American Naturalist, 164:683–695. DOI: 10.1086/426002

and is based on ideas described in

T.F. Hansen (1997). Stabilizing selection and the comparative analysis of adaptation. Evolution, 51:1341–1351. DOI: 10.1111/j.1558-5646.1997.tb01457.x

New results describing the statistical properties of OUCH models, and more complex models based on them, are described in

C. E. Cressler, M. A. Butler, and A. A. King (2015). Detecting adaptive evolution in phylogenetic comparative analysis using the Ornstein-Uhlenbeck model. Systematic Biology 64:953–968. DOI: 10.1093/sysbio/syv043


Install the latest release from Github by executing the following in an R session:


Install from CRAN by executing



The package manual is available in HTML and PDF formats.


Report bugs on the Issues page.

link to NSF

Development and maintenance of ouch made possible through the support of the U.S. National Science Foundation (Grants DEB-0515390 and DEB-0542360).