# `natsel_timehet` – a test of branch heterogeneity

We employ codon models to test whether the mode of natural selection affecting human and chimpanzee lineages is distinctive. This is done by specifying the edges of interest (Yang 1998).

Warning

I’m setting `optimise_motif_probs=False` to speed up execution of the examples, not because it’s a good idea!

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`natsel_neutral` – a test for selective neutrality

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`natsel_sitehet` – a test of site heterogeneity