Like many other mammals, including horses, chimpanzees and gorillas cannot choke on food, since their ability to swallow relies on the epiglottis being closed. In humans, the descent of the larynx over the past 4 million years has led to the ability to have food go "down wrong pipe".

The uvula has increased in size in humans, to use and amplify the gag reflex as a way to compensate for the loss of the epiglottis as a barrier between the air pipe and the oral cavity.

Uvular consonants, co-opting a bigger uvula for speech

The descent of the larynx happened as Australopithecus adapted to water, a water-adapted ape similar to how otters are water-adapted mustelids (Morgan, 1990), and its speciation to begin with, as Popadin et al showed last year^[1], a result from interbreeding between ancestors of gorilla, and the common ancestor of humans, chimpanzees, and Paranthropus, most probably gene transfer of higher opposable thumb index to the human lineage (gorilla have second highest index, after humans^[2]), as well as for high amounts of subcutaneous fat.

Later adaptations (cerebral) for vocalizations for language co-opted the extended vocal tract, and, also the enlarged uvula, which is used when vocalizing uvular consonants like R.

References

1. K. Popadin, K. Gunbin, L. Peshkin, S. Annis, Z. Fleischmann, G. Kraytsberg, N. Markuzon, R. R. Ackermann, and K. Khrapko. Mitochondrial pseudogenes suggest repeated interspecies hybridization in hominid evolution. bioRxiv, 2017. doi: 10.1101/134502. URL https://www.biorxiv.org/content/early/2017/10/19/134502

2. A lmécija, S., Smaers, J.B., Jungers, W.L., 2015. The evolution of human and ape hand proportions. Nature Communications 6, 7717. doi: 10.1038/ncomms8717. URL http://dx.doi.org/10.1038/ncomms8717