Shrestha B, Reed JM, Starks PT, et al. Evolution of a major drug metabolizing enzyme defect in the domestic cat and other felidae: phylogenetic timing and the role of hypercarnivory. PLoS ONE 2011;6:e18046.
Cats are very sensitive to certain drugs such as acetaminophen and aspirin. The enzyme responsible for metabolizing these drugs and related compounds is lacking in the feline liver. It is known that defects in the gene coding for this enzyme are present in all domestic cats. These researchers looked further to discover when this evolutionary development occurred. They found that this occurred when Felidae split from others in the suborder Feliformia, which includes hyenas, civets, binturongs, and mongoose; this split occurred approximately 37 million years ago. They postulate that this genetic variation arose as a consequence of the felid diet, which is primarily animal-based rather than plant-based. The gene encoding this enzyme is among several genes needed for successful utilization of plant material that are defective in cats, including the gene for the taste receptor for sweets, which are primarily of plant origin (fruits, berries, etc.). Because cats have a mainly animal-based protein diet, these genes are dispensable, and not selected for evolutionarily. Thus modern day cats have more in common with their wild relatives than previously thought. [MK]
Related articles: Li X, Li W, Wang H, et al. Cats lack a sweet taste receptor. J Nutr 2006; 136:1932S-1934S.