> there's an evolutionary advantage for cats to not want to eat anything else
Do we have evidence cats’ ancestors had such a receptor?
If not, it might be simpler to assume there wasn’t evolutionary pressure to not taste sweetness as much as there was a lack of any pressure to taste it.
Hyenas and mongooses are feliforms and can taste sweetness, as can all caniforms (I think). Presumably that means that the carnivoran ancestor could as well.
I'm not a biologist, but the lack of that gene is very conserved across all Felidae, I think (i.e. there isn't a single felid that can taste sweetness) which usually indicates that there's some evolutionary pressure.
What it indicates, rather, is that at the time of divergence from other Carnivora there was a lack of evolutionary pressure for conserving the taste of sweetness.
An example in primates is the loss of Vitamin C synthesis, which would have been a handy adaptation during the Age of Sail, but the gene was lost at a time when our common ancestor at a fruit-heavy diet.
While I would love to meet a talking flying laser cat, all creatures have a fixed energy budget, and implementing any "feature" has an energy cost. So it could well be advantageous for creatures to not have a feature if they don't need it to survive in their EEA. Evolutionary pressure can make a feature go away or become vestigial if the energy requirement to support it is too great. This is how we get blind lizards in dark caves, for example. Or tailless humans (and other great apes).
I'm torn between upvote for funny and downvote for (probably) wrong. :)
The gene is present in all (most?) other mammals except cats. One can reasonably assume that there was some evolutionary pressure to it. A whole family/species most likely does not lose a gene without some major outside pressure. Either the population shrinks suddenly and is recovered from individuals missing the gene, or that gene is eliminated presumably for good reason. This is not evidence but it's the more likely explanation.
Of course laser eyes are great only for the first individual that evolves them. Then basically every other population tends to start dying off because you can't just not use them.
> Do we have evidence cats’ ancestors had such a receptor?
They say that all mammals studied so far, including ones close to cats, have the gene except cats... This seems to almost demonstrate that cats must have lost that gene at some point.
Do we have evidence cats’ ancestors had such a receptor?
If not, it might be simpler to assume there wasn’t evolutionary pressure to not taste sweetness as much as there was a lack of any pressure to taste it.