How many taste buds does a human have?

How to get close to this number

Reason from the surface. A tongue is a few tens of square centimetres, taste buds sit inside visible papillae with several buds each, and the papillae are spaced a millimetre or so apart. Area divided by spacing, multiplied by buds per papilla, gives a figure in the thousands to tens of thousands.

The replacement rate in the explanation is the interesting biology: taste buds are renewed roughly every two weeks, and that renewal slows with age. That is a direct physiological explanation for why food tastes blander to older people, and it is a rare case where a subjective experience maps cleanly onto a measurable cell turnover rate.

The catfish comparison recalibrates what a taste bud is for. A fish with over a hundred thousand of them spread across its whole body is using taste as a distance sense in water, not as a check on food already in the mouth. Our count is low because we can see and smell what we are about to eat; an animal that cannot needs to taste its surroundings.