I was curious about the root so I looked it up. If anyone else was wondering, mam' is a root meaning "breast" (as in ❤❤❤❤❤) and it takes the -ul- suffix to refer to the group of breasted animals (mammals).
Well, I have noticed that when you (impersonal 'you', here. Just to be clear :þ) are sucking on a breast, you do tend to make a kind of mamamama sound if you engage your vocal chords.
Mamar is also the verb to suck in Spanish, ie the popular Mexican expression "No mames guey".
Bloodhound Gang "Bad Touch"
You and me baby ain't nothin' but mammals
So let's do it like they do on the Discovery Channel
Why "Humans are mammal" is wrong? I am not saying in context of word to word transaltion but doesn't it mean the same?
In English, nouns need to agree in number too - A human is a mammal, but people (many humans) are mammals (plural).
I think they mean it as an adjective - but that's not the calque translation that Duolingo wants.
- "mammal" isn't an adjective.
- The original Esperanto sentence uses the noun instead of the adjective, so even if "mammal" were an adjective, it'd be most logical to use the noun.
As others have pointed out, the English word "mammal" cannot be used as an adjective. But that doesn't mean that there is no corresponding adjective in English. It's "mammalian". See https://en.wiktionary.org/wiki/mammalian
(Whether "Humans are mammalian." should be considered a correct translation, I'm not sure, as the Esperanto sentence used the noun, too.)