The Modal Verbs Might and May, Plus an Infinitive, Show That We're Talking About a Present Possibility Not a Certainty

Fiona uses the modal verbs might and may, plus an infinitive. This shows that we're talking about a present possibility, not a certainty. We use can't when we believe strongly that something isn't possible. The researchers believe strongly that the fossils don't belong to any known human species. So, they must be from an unknown human species. That's right. It's a modal verb plus a continuous form of B plus verb ING. But what about this sentence? Listen. It seems that the fossils can't be from any known human Species. Fiona uses the modAL can't there. She says could be looking, might be looking, or may be looking