orangutan tools and language are still developing

Wild Orangutans have surprisingly complex language and tool skills. 
     A study in 2024 focused on the language of the wild Bornean orangutan (Pongo pygmaeus wurmbii), especially in the “long call”. They found two levels of rhythmic hierarchy, which implies recursion. That is, it contained standard elements that were organised into different units, like our words are organised into phrases.  Another study of wild female Sumatran orangutans found three levels - as if those phrases were organised into sentences.
     They only have a few fundamental units, unlike our hundreds of thousands of words. Their language is more like short sections of classical music which has 12 notes organised into phrases which are rearranged into different motifs. Their language also uses different rhythms and speeds for different types of messages. The researchers (Adriano Lameira et al) conjecture they share the neurological structures used for human language and song. 
     They can also use spears for fishing. Chimpanzees have sharpened sticks with their teeth to impale bush babies for food, when they are hiding in holes. But Orangutans have taken this further by attempting to spear moving fish, which they appear to have learned by mimicking humans.
        Orangutans separated from the hominid line about 15m years ago - about four times our distance from 3.2m year-old Lucy. But like us, they have been changing in the mean time. And it appears they are continuing to learn. 

Article on language:
https://theconversation.com/what-the-hidden-rhythms-of-orangutan-calls-can-tell-us-about-language-new-research-257400
Paper on language:
https://elifesciences.org/articles/88348
Article on spearfishing:
https://primatology.wordpress.com/2008/04/29/orangutan-photographed-using-tool-as-spear-to-fish/