Hominoid evolution is not so difficult in general (even I can understand...).
Bipedal wading is seen in e.g. Nasalis proboscis-monkey in mangrove forests, they also climb sometimes arms overhead.
India approaching S-Asia c 30-20 Ma formed island archipels, full of coastal forests:
Catarrhini reaching these islands became wading bipedally + climbing arms overhead = aquarboreal Hominoidea.
India further underneath Asia c 20 Ma split hylobatids (E) & other=great apes (W) in coastal forests along N-Tethys Ocean.
The Mesopotamian Seaway closure c 15 Ma split pongids (E) & hominids (W): Medit.Sea:
Hominids s.s. (Gorilla-Homo-Pan) coloonized the (then incipient) Red Sea swamp forests: bipedal + stone tools for removing oysters etc. from mangrove trees + opening them?
When the N-Rift formed, it was followed by Gorilla -> Afar -> Praeanthr.afarensis (Lucy) ->boisei, today G.gorilla & beringei.
6-5 Red Sea opened into Gulf (Francesca Mansfield thinks caused by Zanclean mega-flood 5.33 Ma):
-- Pan went right: E.Afr.coastal forests -> S-Rift -> Transvaal -> Austr.africanus->robustus (// Gorilla) -> today Pan trogl. & paniscus.
-- Homo went left: S.Asian coasts -> Java early-Pleist. -> shallow-dving: pachy-osteo-sclerosis, DHA, brain+, tool use, shell engravings...
mid->late-Pleist.: diving->wading->walking H.sapiens.
Simple, no?
https://www.gondwanatalks.com/l/the-waterside-hypothesis-wading-led-to-upright-walking-in-early-humans/
Only: why the shift from aquarboreal "apes" to shallow-diving H.erectus?
more abundant edible shellfish early-Pleist.? Tp? ...?
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