My copy of Martin Chuzzlewit has a note on Lord Monboddo (1714-1799). He wrote a 6 volume work "Of the Origin and Progress of Language" in which he put forward the idea that Man and Orangutan are the same species, only human mental powers had developed more, part of which was the development of language.

There seems to be quite a bit about him on the Internet, including his correspondence with Sir William Jones, who first put forward the idea of Indo-European being behind Sanskrit, Latin, Greek, Germanic, Celtic, etc.

http://www.aaanet.org/gad/history/020cannon.pdf

Since Martin Chuzzlewit was published some 15 or 16 years before Origin of Species, Monboddo was more naturally associated with the idea of humanity and other primates being related.

Edit. I've also just found this bio. of Monboddo: http://www.electricscotland.com/history/other/burnet_james.htm. It's a shame they don't say where they got it from. I assume this is not Electric Scotland's normal style of writing.

Bingley

Bingley