The northern monkey.
Never in need of a lift
with its pseudothumb.
The aye-aye is a curious primate found in Madagascar that has possibly the most unusual hands in the animal kingdom. Their hands are so elongated that they account for around 41% of their total length of the forelimb. The aye-aye’s long, bony third finger is its calling card – unique in the animal kingdom, it’s a specialised tool for getting grubs out of deep holes and probing for food whilst foraging.
Yet such specialisation can have costs, including weakening the ability of aye-ayes to grip. Hartstone-Rose & Dickinson et al. (2019) suggest that the aye-aye’s pseudothumb may have evolved to combat this disadvantage. The researchers found the pseudothumb has bony, cartilaginous and muscular features, suggesting that it enhances the aye-aye’s grip of smaller items such as thin branches.
A note about the sciku – Aye-ayes are lemurs and are not monkeys (they’re strepsirrhine primates). The sciku calls them northern monkeys because ‘aye’ is a common term in the north of England and in Scotland meaning ‘yes’, and ‘why-aye’ or ‘wey-aye’ are northern (mainly Geordie) terms for ‘well yes’ or ‘well, yes of course’. The term northern monkey is also a derogatory term in the UK for someone from the north of England (the counter of which is southern fairy).
Original research: https://doi.org/10.1002/ajpa.23936