Dang beat me to it. I actually own one of these in red.
Not sure if it has been mentioned yet but the hole on the bottom is so that it can be used as an amulet with a medal or coin at the bottom. The chain goes between the arms, down through the hole in the bottom, then is affixed to the medal which acts as the stopper.
Whether there is any truth to this "myth" is unknown, but one virtually identical in carving and form was featured in a famous photograph in which it was attributed the "lucky" amulets worn by certain British and Irish soldiers in WWI. Lots of soldiers wore amulets in WWI, this was just one that was popular for some of those folks. As always, this particular monkey of the trio is much more popular for some reason. These appear to have been produced in at least somewhat moderate quantities up through the 1970s or so, as far as I can tell. I think they were popular with hippies or something. As far as mine, my grandmother gave it to me in a box of junk from her basement. She has no idea what it is or where it came from. But one other thing in the box was an 1890s-1910s era or so clay pipe. So who knows.