The word "monkey" is often tossed around a lot to mean various things, but usually to imply a "chimpanzee" or other Great Ape. Evidence for use of hammers in species prior to humans is quite evident, and humans evolved from (and still are considered) monkeys. Thus, to find archaeological evidence relating to usage of hammers (tools designed to deliver an impact to another object) should be quite feasible.
Homo habilis (a.k.a. "Handy man") is a possible human ancestor who is known as the first hominid to use stone tools. The debate still continues to this day as to whether or not habilis gave rise to Homo ergaster (a direct human ancestor) or was simply an evolutionary offshoot. Archaeological evidence shows that habilis was the first (controversially) to utilize stone tool technology among bipedal hominids. Being a direct human ancestor, this qualifies the species as a monkey who had many tools, including hammers. The Homo habilis species is considered the master of the Oldowan tradition, which included "pounders". Sites of habilis remains include: KNM ER 1813, OH 7, OH 24, and KNM ER 1805.
The Oldowan tool industry is the oldest tradition of tool manufacture in human history. Homo habilis and Homo rudolphensis appear at the same time this tool tradition does, thus insinuating that habilis may also have had company while innovating a system of tool-making. While Australopithecines prior to the genus Homo may have had tools (and consequently hammers) there is no evidence to support such claims as of yet. The later Homo erectus and Homo ergaster were found with slightly more advanced tools, quite possibly of the Acheulean tradition (which is the successor and more efficient model of the Oldowan industry), with "hammers" being found among their remains.
The Acheulean tool-making tradition soon followed the Oldowan. Acheulean hand axes are far more superior and efficient. In fact, it was the Acheulean tool makers (i.e. erectus) who were the first to leave Africa, as well as many other accomplishments. The wide variety of their tools was a prime example of the makers' and users' intelligence. The Acheulean was the longest lasting tool-making industry in all of Human history.
Succeeding the Acheulean, in large part, was the Mousterian tradition, which is largely associated with the famed Neanderthals. This is generally referred to as "Mode 3" stone tool technology (with Oldowan and Acheulean being Modes 1 and 2 respectively), which was replaced by Modes 4 and 5. By the end of the stone tool manufacturing industries, hammers were more than commonly used by monkeys. Modern day chimps are known to utilize tools and hammers, as well, leaving one to wonder if our shared ancestor (about 6 million years ago) was even able to use them!
- OriginsNet, Oldowan Era