Science News Flash: Stone Tool Use by Capuchin Monkeys Challenges Human Evolution

I love cashew nuts! Apparently, so do capuchin monkeys.

A team of scientists from Oxford University (in the UK) and the University of Sao Paulo (in Brazil) report that capuchin monkeys in the northeast forests of Brazil make sophisticated use of stone tools to extract cashew nuts from shells.¹

These researchers claim that this find sheds light on the evolution of human behavior. However, I take a different view. I maintain that this discovery actually undermines the standard model for human evolution. At the same time, this work highlights human exceptionalism, which finds ready explanation in the biblical human origins account.²

Tools Engender New Scientific Possibilities

This discovery, reported in the journal Current Biology, has found its way into popular science outlets, spurring headlines such as “Scientists Unearthed a Trove of 700-Year-Old Stone Tools—Used by Monkeys.” And with good reason. It is the first archaeological evidence for the use of stone tools by nonhuman primates outside of Africa, suggesting a whole new arena of scientific investigation. Lydia Luncz, a member of the research team, stated, “We think we’re just at the beginning.”³

To get to cashew nuts, capuchins go through an elaborate process. These monkeys carefully select large flat sandstones and quartzite to use as an anvil and hammer, respectively. They transport these stones to the base of the cashew trees. There, they place the cashew nut on the flat anvil (which is about four times the size of the hammer) and carefully strike the shell with the hammer (which is about four times the size of an average stone) breaking it open so they can get to the nut inside. Once they are done with the tools, the capuchins leave them at the base of cashew trees. A walk through the forest reveals a number of cashew nut processing centers, established by these industrious creatures.

To determine how long capuchins have engaged in this behavior, the research team excavated beneath several cashew trees located in the Brazilian forest. They discovered stone tools at least 2 feet beneath the surface that date back to about 700 years old. The excavated tools had a dark organic residue on them. Analysis of the residue indicates that it is the leftover remnants of cashew nuts, confirming the use of these stones as tools. Based on the excavations, it appears that about 100 generations of capuchins have employed stone tools to extract cashews from shells. It is reasonable to think that this behavior extends even further back in time.

This discovery follows on the heels of earlier work by the same team. In a previous study, these scientists observed Burmese long-tailed macaques in Thailand using stone tools to crack open shellfish, crabs, and nuts. Excavations at macaque sites on the island of Piak Nam Yai have identified stone tools that are about 65 years in age, going back two generations.

The use of stone tools among nonhuman primates is not limited to capuchins and macaques. Researchers have also uncovered evidence for chimpanzee stone tool use in Africa that dates back to over 4,000 years ago.

It seems as if hominids aren’t the only primates to leave behind an archaeological record.

Tools Throw Evolution into Question

The use of stone tools by capuchins, macaques, and chimpanzees has important implications for the creation-evolution debate. The tools used by these nonhuman primates is reminiscent of tools used by hominids. The similar behavior of hominids, Great Apes, and Old and New World monkeys renders the activities of hominids much less remarkable. I wrote elsewhere about the implications of tool use by chimpanzees (see here). The point I raised applies to the use of stone tools by capuchins and macaques:

“Chimpanzee behavior is closer to what we infer about hominid behavior from the fossil record, particularly Homo habilis and Homo erectus. These creatures, too, made tools and engaged in hunting and scavenging activity. The temptation is to see hominid behavior as transitional, representing a path to modern human behavior. Yet the newly recognized behavior of chimpanzees distances the hominids from modern humans. Just because the habilines and erectines made tools and engaged in other remarkable behaviors doesn’t mean that they were ‘becoming human.’ Instead, their behavior appears to be increasingly animal-like, particularly when compared to chimp activities.”⁴

And, I would add, hominid behavior becomes even more animal-like when compared to the behavior of capuchins and macaques.

Resources
Who Was Adam? (book)
“Chimpanzee’s Behavior Supports RTB’s Model for Humanity’s Origin” (article)
“Chimpanzees’ Sleeping Habits Closer to Hominid Behavior Than to Humans’” (article)