About Dirk

As curator of anthropology, Dirk is responsible for the museum’s artifact collection and is involved in its temporary and permanent anthropology exhibits. Dirk is an expert in human cultures; he curates the Museum’s Hall of the Americas and specializes in native American cultures like the Aztec and Maya.

News from the trenches: Diggers make significant discoveries at Sanxingdui

Archaeology is a profession that requires patience, persistence, and luck. In fact, a great deal of luck seems to be a prerequisite to make a great discovery; some of these involve kids and dogs. We are fortunate to know about the Lascaux caves because of a boy and his dog. A similar scenario led to the discovery of a new hominid fossil, Australopithecus sediba, near the Malapa cave in South Africa. The famous Chinese terra cotta warriors were found by farmers digging a well. The first artifacts at Sanxingdui were discovered by a farmer, as well.

Fairly recently, some eighty-five years after the initial discovery of the site, interesting new finds at Sanxingdui have been announced.


According to recent reports, archaeologists discovered a portion of the northern wall at Sanxingdui. The northern part of the wall would have run along the Jian River, according to this site map. (Image licensed under CC BY-SA 3.0 via Wikimedia Commons).

Archaeologists have discovered what may be a section of the north wall at Sanxingdui. In addition, three tombs were found. A well preserved human skeleton was uncovered in one of these. It was dated to the Neolithic, well before the Sanxingdui site was occupied. As far as we know, human remains dating back to the actual Sanxingdui – Jinsha timeframe have only been discovered at Jinsha.

chinese vice premier

Vice Premier Liu Yongdan, who visited the Houston Museum of Natural Science on June 21 2015. (Image courtesy of the U.S. Department of State from United States)

The complete lack of known written sources at Sanxingdui and Jinsha continues to hamper our understanding of this amazing and sophisticated culture. In her recent visit to the exhibit China’s Lost Civilization: The Mysteries of Sanxingdui at the Houston Museum of Natural Science, Vice Premier Mme. Liu Yongdan said this was indeed the biggest obstacle to our appreciation of the culture. She expressed hope that ongoing research would eventually uncover such information, a development which would bring Sanxingdui out of the shadows of prehistory and into the light of history. Discoveries like these can only strengthen China’s submission of the site as a potential UNESCO World Heritage Site.

Hard currency: Stone money of the Yap Islands

We have all grown accustomed to seeing new forms of payment pop up every day. Cash is used less and less. To be “with the times” now requires making payments electronically, and invisibly. Actual tangible objects, such as coins or bills, are exchanged less and less. Instead, electrons silently move funds from one account to another. Payment is still made, but the way in which it is done has changed dramatically. This blog entry deals with a form of payment that is quite different from what we would consider normal in the Western world. How would you feel about making payments with stone money?

The inhabitants of the island of Yap do exactly that: they pay with stones. They also use shells as currency. Each one of these forms of payment has one thing in common: the exchange medium represents something rare, or something that requires hard work to obtain, thus making it valuable.

We will start out this blog by finding where in the world Yap is located. Then we will see how the Yapese made their stone money, and where they went to get the stone (you will be surprised). Finally, we will answer the question: is this still used today, or is it ancient history?

Micronesia, Federated States of - . Map.

Federated States of Micronesia. The Yap Islands can be found in the far western portion of the Federated States.

Yap Island is part of the Federated States of Micronesia. With a total surface of 271 square miles, the land area of the entire Federated States represents about four times the size of Washington, DC.


The Yap Islands are comprised of several islands, the largest of which is the eponymous Yap Island. (“Yap Islands”. Licensed under CC BY 2.5 via Wikimedia Commons.)

Wikimedia Commons

Yap Islanders use stone and shells as currency, or more specifically, as an “exchange valuable” (Fitzpatrick 2003:67). Yap stone money discs take the shape of a donut. They range in size from small (measuring just a few inches in diameter) to enormous (12 ft in diameter, 1.5 ft thick and weighing 8,800 lbs).

The origin of these stone discs remains murky. Some researchers have suggested that the earliest stones, alleged to have been very small, might have imitated stone or shell beads (Fitzpatrick 2003:68).

The intrinsic value of such a Rai stone, as they are known among the locals, is based on the effort that went into quarrying it, the quality of its finish, and its history. The latter is important, if not a bit morbid. If it is known that a person lost his life while bringing the stone back to Yap, then the value of that stone increased (Fitzpatrick 2002:229; 2003: 77-79). You read this right: they brought the stones back to Yap. The stone used to make these money discs does not come from Yap Island. Rai stones were made from limestone (Fitzpatrick 2003:68, 116-124) from the islands of Palau, located 280 miles southwest of Yap Island. To a lesser degree, the Yapese also traveled in the opposite direction, to Guam, to quarry stone money (Fitzpatrick 2003:70). This was quite a feat. How was this done?

Palau Islands

ps_large_locator Palau Islands and their location in the Pacific.

Excavations and radiocarbon dates have revealed that the quarrying activity took place in Palau (Fitzpatrick, 2002: 227, 239) at least several hundred years prior to European contact; it intensified shortly thereafter. About ten quarries in Palau from which the Yap islanders extracted their stone money have been recorded; more remain to be investigated (Fitzpatrick, 2003:8). One of these localities was Omis cave. It contained several unfinished money discs (Fitzpatrick, 2003: 138-160). Radiocarbon dates suggest that work in this cave was carried out during the historic period, going back around two to three centuries ago (Fitzpatrick, 2003: 159).

Work done by archaeologists in 1999 and 2000 identified at least 15 stone money discs in various stages of production in the vicinity of four quarries on the Island of Palau. Shellfish and other faunal remains were also found (Fitzpatrick, 2002: 228; Fitzpatrick, 2003:299).

As far as we know, Palauans never traveled to Yap to participate in trade; instead this was a one-way trade, with Yapese setting out for Palau and returning with the much desired stone money (Fitzpatrick, 2003: 6, 40).

Imagine setting out in your outrigger canoe to travel from Yap Island to Palau to mine stones and shape them into the stone donuts we have come to know. This process involved several stages (Fitzpatrick, 2003: 295-297).

Selecting the quarry: Yapese workers had to obtain permission from Palauan chiefs to quarry. Once they did, they would select a cave or rock shelter along the coast.

Perform carving: upon selecting a suitable deposit of limestone, a general shape was “roughed out.” This was done in situ, meaning the blocks were not hauled off to another area to be transformed.

Detailed carving: Yapese workers used gouges and chisels to create a flat and smooth surface. The disc was probably removed from the limestone deposit during or after this stage.

Abrasion/flattening: after the shape of the disc was complete, the surface was further flattened using a chisel made from shell, stone or iron.

Perforation: the disc was then perforated in the center. Oral traditions tell us this was initially done with coral and a fire drill. Later, iron tools were used.  

Polishing: this represents the final stage of the process. The use of an abrader, such as pumice, mixed with water resulted in a smooth finish of the stone’s surface.

Getting to Palau was one thing, returning with a heavy stone disc must have been quite an experience. First they would have to be brought down to the water’s edge. This is where the hole in the center comes in handy: a sturdy wooden pole would enable porters to lift it and move it to the beach.


Logistics of moving Yap money around. Note the wooden poles sticking through the stones.

At least three modes of transportation were used to get the stone discs from Palau to Yap. The first form of transportation involved the traditional watercraft in this part of the world, a canoe, or two canoes in the case of a large stone. A late 19th century account relates that the stones had “a large hole in the centre through which a log is passed and this, when laid across two canoes, is sufficient to support the stone in transit.” (Le Hunte, 1883:25). Another approach seems to have been to fill the canoes with water, then load the disc and bail out the water (Fitzpatrick, 2003:311).

A second way of moving the stones involved rafts (Fitzpatrick, 2003: 310-311). A late 19th century illustration depicts a set of Rai money discs resting on a raft. Oral traditions on Yap mention how an early Yapese navigator was caught in a typhoon as he was trying to return home with several stones. We learn that the typhoon “[s]plit the canoes into pieces, and some of the rafts carrying the stones sank, and other rafts were separated from the canoes. But Anguman [the navigator] was able to bring some pieces on his rafts trailing after his canoes” (Fitzpatrick, 2003:73-74).

Investigations close to Omis Cave have revealed the presence a dock at the entrance to the cave. At high tide, the dock is almost fully submerged; at low tide, it is fully exposed. This would have “facilitated the loading of stone money onto watercraft. Rafts could be placed on or adjacent to the dock at low tide and discs moved or rolled on top and secured. At high tide the raft could then be maneuvered out of the shallow lagoon into the deeper channel for eventual transport back to Yap” (Fitzpatrick, 2003:146).

Not all stone discs made it to their destination. Some found a watery resting place. Modern divers have encountered many sunken stone discs in the waters of these islands; there must be many more resting on the bottom of the ocean.

Yap harbor

Yap harbor, showing a raft supporting two stone discs. (From Hernsheim, Franz, 1883. Südsee-Erinnerungen (1875-1880). Berlin : A. Hofmann, p. 125.)

A third form of hauling the stone money was with European ships (Fitzpatrick, 2002: 228; 2003:311-312). This form of transportation allowed many more stones to be shipped safely to Yap. By the late 1800s Yap was inundated with stone money. The Yap islanders paid for these stones with copra (Fitzpatrick 2003:101). The Japanese counted over 13,000 disks during their administration in the 1930s. Typhoons, flooding, and the use of these stones as anchors and construction materials during WWII cut this number in half (Fitzpatrick 2002:229; 2003:111).

Transport by canoe and rafts depended on prevailing trade winds and open ocean currents. The best time to transport discs from Palau to Yap would have been between late April and the beginning of October. The ideal time for Yapese workers to come to Palau to prepare a load of money discs would therefore have been from September to February (Fitzpatrick, 2003:311 – 312).

Just in case you are wondering, the US dollar is now the common currency in Yap. The last stone disc was carved and brought to Yap in 1931 (Fitzpatrick 2003:111-112). From that moment on, the US dollar replaced it as commonly used currency. However, stone money is still used to this day for major transactions like payment of dowry or purchase of land. Moreover, small pre-contact discs are considered more valuable than larger post-contact discs (Fitzpatrick, 2003:302).

Because of their size and weight, the largest stones have not moved since the day they were brought ashore in Yap. We find them lining roads, propped up in front of a house, or standing in someone’s backyard. When transactions involving Rai money occur, ownership of the stone is transferred, but the stone itself does not move. People just know that someone else now owns it.

Yap license plate

Old currency proudly remembered on modern license plate on Yap Island.

More prevalent and much easier to transport are the images of Rai money. As a symbol of Yap Island, they can be found on the island’s license plates.

Speaking of the stone money being a national symbol, one stone disc was presented on the inauguration of the Federated States of Micronesia (July 12, 1978).


Yapese stone money for FSM

Presentation of Yapese stone money for FSM (Federated States of Micronesia) inauguration.

Today they help draw and entertain tourists. On Yap Day, March 1st and 2nd (sic), strong island men carry “small change” around, much to the delight of assembled tourists.  Speaking of small change, the Houston Museum of Natural Science also has a small (but still heavy) example of this Rai money.

HMNS stone money

Stone money disc, Yap Island. (HMNS collection.)

Much smaller and rarer than Rai money is Yapese shell currency. In earlier days, shell money served as small change. Two kinds of shell money existed: the mother-of-pearl (yar) and non-native Spondylus shell (gau) (Fitzpatrick, 2002: 228; 2003:7).

Fitzpatrick, Scott M., 2002. A Radiocarbon Chronology of Yapese Stone Money Quarries in Palau. Micronesica 34(2):227-242. [link].

2003. Stones of the Butterfly: An Archaeological Investigation of Yapese Stony Money Quarries in Palau, Western Caroline Islands, Micronesia. Ph.D. Dissertation, Department of Anthropology, University of Oregon. [link].

Le Hunte, J.R., 1883. Report of HMS Espiegle to Sir G.W. Des Voeux, Acting High Commissioner for the Western Pacific, 10 October 1883. General Proceedings (1-83). Central Archives of Fiji and the Western Pacific, Suva: Fiji.

Museum curator thanks his inspiration: a sixth-grade history teacher

As a museum curator, I have the pleasure of working with lots of volunteers. Most of them are students who are interested in archaeology, anthropology and museum careers. This time of the year, as graduation nears, there is an uptick in requests to come visit with me and ask for information and advice. “How did you become a museum curator?” is a question I hear often. “How long do you need to study?” is another one. One of the first things I bring up is that finding employment in anthropology is not easy. However, it is possible. Moreover, I ask my visitors to suggest one field of study where one would be guaranteed a job upon graduation. I can think of only very few.

Van den Bossche, Gaston

Gaston Van den Bossche, a man who made a difference with his students.

The first question – How does one become a museum curator? – has many answers, I am sure. In my case, there was one elementary school teacher who made a difference, now 44 years ago, to be exact. The sixth and final year in elementary school, my class had a teacher who loved history. He loved the city we lived in too, and it just so happened that city had a very long history.

As the year went by, he organized us into groups and assigned various projects. One involved painting a bird’s eye view of what our hometown would have looked like in the Middle Ages. That required research. It also entailed getting covered in paint as we worked on that assignment. Eventually two different canvases were finished. Much to our delight, they were hung in the entrance to the library. In another assignment, we were divided into five or six groups, each named after a Medieval guild. Some of us were the “coopers” or barrel makers, others the “tanners,” “bakers,” etc.  We were given assignments. To get the answers, we had to visit museums and churches, observe and ask questions. It made us interact with the past, and made this past come alive. It became part of what I got interested in. All because of a teacher.

As time went by, that sixth grade class went on to graduate. I found myself continuing down this path of “studying old things.” This took me from a university in Belgium to a U.S. institution in New Orleans, always pursuing the study of these “old things.” Over the years, that meant studying Roman and Greek history, some Egyptian history, and ultimately the art, archaeology, and history of American cultures, especially the Maya.

Photo by Robin Merrit

Photo by Robin Merrit

I have been very blessed to find a job, and to find myself working at a museum, where I now teach visitors, young, old and anyone in between. Sharing what you have learned about a culture that happens to be the topic of an exhibit is a joy. It is very rewarding to see the light come on in a child, when they “get it.” I love hearing visitors say to each other “I did not know that…” as they walk out of an exhibit. I am indebted to my old teacher for this sense of awe. It never left him. I hope it will never leave me.

Sadly, I recently received news that the man who sent me on my quest, and created that spark in me, had passed. Reason for sadness? For sure. Another reason to keep guiding people as much as possible, and maybe, just maybe, make a difference with one or two people? Absolutely. Next time you see a teacher at a reunion, and you know they made a difference in your life, say so. Give them a hug. They deserve it.

In search of the first settlers of the Americas, scientists keep finding surprises

The genus Homo, to which we belong, was the first to leave Africa and explore the world. Homo erectus, one of our ancestors, explored Asia and Europe as early as 1.8 million years ago. However, one huge landmass was left unexplored by these early humans: the Americas. Humanity did not reach this part of the globe until our own species, Homo sapiens, had evolved. We got there very late. Exactly how late is still a hot debate topic. However, once there, we spread rather fast across the landscape. To put things in perspective, it took these early pioneers a mere few thousand years to inhabit North, Central and South America; Ancient Egyptian history covers about the same amount of time.

What makes this dispersal across the landscape so remarkable is that these first Americans had to adapt to a wide range of landscapes, natural resources and climates. Their success in doing so reflects a great intellect and adaptability. Did they take in their new surroundings with a sense of awe and wonder? We will never know for sure, but I have a feeling they did. These earliest inhabitants of the New World did not have a name; archaeologists generally refer to them as Paleoindians, meaning “Ancient Indians.”  


This is a blog on one of the oldest known Paleoindians and her contemporaries.

Imagine a cave, a dark, damp and foreboding cavern forming an underground labyrinth more than a mile long. Some ten thousand years ago, in what is now Mexico, a young girl entered this cave. Most likely Naia was searching for water.

Yucatán does not have surface rivers, and people get water from caves or sinkholes. She never left. Welcome to Hoyo Negro, or Black Hole, the final resting place of one of the oldest known inhabitants of the Americas. Hoyo Negro is one of many cave complexes found on the Yucatán Peninsula in southern Mexico. The presence of stalagmites in Hoyo Negro tells us that the cave was dry at one point. 

Dirk Settlement Americas 1

Map showing location of the Yucatán Peninsula.

Most of this peninsula is composed of limestone, which easily dissolves in water. Over time this leads to the formation of extensive cave systems, a phenomenon known as karst formation. Because of this, the peninsula is riddled with caves. Quite often, the roofs of these caves have collapsed, resulting in a sinkhole, or cenote.

Hoyo Negro is part of a larger system that is now completely flooded. In 2007 members of the Proyecto de Espeleología de Tulum (PET) discovered the cave. Their exploration was part of a three-year concentrated effort to map the underwater caves of the Ejido (township) of Jacinto Pat, some 20 km (about 12 miles) north of the city of Tulum, on the Caribbean coast of the Yucatán Peninsula. What they found surpassed their wildest imagination.

Dirk Settlement Americas 2

Quintana Roo (seen in red) is one of three Mexican states that make up the Yucatán Peninsula.

Dirk Settlement Americas 3

Map showing the location of Tulum in the state of Quintana Roo.

At one point in their dive, the divers entered a huge cavern and noticed that their lights did not illuminate the opposite walls of this space. It was as if their lights got swallowed up by this huge “black hole,” and that is where the name of this cavern came from. As they reached the bottom of this huge space, they found the remains of an adolescent girl. As is tradition in anthropology, this prehistoric individual received a nickname, Naia.

Together with Naia’s well preserved remains, the divers found those of now long extinct animals dispersed throughout the cavern. Among these prehistoric animals were giant ground sloths, gomphotheres, saber-toothed cats, bears, pumas, peccaries. About ten thousand years ago, sea levels were about 300 feet lower than today; because of this, these animals could walk through the cave in search of water or refuge. Some never left.

Dirk Settlement Americas 5

Cross section of the cave system of which Hoyo Negro is part.

How long ago did Naia enter this cave? The associated prehistoric megafauna had become mostly extinct by 13,000 years ago. Dating of the calcite that had encrusted her bones yielded a date of 12,000 years ago. Naia lived sometime between 13,000 and 12,000 years ago. At the time of writing, scientists are attempting to sequence Naia’s nuclear DNA in an attempt to better understand her relationship to other Paleoindians.

Naia was not the only person living in the Yucatán. As mentioned earlier, archaeologists refer to the earliest presence of humans in the Americas as the Paleoindian period. These were the true pioneers, arriving from Asia, as genetic studies show, penetrating a new world full of unknown plant and animal life, the latter encompassing mostly impressive megafauna. Paleoindians were Stone Age people, skilled in stone tool making. They eventually populated all of the Americas.

Our understanding of these earliest settlers has slowly expanded since the first stone tools were found embedded in the bones of extinct animals. In November 1932, a road crew working in eastern New Mexico unearthed a jumble of ancient giant animal bones. The following summer, Edgar B. Howard, an archaeology research associate at the University of Pennsylvania Museum, started a field project in that area. He encountered “matted masses of bones of mammoth,” and mixed in with the bones were slender, finger-long spear points—Clovis points, as we know them today. Wisely, Howard left them in place. Over time archaeologists found more sites with Clovis points, around 1,500 by 2011. Only in a small number of cases did the Clovis points appear in association with animal remains. It appears that the Clovis people were mostly gathering and fishing.

We are left with a lot of questions. Clovis points are unevenly distributed across the landscape.  Archaeologists have found more of them east of the Mississippi than west of that river. In the west, there are other stone tools made, generally referred to as Western Stemmed projectile points. Some of these seem to pre-date Clovis points, others are contemporary with them. What are we dealing with here? Who were these people? We cannot say for sure.

What the Western Stemmed projectile points have made clear is that there were humans here before Clovis points were made. Initially highly controversial, this presence is now widely accepted. One of the sites where pre-Clovis materials has been found in large quantities, is the Debra L. Friedkin site in central Texas.

Map showing the location of the Debra L. Friedkin site in central Texas.

Map showing the location of the Debra L. Friedkin site in central Texas.

This site is located in Central Texas, about 250 meters downstream from Gault, another famous Paleoindian site. Archaeological investigations, undertaken by Texas A&M University’s Center for the Study of First Americans, uncovered layers dating to Late Prehistoric, Late Archaic, Early Archaic, Paleoindian, Folsom, Clovis and the pre-Clovis horizons. The latter, known by its local name as the Buttermilk Creek Complex, dates to between 15,500 and 13,200 years ago. It pre-dates Clovis technology, which starts around 13,100 years ago, ending by 12,800 years ago. This makes it the “oldest credible archaeological site in North America,” according to Dr. Michael Collins.

More than 15,000 stone artifacts were retrieved, all of them made from Edwards chert, found in abundance in Central Texas. The majority of these artifacts consisted of the waste generated by stone tool making; only a very small number has been identified as tools. Moreover, these tools are small in size and lightweight, consistent with a highly mobile lifestyle. A small nodule of polished hematite was also retrieved. While thus far only stone tools have been found, some of these have wear that reflects use on both soft and hard materials. This raises the possibility that organic (and thus perishable) materials were also part of this assemblage.

Current thinking among archaeologists is that the Pre-Clovis people visited Buttermilk Creek to exploit the locally available chert, making stone tools and doing some animal butchering and/or wood working before moving on.  The techniques used to manufacture stone tools are seen as precursors to later Clovis technologies.

The last word on Paleoindians has not been said or written. There will always be new discoveries that help us better situate and understand these forbearers of modern American Indians. One wonders what they would make of our attempts to make sense of their lifestyle. What did we get right? Where did we go wrong?

Although Clovis points are no longer in use, they remain a symbol of this human sense of awe and wonder. It is doubtful that the Paleoindians realized they were moving ever deeper into a new continent. It is certain that they represent the final phase in human dispersal across our planet. It does not stop there, however. In December 1990, when the space shuttle Columbia launched, Commander Vance Brand took with him a ten thousand-year-old Paleo-Indian spear point that had been discovered on Colorado’s eastern plains. One wonders what the thundering liftoff of a NASA space shuttle might have looked like through the eyes of the earliest Americans, and what the next ten thousand years holds for human exploration of space in the solar system and beyond.

For those who read this before Nov 12, 2014, and are interested in knowing more, come listen to a lecture on Naia by Dr. Dominique Rissolo at the Houston Museum of Natural Science. This lecture is presented by the Archaeological Institute of America, Houston.

Anyone who is interested in reading more about this topic, can peruse a wide offering of academic publications, including those of the Center for the Study of First Americans at Texas A&M University.