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.

Thank an archaeologist for human history on International Archaeology Day!

On Oct. 17, we celebrate International Archaeology Day. Last year, the Houston Museum of Natural Science participated on a large scale for the first time in a long time. This year, we will have our “Second Annual” version of the same. So what is archaeology and who are these characters that practice the art of archaeology anyway?

Ask anyone and they will answer “Indiana Jones!” when asked to name a famous archaeologist. Hollywood and the media in general tend to gravitate to this entertaining, but totally off the mark, representation of what it is to be an archaeologist.


Archaeologists are people who study the past. They do so with one goal in mind: reconstructing what our ancestors were up to. In the end, while we might find broken pottery, stone tools, or more sophisticated or larger artifacts, what really counts is the answer to questions like these: Who made this? Why? How? How long ago was this?

It takes a special person to be an archaeologist. Patience truly is a virtue. Doggedness comes to mind as well. It won’t hurt to be lucky, but having knowledge will guide you to that breakthrough you’ve been looking for. You’ll need willingness to continue learning, going hand-in-hand with the admission that you really don’t know all that much. All of these are good traits to have.

Luck is part of all this, but the insights archaeologists come up with and share with all of us can be a whole lot more interesting and head-scratching than any Indiana Jones movie. In that regard, archaeologists are like time travelers, our contemporaries who bring ancient cultures back to life, sometimes so much so that you can almost feel it and smell it.

Recently, I’ve been reading up on the presence of early humans in what is now called the Amazon rainforest. My perception of the prehistory of this huge area is changing quickly. Yes, there were early settlers in this part of the world. Paleoindians did reach Brazil, Bolivia, Peru, Ecuador and the Guyanas. Our knowledge of these early immigrants in this part of the world is so small compared to what we know of North American Paleoindians. But… all that is changing, thanks to the determined efforts of a handful of archaeologists, the very same people whose work and insights we celebrate on Oct. 17.

Take Dr. Anna Roosevelt, for example. A professor at the University of Illinois in Chicago and a curator at the Field Museum in the same city, Dr. Roosevelt has been investigating early human presence in the Amazon for decades now. The information she and her team have uncovered now point to an Amazon region that was very different thousands of years ago — well before the arrival of the Europeans. It was so different that these Amazonian Paleoindians would have a hard time recognizing the current landscape, just as much as we have a hard time coming to grips with the existence of large, densely populated settlements in many portions of the Amazon.

Marajo Island - location (2)

Map of Brazil, with the location of Marajó Island.

To get to this point, Dr. Roosevelt and her colleagues worked for years in the Amazon, in places like Marajó Island as well as rivers further inland. Marajó, an island the size of Switzerland located at the mouth of the Amazon River, yielded evidence of densely-populated settlements, occupied for centuries. This research took years to complete in circumstances where creature comfort was sometimes a distant notion. It took perseverance as well, as the new data and new interpretations ran counter to older, more established explanations of the prehistory of the region. Research in the interior relied on the willingness of non-archaeologists to share news of interesting finds on private properties. Sadly such willingness is not always forthcoming, resulting in the loss of an unknown quantity of materials all over the world.

Building trust among the locals and upholding that reputation is not easy. One has to be determined, focused and dogged in the pursuit of knowledge. Dr. Roosevelt’s team checked off all these boxes, and came up with cool finds, some on land, some underwater.

Diving in the Xingu River, 2001

Archaeologist Dr. Anna Roosevelt diving in the Xingu River, 2001.

On International Archaeology Day, we pay homage to the work done by people like Dr. Roosevelt. Local archaeologists, professional and avocational, physical anthropologists, and artists who work on facial reconstructions will all be at HMNS. Museum docents will share their insights and enthusiasm about archaeology with hands-on experiences, pointing to the various halls in the museum where archaeology is covered. These include the John P. McGovern Hall of the Americas, the Hall of Ancient Egypt and the section of human evolution in the Morian Hall of Paleontology. The event starts at 10 a.m. and ends at 4 p.m. Dig it!

A New Branch: How anthropologists added Homo naledi to our family tree

In a well-deserved world-wide wave of publicity, the existence of a new hominid species was announced recently. Fossil hominins were first recognized in the Dinaledi Chamber in the Rising Star Cave system in October 2013. Now, some two years later, and after exhaustive analysis of more than 1,500 bone fragments, the team decided to go public with this first milestone: the identification of a new human ancestor.

A selection of these bones have been scanned and uploaded to the internet. They also wrote up their findings and published them in an open-access source, eLife, rather than more established channels such as Nature or Science. (A brief side note: as can be seen in this video, one of the thirty specialists involved in the initial evaluation of these remains was Viktor Deak, who was part of the Houston Museum of Natural Science’s team putting together the Lucy’s Legacy exhibit as well as the section on human evolution in the museum’s Morian Hall of Paleontology.)


Fossilized bones discovered in Rising Star Cave in South Africa belong to a new species of hominid.

While social media are currently lit up with all kinds of references to this new species, it might be interesting to address this fundamental question: how does one define a new
hominid species? In other words: “Why is naledi called naledi?“

A starting point in this process is to identify a type specimen. Such a specimen is described in great detail, listing the similarities to and differences from closely related species. There is no central authority that decides on the validity of a species. Rather, this depends on the acceptance of such a designation within the scientific world. New discoveries and more information have given impetus to revisit previous species designations and change them.

As a result, “[i]f two type specimens are later determined to belong to the same species, then the first one named takes priority. For example, when it was decided that the 2nd known australopithecine fossil, assigned to Plesianthropus transvaalensis, actually belonged to the same species as the first that name became invalid and all Plesianthropus fossils were reassigned to Australopithecus africanus.


Skull fragments from the holotype specimen show Homo naledi had a brain about the size of an orange.

If it is decided that the fossils previously assigned to a species actually belong to two different species, then the type specimen and any other specimens belonging to the same species as it keep the old name. The other fossils will take the name of whichever specimen among them is first used as a type specimen for a new species definition. An example is Homo habilis (type specimen OH 7); the species Homo rudolfensis, with type specimen ER 1470, consists of fossils formerly assigned to habilis.”

This new species belongs to the genus Homo. Traditionally, one is a member of that genus if the following criteria are met (Since these are set by human researchers, they are subject to periodic re-evaluation):

  • Brain size: at least 600 cubic cm.
  • Possession of language
  • Opposable thumbs and precision grip
  • Ability to manufacture (stone) tools

We all belong to the genus Homo, species sapiens and subspecies sapiens. We are “Humans, wise, wise” or “very smart humans.” (Since we are the humans investigating ourselves and our ancestors, it should not come as a surprise that we have kept the most honorific label for ourselves.)

If we translate Homo naledi into plain English, we can start with naledi. The species was named Homo naledi; ‘naledi’ means ‘star’ in Sotho (also called Sesotho), one of the languages spoken in South Africa.

According to the research team, the definition of the new species was not “based on a single jaw or skull because the entire body of material has informed our understanding of its biology.”

Interestingly, Homo naledi’s brain size is in the 400 to 600 cubic cm range, yet they are considered to be members of the genus Homo. Here is why: “The shared derived features that connect H. naledi with other members of Homo occupy most regions of the H. naledi skeleton and represent distinct functional systems, including locomotion, manipulation, and mastication.”

Homo naledi - brain size - range

Brain size and tooth size in hominins. (Lee R. Berger et al. eLife Sciences 2015; 4:e09560)

Fossil Dating

One aspect currently left unanswered is when Homo naledi lived; the scientists offer what-if scenarios for dates ranging between one and two million years ago, some even more recent. These are just that: scenarios. They do not provide a date, as none exists at this point.

That brings up the question: how does one date a fossil? Knowing when a human ancestor lived helps us understand the affiliations of different species and who might have evolved from whom. Scientists have access to a wide array of dating techniques.


Homo naledi had human-like hands, though smaller than our own.

Radiometric Dating

Several techniques measure the amount of radioactive decay of chemical elements. Known as radiometric dating techniques, these include potassium-argon dating, argon-argon dating, carbon-14 (or radiocarbon), and uranium series. This radioactive decay occurs in a consistent manner over long periods of time. A benchmark concept in using this approach is that of a “half life,” defined as “the time it takes for one-half of the atoms of a radioactive material to disintegrate.” Early hominid sites in Eastern Africa have stratigraphic affiliations with volcanic layers. These layers can be dated with the radiometric dating techniques just described. As we will see below, the situation in Southern Africa is different.

Measuring Stored Electrons

Thermoluminescence, optically stimulated luminescence and electron spin resonance measure the amount of electrons that get absorbed and trapped inside a rock or tooth over time. The application of these techniques to date fossils highlights how the study of human origins truly is a multi-disciplinary effort.

Thermoluminescence “(or TL) is a geochronometric technique used for sediment. The technique has an age range of 1,000 to 500,000 years. The technique is used on sediment grains with defects and impurities, which function as natural radiation dosimeters when buried. Part of the radioactive decay from K, U, Th, and Rb in the soil, as well as contributions from cosmic rays, are trapped over time in sediments. The longer the burial, the more absorbed dose is stored in sediment; the dose is proportional to a glow curve of light obtained in response when the sample is heated or exposed to light from LEDs. Greater light doses indicate an older age.”

Luminescence dating is “a form of geochronology that measures the energy of photons being released. In natural settings, ionizing radiation (U, Th, Rb, & K) is absorbed and stored by sediments in the crystal lattice. This stored radiation dose can be evicted with stimulation and released as luminescence. The calculated age is the time since the last exposure to sunlight or intense heat.”


Homo naledi’s feet appear nearly human.

Finally, “electron spin resonance (ESR) measures the number of trapped electrons accumulated, since the time of burial, in the flaws of dental enamel’s crystalline structure. At sites containing human and animal teeth, ESR can be used to determine how long the teeth have been in the ground, but finding teeth at an archaeological site is unusual, so this dating method is not as common as thermoluminescence or radiocarbon dating.”

Another dating technique altogether is paleomagnetism. It compares the direction of the magnetic particles in layers of sediment to the known worldwide shifts in Earth’s magnetic field, which have well-established dates using other dating methods.

Sites in Southern Africa cannot be dated with techniques outlined earlier. A lot of the fossil remains are found in a stone matrix, rather than on the surface. These fossils can be dated using biochronology. Most often – though not always – hominid remains are found in stratigraphic association with animal bones. Quite often, these animal remains belong to animal species that roamed elsewhere in Africa, where absolute dates are available. In this way, sites that do not have radioactive or other materials for dating can still be given a reliable age estimate.

Finally, one can estimate the time that elapsed since two species separated from a common ancestor. This is based on the concept of a molecular clock. This method compares the amount of genetic difference between living organisms and computes an age based on well-tested rates of genetic mutation over time.  Since genetic material (like DNA) decays rapidly, the molecular clock method cannot date very old fossils. The most ancient DNA that has been retrieved thus far dates back to 300,000 to 400,000 years ago.

There is no doubt that more information will be forthcoming from the Rising Star Cave system in South Africa. Over the last two years, the researchers have literally scratched the surface of what is in the cave. As mentioned earlier, the genus Homo is defined by a number of features. One of these used to be that we buried our dead. This appeared to have happened in this case as well. Once the remains are dated, we will know if this fundamentally human trait extended further back in time than we ever imagined. Or not.

Egyptian Nefertiti replica ends in a bust: ‘Ugly’ statue brews social media storm

A mini controversy has just broken out in social media about a rather ugly new rendering of the famous Nefertiti bust. The original bust, currently on display at the Neues Museum in Berlin, is one of the most iconic pieces of Egyptian art, recognized as easily as King Tut’s gold mask. It was not a surprise, therefore, that Egyptian authorities recently decided to erect a larger-than-life replica of the same bust at the entrance to the city of Samalut, to honor her memory.

This effort ended in – pardon the pun – a bust in its own right. The image, which only bears a very superficial resemblance to the original, has caused a storm in Egyptian social media, attracting worldwide attention. While the original bust is very well known, the story of its discovery is perhaps less well known. Nefertiti’s bust was discovered in the ruined workshop of the sculptor Thutmose on December 6, 1912 by a German archaeological team.

Bust being handed over to German archaeologist

Presentation of the Nefertiti bust shortly after discovery in 1912. (Left to right: Hermann Ranke, Paul Hollander and Mohammed es-Senussi)

Although the bust is uninscribed, Ludwig Borchardt, the dig director, immediately realized who was represented: the tall blue crown with uraeus serpent must belong to the queen. “No use describing it, you have to see it” he wrote.


Handwritten note by Ludwig Borchardt on the discovery of the bust. Aside from a quick sketch, it contains the remark “No use describing it, you have to see it.”

The Egyptian government gave the bust, and other finds, to the German expedition at the end of the season, according to a custom of the time, known as “partage.” It was not until ten years later, after World War I, that the bust was put on display in the Egyptian Museum in Berlin. The reaction was immediate: Nefertiti became an icon and the Egyptian government demanded her return, claiming that she had been allowed to leave the country by subterfuge. The matter remains unresolved to this day, and Nefertiti has survived two world wars in Berlin.

Nefertiti was the principal wife of the New Kingdom pharaoh Akhenaten (ca. 1350 – 1335 BC). Akhenaten tried to revolutionize Egypt, outlawing the worship of a host of gods, headed by Amun, the king of the gods. In their place he proposed the worship of the Aten, the sun-disc that gave life to the world. He moved the capital of Egypt from Thebes to a virgin site 250 miles to the north. This new capital he called Akhetaten (“horizon of the sun disc”), the modern site of Tell el-Amarna. Akhenaten’s changes did not find favor, and after his death the site was abandoned by his successor – the more familiar Tutankhamun – as the capital moved back to Thebes. Amun had restored the status quo.

A new religion required a new artistic style to express itself. Set against earlier Egyptian objects, Amarna art can appear more naturalistic, softer and more intimate. Images of Akhenaten, his wife Nefertiti, and their six daughters were the icons of this new creed, and Amarna was filled with sculptor’s workshops producing decoration for the city. The bust of Nefertiti, with its unusual shape, was probably a model used to define and standardize images of the queen.

The latest update on the “controversy” tells us that the Samalut bust is to be replaced with a statue of a peace dove. So all is well that ends well.

The original bust continues to attract huge throngs of tourists in Berlin. A museum quality replica of the same bust, manufactured by highly talented artists at the Neues Museum, has been on display in the Hall of Ancient Egypt at the Houston Museum of Natural Science since 2013. She looks forward to seeing you there.


Her Majesty awaits your visit at the Houston Museum of Natural Science.

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.