Amazon Scavenger Hunt: a Fun Way to Explore Rainforest Sustainability

Recently my daughter and I were making cookies when she asked me, “Where do chocolate chips come from?”

I considered the glib answer, “From the chocolate chip factory,” but decided to take advantage of a teachable moment and said, “Well, chocolate is made from seeds of the cacao tree that grows in the South American rainforest.”

If you know any six-year-olds, one question inevitably leads to another. So began a conversation about rainforest plants, animals and people that tested the limits of my understanding — all for the love of cookies.


Chocolate, cinnamon and vanilla beans, all from the Amazon.

As we enjoyed our cookies, we talked about other things in our house that came from rainforests. A quick online search later and we were off counting different foods, checking out the furniture and even kicking the tires on the car. As it turns out, a lot of things in our home originate in a rainforest. We easily found 30 items!


Example of mola on a quilt.

 Indigenous peoples sustainably use rainforest resources. Besides food, clothing, tools and homes, some cultures harvest rainforest animals and plants for ceremonial clothing that is passed from one generation to the next. Many cultures trade in non-food items like handmade baskets and bowls, and art produced by some cultures has found its way into our lives. The ornately patterned molas made by the Kuna Indian women of Panama can be found on purses, wall hangings or even quilts.


Example of another mola.

As a consumer, supporting companies and artisans that sustainably harvest these products can make a difference a world away. To raise awareness and enrich your child’s education, why not have your own Rainforest Celebration Day? Get your kids involved and try a rainforest product scavenger hunt or have a rainforest food-tasting party. Feeling crafty? Try making a mola out of fabric you have at home, or if like me you’d probably appliqué yourself to it, try making it out of construction paper instead! Brightly colored craft feathers (chicken, peacock, and pheasant) can be used to make necklaces, arm bands or if you’re really excited, headdresses or crowns for the little princesses in your life. 


Macaw feather headdress.

For more information on indigenous peoples, check out our John P. McGovern Hall of the Americas or the upcoming exhibit Out of the Amazon: Material Culture, Myth and Reality in Amazonia. The Cockrell Butterfly Center offers a taste of the rainforest, literally! Check out the vending machine downstairs, complete with edible bugs. Ask about our Wildlife on Wheels Rainforest topic to bring to your child’s school.

Experience a rainforest close to home with these ideas and your imagination. Happy hunting, and may all your scavenger hunts include cookies!

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.

Una Visita al Templo Mayor: HMNS Discovery Guide experiences Mexico City

by “Cretaceous” Chris Wells

It was late morning and the air was still cool and refreshing as my girlfriend, Fernanda, and I walked through the historic center of Mexico City. I had not expected the weather to be so fair, and in truth there would would be the dry, white sun to contend with shortly. But in the shade of the decaying colonial structures around us, it was very pleasant. The interiors of these buildings were made up in modern styles for the tourists, but the facades betrayed every bit of their declined elegance. The old homes and businesses were grey or red or blue and rose abruptly from varying distances and angles from the street, the structures so old and quirky they felt like natural formations. In their shadows, it felt like we were passing through a cavern. Well… a cavern with a skylight.


The cavernous space between the buildings of the historic districts.

It was all really exotic to me, and on top of that, the streets were packed with people who were heading towards the National Plaza where thousands were gathering to watch Mexico play Brazil in the World Cup. For the viewing pleasure of these masses, three enormous screens had been erected among the old seats of government — grand and impressive buildings whose facades had once been a purer off-white but had since been corrupted by dirt and grime into a shade of gray. In these surroundings, the screens didn’t seem at all out of place because the game was as much a symbol of national pride as any politician. Perhaps more so.


Zocalo Square (AKA the National Plaza).

It was our first international trip together. Fernanda is Brazilian, and of course she wanted to stay and watch the game a little, but I was much more excited about something else. I’ve studied Latin American history in college for years. It’s my favorite subject. Earlier on the trip, we had visited the ancient city of Teotihuacán, one of the oldest centers of civilization in the Americas, and the Museo Nacional de Antropología, which holds some of the finest collections of Mexican indigenous artifacts in the world — artifacts from the Aztec and Mayan cultures and many other civilizations history books have chosen to forget. We had even seen the palace of the Emperors of Mexico, lording over the city from atop a mountain, its grounds adorned with grim-faced marble statues of men holding machetes, the men who had helped bring an end to that decadent age. But all the amazing things we had seen did not compare to the place we were about to visit: the Templo Mayor.


The cathedral built almost directly over the old Templo Mayor. Christianity triumphs over the pagan gods of the Aztecs.

Forgetting my usual policy of early relationship affability, I insisted we press on, past the crowded plaza and cheering fans, past the gloomy cathedral the Spanish had placed at the head of the plaza, to what looked like a pile of rocks huddled behind a fence. This, the old pyramid’s foundations, was all that remained of the most important religious site in Tenochtitlan, the ancient capital city of the Aztec Empire. The conquistador Hernando Cortéz and his men had been efficient in their practice of dismantling the structures of the old city and using the stones to build the new Spanish capital. Of course, by the time he had captured Tenochtitlan for the second and final time, most of the buildings had been destroyed by the cannon balls with which Cortéz had bombarded the city into submission.


From farther away, the cathedral towers over the remains of the Templo Mayor.

But there was still much left to see. Portions of the lower parts of the walls were preserved, rising about twenty feet in the air in all directions and angles. If the Spanish city felt like a cavern, the Templo Mayor looked more like a windswept, craggy range of mountains, like those found in the Antarctic. The unnatural angles were created by people plundering the architecture for building materials over the years since the fall of Tenochtitlan. I got a cold impression from that place, even with the white sun burning the back of my neck.


Serpent head surrounded by two braziers, originally it would have guarded the Templo, which once rose behind it.

We approached what was left of the two stairways that had originally led up to the two shrines at the head of the temple. One shrine was for Huitzilopochtli, the sun god and another was for Tlaloc, the god of rain and thunderstorms. Today, the stairs rise about 20 feet before ending abruptly in crumbly, eroded peaks. Originally, they would have ascended 300 feet. At the base of these stairs, we were greeted by serpents’ heads carved at the foot of the stairways on either side — Quetzalcoatl, the feathered serpent, whom Cortéz was mistaken for by King Moctezuma. This case of mistaken identity is why Cortéz and his men were able to march unimpeded into the city. Many of Moctezuma’s commanders and trusted officials had advised against it, saying the Spanish should be treated like an enemy, but the emperor disagreed and all must obey the emperor.


Serpents’ heads that once guarded the staircases leading up to the shrines at the top of the Templo Mayor.

In an alcove carved out behind one of the staircases, there was a stone medallion depicting the dismembered body of a woman. The woman was Coyolxauhqui, the older sister of Huitzilopochtli. According to the myth, Coyolxauhqui became angry when she learned that her mother would have a baby, so she allied with her hundreds of brothers and sisters and plotted to kill both mother and child. Huitzilopochtli heard this plan from his mother’s womb, so he made himself emerge a full-grown warrior and killed his sister. Then he chopped her body up and threw her pieces down a hillside.


The oldest remains of the Templo Mayor. For centuries is was encased in several layers of stone facades, but now it breathes air again and is in pristine condition.

For the ancient Egyptians, pyramids were meant for burial, but for the Aztec, pyramids were stages — platforms raised high above the plaza so spectators could gather and see the rituals being performed at the top. On the Templo Mayor, in front of the shrine of Huitzilopochtli, it is believed priests would reenact the story of Coyolxauhqui by decapitating prisoners and rolling their bodies down the steps of the pyramid. The bodies would come to rest near the medallion depicting the goddess whose story their sacrifice symbolized.


The medallion depicting Coyolxauhqui, after she was dismembered by her brother.

But why was the medallion behind the staircase? Over time, the Aztec kings added onto the temple as a show of their success and of their devotion to the gods. They would build a new shell right over the old pyramid. With the top gone, now the structure looks a bit like those Russian nesting dolls, with one facade, one staircase and one medallion behind another. There are seven layers of facades, and inside those, in the center of the structure, is the very first temple, magnificently preserved. It’s a stunted-looking pyramid from the early days of the city.


Two of the Templo’s old facades, one inside the other.

Near the temple, a few other structures are preserved, including the House of Eagles, where members of the order of Eagle Warriors would gather for rituals, some of which involved human sacrifice. There are beautiful stone benches lining the walls, whose intricate relief images still bear their original paint. Archaeologists have found traces of what could be blood on these benches. It has been argued that auto-sacrifice was practiced there. Men would sit and let their own blood as a sign of devotion to their gods.


A stone bench lining the wall of the house of eagles, still with its original paint.

Obviously, there was a lot of violence and bloodshed within the Aztec Empire. Human sacrifices usually would have been prisoners of war. The Aztec were known to start “flower wars” in which they would engage another city in combat for the sole purpose of capturing warriors for sacrifice. In order to become an Eagle Warrior, one had to capture a certain number of prisoners in two consecutive battles. The capture of prisoners was believed to be vital to the future of the kingdom. The Aztec gods required blood. For them, blood was kind of like Gatorade; it gave them energy do perform the celestial duties. Without blood, the sun would not rise, the winds would not blow and life would end. Within the remaining walls of the Templo Mayor, archaeologists have found sacrificial victims from other cultures around Mexico, buried with objects related to their society. These burial caches were meant to symbolize that Huitzilopochtli, the most important Aztec god, held dominion over all the peoples of Mexico. This brutal practice was one of the reasons that Cortéz was able to gather a massive army of indigenous warriors with which to fight the Aztec. The empire had made many enemies.

But besides all the violence and bloodshed, the Aztec were a highly innovative society. The air is rather dry in Central Mexico, and for that reason Lake Texcoco, the lake in which the Island City of Tenochtitlan was built, was a salt lake. However, the Aztec were able to create areas of freshwater by building dams between the areas where freshwater was coming down from the mountains and the briny water in the rest of the lake. Also related to the importance of water is the fact that the Valley of Mexico was filled with many cities and cultures at the time, and there was a fair amount of competition for arable land.

One of the ways the Aztec helped solve the need for more land was to build chinampas, basically islands of rich soil dredged from the bottom of the lake. These man-made islands huddled around the margins of Tenochtitlan and hugged the shores around Lake Texcoco. They created their own farmland. Of course, another way they fixed the problem was to conquer the territory of surrounding cultures.

The Spanish were in such awe of the achievements of the Aztec that they named their new city after the leading tribe among the Aztec people, the Mexica. The seal of Mexico is taken from the Mexica legend of how they settled on the island. The story says that Huitzilopotchli had told the holy men of the Mexica to look for an eagle perched atop a cactus, eating a snake. That would be the sign that they had arrived at their promised land.


In the Historic District, a dilapidated colonial exterior enshrines , of all things, a McDonald’s, along with other modern stores.

Now, the island is gone. It was drained by the Spanish, who did not understand the purpose of the dams. Now most of Mexico City lies at the bottom of the valley, which was once underwater. Flooding is a big problem.  I still remember the last night we were in Mexico City. We had been enjoying the Museum of Anthropology all day, and in the evening (as had happened every evening we were there) the moisture that had evaporated in the dry sunlight all day and had been trapped by the mountains began to rain down as the air cooled. It was a hard rain and we couldn’t get a taxi, so we were forced to brave the torrent. And it was truly a torrent. The rain beat down from the sky and washed into the streets, flooding as deep as a foot in places. There was a point when we had to climb onto the high stone base of a wrought iron fence and scoot along, holding onto the bars to avoid slipping up to our knees into the deep water in the streets. There was a whole crowd, young and old, scooting along with us.


Fernanda trying to stay dry during a flood downtown, which are quite common.

In spite of the rain, it was a wonderful trip, and sometimes I go up to the John P. McGovern Hall of the Americas on the third floor to stand in the re-creation we have of the Templo Mayor and spark memories from the trip. I hope you will come and visit too. Our re-creation is scaled down, but at the top of the structure we have an actual statue of a god related to Quetzalcoatl and objects from different cities cached in our walls, much like in the original. Some of the objects are beautiful (but dangerous) obsidian blades that were actually used by the Aztec, most likely in rituals of burial.

We also have some mummy masks and incense burners for the mysterious city of Teotihuacan, a city so old and so impressive the Aztec believed it was built by the gods. They considered it a holy site, and its history is worthy of a blog of its own. When I stand in our little ruined pyramid, all by myself, visions of the white sun come to mind. I remember the dry breeze blowing across the valley and the sound of indigenous flutes being played, albeit by street vendors who always hounded me to buy their stuff. Still, the music they made in attempt to lure tourists and their cash lent a mystical air to the site which I really appreciated. So if you’re planning a trip, come get inspired like I do. In the Houston Museum of Natural Science, we have many pieces on display and all of them have a cool story and a place of origin. Maybe you will discover a new destination.

Editor’s Note: “Cretaceous” Chris Wells is a Discovery Guide at the Houston Museum of Natural Science.

HMNS changed the way I think about Earth, time, humanity, and natural history

After 90 days working at the Houston Museum of Natural Science, here’s the verdict:

I love it here!

Through research required to compose and edit posts for this blog, I have learned about voracious snails, shark extinction, dinosaur match-ups, efforts to clean up ocean plastic pollution, Houston’s flooding cycle, a mysterious society in south China, and the inspiration for the design of costumes for Star Wars.


Look at the size of that T. rex! My love for the Houston Museum of Natural Science began with an affinity for dinosaurs.

I’ve learned about many, many other things, as well, and I could feasibly list them all here (this is a blog, after all, and electrons aren’t lazy; they’ll happily burden themselves with whatever information you require of them), but the point of this blog is to excite our readers into visiting the museum, not bore them with lists.

Coming to the museum is a grand adventure, and it’s my privilege to be here every day, poking through our collection and peering into the the crevices of history, finding the holes in what humanity knows about itself and speculating about the answer. That’s what science is all about, after all. Learning more about what you already know. Discovering that you’ve got much more left to discover.


As a writer, I identify with the oldest forms of written language, like this tablet of heiroglyphs. You can even find a replica of the Rosetta Stone in our collection!

When I took this job, I was a fan of dinosaurs and Earth science. I could explain the basic process of how a star is born and how the different classes of rock are formed. Igneous, metamorphic, sedimentary. Now, I can tell you which dinosaurs lived in what era and the methods paleontologists use to unearth a fossilized skeleton. I know that a deep-space telescope owes its clarity to a mirror rather than a lens, and I can identify rhodochrosite (a beautiful word as well as a fascinating mineral) in its many forms. And there are quite a few.


Rhodochrosite. My favorite mineral. Look at that deep ruby that appears to glow from within, and it takes many other shapes.

I have pitted the age of the Earth against the age of meteorites that have fallen through its atmosphere and have been humbled. The oldest things in our collection existed before our planet! How incredible to be that close to something that was flying around in space, on its own adventure across the cosmos, while Earth was still a ball of magma congealing in the vacuum of space.

Time is as infinite as the universe, and being in this museum every day reminds me of the utter ephemeralness of human life. It advises not to waste a moment, and to learn from the wisdom of rock about the things we will never touch. Time and space reduce humanity to a tiny thing, but not insignificant. Our species is small and weak, but we are intelligent and industrious. We have learned about things we don’t understand from the things we do. The answers are out there if you know where to look for them.


Everything turns to stone eventually, even this gorgeous fossilized coral.

I was a print journalist for three years, and I am studying to become a professional writer of fiction at Vermont College of Fine Arts. (Don’t worry. It’s a low-residency program. I’m not going anywhere.) I am a creator of records of the human experience, according to those two occupations, and in some ways I still feel that as the editor of this blog, but there is a difference.


This epic battle between a sperm whale and a giant squid recalls scenes out of Herman Melville.

Here, rather than individual histories — the story of one person or of a family or of a hero and a villain — I’m recording our collective experience, our history as a significant species that participates, for better or worse, in forming the shape of this world. We were born, we taught ourselves to use tools, we erected great civilizations, we fought against one another, we died, those civilizations fell. We have traced our past through fossils and layers of rock and ice, we have tested the world around us, and we have made up our minds about where we fit into the mix.

We are a fascinating and beautiful people, and through science, we can discover our stories buried in the ground, often just beneath our feet. To me, this is the real mission of our museum. To tell the story of Earth, yes, but to tell it in terms of humanity. In the Cullen Hall of Gems and Minerals, we wonder what makes certain minerals precious to us when they’re all spectacular. In the Morian Hall of Paleontology, we trace the fossil record back in time and wonder how things were and could have been had dinosaurs not gone extinct. In the Cockrell Butterfly Center, we connect with the little lives of insects, compare them to our own, and fall in love with our ecosystem all over again. In the Weiss Energy Hall, we learn how life and death create the fossil fuels that now power our society. We find both ingenuity and folly in the values of old civilizations in the Hall of Ancient Egypt and the John P. McGovern Hall of the Americas.


These chrysalises, a powerful symbol of personal growth and change, teach a lesson in natural cycles and big beauty in tiny places.

I have often wondered how we justify placing a collection of anthropological and archaeological artifacts under the heading “natural science.” Why don’t we consider our institution more representative of “natural history?” In my first 90 days, I think I’ve found the answer. It’s not just about the story of humanity; it’s about the story of the science we have used to learn what we know.


The Houston Museum of Natural Science, including the Cockrell Butterfly Center, is truly one of a kind.

Our goal at HMNS is to inform and educate. To challenge your assumptions with evidence and bring the worlds and minds of scientists to students and the general public. It’s a grand endeavor, one that can enrich our society and improve it if we pay attention.

A ticket to the museum isn’t just a tour through marvels, it’s a glance in pieces at the story of becoming human. After 90 days here, by sifting through the past, I feel more involved in the creation of our future than I have ever been.

And that feels pretty great.