Saturday is STEM/Nova Day for Scouts at HMNS!

Hey, Scouts! Spend the day at HMNS this weekend and work on earning your Nova Award during STEM/Nova Day! The Houston Museum of Natural Science is the perfect place to complete your badge requirements. Visit our permanent exhibit halls, watch a Burke Baker Planetarium or Wortham Giant Screen Theatre movie, and ask some of our docents your best science questions!


Cubs and Webelos can work on their requirements for the “Science Everywhere” or the “Down and Dirty” Nova Awards. Watch one of our films about geology, oceanography, or weather, and explore permanent exhibit halls like the Weiss Hall of Energy and the Morian Hall of Paleontology. Wolf Scouts can sign up for Digging in the Past, and Webelos can choose from Adventures in Science, or Earth Rocks! classes. Bear Scouts can take one of our fall classes to finish their Nova Award requirements. We’ll also have Investigation Stations in the Alfred C. Glassell, Jr. Hall (under the fish) so you can explore different scientific topics through hands-on activities!


Boy Scouts will also be able to fulfill some of their “Shoot!” Nova Award requirements. Visit the Burke Baker Planetarium or Wortham Giant Screen Theatre to watch a movie about weather, astronomy, or space technology. Stop by some of the Investigation Stations to participate in hands-on activities involving physics and engineering. (Please note that Boy Scouts will be unable to fulfill every requirement for the “Shoot!” Nova Award at this event.)

STEM/Nova Day will be from 9 a.m. to 1 p.m. on Saturday, Sept. 26. If you are taking a class to complete any Nova requirements, classes will run from 1 to 3 p.m. Scouts can also get field trip rates for the Burke Baker Planetarium and Wortham Giant Screen Theatre shows that day. Participation in STEM/Nova Day requires admission to the permanent exhibit halls. Become a member and get free admission to the permanent exhibit halls year-round!

We look forward to seeing scouts at the STEM/Nova Day at HMNS!

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.

Stego says HMNS makes field trips easier on teachers

by Kaylee Gund

Hi all,

Stego the Stegosaurus here, putting my best plate forward for the beginning of the school year!


Stego the Stegosaurus, team leader for the field trips department.

I was chatting with my Discovery Guide pals the other day and we’re all looking forward to the great school field trips we see every year. But surprisingly, a few local teachers they’ve spoken to are intimidated by the prospect of planning a field trip.

I have to admit, the idea of taking more than 500 students off campus and bringing them back in one piece does sound overwhelming, but here at HMNS, it’s our job to make field trips the best possible experience for everyone involved.

As the face of the Youth Education Sales team, I, Stego the Stegosaurus, feel duty-bound to dispel the myth that organizing a field trip is by nature stressful. In fact, I’d like to take this opportunity to introduce you to two wonderful ladies who can give you all sorts of great tips and ideas for students to put a spike in their learning curve (pun intended).

Karly - Paleo

Karly Hunt, Marketing Coordinator (

The newest member of our team, Karly Hunt, is the Marketing Coordinator for all districts west of Houston. She comes to us from Liberty Hill ISD, where she taught high school science. Karly, by the way, appreciates a good chemistry joke, but unfortunately all the good ones Argon… Get it?

This is Karly’s first year at HMNS, but she is already hard at work sharing her love of all things scientific with Houston educators. Her favorite part of the museum is the Morian Hall of Paleontology.

“We have such an amazing collection that really puts prehistory in perspective,” Karly said.

Needless to say, being a dinosaur myself, I like her already!

When she’s not traveling to schools, you’ll find Karly spending time outside, enjoying music of all genres, and playing with her dogs.

Cathy - Jurrasic Bark

Cathy Walton, Lead Marketing Coordinator (

Cathy Walton, our Lead Marketing Coordinator, is the museum representative for schools in Houston ISD, districts centrally located in the metroplex, and districts to the East. Having originally taught World Geography in Tennessee, she began her career at HMNS three years ago. Cathy is a wizard at finding field trip packages that fit an individual teacher’s needs, and she loves being able to work with amazing educators to help them inspire their students. She encourages teachers to “be as creative as you can to get students excited about learning!”

Cathy enjoys hiking, cooking, and entertaining (when she’s not hanging out with us dinos, of course). Fun fact: she grew up in Shelbyville, Tenn., better known as “Pencil City,” home of the No. 2 pencil!

If you have any questions or would like to know what exciting new exhibits your students can learn from next, feel free to contact one of these representatives. Check out our free curriculum and our field trip preparation guide for more info, too. And you can fill out a booking request form online if you already have an idea of what you’d like to do at the museum.

Have fun, keep learning, and we’ll see you soon!




Editor’s Note: Kaylee Gund is in Youth Education Sales at the Houston Museum of Natural Science.

Go ahead. Take your toddler to the museum!

by Victoria Smith

When my children were younger, and I was hip to the toddler scene, I would schedule play dates at all the usual places: I’d push the stroller to the park, load up the red wagon for the zoo, and slip Cheerios to fussy babies during story time at the library. The Houston Museum of Natural Science was also on the top of my list, and I was surprised other moms thought their kids were too young to appreciate it.


“Oh, no! He’s after us!”

The museum is fantastic for small kids! It’s got air conditioning, wide spaces to navigate, and if you have a two-year old who will only eat peanut butter sandwiches cut in squares, not triangles, you are welcome to bring your own food.

And of course, DINOSAURS! They’re huge, they’re exciting and they have pointy teeth (at least the carnivores do). Even if you don’t have a toddler who can identify every prehistoric creature and pronounce the names better than most college graduates, every kid loves dinosaurs. (Thank you, Dr. Scott the Paleontologist!) In the Morian Hall of Paleontology, the dinosaurs are mounted in active poses, bringing these ancient creatures to life for young visitors. The displays tell a story, and the murals illustrate it.


It’s the Circle of Life, baby.

Speaking of stories, my youngest daughter’s favorite story is the lion chasing the zebra in the Hall of African Wildlife.  Even though she knows how it’s going to end for that poor zebra, every time she asks, “Mommy, tell me the story of the lion and the zebra.” It’s not only a great chance throw in a few Mufasa quotes, but it’s also great to discuss how nature doesn’t waste anything because after the predators come the scavengers. I usually manage to work in a moral lesson about the selfish leopard who won’t share, too. There are interdisciplinary opportunities at every turn!


Let me know when the wonderment is over, so Momma can sit down!

The Cockrell Butterfly Center is one of our favorite spots to visit, and perhaps even my favorite place in the museum, period. Yes, the awe and delight in a young child’s face is a daily miracle, but they’ve got cushioned benches and free wi-fi! When you’re through with the center, there’s a beehive-themed play area with puzzles and blocks, and most importantly, it’s enclosed!


My daughter at age four, as an assistant in a chemistry demonstration…

If you want your daughters (and sons, of course) to grow up to interested in science, it’s never too early to start. Let them know that science is fun and not scary. The museum has dedicated tour guides who specialize in making the exhibits come alive for young children, and docents who offer many hands-on experiences. Kids can touch real fossils, feel if minerals are rough or smooth, and guess if an animal was an herbivore or carnivore while holding an actual tooth! It’s all there, at their eye-level.  


…and at age eight, taking on a brain dissection at Xplorations summer camp.

So now that the big kids are back in school, it’s a great time to plan a visit to the museum. If you’re lucky like me, you can convince their grandparents that even though your one-year-old can’t talk, he really wants a membership for his birthday, and not another toy to clutter the playroom.

Editor’s note: Victoria is the Executive Assistant to the President of the Houston Museum of Natural Science.