Some New InSight

Yesterday the NASA InSight mission successfully touched down on Mars. While it was the eighth NASA mission to reach the red planet's surface, it was the first in a few new categories: first mission to send information via cubesat orbiters, first mission to deploy instruments by itself upon reaching the surface, the first mission to launch from the west coast of the United States, and the first mission to drill into another planet. Sure, all those things sound cool, but why should we care?

Celebrations in the mission control room at JPL in Pasadena, CA after
confirmation of InSight's successful landing came through.

First, a bit of backstory. Every NASA mission that has flown in the past decade has been the winner in a multi-stage selection contest that NASA administrators run. We'll go into more detail in a later post since the process is fairly intricate, but the basics are that many missions submit their plans to a NASA request for proposals, then some of those are selected to move on and create prototypes and more precise mission plans, and from those only one mission is selected. The InSight mission was initially one of 28 mission proposals submitted to NASA in 2010. In May 2011, it became one of three selected from the whole pool to develop more details about the mission and begin some work on building and testing instruments. In August 2012, just days after the Curiosity lander successfully landed on Mars, the InSight mission was selected for development and flight.

InSight uses updated versions of technology that was first included on the Phoenix Mars lander, which successfully landed on Mars a decade ago (2008). To reduce the risks of future missions, NASA likes to select missions that make use of any instrument or mission piece that has already flown on a mission and worked. These missions components are called heritage pieces because they have been inherited down to a newer mission from an older one. The instruments are never exactly the same, even if scientists and engineers want them to be--manufacturers discontinue electronics, technologies improve, etc. Engineers are responsible for extensively testing every single mechanical aspect of the mission in a number of ways--extreme heat, extreme cold, and high radiation are only a few of the environmental factors that a space mission will experience in its lifetime. Of course, the instruments must not only survive, they need to work too, and it's much better to work out issues ahead of time than after launch.

Testing the robotic arm that will deploy the SEIS
instrument. Photo credit: NASA/JPL/Caltech

The seismometer on InSight is a good example of when extensive testing uncovered a problem that could have jeopardized the whole mission. The Seismic Experiment for Interior Structure (SEIS) instrument was built by the French National Space Agency CNES, and will be responsible for obtaining seismic data of Mars, which is effectively the reason that this mission was selected in the first place. Without it, the mission will not be able to collect any seismic information of Mars. Clearly, it was a key part of the mission. During testing, the engineers discovered multiple small leaks in its vacuum chamber that actually holds the seismometer. The leaks were severe enough that the mission's launch date was pushed back from March 2016 to May 2018. The overall cost of this delay was great in both time and money; it cost roughly $150 million to redesign the vacuum chamber, rebuild it, retest it, and pay for the time of the people who worked on it.

InSight launched on May 5, 2018 from Vandenberg Air Force Base in California, a location on the coast in between San Francisco and Los Angeles. Most NASA missions launch from Cape Canaveral in Florida, though some launch from the Wallops Island Flight Facility in Maryland, so InSight is unusual in this regard. Vandenberg was selected because of its good positioning to aim the spacecraft to enter the Mars atmosphere at the correct angle of 12 degrees. Any steeper and the mission would burn up. Any shallower and the mission would "bounce" off the top of the atmosphere and continue off into deep space, lost forever. It was 12 degrees, or failure. If anything, this illustrates to me that there are many precise calculations that go into making every single decision on a NASA mission, and one miscalculation could cost the whole mission.

After 6 months and 301 million miles, InSight finally entered Mars' atmosphere at a perfect 12 degree angle. Much has been written and said about what happened during the landing, so we'll point you to one of our favorites instead of rehashing it here. In about 3 month InSight will deploy its own instruments, including the seismometer and an instrument that will drill 16 feet down into Mars' crust to study the thermal environment of Mars beneath the surface.

A screenshot of the NASA InSight landing live-feed on November 26, 2018, showing the first picture InSight took of Mars' surface. The line in the background is the Martian horizon. The camera lens is still behind the dust cap in this image,  but that piece will be removed in a couple of days, after the dust settles.

Just to prove that it made it to the surface, InSight was programmed to take a couple of pictures at the surface and send them back to us here on Earth. Its relay system is the Mars Cube One (MarCO), an important first for this mission as well. MarCO are two 6U cube sat missions that was designed to relay messages back and forth between Earth and InSight on Mars while it was going through its landing process. What is a cube sat? Generally the larger a mission is, the more expensive it is. A cube sat is a mission that is roughly the size of a shoebox, and it's a type of mission that has become more popular in the past 5 years because they are small, quick and easy to build, and inexpensive. A "U" is a shorthand to refer to the size of a cube sat mission, where a U is a cube with 10 cm sides. A 6U cube sat, therefore, is one that is 30 cm long, 20 cm wide, and 10 cm tall. MarCO was a test to see how well cube sats would work in a deep space environment, one that it passed with flying colors. This will pave the way for future cube sat add-on components to larger missions and even individual cube sat missions (see LunaH-Map here).

All of these accomplishments were the results of years of hard work by its team members and the mission failures that happened before. We thank all the scientists and engineers who have study and do study Mars, and all the people who support them, and wish them all many congratulations! Here's to future breakthroughs on Mars!

Thanksgiving Plants

Last week we told you all about the domestication of the chicken-peacock, a.k.a. the turkey. Since there will be many vegetables present on Thanksgiving tables this week, it's only fair to talk about them too! Here are the histories of some of the most popular plants that we love to eat (or love to hate, we don't judge)!

Sweet potatoes, baked and delicious. Photo from: Food Network

Sweet potatoes: Ipomoea batatas, or the sweet potato, was first domesticated somewhere between the Orinoco River delta area of modern day Venezuela and the Yucatán Peninsula in Mexico around 5,000 years ago. The second name of the sweet potato, batata, is the original Taíno word for the plant, though the Quechua people in Peru call it kumar. Surprisingly, it is only distantly related to the white potato, and is a genetically different plant from a true yam. In fact, the sweet potato is fairly closely related to the morning glory flowers, and the flowers of a sweet potato plant are even called tuberous morning glories! As with most of the plants on this list, it was first introduced to Europe via Spanish conquistadors, and to China via Portuguese traders. Sweet potatoes were used around the world to supplement the lack of other food due to poor harvests or other natural events. For example, after the sweet potato was introduced to Japan in the early 1600s, it became an important plant that prevented starvation in years when the rice harvest was poor. It is a popular plant because it grows well and without pesticides in a variety of climates, though it will not survive the cold and requires roughly 36 inches of water a year to grow.

The Three Sisters plants. Image from:
University of Illinois Extension

Squashes and pumpkins: The domestication of squashes and pumpkins (all part of the genus Cucurbita) is one of the best known stories, and one of the oldest: there is archaeological evidence that puts the domestication of squashes before 10,000 years ago! The wild relatives of squashes produce fruit much smaller than what we know today, and the plants were bitter, even toxic. Only the intense domestication efforts of the indigenous people in Central America saved the squashes we enjoy today. These plants are highly adaptable, and grow in many diverse climates. The reason there are so many types is because they have been traded and transported around the world to many different places, and these plants needed to adapt to survive in their new habitats. The English word squash comes from the Naragansett word askutasquash (a green thing eaten raw), excellent evidence that the plant was able to adapt from its Mesoamerican origins to survive in Rhode Island!

An important point is that squash, beans, and corn are called the Three Sisters of plant husbandry because they are mutually beneficial organisms. Basically, they help each other grow so well that the native peoples in the Americas often planted the three of them together! Squash was the first of the Three Sisters to be domesticated, followed by corn and beans.

Corn: Corn was domesticated from maize by the indigenous peoples roughly 10,000 years ago in what is now southern Mexico. The word "maize" comes from the Spanish version of the original Taíno word for it: mahiz. While the consensus used to be that the Tehuacán Valley was the center of domestication, newer analyses show that the the nearby Balsas River Valley is the true origin point of what we know as corn. A study in 2002 showed that modern corn comes from a single domestication event of maize at least 9,000 years ago, and other studies put this date even earlier. Another study argued that knowledge of corn cultivation was spread through two different events thousands of years apart: one event spread corn cultivation down the Andes Mountains around 6,700 years ago, and the second event spread it across the rest of South America roughly 2,000 years ago. It was taken back to Europe by Spanish conquistadors, and quickly became a popular plant around the world because of its ability to grow in many climates, but it is very sensitive to cold and to droughts, and strong winds can uproot it because of its shallow root structure. Today there are many forms of corn, though most of them are grown for industrial purposes (corn ethanol, animal food, etc.).

Beans: Unlike other plants on this list, beans were known in Europe and around the world before any Spaniard set food on the American continents. The beans that are part of the Three Sisters, however, were originally domesticated in (as you may have guessed) Central America. Some bean remains in the Guitarrero Cave in Peru date beans there to 4,000 years ago, though genetic analysis has proved that those beans were merely cultivated there. Beans, along with corn and squash, gradually spread south as knowledge of their cultivation also spread. Beans need support as they grow, and growing them near corn stalks provided that support. Beans in return pull nitrogen from the air and put it in the ground for corn and squash to use. They grow best in the summer and with lots of water. Currently the genetic information for 40,000 species of beans are held in genebanks, but only 30 of those are actually eaten.

Cranberries on a bush. Photo from: FastGrowingTrees.com

Cranberries: Cranberries were domesticated very recently, only about 200 years ago in Cape Cod, Massachusetts. Before then they were wild plants that the Native Americans would collect and use in a variety of different ways, from preserving fish and meat to mixing them into a poultice to use on wounds. Because the cranberry is a relatively young domesticated plant, it hasn't changed much from its wild variety. Cranberries are closely related to blackberries, huckleberries, and the flower rhododendron (that part blows my mind), and distantly related to the fruits kiwi and persimmon. Most cranberries today are grown in the United States, specifically Massachusetts, Wisconsin, New Jersey, Oregon, and Washington, though they are also grown in five provinces in Canada, and parts of Europe and Chile. They are tough plants but do best in wet, cold regions. Cranberries also are high in polyphenolic antioxidants and have some anti-cancer properties. So, eat up!

We here at Science on Main wish you a very happy Thanksgiving, and thank you for reading!

Sources:
 Zhang, D.P.; Ghislain, M.; Huaman, Z.; Cervantes, J.C.; Carey, E.E. (1999). AFLP Assessment of Sweetpotato Genetic Diversity in Four Tropical American Regions (PDF). : International Potato Center (CIP) Program report 1997-1998. Lima, Peru: International Potato Center (CIP). 
 http://bioweb.uwlax.edu/bio203/2011/keesler_cole/
https://www.sciencedirect.com/science/article/pii/S1055790317301811 
https://www.smithsonianmag.com/smart-news/domestication-saved-pumpkin-and-squash-180957314/
"Origin, History and Uses of Corn". Iowa State University, Department of Agronomy. February 11, 2014.
Piperno, Dolores R. (2011). "The Origins of Plant Cultivation and Domestication in the New World Tropics: Patterns, Process, and New Developments". Current Anthropology. 52 (S4): 453–S470. 
Bitocchi, Elena; Nanni, Laura; Bellucci, Elisa; Rossi, Monica; Giardini, Alessandro; Zeuli, Pierluigi Spagnoletti; Logozzo, Giuseppina; Stougaard, Jens; McClean, Phillip; Attene, Giovanna; Papa, Roberto (3 April 2012). "Mesoamerican origin of the common bean (Phaseolus vulgaris L.) is revealed by sequence data". Proceedings of the National Academy of Sciences. 109 (14): E788–E796. 
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4076063/
 

Turkey Tale

Soon, families in the United States will sit down around a table to consume a famous dish: the Thanksgiving Turkey. According to a study done by the National Turkey Federation (yes, it's a real thing), 88% of Americans eat turkey on Thanksgiving, which amounts to around 46 million turkeys every year for Thanksgiving alone. Turkey has become more popular as an alternative to red meat in recent years as more varieties of turkey burgers, sausage, and cold cuts are added to supermarkets, not to mention all the dishes you could make with leftover turkey after Thanksgiving! Yet how much do you really know about that bird on your plate?

Gobble gobble! What a beautiful bird. Photo from:
http://jacksbbq.com/home/turkey/

Turkeys are native to North America, mainly the vast area east of the Rocky Mountains and some parts of central Mexico. There are two species of turkey in North America: the familiar Meleagris gallopavo and the slightly-less-common ocellated turkey, Meleagris ocellata, which can only be found in Mexico's Yucatán Peninsula. The wild and domesticated turkeys belong to the same species, M. gallopavo, whose name literally means "chicken peacock." There are also five different subspecies of turkey that are found in different places of the United States, Mexico, and Canada: the eastern wild turkey, the Osceola (Florida) wild turkey, the Rio Grande wild turkey, Merriam's wild turkey, and Gould's wild turkey. 

Turkeys were first domesticated by the indigenous people of central Mexico in the modern-day states of Jalisco, Guerrera, and Veracruz around 2000 years ago. The birds were an excellent food source in both their meat and their eggs, and their feathers were used in decorations. Perhaps because of its silly appearance and perceived personality, the turkey was associated with the Aztec trickster god, Tezcatlipoca, a central deity of Aztec religion. New DNA analysis of turkey bones from the southwest United States suggest that a second, separate domestication event took place between 200 BCE and 500 CE. The evidence suggests that these turkeys lived in civilizations that were in central Arizona and New Mexico around and on the Colorado Plateau, which strongly implies that these animals were specifically bred by people instead of naturally migrating north from Mexico.

A ceramic whistle that looks like a turkey, from the Colima
shaft tomb culture in Jalisco, Mexico. 300 BCE–400 CE.

After the Spanish landed in the New World, they took some of the animals back with them to Europe.
The name turkey probably came from some of the birds coming into British ports via ships that traveled from the eastern Mediterranean Sea. They were incorrectly associated with the African guinea fowl, whose name back in the 1500s was the turkey cock, which was thought to have come originally from the country of Turkey. From there, the name stuck, and persists to the modern day. As a result of selective breeding in Europe, there are now many different varieties of turkeys, all part of the same original species. All of the domesticated turkeys today come from the original population that was domesticated in central Mexico thousands of years ago.

The names used to describe turkeys themselves are quite silly. Males are called toms, and females are called hens, which are actually normal names for birds. The two names for the young are rather odd though: poults and turkeylings (the best name I've ever heard for baby animals). The red pieces of flesh on the beak of the toms also have names. The flesh that connects to the bottom of the beak is called the wattle, and the flesh that connects to the top of the beak is called the snood. The average size of a turkey is 29.8 pounds and 3.5 feet long, but the largest turkey weighed 86 pounds and was 4.1 feet long!

An adorable turkeyling!
Photo by Kristie Gianopulos.

Finally, as you go to break the wishbone of the turkey after the meal, remember that the scientific name of that bone is the furcula, the "little fork" in Latin. The furcula is an ancient bone that is present in some theropod dinosaurs (think Velociraptor and Tyrannosaurus), which was used as evidence to show how birds are modern dinosaurs. Furcula in birds are used to anchor the muscles that power the wings and help the birds to fly, but in domesticated turkeys, those muscles aren't really needed. Two people breaking the bone as a sign of good luck is a tradition that dates back to the 1600s, though it was not called officially called a wishbone until 1860.

Personally, the most interesting thing I knew about turkeys before today was that Benjamin Franklin once thought they should have been the national bird instead of the bald eagle. Knowing what I know now, I have to agree with him: the turkey deserves a lot more attention than as a centerpiece once a year. Thank you for reading!

Sources:
http://extension.illinois.edu/turkey/turkey_facts.cfm
http://www.nwtf.org/hunt/article/wild-turkey-subspecies
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2840336/ <--Turkey DNA study
Webster's II New College Dictionary. Houghton Mifflin Harcourt 2005, ISBN 978-0-618-39601-6, p. 1217

November update

Thank you, readers, for your patience! Unfortunately there will not be an article this week, as the author's car got a flat tire and she spent all of her normal writing time fixing that. Part of being in grad school is making choices about how to spend time, and she needs to spend her work week on the stuff that will actually help her graduate.

There are at least three article topics lined up already for you, one of which will involve input directly from an outside source. We'll see you back here on Monday!

Blood Colors

First of all, we want to wish all of our readers a Happy (and safe) Halloween! Now, onto the science of blood.

Some of the most iconic monsters of all time seem obsessed with blood. Of course, vampires are the most famous among mythical creatures, but sharks can smell blood in the water from miles away, and vultures and ravens are attracted to the smell of blood and decaying flesh on land. All animals, with the exception of some very simple invertebrate animals like jellyfish, coral, and flatworms, have blood. An average human will have between 1 and 1.5 gallons of blood in their body at any time, and blood accounts for roughly 7% of the person's weight. It's an essential, valuable thing.

In general, human blood is made up of four major parts: white blood cells, plasma, platelets, and red blood cells. White blood cells, or leukocytes (luke-o-cites), are part of your body's immune system, and they are responsible for responding to microscopic threats that your body faces from bacteria, parasites, and infections. Platelets, or thrombocytes, are the small cells that stick together to form scabs and stop vessels from bleeding. They are the reason why all your blood doesn't spill out when you get a cut! Plasma is the colorless liquid that the other components are suspended in, and is mostly made of water.

Red blood cells, photographed with a scanning electron
microscope. Photo by the Wellcome Trust/Marc Turner.

Red blood cells are also called erythrocytes (air-ith-throw-cites), and they give blood its red color. Their job is to carry oxygen to every cell in your body. The cells then use the oxygen to create food and energy. The red blood cells also take waste away from the cells. As the red blood cells pass through organs like the liver and the kidneys, the waste is filtered out and eventually expelled from the body. Red blood cells are born in a person's bone marrow, and every cell will live roughly 120 days (about 4 months). Once they die, the spleen filters them out. The spleen also removes any red blood cells that are misshapen or damaged.

Of course, the color most associated with blood is red (I mean, it's right there in the name of the cells!). But blood actually comes in a rainbow of different colors, and it all has to do with the types of chemicals that it contains. Most vertebrates (animals with backbones) have red blood because our red blood cells contain hemoglobin, an iron-based protein. Each hemoglobin protein is made up of individual hemes, which bind iron particles. The iron particles in turn bind oxygen, which is then carried to the rest of the body. A deficiency in iron is called anemia, and is actually a fairly common deficiency in America. Since a low iron level makes it harder for blood to carry oxygen to cells, a person with anemia may become tired and short of breath more easily than someone with higher iron levels.

The different colors of blood. Image by Compound Chem.

Red blood is just one color though. Animals like horseshoe crabs have blue blood because instead of hemoglobin, they carry a protein called hemocyanin. This protein contains copper in place of iron, but it functions in much the same way. When hemocyanin-rich blood is carrying no oxygen, it is actually colorless! These animals have evolved a different type of blood circulation system that doesn't require as high of an efficiency rate, so copper sufficed.

Green blood is also seen in nature, but almost exclusively in worms and leeches. The protein that makes blood green is called chlorocruorin. Chlorocruorin also contains iron in its center, but one branch of the protein is replaced with a different chemical structure, which alters the entire protein. There is one lizard, aptly called the green-blooded skink, whose blood is indeed green. This lizard actually has true hemoglobin in its blood, but when its cells die, its body cannot break the protein down as far as our bodies can. The result is that the lizard's blood has a higher concentration of a by-product called biliverdin, which gives the lizard's blood a green color.

The green-blooded skink. Photo by Christopher Austin,
Louisiana State University Museum of Natural Science

One last shade of blood is bright violet-pink, which is the rarest color of all, occurring only in some species of marine worms. This blood's color is from a protein called hemerythrin, which is made of individual chemical units which all contain iron. This protein can only carry about 25% of the oxygen that hemoglobin could carry, unfortunately for the worms!

As much as modern science has learned about blood over centuries of study, the one thing no one can yet do is manufacture blood. Since blood is such a vital resource, and because it cannot be created, the only source of blood for people is other people. This is why blood drives are so necessary for people suffering from diseases or recovering from major accidents. If you are able and willing, please try to donate blood soon. Perhaps you can even make a joke about how the blood drive workers just wanted to suck out your blood!

Sources:
http://science.sciencemag.org/content/192/4237/335
https://www.compoundchem.com/2014/10/28/coloursofblood/
http://scienceline.ucsb.edu/getkey.php?key=2419
http://idahoptv.org/sciencetrek/topics/blood/facts.cfm
http://www.chp.edu/our-services/transplant/liver/education/organs/spleen-information

Fear of the Dark

Imagine a scary setting. Whatever kind of environment would make the hair on the back of your neck stand up straight and give you the feeling that someone–or something–is watching you, imagine it. I'll make a bet that the majority of these scenes are set sometime during the night. And why not? To some extent, everyone has a fear of the dark. Nyctophobia, or a deep and severe fear of the dark, is one of the more common phobias in humans. Where does this fear come from?

There is a lot of evidence to suggest that a fear of the dark is deeply rooted in our evolutionary history. 4.5 million years ago, the early ancestors of Homo sapiens were not the masters of the planet like the species is today. Instead, animals like Australopithecus afarensis were prey for bigger, stronger, faster animals. One advantage our ancestors had were that they were social animals, relying on each other to watch out for danger. This was an effective strategy, but only during the day. At night, their vision failed them. That meant they were vulnerable to attack. Truly, it was never a fear of the darkness itself, but the dangers the darkness concealed that fueled fear. The advent of anthropogenic fire certainly helped protect and defend us, but only if one stayed close to the flames. Eventually hominids started to build shelters, which added another layer of protection from both the elements and the predators.

The Tsavo Lions exhibit at the Field Museum in Chicago, IL
Photo credit: Jeffrey Jung

Even today, in areas where lions and humans live near each other, the risk of of a human being attacked by a lion is roughly 60% higher after 6 pm, according to a study published in 2011. This is partially due to the fact that lions generally hunt at night; the reasons for this are a combination of lower temperatures and an inherent advantage that predators have over their prey. One of the most vicious and notorious lion attacks were those committed by the Tsavo Lions, who preyed on the workers of the Kenya-Uganda Railway in 1898. These two lions were bold and their attack style was unprecedented: they would come into camp at night and drag workers from inside their tents. Any attempts to stop the lions from entering the camp with fire or fencing were thwarted by the lions. Workers left the construction site in large numbers and all progress on the railroad halted until British Lt. Col. John Henry Patterson hunted and killed both of the lions in December 1898.

The movie poster for the 1996 film about the
Tsavo Lion attacks in Tsavo, Kenya.

After their deaths, the legend of the Tsavo Man-Eaters grew. Patterson took their skins and made them into floor rugs, as was the style of the time. In 1924, the rugs were sold to the Field Museum of National History in Chicago, IL for a sum of $5000 (about $73,400 in today's money). The skins were in poor condition from a quarter century of being walked on, but now the skins and the skulls of the lions are on display in the lower level of the Field Museum. Isotopic analysis of the keratin in the bones and hair suggest that one lion ate the equivalent of 10.5 humans, and the other ate the equivalent of 24.2 humans. From Patterson's personal journals, the Tsavo lions killed between 28 and 31 people. The discrepancy in the numbers may reflect people the animals are known to have killed, but not necessarily eaten. The story of the Tsavo Lions continues today in modern entertainment, and appears in video games, movies, and books. My favorite is The Ghost and the Darkness, a 1996 movie starring Val Kilmer as Patterson.

What makes lions so adept at hunting at night? One of the many tools available to lions is their night vision. Cats need just 1/6th of the light humans need to see, giving them a significant advantage in low-light environments. Their eyes are also better at focusing that light more effectively than ours are. The curved cornea and large lens allow the cat eyes to take in all available light, and they also have a higher number of rods that are sensitive to dim light in their eyes than humans do. Cats also have a special layer in their eyes that hominids lack, called the tapetum, which directs light to sensory cells that bathes the retina in 50% more of the available light than the cells would receive otherwise. While a cat cannot see in fine detail or in as many colors as we can see, their eyes are designed to hunt, particularly at night. It's no wonder that cats are likely apex predators in their habitats, considering this and all their other tools!

Eye structure and function in cats by K. N. Gelatt,
seen in Merck Veterinary Manual.

The night is not just a place where scary things hide; it can hold discovery as well. It is needed to study distant stars and to see the Milky Way from Earth's surface. It is also associated with rest, sleep, and safety, a time when families gather in their homes and prepare for the next day. With all the artificial light available to humans now, true darkness can be hard to find, at least in the United States. Light pollution is a problem that affects migrating animals and can affect a human's ability to sleep soundly. Minimizing the disruption to our bodies' rhythms is why companies like Apple have "night modes" for their technological products. I myself have a rule that I am not allowed to look at my phone or computer screens after 9:30 pm, or else I sleep poorly and can hardly think the next day.

Perhaps the lesson here is that everything, even light, has a dark side. That nervousness I feel walking alone at night is just a normal evolutionary response that served my ancestors well, but it never stopped me from Trick-or-Treating after sunset when I was younger. There are still dangers in the dark, of course, but at least they are (probably) not lions anymore!

Sources:
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0022285
https://www.sciencedirect.com/science/article/pii/S0149763410001399 
Kerbis Peterhans, J. C. & Gnoske, T. P. (2001). "The science of 'man-eating' among lions Panthera leo with a reconstruction of the natural history of the 'man-eaters of Tsavo'". Journal of East African Natural History. 90 (1): 1–40.
http://www.pnas.org/content/106/45/19040
The Man-Eaters of Tsavo and other East African Adventures by Lieut.-Col. J. H. Patterson

Cryptozoology

Now that it is most definitely October, we thought it'd be fun to talk about the science behind some of the classic horror stories associated with Halloween, and about some animals that are generally associated with the spooky, occult, or unknown. Until Halloween, we'll be focusing on these topics to help get everyone into the spirit! Our first topic is the study of hidden monsters: cryptozoology.

Cryptozoology is the name for the field that focuses on finding cryptids, or animals that, so far, only exist in folklore and oral traditions. Some examples of these unknown animals are Bigfoot (or Yeti in the Himalayas); Nessie, the Loch Ness Monster in Scotland; and the chupacabra of Mexico and the southwestern U.S. states, but it turns out there are hundreds of creatures that fit into the cryptid category. Because it does not follow the scientific method, a process where hypotheses are proposed, evidence is collected and analyzed, and conclusions are drawn that either reject or support the hypotheses, cryptozoology is considered a pseudoscience, halfway between zoology and the branch of cultural anthropology that focuses on folklore and legend.

A map showing some of the cryptids of American folklore and oral tradition.
From: https://www.hogislandpress.com/product/monster-map

I first heard of some of the animals in the graphic above from a television show that aired on Animal Planet. I used to wake up very early before school started, which meant my options for TV shows were limited. Animal Planet always had something on though, and for a while one of the shows I watched was Lost Tapes. Every episode focused on a different cryptid's story, going through the original folklore in between flashbacks from "lost tapes" that show a victim's interaction with one of the fearsome, mysterious animals. Every story was fictional, but some were done so well and were so unnerving that I think about them to this day.

The show only lasted for 34 episodes, unfortunately, and exposed its audience to monsters such as the Thunderbird, Wendigo, Hellhound, and the Jersey Devil. The descriptions of these animals and the legends behind them can be skin-crawling, and I think the show did an excellent job of presenting the monsters in a way consistent with the right levels of reverence and fear. I personally enjoyed learning about the history of the legends more so than seeing the flashback parts of the episodes, but sometimes they'd also share information about recent possible sightings of the animals. It always made me want to go out and try to find something on my own.

Luckily Animal Planet has another show about hunting a cryptid that I can watch instead of camping all over the country (even though I'll probably do that on my own anyway). This show is, of course, Finding Bigfoot. On the show a small team of Bigfoot enthusiasts go to towns where Bigfoot sightings have occurred and then attempt to have their own encounters. This team takes their work seriously, even though there is no concrete physical evidence of any kind of large ape living undetected in the continental U.S. and Canada. The team meet with local people who have stories to share, and then the team goes out into the area where the sightings occurred to recreate the encounter. They do this to figure out what kind of animal could fit the description the witness gives. A majority of the time, the team actually rules out Bigfoot as the culprit for an unusual sound at night or a quick glimpse in the woods, and instead attributes the encounter to a bear, elk, or deer.

The team also spend time walking around the woods at night, making Bigfoot calls and knocking on sticks as Bigfoot is thought to do. They use thermal imaging and night vision goggles to heighten their sense of sight and maximize any chance of seeing a Bigfoot. Their ultimate goal is to find definitive proof that Bigfoot exists, and the show exists to document their adventures. The probability that a large, bipedal primate (aka Bigfoot) has consistently escaped any kind of detection by modern humans is very small, but non-zero. This uncertainty fuels their curiosity and drives them to keep looking.

Model of Latimeria chalumnae in the Oxford Univ. Museum of Natural History.
Photo by: Ballista at the English Language Wikipedia

While it is unlikely that anyone will ever find hard evidence of Bigfoot's existence, it is important to acknowledge that there are still many things that science cannot answer. Wildlife biologists discover new species every year, and while the vast majority are new insects, invertebrates, and amphibians, sometimes a new mammalian or even primate species is found. Sometimes animals thought to be extinct reappear in the modern day; for decades, paleontologists thought the ceolacanth fish extinct since the Cretaceous, until one was caught off the east coast of South Africa on December 23, 1938. It was Marjorie Courtenay-Latimer, curator at the East London Museum, who recognized the unusual fish in the catch of a local fishing captain, and brought it to the world's attention. Today, there are coelacanths in museums around the world.

Any scientist needs to walk a razor's edge between keeping an open mind to all possibilities while carefully and critically examine all the evidence in front of them to find the best answer. Often this means that there are far more likely explanations for something than "Bigfoot did it," hence why the existence of these animals isn't in any way guaranteed. What is fascinating to me is seeing all the ways that humans have explained nature around them and passed stories down through the centuries, and how they have spread across cultures. It also reminds me that there is much left in our world to discover and investigate, some of it fairly nearby! I'd love to get a story about the Mogollon Monster this weekend when I go hiking. I guess you'll have to wait for next week's blog article to find out what happens!

Sources:
https://en.wikipedia.org/wiki/Lost_Tapes
http://aplostapes.wikia.com/wiki/Lost_Tapes_Wiki
https://www.animalplanet.com/tv-shows/finding-bigfoot/
http://www.dinofish.com/discoa.htm

The Nautilus Mission

The bottom of the ocean is one of the most unknown places on Earth. Deep canyons and high seamounts dominate the landscape. There are black smokers, small vents in Earth's crust, spewing hot water and toxic chemicals into the water. There is no plant life; sunlight cannot penetrate water that deep. The animals that live down there come in odd, pliable shapes, and some use their own bioluminescence to lure prey in. Even though it is on the same planet, the deep ocean is not of this world.

The Papahānaumokuākea Marine National Monument.
From: https://www.papahanaumokuakea.gov/

It is because it is so unknown that marine scientists are so eager to explore it, and one current mission is doing just that. The Nautilus Expedition is a massive effort to characterize and study the geology, biology, and archaeology of a few key areas of the Pacific Ocean between Hawaii, California, and Alaska. Currently, the ship is west of Hawaii, in the Papahānaumokuākea Marine National Monument (MNM), the largest marine conservation area in the world. The mission is operated by the Ocean Exploration Trust, a non-profit organization founded in 2008 to engage in pure ocean exploration. Its founder, Dr. Robert Ballard, is the man is credited with discovering the remains of the ill-fated Titanic, and is current a National Geographic Explorer in Residence. If something is going to be discovered, this is the team to do it.

So what are they looking for? For one, they are now looking closely at the underwater geology around tectonic plate boundaries, and the western coast of North America is an excellent place to do it. Multiple tectonic boundaries, including the Cascandia fault line of the subducting Juan de Fuca plate, are responsible for creating the landscape of the west coast. The Nautilus is there to photograph and map areas of the seafloor that have been missed by previous studies, and to measure the chemicals in the ecosystem around it.

Dr. Marc Fries examines this fragment of fusion crust that
may have come from a meteorite that fell in March 2018.
Picture by Susan Poulton, Ocean Exploration Trust.

Its trek began in Southern California, where it studied the deposits of underwater landslides caused by movement along the San Andreas fault, and traveled up to the Cascadia Margin near Washington and Oregon. As it moved from Astoria, WA to Sydney, British Columbia (Canada), the Nautilus also looked for fragments of a meteorite that fell in March 2018. Preliminary findings indicate that they did indeed collect two small pieces of the fusion crust that forms on meteorites as they burn up in Earth's atmosphere, and it's all because of the Nautilus mission.

The Cascadia Margin is not just of geologic interest; the large volumes of methane gas and hydrate stored in the area makes it an interesting spot for studying the chemistry of the area as well. According to the Nautilus website, "establishing a baseline by documenting and characterizing these sites is timely because geological events, such as earthquakes or submarine landslides, could result in important environmental impacts due to sudden methane release." Over the past two years of research, the Nautilus team has discovered over 2700 bubble streams at 1000 distinct locations along the Cascadia Margin. Before this mission began, it was unclear exactly how much methane was near the Cascadia fault, and how (or even if) it was being released.

As impressive as the geology and chemistry are, perhaps the most awe-inspiring is the biology discovered. At almost every location, the Nautilus stayed for at least two weeks, taking pictures and streaming live video narrated by the crew and scientists on the expedition. One of the best parts of exploring is being surprised by what is found, and this video is an excellent example of this. Taken by the Nautilus crew on September 20, 2018, this video is rare footage of an animal called the pelican (gulper) eel in Papahānaumokuākea MNM. And this was only one of the animals observed!

As it traveled to Hawaii, the Nautilus also studied multiple geologic features called seamounts, which are undersea volcanoes that have not breached the ocean's surface yet. Before the Hawaiian islands were, well, islands, they began as seamounts. Over a long period of time, the underwater volcanic eruptions built up the seamounts until they became a large island. These eruptions still happen, but because of the "hot spot" volcanic activity near Hawaii, the volcano's position is not constant. A new seamount, and future Hawaiian island, is being formed right now off the southeast coast of the large island of Hawaii. Its name is Lō'ihi, and its exploration has the potential to tell us about the habitability of other places in our solar system. From the website:

"The expedition of Lō'ihi marks the beginning of the multi-year SUBSEA (Systematic Underwater Biogeochemical Science and Exploration Analog) Research Program, a partnership between NASA, NOAA, and various academic centers. Bringing together both ocean and space exploration teams aboard E/V Nautilus, SUBSEA blends ocean exploration with ocean worlds research to address knowledge gaps related to the habitability potential of other planets in our Solar System." 

A "gripper" used for collecting samples from seamounts. This novel
tool was developed by the Jet Propulsion Laboratory, and is mounted
on the ROV Hercules, one of the robots on the Nautilus expedition.

 While it was around Lō'ihi, it documented the biological communities that live around the seamounts it observed. Because Lō'ihi is an isolated seamount (one that is not near any tectonic plate boundary), it is considered a strong analog for any kind of venting system that might exist on an ocean world like Europa, an icy moon of Jupiter. By collecting samples from fluid venting locations, geologists and biologists will be able to study the interaction between a seamount and the life that survives there. How cool is it that studying the environment around seamounts in the Pacific can tell us about potential life on other planets? 

It is impossible to put the full scope and findings of the Nautilus mission into a simple blog post, but these are just a few of the highlights that happened in the past few months. If you'd like to read more or follow along with their live-streaming, the website is here: http://www.nautiluslive.org/

Happy exploring!

What drives ocean currents?

Welcome to the second installment of the Science on Main ocean-related blog posts! This week's topic comes from a part of the field called physical oceanography. This piece of the broader field of oceanography focuses on understanding the large-scale forces that drive ocean events, including currents, the topic of this week's post.

For most, especially anyone who has seen the movie Finding Nemo (Disney-Pixar, 2003), the fact that the ocean has currents is old news. Ocean currents are powerful features of their environments, continually pushing large volumes of water from one location to another, potentially thousands of miles away. One of the most famous ocean currents is the Gulf Stream, which is part of a larger circulation current called a gyre. There are five major gyres in the oceans: the north Atlantic, south Atlantic, north Pacific, south Pacific, and Indian.

Figure 1: The deflection of air currents due to the
Coriolis Effect

In the northern hemisphere, the gyres circulate in a clockwise direction. In the southern hemisphere, they circulate in a counter-clockwise direction. This is due to the Coriolis Effect. The Coriolis Effect is the name for the deflection of air currents in the atmosphere due to the rotation of the earth underneath it. If Earth didn't rotate, the air would naturally flow in a straight line from the high-pressure areas around the poles to the low-pressure equatorial area. Air deflects in opposite directions in the northern and southern hemispheres because of the direction of earth's rotation (Figure 1). So what does this have to do with ocean currents?

You may be surprised to learn that it is actually the wind that drives surface ocean currents! Each of the oceanic gyres has one eastern and one western boundary current, for a total of 10 major currents in the modern day oceans. The eastern boundary current is usually wider and travels slower, while the western boundary current is narrower and travels quickly. This is because the winds that drive surface currents are deflected out, the start to lose energy. Since they spiral west to east, the air currents are stronger on the western sides. The air pushes and shears the surface of the ocean, which causes the water to follow along. This is part of why hurricanes with high winds can produce huge waves and strong ocean currents.

Figure 2: The Gulf Stream. Warm colors represent warm water,
carried by the current to England and northern Europe.

One of the most famous currents is the Gulf Stream, which carries warm, nutrient-rich water from the Caribbean, up the east coast of the United States, and then up and over to England, Iceland, and the Norwegian Sea. Despite England's high latitude, it has a relatively mild climate, and it is primarily due to the Gulf Stream, and the water it carries with it.

The Gulf Stream is only a surface current, however. There are also currents that bring nutrients from deep in the ocean to the surface, which are used to feed phytoplankton and other small animals. As phytoplankton may be responsible for up to 80% of all organic matter on Earth, it's important to keep them fed! These deep currents also bring oxygen with them, which every animal needs to survive. Water that has no oxygen in it are called hypoxic, and cannot support life. Without these deep currents, life in the oceans could not survive.

One example of phytoplankton, a diatom called
Amphiprora. From Dawn Moran, WHOI.

Deep ocean currents carry water along the bottom of the ocean, collecting nutrients and oxygen, before they are brought to the surface. This changes some of the water's properties within the current, including its density. When the density of the water on the bottom of the ocean is less than the density of the water above it, the ocean begins to overturn. There are specific locations in the oceans where upwelling occurs, when less dense water rises to the surface, and locations where the opposite, downwelling, happens. This density-driven circulation is necessary to keep the surface water healthy for all the plants and animals that rely on it.

It is important to study the oceans because they are responsible for moderating climate, driving weather, and maintaining the global food-web. Currents are an important piece of the puzzle of how the oceans work, as they transport materials from one place to another, but there are still many questions that remain. If you studied the ocean, what question would you want to work on? What do you think would happen if all ocean currents suddenly disappeared?

Sources:
https://oceanservice.noaa.gov/education/kits/currents/05currents1.html
https://oceanexplorer.noaa.gov/facts/currents.html
https://www.nationalgeographic.org/encyclopedia/coriolis-effect/
http://www.edc.uri.edu/restoration/html/gallery/plants/phyto.htm
https://www.whoi.edu/main/topic/phytoplankton

Can Sharks get Rabies?

Last Friday, September 14, we had another Science on Main event on Main Street in Mesa, AZ. This month's theme was Pirates' Block Party, which conjures images of the sea, Jolly Roger flags, and colorful men and women who defied the laws of the powerful Navies of the day. In honor of this theme, the next few blog articles will be on topics related to the ocean and all its mysteries.

One of the best parts of being part of Science on Main is when I hear a question I've never before considered. This week's blog topic is a question that we were asked by a young scientist a few months ago, and it's one that definitely took me by surprise. Can sharks get rabies?

Jim Abernethy, National Geographic Creative

Rabies is a viral disease that is transmitted between animals and people via bodily fluids, usually through bites but rarely through scratches. According to the World Heath Organization (WHO), up to 99% of all rabies infections come from bites from domestic dogs, especially in countries like India, where there are many stray dogs. In the Americas and some southeast Asian countries, bats are the most common carriers. Most rabies deaths today (95%) occur in Africa and Asia, and up to 40% are in children under the age of 15, who may not recognize the signs of a rabid animal. These signs include hyperactivity, a fear of water or drafts, and partial paralysis, especially around the infection site.

Rabies is almost always fatal, and was responsible for many deaths up until the late 1800s. Thankfully, Louis Pasteur and Émile Roux developed the first rabies vaccine in 1885. If a human was bitten by a rabid animal and received treatment within 10 days, that person was very likely to survive. According to WHO, over 15 million people per year receive a post-bite rabies vaccination, which saves an estimated hundreds of thousands of lives. More vaccines have been developed since and are used to prevent infection in the first place. If you have a pet dog in the United States, chances are high you've had to get this vaccine for your pet from the vet!

Dog bites are the #1 cause of rabies in humans.
Picture from Anoir Chafik via Unsplash

Now that we understand what rabies is, we can approach the original question regarding sharks. One interesting fact is that rabies is a disease that occurs only in mammals. No animal other than mammals has ever been reported as rabid. Birds were artificially infected with rabies in 1884, but they developed few or no symptoms, and always recovered. A study in 1988 confirmed that blood from infected birds contained "no significant antibody titers," and therefore supported the conclusion that wild birds are not a significant source for rabies. Curiously, though rats and rodents can be vectors for other serious diseases, rodents are rarely found to be infected with rabies, and no cases of rodents transmitting rabies to humans have been reported.

Sharks are not mammals, so it is not possible for them to get rabies. It is hard to imagine a shark getting bitten by a dog anyway! But there are many mammals that live in the sea. Could they get rabies?

Simply put, the answer is yes, but it is very, very rare. In the Arctic regions in northern Canada and Alaska, the Artic fox is the main rabies carrier, as one of the only canid species in the area. In 1980, rabies was detected in 12 foxes, 3 reindeer, and one ringed seal in Svalbard, an archipelago near the North Pole. The seal that had contracted rabies was found 200 m away from a blow hole, where a seal will come up for air while swimming under the thick ice. A subsequent rabies screening of hundreds of animals all came up negative. This may be the first known case of rabies in a marine mammal.

Luna, an Arctic fox at the Maryland Zoo in Baltimore.

Foxes are known to prey on young seal and walrus pups, which may be where they come into contact with the adults. If an infected fox bites a seal, the seal can develop rabies. But this is a very rare and usually accidental event, and "there is no indication that rabies is endemic in" Arctic fox, seal, and reindeer populations.

There is one case of rabies reported in a polar bear. In 1989, this bear was found dragging its back legs 1.2 km inland in northern Canada, and was shot dead by a group on Inuit hunters, who left the meat untouched because of the unusual circumstances of its death. Scientists tested its spinal fluid and found evidence for partial paralysis and rabies antibodies, confirming the bear was indeed rabid. No other polar bear has ever been reported to be carrying rabies.

People should always be careful and wary of all wild animals, whose behavior is unpredictable. Animals who are acting unusually should absolutely be avoided and reported to local wildlife authorities. That being said, the risk of contracting rabies is especially low, and should never stop you from enjoying the outdoor world. What are you waiting for?

Sources: 
http://www.who.int/news-room/fact-sheets/detail/rabies
http://www.jwildlifedis.org/doi/abs/10.7589/0090-3558-24.2.264?code=wdas-site
https://www.researchgate.net/profile/Morten_Tryland/publication/292257698_Zoonoses_of_arctic_marine_mammals/links/5707a27108aea66081331319/Zoonoses-of-arctic-marine-mammals.pdf
http://www.jwildlifedis.org/doi/abs/10.7589/0090-3558-27.2.337?code=wdas-site
https://www.jstor.org/stable/3560403?origin=crossref&seq=1#metadata_info_tab_contents

The History of the Spherical Earth Idea

When I was in elementary school, I learned that the Earth was round. I even remember a silly rhyme in a cartoon I watched in school about Christopher Columbus, who "proved" the Earth was round. To me, the fact that the Earth is round seems almost like an instinct. That being said, I never looked up the history of why and how it's known the Earth is round. Today I started to correct that.

The idea that the Earth is a sphere can be traced back as far as the ancient Greeks. Although the idea is attributed to Pythagoras, a Greek polymath most famous for his Pythagorean theorem of triangles, both he and his contemporary Parmenides of Elea are known to have taught the idea of a spherical Earth. Moreover, it is possible the discovery was made by another Greek and falsely associated with Pythagoras by historians. Aristarchus and Eratosthenes improved on this work by estimating the circumference of the Earth, and noting how the visible constellations changed as the observer traveled nearer to and farther from the equator.

It is also possible that other cultures (Chinese dynastic empires, African tribes, Egypt, and Native Peoples in the Americas) noted evidence that the Earth was round, but few, if any, records of these people survive. Future discoveries may change this. In ancient India, for example, a Greek ethnographer wrote in 300 B.C.E. that the Brahmans (the high scholarly caste in Hindu society) believed that the spherical Earth was the center of the universe. As Hellenistic ideas spread via Alexander the Great's conquest, the Greek ideas merged with those of the Brahmans, and survived well into the next millennium. Aryabhatta I, an classic Indian astronomer and mathematician who lived from 476–550 C.E., wrote in his work, the Aryabhattiya, that the Earth was spherical. He also made an incredibly accurate estimation of the Earth's circumference of 4,967 yojanas, which is equivalent to 24,835 miles. The equatorial value of Earth's circumference is today calculated at 24,901 miles.

In any case, the spherical Earth idea was a moderately popular one in the ancient world, as it persisted throughout Greek dominance and was later adopted by Roman astronomers as the standard. Later on, Ptolemy of Alexandria wrote one of his best-known books, Almagest, in which he defended and built on the arguments for a spherical Earth. He also argued that the Earth could curve in both north/south and east/west directions. The Almagest remained one of the standard astronomy texts for the next 1,400 years. As Europe experienced its Medieval period, the knowledge of a spherical Earth was retained by monks translating ancient Greek and Roman texts. It was also kept alive, and eventually reintroduced to Europe, by many Muslim astronomers, including Ibn Hazm, Al-farghānī (Alfraganus), and Abu Rayhan Biruni. These and other early scholars used this information to develop spherical geometry, an important tool still very much in use today.

A page from Almagest. U.S. Library of Congress.

So exactly how did they all know that the Earth is spherical? Much of it came from the knowledge of sailors. For example, as mountains appeared over the horizon from the top down. Had the Earth been flat, the mountains should have appeared in full as soon as the ship passed any obstructing object in front of it. Another piece of evidence is the shape of the terminator on the moon. A solar terminator is the line that divides the "day" from the "night" side of a planetary body. For us here on Earth, it's the line edge of the shadow that passes over the Moon when it's not full. Ancient astronomers recognized this line as a representation of the shape of the Earth as it passed between the Moon and the Sun. This line is curved, and so the shape of the Earth must too be curved.

https://www.farmersalmanac.com/terminator-22380

Finally, there was the sky itself. The sun is always directly above one point on Earth at solar noon, and this happens predictably for a single location on a yearly schedule. The north star, Polaris, never moves from its place in the night sky, but its declination, or height above the horizon, does change with an observer's latitude on Earth. There are also stars that are not visible from certain points on Earth. If the Earth were flat, then all stars should be visible at all times, as a view from a plane should only rotate in one direction. This logic, coupled with knowledge of geometry, was yet more evidence for a spherical Earth.

Of course, the fact that Ferdinand Magellan and his company sailed completely around the globe between 1519 and 1522 was perhaps the most solid piece of evidence for a spherical Earth before the space age. Now, satellites have orbited the Earth, Moon, Mars, Mercury, Jupiter, and Saturn, returning pictures of all of these that show they are spherical. It would not be possible to orbit a flat plane. Why planets are spherical is another discussion. For now, it is enough to discuss an abridged history of the spherical Earth idea and a few of many pieces of evidence that support it.

Sources:
Burkert, Walter (1 June 1972), Lore and Science in Ancient Pythagoreanism, Cambridge, Massachusetts: Harvard University Press, ISBN 0-674-53918-4, page 306.
https://en.wikipedia.org/wiki/Spherical_Earth
https://www.scientificamerican.com/article/why-are-planets-round/
https://www.livescience.com/60544-ways-to-prove-earth-is-round.html
Direct adoption by India: D. Pingree: "History of Mathematical Astronomy in India", Dictionary of Scientific Biography, Vol. 15 (1978), pp. 533–633 (554f.); Glick, Thomas F., Livesey, Steven John, Wallis, Faith (eds.): "Medieval Science, Technology, and Medicine: An Encyclopedia", Routledge, New York 2005, ISBN 0-415-96930-1, p. 463
Cormack, Lesley B. (2015), "That before Columbus, geographers and other educated people thought the Earth was flat", in Numbers, Ronald L.; Kampourakis, Kostas, Newton's Apple and Other Myths about Science, Harvard University Press, pp. 16–22, ISBN 9780674915473
Otto E. Neugebauer (1975). "A History of Ancient Mathematical Astronomy". Birkhäuser: 577. ISBN 3-540-06995-X. 

Movie Science: Alpha

I saw the movie Alpha with friends last Saturday night. When my friends and I go see movies, we whisper to each other the whole time, pointing out flaws in both the plot and the science it implies. Alpha was a rare treat for me: a movie that highlighted large-scale terrain and large, extinct animals. I knew I would like it.

The movie begins with a sequence of landscape shots, some with animals. The first animals we see are woolly mammoths, traveling in a characteristic herd. A few seconds later, a small group of woolly rhinoceros move through what appears to be a glacier-scarred landscape. Hyena and wolf packs prowl and vocalize. Words appear on the screen informing us that the setting is Europe, 20,000 years ago.

With a date and general location, it is now straightforward to examine the science behind the plot. 20,000 years ago puts the movie near the end of the Pleistocene period, otherwise known by its more famous alias, the "Ice Age." There's a lot to say about the science behind the many ice ages of Earth, so we'll save that for another blog post. This one will focus on the animals seen in the movie, and whether or not they belong there.

First up is identifying the animals seen in the opening sequence. Elasmotherium could be the woolly rhinoceros, as it lived in Europe in the Pleistocene, but the youngest fossils date from 29,000 years ago, slightly before the movie's setting. Another genus of animals, Stephanorhinos, also lived in continental Europe around the same time, but it's not as woolly as the ones in the movie, and their horns are a bit short. My guess is that the animals are Elasmotherium, and maybe they are the last of their kind alive. In any case, it checks out.

American Mammoth skeleton on display at the George C. Page Museum. Photo credit: J. Noviello

The most iconic animal of the Pleistocene is the mammoth, and it's no surprise those animals appear early in the film (though it's a shame that they aren't seen again). The oldest woolly mammoth fossils are found in east Asia. From there mammoths migrated out, eventually evolving into a few different species. Europe was definitely one of those places, as their bones are fairly common in many countries, and mammoths are seen in cave paintings made by ancient humans. While most mammoths were extinct by 10,000 years ago, small populations of isolated animals may have survived until as late as 4,000 years ago. One quick note is that the mastodon is a totally different animal from the mammoth, and only found (so far) in north and central America. This one too checks out.

The humans in the movie (which are very likely true Homo sapiens, even though Neanderthals certainly inhabited the area) are first seen hunting buffalo. This checks out as well, as there are many different species of bison in the Pleistocene fossil record. The length and curvature of the horns, as well as the size of the bison itself, at first made me think of Bison latifrons, but that animal only lived in North America. A better choice for the buffalo hunted in the movie is the steppe bison, Bison priscus, as it was a widespread species and definitely lived in Europe; it also makes many appearances in cave paintings, especially at the Cave of Lascaux in France. This checks out too.

From: https://www.lascaux.fr/en/prepare-your-visit/visit-lascaux/lascaux-2

Wolves and hyenas also check out, though the animals seen in the movies are their modern-day counterparts. Cave hyenas were massive, about twice the size of extant hyenas. Judging from the presence of bones in different caves, it appears that cave hyenas and humans actively hunted each other, or at least scavenged from each other's kills. These hyenas lived across Europe and Asia until about 20,000 years ago, after which their populations severely declined. In any case, this too checks out. Of course wolves check out because we know that dogs are descended from wolves, so the question becomes what kind of wolves these are. While I initially thought they could be dire wolves, they are only found in North America. The wolves in the movie are probably simple cave wolves.

Finally, there is the closest thing to a villain in the movie: the saber-tooth cat. While we only are ever shown a shadowy outline of the beast that kills a hunter early in the film, its profile is unmistakable. Sabre-tooth cats (the most famous of which is Smilodon fatalis, though there are a few) were fearsome predators that went extinct about 10,000 years ago, so the timeline checks out. Now onto where they lived. The most famous location for their bones is the La Brea Tar Pits in Los Angeles, California, but they are found as far south as Argentina. While saber-tooth cats were thought to be extinct in Europe as early as 300,000 years ago, a new jawbone discovered in the Netherlands has been dated to as late as 28,000 years ago, significantly later than what scientists originally thought! Therefore, while it is far more likely that saber-tooth cats lived in the Americas around the time of the movie, it is not impossible they were also in Europe. This checks out, albeit tenuously.

Maybe it's because I'm a scientist at heart, and that prehistoric animals are very close to my heart, but while watching this movie, I automatically evaluated it. I try to remember that it's been made for entertainment purposes, not for education. Even so I can appreciate attention to detail, and I think Alpha did a good job overall representing the paleobiology of Pleistocene Europe. And, if I may say so myself, the movie itself was good too.

Sources:
https://www.nature.com/news/sabre-toothed-cats-prowled-europe-200-000-years-after-supposedly-going-extinct-1.22861
https://en.wikipedia.org/wiki/Cave_hyena
https://en.wikipedia.org/wiki/Steppe_bison
https://en.wikipedia.org/wiki/Megafaunal_wolf#cite_note-goldfuss1823-4
https://en.wikipedia.org/wiki/Woolly_mammoth
https://en.wikipedia.org/wiki/Elasmotherium