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

Sniffing for Disease

Anyone who has been to an American hospital has probably noticed its smell. It's hard to describe it exactly, because it's unique, but personally I'd use words such as "sterile," "plasticky," and "nauseating." Clearly I'm not a fan. When I or someone in my household needs to stay home from work because of sickness, I've noticed that there's a smell that hangs around for a couple of days. I chalked it up to simply not showering for a little while.

It turns out there's a lot more to the story than that.

In the days before blood tests and lab results (which is most of human history), doctors had only their senses and logic to treat patients. While most doctors today use sight, hearing, and/or touch to diagnose patients, most of the doctors who came before had to rely on smell and, in some cases, taste as well! In fact, the use of smell as a diagnostic tool goes back thousands of years, and can actually be quite effective.

The Sushruta Samhita is an ancient Sanskrit text that has one of the first mentions of using smell as a tool. In the document, it states: "[B]y the sense of smell we can recognize the peculiar perspiration of many diseases, which has an important bearing on their identification." The history of this document is a fascinating one, and probably deserves its own blog post, but what is clear is that the Sushruta Samhita was written sometime in the middle of the first millennium BCE (though age estimates range from 1000 BCE to 500 CE). This means that the technique of identifying diseases based on smell was probably discovered and passed down through many generations of doctors through oral teachings before it was written down by the original author of the Sushruta Samhita. Later on, more doctors added to its contents, and today it survives as one of only two foundational Hindu texts on the medical profession from ancient India.

From Penn and Potts, 1998. TREE vol. 13, no. 10, pg. 391–396.

When humans began to concentrate more in cities, public health became an important concern for city officials. If a sickness broke out, it could mean the deaths of thousands, if not millions, of people. Bubonic plague, typhoid fever, cholera, and smallpox were (and in some places, still are) serious diseases that kill quickly. If doctors could identify the illness, then they are better able to treat those afflicted and stop the spread of the disease, saving lives. The scent of a patient, especially a strong and unmistakable one, gave doctors the chance to identify the disease quickly. The figure shows the scents of some diseases, though there are quite a few that aren't on the list.

Skip ahead thousands of years to the modern day, and smell is still the defining characteristic of certain illnesses. One disease in particular, called maple syrup urine disease (MSUD), is identified by the unmistakable smell of maple syrup (or fenugreek, if you're not from an area where maple syrup is common). The pleasant smell belies the seriousness of the disease, however. The sweet smell comes from the body's inability to break down long branched chains of amino acids, which causes them to build up to toxic levels in the body. Infants who have this disease initially start out healthy, but then quickly deteriorate. If left untreated, MSUD will lead to permanent brain damage, and in extreme cases, death within a few months. Older adults can develop this disease, and without proper recognition and treatment, may eventually cause the patient's death. If you ever notice that your urine smells like maple syrup, definitely tell your doctor!

Many service animals are trained to alert their charges if they are about to experience an episode or have an attack. Experts think dogs are actually detecting a change in the scent of their charge, as dogs have a much stronger sense of smell than humans do. Some dogs are even trained to sniff out cancer (though their effectiveness at accurately diagnosing cancer has been criticized).

In some cases, smell was not enough, and the doctors actually had to taste the excretions of their patients. This was the most common way for diabetes mellitus (which means "passing through sweet") to be diagnosed--the doctors had to taste their patient's pee! This knowledge was actually fairly well-known even among people outside of the medical profession, as the disease was also called "pissing evil" for centuries.

Today we rely more on technology than scent to tell us about our health and diseases. To be fair, the medical knowledge of medieval Europe certainly got a lot of things wrong, so it's overall a very positive thing that medical practice has changed so much. What hasn't changed is how much humans rely on their senses to explain the world around them. Smell may not be the most glamorous sense, but it was certainly an effective one, and remains an important tool to this day.

Sources:
Brown, R. (1995) What is the role of the immune system in determining individually distinct body odours? Int. J. Immunopharmacol. 17, 655–661.
Liddell, K. (1976) Smell as a diagnostic marker, Postgrad. Med. J. 52, 136–138.
https://www.popsci.com/problem-with-cancer-sniffing-dogs#page-2

Naming a Dinosaur

Most people know about dinosaurs, the “terrible lizards” that dominated the Mesozoic Era from about 252 million years ago until an asteroid hit the Yucatán Peninsula at the end of the Cretaceous period 65 million years ago. At last count there are at least 700 distinct species of dinosaurs discovered and written about in scientific journals. They range in size from the miniscule Compsognathus longipes to the massive (and recently discovered) Dreadnoughtus schrani. Their names often trip the most practiced tongues because of their lengths and their syllabic complexities.

So how do dinosaurs get these names anyway?

First, it’s important to remember that the field of paleontology itself is fairly young; Sir Isaac Newton had invented calculus about 150 years before fossils were recognized as something that belonged to ancient creatures! Even before paleontology emerged as a new scientific field, many people realized that there was something different about these rocks. U.S. President Thomas Jefferson thought the fossils were from animals that could be found elsewhere on the North American continent, so he instructed Lewis and Clark to pick up any fossils they found to bring back. They only found one during their expedition up the Missouri River, but in 1807 and 1808, Jefferson commissioned Clark to collect mastodon bones and teeth, which is now called the Jefferson Collection. It and other fossils are now housed at the Academy of Natural Sciences in Philadelphia, where they are still used for modern scientific study.

Prof. Ted Daeschler (Drexel University) showing off the Jefferson Collection of mastodon bones and teeth at the Academy of Natural Sciences in Philadelphia, PA.

The second thing to remember is that all dinosaurs have two names, according to the Linnaean system of classification devised in the 1750s. The first part of a name is the genus, which is analogous to a surname in English. That first informs the reader what small and specialized group of animals the author is writing about. The second name is their species name, which is the specific animal within that group, analogous to a given name. These names are italicized to note that they are special names, and often the genus name is omitted when talking about multiple species within that group. When that happens, the species name is not capitalized. This is why it is correct to write T. rex, but not T. Rex!

Many of the first dinosaurs described in scientific literature were named simply for their basic  characteristics, translated into either Greek or Latin to distinguish a species name from its description in English. For example, the very first dinosaur described, Megalosaurus bucklandii, literally means “great lizard” in Greek. The second dinosaur described, Iguanodon bernissartensis, simply means “iguana tooth,” reflecting that the first part of its skeleton discovered, the tooth, was initially thought to be from a large iguana. Of course, Tyrannosaurus rex means “tyrant lizard king,” even though recent evidence shows that dinosaurs are likely not lizards at all!

The genus names come from a dinosaur’s general features, but what about the second name? Those are often used to denote the place of the animal’s discovery or where it lived or lives (in the case of extant, or modern, animals). A good example is Velociraptor mongoliensis, which means “swift thief of Mongolia” in Latin.

Another way to name a dinosaur is to honor a paleontologist or another person. For example, Megalosaurus bucklandii is named for William Buckland, Professor of Geology at the University at Oxford and the first scientist to describe Megalosaurus in scientific literature. Today, it is not considered good etiquette to name a dinosaur after yourself, and it is a great honor to have a dinosaur species named after you. Some are named after musicians (Masiakasaurus knopfleri), and some are named after the person who discovered the bones, even if that person didn’t describe them to science (Vectidraco daisymorrisae).

Of course, there are some names that come out of pop culture. Dracorex hogwartsia was discovered by three amateur paleontologists in South Dakota, and was named after the school from the Harry Potter series. Another dinosaur, Zuul crurivastator, is named for the monstrous deity from the original Ghostbusters movie.

New dinosaurs are discovered every year all over the world, so it is possible to one day get the chance to name your own. What would you call yours?

Sources: Behind the Bones documentary: https://www.youtube.com/watch?v=T8wySyiynHk

https://www.rom.on.ca/en/collections-research/research-community-projects/zuul

https://phys.org/news/2006-05-dinosaur-hogwarts-school.html

Paleomagnetism

Our August table’s theme was magnets and electromagnetism. We brought out lots of demonstrations, including a ferrofluid tube, and we had many great interactions with everyone who stopped by our booth. There is one major part of magnetism that we left out, however, so this blog post is dedicated to Earth’s magnetic field. 

While less than 1/100th of the strength of a refrigerator magnet, Earth’s magnetic field is still an important, useful tool. Most of us have used a compass before, so we know that Earth’s magnetic field can be used to find our way. We understand that the magnet inside of the compass will rotate so that the red arrow will always point a certain way. That red arrow is the north part of the magnet, and will always align so that it, indeed, points towards north. It seems trivial: the north part of the magnet points north, and the other end points south. 

Except that it hasn’t always been that way—and it won’t be that way in the future. Using rocks to study how Earth’s magnetic field changed over time is a scientific discipline called paleomagnetism.

The Mid-Atlantic Ridge spans from the Arctic to the Antarctic. It is a series of divergent and transform plate boundaries.

Evidence from the geologic record proves that Earth’s magnetic field has reversed itself many times over Earth’s 4.5 billion year history. Most of this evidence comes from the seafloor in the Atlantic ocean, specifically the Mid-Atlantic Ridge (see picture above). The Mid-Atlantic Ridge stretches from the Arctic to the Antarctic along the bottom of the ocean, and is actually a series of connected divergent plate boundaries (but we’ll get into plate tectonics later). This means that every year, the continents North and South America and Europe and Africa get a little farther away.

At the Mid-Atlantic Ridge, the forces that push the continents apart also send melted rock, magma, up from inside Earth to the ocean floor. This is how new oceanic crust is created, and is some of the youngest rocks on Earth. This deep-ocean crust is also rich in heavy metals, such as iron, because it is formed from magma that comes from inside the Earth, where there is a higher concentration of such elements. Many of these metals are also magnetic. 

While these rocks are still hot, the magnetic dipoles inside of them will act as the needle in a compass does, and align themselves with Earth’s magnetic field. When they cool down to a certain temperature, called the Curie temperature, the rock will maintain the orientation of Earth’s magnetic field. As time passes, more rock is created, pushing the old rock to the side. 

When Earth’s magnetic field switches, the new rocks record an opposite orientation. In the picture below, the black bars represent periods of the current magnetic field's orientation, and white bars represent periods of reversed orientation. Geologists who study paleomagnetism measure the ages of the rocks and the orientation of Earth’s magnetic at the time those rocks cooled. By doing so, geologists piece together the timing of the reversals in Earth’s magnetic field. Their work on rocks from the Atlantic seafloor has revealed that Earth’s magnetic field has reversed orientation many times in the past 180 million years. Curiously, there is no regular pattern to the switches, as they appear to happen rapidly and at irregular times. What causes these reversals is still an open question in geology.

The paleomagnetic record

It is not clear when the next reversal will take place, or how long it will take when it starts to happen. It is an event that has never been observed by humans. Like so many other events in Earth history, the only record we have of this phenomenon is the rocks they left behind. Through geology, scientists discover the history of Earth and how it’s changed, and use it to predict what may happen to Earth in the future. For now, however, simply holding a compass is enough to observe Earth’s magnetic field. 

Sources: http://web.ics.purdue.edu/…/teach…/eas450/paleomagnetism.pdf
http://www.grisda.org/origins/10066.htm
https://www.tes.com/lesso…/QzyoecA6gyWRFw/mid-atlantic-ridge

A word about our collaborators and partners

It's getting warmer out, and we certainly kept busy last week for Dog Daze. In case you didn't have a chance to stop by, we had a smelling station for different human diseases. Some weren't too bad (maple syrup, bread), but others might have traumatized some kiddos that stopped by (fish sauce). We'll be sure to have a warning label next time!

You might have noticed that our friends from the Museum of Human Experience joined the fun for Second Friday! They're building a unique, interactive museum that focuses on our individual and collective human experiences, and what makes us all human. They certainly drew in a crowd with their biomimicry exhibit! We hope they'll join us again on Main Street soon!

Also, fair warning for next month's Science on Main: some of our experts will be volunteering at the Arizona Museum of Natural History for their annual fundraiser "Beer N' Bones." The funds go directly to the AzMNH (and to us by proxy, because they're awesome supporters of Science on Main!). Christina will be speaking on a Brewology panel, and you might get a shot with her at Speed Date a Scientist! Joel and Jessica will be around the museum as well, so be sure to say hey. Send us an email if you want in on hanging at a museum and drinking local brews after hours :-)

That said, Joe and Ryan will still hold down the fort on April 13th in our usual spot with Science on Main. One of our core values for our program is that science is for everyone, and which is why we provide the information for free in an open, accessible space. We will still be there for you to talk about cool science and answer your questions!

Looking forward to it!

Because we love Science

Busy, busy! We had 5 experts out on Main Street this past Friday night. We had some personal collections to show everyone, including rocks and dinosaurs (because who doesn't love dinosaurs?).

We saw a lot of familiar faces, which is awesome. Apparently we have a fan base now (woo hoo!). We were delighted to answer more questions and hang with you all. We saw a lot of new people as the night progressed. We better enjoy this weather before it starts getting hot again!

We met a guy with a Polaroid camera, and he was nice enough to give us our picture. These exposures aren't cheap!!
Thank you, Kind Sir!

As soon as we wrapped up for the night, Joe and Christina went home and ate a late meal, then got up early the next morning to work with our partners at the Arizona Museum of Natural History for "I Love Science Day" (because really, we love science). We performed a Chemistry Magic Show, using only materials that you can buy at the grocery store! Then we went home and had a nap. We were beat. Science is sometimes a tough love to have.

Maybe it was the exhaustion of a late night and busy morning, but it looked like some folks we met at Science on Main were also at "I Love Science Day" :-) Thank you so much for supporting our partner organization!

We think it's really important for science to be accessible to everyone, which is why we work with "2nd Friday Night Out" so that anyone can talk to us for free. No admission required. The AzMNH loans us some materials (and some experts) to help us keep Science on Main free to the public. We really appreciate their help and support, and they love having new guests at the museum!

The AzMNH also believes in science for everyone, so they host a Free Sunday every 3 months, with extended hours! A little shameless advertising on their behalf, the next Free Sunday is on March 4, 2018 from 12-5p. No admission required, but you'll want to arrive early!

Can't wait to see you again in March! Thank you!

Science on Main: Film Frenzy!

Well, we made it out on Main Street again. And again, we had a lot of fun, and I think everyone came away learning something new!

Joe and Ryan, feeling pretty exhausted after so much great discussion!

In light of "Film Frenzy" at Mesa' 2nd Friday Night Out, we brought out Joe's great-great-grandfather's camera, circa 1888. We talked a little about optics and how photography works. In all reality, we could still use that old camera to take photos, provided we could find a good source of glass plate negatives. 
Of course, the camera was just a fraction of what we talked about. One guest wanted to know the relationship between our gut bacteria (AKA microbiome) and how they might effect the drugs and medications we take. We also talked with another guest about bio-luminescent bacteria, and bacteria that might be used for energy. Another guest wanted to know how citrus fruits or vinegars might off-set the spiciness of hot peppers.

Here's what's so cool about this program: not only do the experts share knowledge of their fields, but our experts learn so much from the public, too. Admittedly, we didn't know exactly how to operate Joe's camera, and spent an evening trying to figure out how to use the 'viewfinder' to determine the right focal length. Naturally, we had a photography enthusiast come by our table, who was super-excited to see our camera, and gave us some more insight into how the camera worked (Thank you, sir!).
We're honestly amazed by how much research that people do on their own. We're so excited to see that people how much curiosity people have on a HUGE range of topics!! In that sense, we're glad to talk with people, rather than give lectures on what we think is interesting.
Although, we did get a cool question from a guest last night: "What questions do YOU have?" Well, we were happy to talk about our research questions that we work on in the lab.

A little shameless advertising here, we owe our gratitude to the Arizona Museum of Natural History, who is contributing some materials for us to use. We highly recommend you stop by and check out the museum on MacDonald Street when you have a chance. Some of our experts are regular volunteers there as well!
We also want to shout-out to our friend at HeatSync Labs on Main Street in Mesa. They have a pretty cool space for tinkering and building things, so we recommend checking them out, too!

Since we're still exceeding our expectations for Science on Main, and since we're learning so much from hanging out on Main Street talking about science, we will be back in February! See you all on Feb 9 in front of Pomeroy's 6-10pm :-D

Metabolism happened First: The Origin of Life

This paper was written for Joe's Astrobiology class, and describes one hypothesis about how life might have started on Earth. Send us an email if you have further questions for Joe!
He also posted this essay on his personal site Forbland.com
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     Self-sustaining chemical reactions are the hallmarks of life on planet earth. These reactions drive the processes that provide cells with energy, as well as allow them to grow and reproduce, also known as metabolism. In searching for life on other worlds, finding for evidence of the earliest metabolism would provide us with the first glimpse of a biotic world. Elements such as DNA and phospholipids found in the cell membrane would not be able to be constructed without metabolic reactions. For this reason, the “Metabolism First” world seems the most probable to create the first precursor to life, because the complexity of biomolecules would require an efficient, and preexisting, metabolic energy source for formation in a pre-biotic world. This paper will explore the various ways in which self-sustaining reactions could have formed in the pre-biotic ocean, focusing on pyrite formation found in hydrothermal vents. Descriptions of possible reactions that could have occurred, supported by computational modeling will provide evidence to the first step in the origin of life.
      Every ancient culture has a theory as to how life formed, principally because it is the fundamental question that drives the search of all knowledge. In earliest times, it was thought to be a divine being who willed life into existence. As humankind's understanding of the physical world grew, the theories as to how life formed adapted to the new information. With a general understanding of the basic elements of life, where genetic material encased in a protective membrane is capable of generating its own chemical reactions, researchers began to try and find how the creation of these building blocks of life might be used to find the origins of life. Some researchers speculated that the cellular casing might have been the first to form, and then the other elements of life either found their way inside it, or formed inside it. This “Cells First” or “Lipid World” idea is based around the way that oily organic molecules can interact with water (Segré et al. 2001),⁠ however it is difficult to see how a drop of oil in water can be confused for a precursor to life. Alternatively, the “Genes First” scenario is based on the concept of a “RNA World” (Gilbert 1986).⁠ In this world, proto-RNA molecules self-assembled, along with a ribosome, and managed to insert themselves into a membrane where they were able to catalyze their own reactions and self-replicate. This “RNA World” scenario for the origins of life is very well studied and is preferred by many researchers because of the ability of the RNA molecule to perform multiple tasks, as well being a system that is truly self-replicating system. However, problems with this system arise with the fact that so many things had to happen in order for it to work, especially that the RNA molecule had to self-assemble twice (as the RNA template and the Ribosome). The final idea for the origins of life is “Metabolism First” (Wächtershäuser 1988),⁠ where self-sustaining chemical reactions gave rise to the formation of organic molecules, and then into life. Central to “Metabolism First” is the idea of the Iron-Sulfur World, where many of these pre-biotic reactions ran on clusters of pyrite (FeS₂) that existed in the oceans. Pyrite clusters have been dated to as early as 4.31±0.06 Ga, which coincides well with time periods in which life was first thought to have formed (Smith et al. 2005).⁠ This “Metabolism First” scenario provides the most straightforward approach to discovering the origins of life because it provides a mechanism by which all the other elements of life can be constructed.
      As previously stated, crucial to the “Metabolism First” model is the presence of pyrite, or iron sulfide (FeS₂), in the oceans of early earth. German chemist Günter Wächtershäuser introduced the model in the 1980’s, and the model has been refined by researchers since then. Wächtershäuser’s model shows that pyrite can be formed by the following reaction:

FeS +H₂S–›FeS₂+H₂

which releases -87.0 kJ mol^-1 of free energy and hydrogen, and that would be enough to catalyze reactions with CO₂ to form organic molecules (Kundell 2011).⁠ Similar to the Krebs cycle, CO₂ can be reduced on the pyrite substrate, and producing CH₃COO⁻ (acetate) and water (Plaxco and Gross 2006).⁠ Over time, these biomolecules could increase in complexity, ultimately leading to complex organic molecules. While Wächtershäuser was only able to perform his experiment in the laboratory using CO instead of CO₂, later researchers successfully demonstrated this reaction with CO₂ (Zhang and Martin 2006).⁠ Wächtershäuser should be given credit though, as his ingenuity in recognizing that biomolecules could be built through self-sustaining metabolic processes. This model was a first step in showing that “Metabolism First” was the manner in which life first took hold.
      Wächtershäuser and others soon put forth many ideas in which life could have formed “Metabolism First.” In 2010, Frederick Kundell performed computational work on many of these ideas and that showed pyrite would be capable of doing far more than generating simple organic molecules, that it could create proto-nucleic acids. Many laboratory experiments that have tried to replicate “Metabolism First” have not fared well, however it is impossible to replicate in the lab what conditions were like in pre-biotic earth, and that is why computational models can be useful. Computer models can show whether a reaction is thermodynamically possible. If the reaction is possible, then over the course of a few hundred million years, provided the reagents are available, it becomes more likely to occur. Kundell systematically identified each of the reactions required to form ribose, a proto-nucleic acid, from iron(II)sulfide and hydrogen sulfide, and showed that these they were thermodynamically possible. As the backbone of RNA, the formation of ribose shows that the building blocks of genetic material can be formed using these self-sustaining metabolic processes. His computations showed that the formation of pyrite (using the above chemical equation) would not only generate free energy, but would also trap the hydrogen gas in the mineral’s disulfide bond, making it available for further reactions (Kundell 2011).⁠ Prior to this work, other researchers were able to show that phosphate ions could be absorbed into pyrite on damaged sections where disulfide bonds had occurred. Kundell was able to show that ribose would be able to from from that position through a series of intermediate steps. (Kundell 2011).⁠ This series of reactions shows that not only is “Metabolism First” the best way to explain the origins of life, but can actually happen faster than Wächtershäuser had initially anticipated.
      What the previous two points of evidence lacked was a means of tying all of the processes of life together. Both examples were able to illustrate that pyrite is able to create organic molecules, and in some cases complex organic molecules, however that does nothing in bringing the whole life system together. In 1996, researcher Matthew Edward was able to theoretically show how pyrite formations were able to create not only organic molecules and nucleic acids, but also lipids that could be used in the formation of a membrane. In this scenario CO, CO₂, or NO₂^- that have bonded to the surface of pyrite are photo-excited by photons (Edwards 1998)⁠ (Edwards 1996).⁠ This mechanism can create a range of molecules (depending on additional metals in the pyrite, Ni for example) including, glycine, acetyl group molecules, and thioacetyls. These primary building blocks can then combine to form longer more complex structures such as peptides and pyruvate. The pyruvate can then continue to combine with other products to ultimately create nucleic acids. What makes this mechanism so convincing is that because the reactions are driven by photoelectrons, with the pyrite only being used as a catalytic base, and therefore able to continue driving the metabolic process. By illustrating how it is possible that pyrite clusters can conceivably generate all the elements of life, this scenario shows that a preexisting metabolic source is indeed the most likely way that life originated.
      These examples showed that “Metabolism First” is the best way to explain life because it provides the mechanism required for building of complex molecules that life needs. As was stated in each case, pyrite, which consists of iron and sulfur, was critical for the reactions in each case. An interesting fact about iron-sulfur is that in all extant life, clusters of iron sulfide can be found in enzymes that are responsible for election-transfer, and conduct such functions as respiration and photosynthesis (Fontecave 2006).⁠ While the presence of iron-sulfur clusters in life does not prove that pyrite directed metabolism came first, it may provide insight into the mechanism of life that started 3.5 billion years ago.

Works Cited:

Edwards MR (1996) Metabolite channeling in the origin of life. J Theor Biol 179:313–22. doi: 10.1006/jtbi.1996.0070
Edwards MR (1998) From a soup or a seed? Pyritic metabolic complexes in the origin of life. Trends Ecol. Evol. 13:178–181.
Fontecave M (2006) Iron-sulfur clusters: ever-expanding roles. Nat Chem Biol 2:171–174. doi: 10.1038/nchembio0406-171
Gilbert W (1986) Origin of life: The RNA world.
Kundell FA (2011) A Suggested Pioneer Organism for the Wachtershauser Origin of Life Hypothesis. Orig Life Evol Biosph 41:175–198. doi: 10.1007/s11084-010-9217-y
Plaxco KW, Gross M (2006) Astrobiology, 2nd edn. John Hopkins, Baltimore
Segré D, Ben-Eli D, Deamer DW, Lancet D (2001) The Lipid World. Orig Life Evol Biosph 31:119–145. doi: 10.1023/A:1006746807104
Smith PE, Evensen NM, York D, Moorbath S (2005) Oldest reliable terrestrial 40Ar-39Ar age from pyrite crystals at Isua west Greenland. Geophys Res Lett 32:1–4. doi: 10.1029/2005GL024066
Wächtershäuser G (1988) Pyrite Formation, the First Energy Source for Life: a Hypothesis. Syst Appl Microbiol 10:207–210.
Zhang X V., Martin ST (2006) Driving parts of Krebs cycle in reverse through mineral photochemistry. J Am Chem Soc 128:16032–16033. doi: 10.1021/ja066103k

Flagship Science on Main

We had our first-ever Science on Main in Downtown Mesa last Friday night.

To all small-business owners and entrepreneurs out there: I salute you. It's a scary thing to put together a network of people, organize an event, order a custom table runner and supplies, and have no idea if it is going to be worth the money and effort. Fortunately, the organizers at Second Friday make it easy and inexpensive to try out a pilot project like this. Thank you Second Friday, and thank you Arizona Museum of Natural History for loaning us some materials!

Here we go! It almost looks like we know what we're doing!

The anticipation is kind of making us flustered.

That said, we had a ton of folks come out and talk to us about some pretty cool topics! Some of our conversations ranged from stellar nucleosynthesis, to the origin of life, to shark rabies, to properties of ice and water. It was so much fun!

In addition to questions, we got some important feedback. One woman commented that she appreciated that we weren't on "a soapbox" with a lecture prepared. Some people were pretty surprised that we had nothing to sell or demonstrate, and that we're just giving away free knowledge. There were other scientists and engineers in the crowd on Friday that seemed inspired by the idea, so let's hope this project spreads! 

Other science people came to talk to us, too! It's always fun finding fellow science people running wild and out in the world (there are more out there than you think!).

Thank you Dr. Smith for taking pics! We were all too engrossed in discussions to think about documenting it ;-)

We had a great question later in the night that I wanted to re-iterate: "So what are you getting out of this? What's your agenda?"
We just think science is cool, and want people to know how cool (and understandable) it is. We want people to know that science experts are pretty regular people. We also want science experts to be more accessible, and be better communicators. That's it.

So, some of our lessons learned from our inaugural Science on Main:
1. People really seemed to like this idea.
     a) People have a lot of fun and interesting questions
     b) Sure, one can always Google an answer to a question, but talking to a real-live science person is more fun. Who knows where the conversation will go next?
     c) Chatting with people is way more engaging than a lecture or demo.
     d) Some people just want to hang and listen to us talk about stuff. By all means, do so!
2. We should probably bring in more experts
3. We should definitely do this again :-)

Most importantly, we want to thank all of the people that came by to see us on Friday. We hear you: this is worth it, and we'll keep bringing this back for you.

Fear not, we'll be out on January 12 in the same spot (in front of Pomeroy's).

Guiding Our Path By Knowing Where We Came From

“Astrobiology,” the word itself conjures images of analyzing aliens on some red-skied moon orbiting a gas giant. However, in the 21^st century, astrobiology does not meet these sci-fi visions. In order to realize these dreams, what question must a 21^st century astrobiologist focus on? NASA defines Astrobiology as, “the study of the origin, evolution, distribution, and future of life in the universe.” If the ultimate end goal of Astrobiology is to answer each of the definition’s four parts, then the most important question would be identifying the origin of life on Earth. Identifying the origin of life would help pave the way to studying all of the other aspects of astrobiology.

As humans, our species is ~3.5 billion years removed from the first life form, yet we still share some of its genetic material. Over those eons of time, our species slowly evolved into the beings we are today: beings that can contemplate where we first came from. Evolution is the change of a species’ characteristics over generations, giving rise to a diversity of species as they adapt to their environment. The entire biosphere of this planet evolved out of a single form of life. By discovering the origin of life, we can trace the course of evolution from its first step.

Our species peers out into the depths of space looking for the answer to the question, Are we alone? Understanding the origin of life on Earth is also understanding how life could form elsewhere in universe. Once we understand how life originated on Earth, we can then use that information to look for life on other worlds where conditions are similar. Right now, the search for life on other planets casts a wide net in hope of finding galactic neighbors, but answering the question of where we came from will help us to at least throw that net in a more likely location.

Finally, the future of life in the universe begins with humanity coming to terms with how amazing life is, because if we do not appreciate it, then we have no hope of seeing the future. Astrobiology has a unique opportunity, a chance to provide the human race the key to the origin of all life on Earth. Realizing the origin of life through astrobiology can tell us where we all came from, the history of all life that led to us, and how special we are in the universe. All we need to do to obtain that key to life is to find the origin of life, and with it, hopefully humanity will be part of the future of life in the universe.