Christmas Trees, Rocket Fuel, and Plastics: Terpenes in Nature and Engineering

When I think of the holiday season, the first thing that comes to mind is all the deep and inviting fragrances that this time of year brings. As we awaken from our Thanksgiving feast-induced stupors, we undoubtedly will be bombarded with the smells of the holiday season for the next 30 days – smells that will trigger memories of holidays past, like warm cookies fresh out of the oven, the rich spices in mulled wine and ciders, and the best smell of all to an outdoor enthusiast like me, the crisp and clean scent of Christmas trees.

The Smell Of Christmas Is In the Air… and bark!

Christmas Tree.jpg

Christmas trees are an evergreen conifer, a type of tree that includes spruce, pine, and fir. Have you ever wondered what gives Christmas trees their signature scent? The answer is a mix of chemicals called terpenes. Terpenes are in the sticky resin substance exuded by these conifers. Terpenes are a class of molecules that give off the sharp and sweet Christmas tree scent. When the tree bark is damaged, such as when the tree is cut down to be sold, the resin flows out of the bark. In nature, the layer of resin hardens to protect the damaged area of the bark. The terpenes in the resin inhibit the growth of fungi and also deter herbivores, notably the bark beetle, which otherwise would feed on the tree.

Terpenes are also released into the air. If you’ve ever been to or seen pictures of pine forests and mountains, you might have noticed a hazy, blue aura and clouds above the trees. Scientists believe that the terpenes released by the trees into the atmosphere react with the air to collect moisture and form clouds in order to protect the trees from harsh sunlight and to keep the forest cool. Terpenes are what make the Smoky Mountains smoky!

 Smoky Mountains National Park

Smoky Mountains National Park

The principal molecule that gives the earthy pine smell to the trees is called pinene. Pinene has two different forms called alpha-pinene and beta-pinene. These two molecules are mirror images of each other,* and beta-pinene is what provides the woody fragrance we associate with pine trees. Both forms of pinene are very flammable and are the reason Christmas trees and pine cones burn easily. This is also why forest fires can spread so quickly. At room temperature, pinene molecules are volatile and evaporate, fortunately, is which is why we are able to smell them so strongly in our homes!

Different species of conifers have distinct smells due to different mixtures of various molecules. For example, bornyl acetate, also called heart of pine, gives off the rich depth of pine scent and is found in pine and fir trees.** This is the compound that is commonly used to make pine fragrances you see sold in stores. Both balsam firs and silver pines (two species of conifers used for Christmas trees) are rich in bornyl acetate. Other molecule compounds that give off distinctive scents include limonene (a citrus scent), camphene (a camphor aroma), and alpha-phelladrene (a minty and citrus-y fragrance).

So now we know that terpenes are made by conifers to protect themselves from other organisms, and they happen to confer that refreshing scent that many of us bring into our homes in December. But, did you know that many non-fragrant consumer products are made with terpenes as well?

Other uses for terpenes

You may guess correctly that the most widely used product made from terpenes bears its name – turpentine. Turpentine is a solvent that is used as a paint thinner. Terpenes are also used in medicine as an anesthetic and even in anti-malarial and anti-cancer treatments. Additionally, plant-derived compounds have been the focus for a more sustainable future. Many scientists and engineers in the past couple of decades have concentrated their efforts to develop processes that might allow terpenes to replace petroleum in both the fuels and plastics industries.

Terpenes and Energy

  E. coli  bacteria - the strain of bacteria genetically engineered to produce terpene. 

E. coli bacteria - the strain of bacteria genetically engineered to produce terpene. 

Chemically, terpenes and petroleum are related because both are mixtures of compounds called hydrocarbons, or molecules composed only of hydrogen and carbon. Although the chemical structures of the compounds are different, scientists are familiar with the processes and procedures needed to manipulate hydrocarbons into useful molecules.  The benefit of using terpenes instead of petroleum is that they are a renewable resource, reducing our dependence on fossil fuels and thus our impact on the environment.

Terpenes are generated in large amounts as a waste product by the lumbering industry, but unfortunately, conifers do not produce enough terpenes to sustain a fuel industry. Two tons of wood chips only provide 4 kilograms (8.8 lbs) of crude turpentine. To address this, scientists are exploring the potential of genetically engineering bacteria to produce these compounds. To this end, a research group at the University of California, Berkeley has created a strain of bacteria that can convert sugar into terpenes, showing that these genetically modified bacteria may be a sustainable source of terpenes in a process that is analogous to brewers using yeast to make beer.

Research conducted in the Navy in the last decade found that two molecules of the pinene joined together has very similar properties to JP-10, a rocket fuel that is widely used in commercial and military launches. This researched has inspired biochemistry researchers to pursue pinene as a cheaper and sustainable fuel. In 2014, a laboratory at the Georgia Institute of Technology created a bacteria strain that produces pinene in the hopes of providing an alternative fuel source. Efforts now in this field are aimed at scaling up pinene production to be efficient and cheap enough to be viable in the fuel industry.

Making Plastics More Sustainable

 Plastic pollution often accumulates on beaches. 

Plastic pollution often accumulates on beaches. 

Another environmental issue being addressed with terpenes is the plastics industry. The large amount of plastic being created and disposed of is filling our landfills and oceans, and entire islands composed entirely of this garbage have been found in the Pacific Ocean. It is amazing and sad to think that almost every piece of plastic that has ever been produced is still in existence because the vast majority of plastics are not biodegradable. Furthermore, the process of creating these plastics requires petroleum. Even biodegradable plastics made from corn or sugar cane require some form of crude oil to manufacture. A research group at the University of Bath is investigating the use of pinene as an alternative to oil to produce these biodegradable plastics, as these polyesters (the main component of plastics) combined with pinene can create a flexible and strong material, completely circumventing the use of fossil fuels. Given the staggering amounts of plastic being created every day, even eliminating just the need for fossil fuels would have a large impact.


Christmas trees throughout history have come to be a symbol of life and hope, staying green through the entire winter and reminding people of the spring to come. Perhaps this year when you take a deep breath and savor that sharp and sweet pine scent, you will have a new appreciation for these trees. These trees are no longer only a symbol of hope, but the very chemical compounds that it produces could be the key to a sustainable and more environmentally conscious future for us all.


*Molecules that are non-superimposable mirror images of each other are called enantiomers.  

**Bornyl acetate belongs to a class of compounds called esters. Esters are found in fruits and are known and used for their pleasant smells.



·      “The Aroma of Christmas Trees.” Compound Interest, 19 December 2014. 24 November 2017.

·      “Bacteria could be rich source for making terpenes.” News from Brown. Brown University, 22 December 2014. 24 November 2017.

·      Conners, Deanna. “Why pine trees smell so good.” Earth. EarthSky, 22 December 2016. 23 November 2017.

·      Helmenstine, Anne Marie. “Why Christmas Trees Smell So Good: Chemistry of the Christmas Tree Aroma.” Science, Tech, Math. ThoughtCo. 24 November 2017.

·      Howgego, Josh. “Terpenes: not just for Christmas.” Education in Chemistry. Royal Society of Chemistry, 1 January 2014. 23 November 2017.

·      Kirby, James, et al. “Enhancing Terpene Yield from Sugars via Novel Routes to 1-Deoxy-D-Xylulose 5-Phosphate.” Applied and Environmental Microbiology 81(1): 130-138 (2015).

·      Romuld, Maggie. “That Christmas Tree Smell Just Got a Lot More Interesting.” Nature. The Science Explorer, 5 January 2017. 23 November 2017.

·      Quilter, Helena C., et al. “Polymerisation of a terpene-derived lactone: a bio-based alternative to ε-caprolactone.” Polymer Chemistry, 8: 883 (2017).

·      Sarria, Stephen, et al. “Microbial Synthesis of Pinene.” ACS Synthetic Biology, 3(7): 466-475 (2014).

·      Vance, Erik. “Atmospheric chemistry: The man who smells forests.” Nature 459: 498-499 (2009).

All images used were found on Wikimedia Commons and are Public Domain

Worms and Flies and Fishies (and MORE), Oh My!

When we think of scientists, thoughts of lab mice are close behind (à la Pinky and the Brain) but did you know that scientists use many OTHER organisms to study both basic and biomedical sciences? Just imagine: biomedical research using fruit flies could relate directly back to you, who, relative to a fruit fly, are much larger and seemingly more complex!

 Black sea urchin. Photo courtesy of Lacen/Public Domain.

Black sea urchin. Photo courtesy of Lacen/Public Domain.

Model organisms are any non-human species that scientists use to understand complex biological processes. Good model organisms are easy to breed, have short life cycles and are often physically small, making them easy to maintain in laboratories and manipulate in experiments. Outside of rodents, common model organisms include, but are not limited to: fruit flies (Drosophila melanogaster), nematode worms (C.elegans), yeast (Saccharomyces cerevisia), zebrafish (Danio rerio), and sea urchins (Arbacia).

As expected, model organisms are great at being, well…models. So, it may be hard to imagine how they can be used to understand human health. However, believe it or not, these organisms are great at doing just that! Despite looking dramatically different from humans, many of the key genes in model organisms have gene counterparts (homologs) in humans and other large mammals. This is why fruit flies are useful to scientists study cleft palate and the mechanisms behind diabetes…though more about that later. First, it is important to understand that non-rodent organisms are a hallmark of scientific research and that their influence on scientific progress cannot be overlooked. Some of these species have even earned scientists Nobel Prizes.

Major biological advances via some unexpected organisms

To grow and develop, organisms need to make new cells from older cells. How does this process work? And how do organisms get rid of these old cells or cells that are “bad”? Using model organisms like yeast and sea urchins, scientists answered these fundamental questions (by discovering the mechanisms behind the cell cycle and apoptosis, respectively) and as a result, expanded our understanding of diseases like cancer at the same time. Yes, sea urchins, like the ones you see at the aquarium, can help us fight cancer!

  Saccharomyces cerevisiae. Photo courtesy of Masur/Public Domain.

Saccharomyces cerevisiae. Photo courtesy of Masur/Public Domain.

In 2001, three scientists won the Nobel Prize for discovering key proteins important in a molecular process called the cell cycle using yeast and sea urchins. The cell cycle is the process by which cells make more cells. They do this through duplication and division of their genetic material and cell growth; it is a highly regulated process. Since cells are the basic building blocks of all living organisms, scientists were lucky to find the ideal model organisms to dissect this mechanism. The first model organism used, yeast, are single-celled, simple eukaryotic organisms whose genome can be easily manipulated, making them popular for genetic studies. They are also inexpensive and easy to grow in lab. Picture Erlenmeyer flasks full of yeast! Sea urchins, the other system used, have eggs that can be harvested and fertilized outside of the animal and, when initiated, divide synchronously, making cell division and development easy to visualize. Using these organisms, the Nobel Prize-winning research discovered several principle cell cycle proteins called cyclins and cyclin dependent kinases (CDKs).

Excitingly, these findings about the cell cycle not only developed our basic understanding of cells but set a foundation from which scientists could better understand disease. Cancer is characterized by a lack of cell cycle regulation. Tumors are the result of acquired genetic mutations and uncontrolled cell growth. Yeast and sea urchins, which appear so different from us, enabled scientists to understand fundamental biological processes yet also also provided mechanisms to target in cancer research and treatment. As startling as it may sound, this was not the only time model organisms helped scientists make landmark, prize-winning discoveries. It has occurred countless times throughout science history!

 C.elegan worms. Photo courtesy of ZEISS Microscopy Germany/Creative Commons.

C.elegan worms. Photo courtesy of ZEISS Microscopy Germany/Creative Commons.

The following year, 2002, three more scientists won the Nobel Prize for their work developing “nematode worms” (C.elegans) as a model organism and using them to study a process scientists call “programmed cell death” or more technically speaking, apoptosis. This is like it sounds. Cells are programmed to self-destruct and this apoptosis is a necessary part of healthy development. Like the cell cycle, understanding apoptosis also improved our understanding of human health. One of the major advantages of C.elegans is that scientists can actually track each individual cell during a worm's development under a microscope. Utilizing the uniqueness of this organisms, scientists observed that the same 131 cells of the total 1090 cells in a developing worm consistently died, indicating that apoptosis was a natural and necessary process and this, in part, led to the identification of apoptosis genes. Apoptosis is evolutionary conserved in other organisms and defects in the process can cause human diseases. It is often triggered when healthy cells detect something wrong. In diseases like cancer, mutations in apoptosis genes allow unhealthy and dysfunctional cells to continue growing. Conversely, an increase in cell death of specific cell types contribute to some neurodegenerative diseases such as Alzheimer’s and Huntington’s Disease.

They are more like us (humans) than you would Think!

Hopefully it is now clear that non-rodent model organisms are crucial tools used by scientists to dissect basic biological processes, but don’t forget - these organisms can also more directly model human health. Just like with mice, there are a lot of genes in these other organisms that have homologs in humans, making them also great for modeling diseases and drug development.

 Drosophila melanogaster (fruit fly). Photo courtesy of André Karwath aka AKA/Creative Commons.

Drosophila melanogaster (fruit fly). Photo courtesy of André Karwath aka AKA/Creative Commons.

For instance, in 1980, scientists discovered the hedgehog gene (hh) which is necessary for Drosophila (fruit fly) body patterning. Soon after, scientists found three similar genes in humans. One of these genes, sonic hedgehog (shh) – yes, it is named after the video game – is also important in early human development. Defects in human shh can result in cleft palate birth defects, which occur in 1 of every 1000 newborns. Scientists are therefore using flies to better understand the underlying mechanisms of cleft palate defects and using these studies to guide future research in larger mammals.

Now these same flies are also helping scientists understand the mechanisms behind diabetes. Despite being different from humans, insulin affects humans and flies similarly. In humans, insulin regulates the ability of cells to absorb glucose from the blood. In diabetes, this process is blocked. When scientists mutated several insulin-like genes in fruit flies, the insects developed diabetic symptoms and preliminary studies suggested that the cellular reason for their symptoms could be similar to those in humans. The hope is to use these fly models to create drugs and treatments that target these commonalities between flies and humans to ultimately combat diabetes.

Of course, as with any model, each system has its limitations, but the importance of using model organisms is clearly not a thing of the past. Studying model organisms and using the information we gain from them serve as the basis of many medical advances. Plus remember: some of the most seminal science discoveries that fill our textbooks were done in these species! Science is an abyss of unknown and model organisms have been, and will continue to be, a vital tool in discovery. Though these studies can stand alone, they also set a foundation for future studies in larger mammals (humans), saving scientists and society time, energy and money.

So the next time you see a fruit fly buzzing around your house, as annoying as it may seem, keep in mind that the species helped make countless scientific breakthroughs.




Picture Credits:

Ocean Acidification & Its Impacts

 Beach in Oahu, Hawaii

Beach in Oahu, Hawaii

With warm weather and summer vacation just around the corner, it is difficult to escape the draw of our oceans and beaches. Almost all of us, especially here in San Diego and other beachside cities, have stories to tell about our oceans, whether it is a fond memory from a family trip to the beach, a fishing voyage with friends, or a solo surf session by a pier at sunset. However, the oceans also tell us stories, and the narrative becoming clearer and more imminent is that of the declining health of our oceans.

  A factory in China . The Industrial Revolution brought about a reliance on burning fossil fuels for energy, which pumps large amounts of carbon dioxide and pollutants into our environment.

A factory in China. The Industrial Revolution brought about a reliance on burning fossil fuels for energy, which pumps large amounts of carbon dioxide and pollutants into our environment.

Since the Industrial Revolution, the use of fossil fuel-powered machinery has emitted billions of tons of carbon dioxide along with other gases into our atmosphere. Today, it is estimated that one million tons of carbon dioxide are emitted every hour – that’s a faster rate than has existed on our planet in tens of millions of years. Our oceans and seas absorb up to one-third of these gas emissions. This helps all of us on land because these greenhouse gases are taken out of the atmosphere, slowing down climate change. But, still, this comes at a cost.  

All solutions are acids or bases, and the acidity or basicity of a solution is defined by its pH value. A pH of 7 is neutral - the pH of pure water. Above pH 7 is basic, and below pH 7 is acidic. The surfaces of our oceans are healthiest when they are slightly basic with a pH of 8.2. Because of the large amounts of carbon dioxide entering our atmosphere, the pH of our oceans is decreasing, which is a process called ocean acidification.

 A scientist in Svalbard, Norway studying the effects of climate change on the oceans' chemistry. 

A scientist in Svalbard, Norway studying the effects of climate change on the oceans' chemistry. 

Because of ocean acidifications, our oceans are now at pH 8.1, and at the current rate, the ocean’s pH is predicted to drop about 0.5 pH units before the end of the century! At a glance, this may seem like a small or insignificant change, but it is enough to cause very serious problems in biological systems. For example, human blood is normally between a pH of 7.35 and 7.45. A drop in pH of 0.2-0.3 can cause seizures, comas, and death. You can imagine the large impact such a change can have on an ecosystem that takes up over 70% of our planet! About 250 million years ago, large levels of volcanic activity caused a similar level of ocean acidification, and this change contributed to the death of 90% of marine species.

So, how does ocean acidification occur? Carbon dioxide in our atmosphere dissolves in water to make a molecule called carbonic acid, so as our oceans continue to absorb carbon dioxide, the waters become increasingly acidic. In the past, basic molecules created by weathering rocks and sediments were enough to balance the carbonic acid and keep the oceans at their ideal 8.2 pH. However, rock erosion is not fast enough to keep up with acidification caused by an increasing excess of carbon dioxide released into our atmosphere.

 An experiment showing how acidic waters dissolve marine organisms' shells.

An experiment showing how acidic waters dissolve marine organisms' shells.

Such a rapid change in our oceans’ chemistry is not compatible with our marine organisms, which have evolved over millions of years in an ocean with a stable pH of 8.2. Ocean acidification affects marine organisms’ ability to communicate, reproduce, and grow. For example, at a healthy pH, about 10% of the carbon dioxide dissolved in the water exists as a molecule called carbonate. To make their shells, marine organisms like corals, clams, mussels, and oysters combine calcium with carbonate. Acidic waters have less carbonate, making it difficult for these animals to survive. Furthermore, acidic waters can chemically change the carbonate in the organisms’ shells to slowly dissolve them.

Acidic waters also lower the pH of the body fluids in all marine life, such as fishes, making it difficult for them to breathe and for their brains to function. It’s similar to if the air we breathe changed. If you have ever been at high elevation in the mountains where there is less oxygen in the air, you might have had a similar experience with difficulties breathing or headaches.

 Coral reefs in the Red Sea

Coral reefs in the Red Sea

In addition to harming marine life, ocean acidification is hurting certain industries, creating economic stress. There is a decline in commercial fisheries, especially those that trade in lobster, scallops, and other shellfish. California, which is home to 31 different kinds of salmon and trout, is predicted to lose 23 of these species within the next century. More gravely, in many fishing villages in Indonesia, The Philippines, and Malaysia, fishing is necessary for survival. Hundreds of communities like these around the world must fish to feed themselves, so the depletion of their food source is a serious issue.

Fortunately, ocean acidification is a somewhat gradual process, giving us time to recognize the impact of human activity and change our behaviors to lessen harmful disruption to our oceans. To lower your own individual carbon dioxide emissions (or “carbon footprint”), you can use less electricity, recycle, and reducing use of your car by biking, walking, or using public transportation instead. If you want to find out your carbon footprint, you can visit The Nature Conservancy’s calculator here. More powerful ways to help the oceans are to support political measures that combat increasing carbon emissions and to donate to or volunteer with local organizations that champion environmental causes. One example is the Surfrider Foundation - an international organization that promotes the health of our oceans and beaches. 

 Fishermen in Pangadaran, Indonesia

Fishermen in Pangadaran, Indonesia

Carbon dioxide is estimated to exist in the atmosphere for hundreds of years, so even if we cut off all carbon emissions today, we will not see a reversal of ocean acidification immediately. By teaching all of our friends and family about how we affect our environment, and by encouraging everyone to reduce our carbon footprints, we can thank our oceans for all that they give to us and ensure that our beautiful oceans and all of its organisms will exist in the future.


For another informative post about ocean acidification, check out John Hawthorne's article



·      Bland, Alistair. “Many Of California’s Salmon Populations Unlikely To Survive The Century.”  The Salt. NPR, 17 May 2017. 19 May 2017.

·      Brewer, Peter G. and James Barry. “Rising Acidity in the Ocean: The Other CO2 Problem.” Sustainability. Scientific American, 1 September 2008. 17 May 2017.

·       “Ocean Acidification.” Pristine Seas. National Geographic. 18 May 2017.

·      “Ocean Acidification.” The Ocean Portal Team and Jennifer Bennett. Ocean Portal. Smithsonian National Museum of Natural History. 18 May 2017.

·       “Ocean Acidification.” Know Your Ocean. Woods Hole Oceanographic Institute. 16 May 2017.

All images used were found on Wikimedia Commons and are Public Domain

The Extraordinary Life and Work of George Washington Carver

This post is the first installment of our "Meet a Scientist" Series

  George Washington Carver in 1910

George Washington Carver in 1910

Meet George Washington Carver – scientist, agriculturist, scholar, inventor, but, contrary to popular belief, not the inventor of peanut butter.  Although none of his hundreds of peanut products achieved commercial success, Carver’s accomplishments have landed him an irreplaceable part in history for revolutionizing agriculture in the United States and overcoming seemingly insurmountable obstacles to become a highly esteemed, African-American faculty member of the Tuskegee Institute in a time of extreme racial tensions.

George Washington Carver was born into slavery in Missouri to Mary and Giles, a slave couple owned by Moses and Susan Carver. The exact date of his birth is unknown, but it is estimated to be in the mid-1860s. Sadly, at approximately one-week old, George, his mother, and sister were kidnapped by farm raiders to be sold in Kentucky. George was located and returned to Moses Carver’s farm, but his mother and sister were not found.

  George Washington Carver at work

George Washington Carver at work

Moses and Susan Carver decided to keep and raise George and his brother. Because no schools accepted black students, Susan taught them to read and write at home. George valued learning from a young age, and enrolled in a school for black children about ten miles from the Carver Farm. When he enrolled, instead of continuing to be referred to as “Carver’s George,” he adopted the name “George Carver.” George pursued his education and graduated from high school in Kansas, but was denied admission to Highland College because of his race.

George enrolled in the botany program at the Iowa State Agricultural College as the first black student at the school. He graduated with a Bachelor of Science degree and, in 1896, a master’s degree, establishing himself as an exceptional botanist in the process. In 1896, Booker T. Washington, president of the Tuskegee Institute in Alabama, took notice of George Carver’s outstanding accomplishments and hired him as the head of the institute’s agricultural department. Carver’s research and work focused heavily on creating alternative uses of common crops, especially the peanut and sweet potato. He developed products from these plants for a myriad of purposes (over 300 products from peanuts and over 100 products from sweet potatoes!), such as paints, plastics, flours, shaving cream, glue, and even a form of gasoline. He is mistakenly commonly credited with the invention of peanut butter, but in reality, peanut butter made from ground peanuts date as far back as the 15th century by the Aztecs and Incas – centuries before Carver was even born.

  George Washington Carver Museum

George Washington Carver Museum

Carver remained adamantly passionate about education. Due to his very humble beginnings, he spent his entire life helping poor farmers, especially African-Americans, improve their crops and get out of poverty, always refusing compensation for his advice. Carver promoted various methods of crop rotation, which is a large part of why peanuts became a large source of his innovations. He promoted the growing of crops that fixed nitrogen, promoting sustainability of nutritious soil and, therefore, healthy crops. Carver lived frugally and used his fame to promote scientific causes. He also started a mobile classroom known as the “Jesup wagon” that visited various farms to educate the farmers about agricultural techniques. He wrote for a newspaper column and traveled around the country, speaking about the importance of agricultural research and innovation. For ten years in 1923-1933, he spoke in support of racial harmony when he visited white colleges in the South for the Commission on Interracial Cooperation and the YMCA. Although he never spoke out directly against racist social and economic injustices of the time, his scientific success and open-minded demeanor still earned him great respect and admiration from both African-American and Caucasian people.

George Carver became so well-known for his work that president Franklin Delano Roosevelt looked to him for advice on agricultural matters. In 1916, Carver became a member of the British Royal Society of Arts, which is a very rare honor given to Americans.



George Washington Carver passed away in 1943 at the age of 78. He is buried next to his friend and colleague Booker T. Washington. President Franklin D. Roosevelt dedicated $30,000 for a monument to be constructed in Carver’s honor, located west of his hometown of Diamond, Missouri. This is the first national monument dedicated to an African-American. Carver’s epitaph summarizes his beliefs and the humble philosophy by which he lived his life: “He could have added fortune to the fame, but caring for neither, he found happiness and honor in being helpful to the world.” To this day, he remains an icon of African-American achievement, scientific achievement, and the transformative power of education.




“George Washington Carver” Editors. The website. September 28, 2016. A&E Television Networks. April 26, 2017.

“Who Invented Peanut Butter?” National Peanut Board. April 26, 2017.

“Major Contributions – George Washington Carver.”  George Washington Carver Biotech. April 25, 2017.

“George Washington Carver.” Linda O. McMurry. The Reader’s Companion to American History. 1991. April 25, 2017.

All images used were found on Wikimedia Commons and are Public Domain

The Colorful Chemistry Behind an Eggscellent Easter

It’s that time of year when we can’t walk into a store without seeing displays of chocolate bunnies, marshmallow chicks, and vibrant bouquets of flowers. Along with all these springtime treats, perhaps the most memorable and engaging tradition (and my personal favorite) is the dyeing of Easter eggs.

By Superbass - Own work, CC BY-SA 4.0,

Decorating eggs is a deeply rooted, international tradition. The oldest examples of this activity are the engraved ostrich eggs found in Africa 60,000 years ago. Eggs across many countries and cultures are celebrated, and whether these activities are based on religion or the coming of spring, eggs represent rebirth and life.

For those who have participated in egg dyeing, you may have wondered: Why is vinegar added to the dye solution? This can be explained through simple chemistry. You've probably heard of acids and bases - it turns out that all solutions have a degree of acidity or basicity. Acids chemically react with bases to create solutions that are more neutral – that is, closer to pure water.

 lkonact via wikimedia commons

lkonact via wikimedia commons

So, back to the initial question – why is vinegar needed to dye an egg? The answer is that most egg dyes need acid to bind the dye to the eggshell.* Vinegar is an acid, and eggshells are bound together by a basic molecule called calcium carbonate. The eggshells base molecules assure that neutral and basic solutions will not change the eggshell. However, vinegar will react with the calcium carbonate shell to dissolve it slightly, allowing the dye molecules to stick to the eggshell, giving you vibrantly colored eggs.* Without adding vinegar to your dye solution, you will likely get very faint coloring.

 Egg in vinegar. The bubbles on the shell are from gas released when the vinegar reacts with the calcium carbonate. Leave this overnight and the eggshell will dissolve!  Image by  Yat-Long Poon , from  Experimenting with Science , published by Wiley

Egg in vinegar. The bubbles on the shell are from gas released when the vinegar reacts with the calcium carbonate. Leave this overnight and the eggshell will dissolve! Image by Yat-Long Poon, from Experimenting with Science, published by Wiley

Have you ever tried changing the amount of vinegar added to your dye solution? Because acid is needed for the dye molecule to stick to the egg, you might predict that adding more vinegar to the solution will give you more colorful eggs. This may be true to an extent, but be careful! The acid reacts with calcium carbonate to produce carbon dioxide gas, which will float out of the solution, like carbonation in soda. This gas forming on the surface of the eggshell can leave behind streaks, causing a blotchy dye job. That is why there is an optimal amount of vinegar recommended for the dye solution. Too much vinegar or leaving the egg in the solution too long will eventually dissolve the eggshell. For a neat science experiment exploring this, click here ; you can also find this experiment in Dr. Olivia Mullins' book here!

Have you ever seen someone dye eggs with a silk tie? (If not, watch this clip from Martha Stewart!) The patterns on a silk tie can be transferred from the tie onto the egg by wrapping the egg in the tie and submerging it in water with vinegar. Eventually, some of the dye from the tie will be transferred to the eggshell. This is because silk ties are usually dyed using dyes that require an acid to bind – the same reason that dyeing eggs requires vinegar. By adding vinegar to the water, the tie’s dye molecules can be transferred over to the eggshell.

Now that you know the chemical principles behind this tradition in addition to some tips and tricks for optimal coloring, there is no reason for not making this Easter your most colorful yet.

*Going further: Egg dye molecules are typically sodium salts of a negatively charged molecule called a phenolic acid. In an acidic solution, it gains a H+, allowing it to interact with the surface of the eggshell. In particular, dye molecules interact with slightly negative parts of the eggshell, including the calcium carbonate and some parts of proteins.

Other fun egg experiments

Grow Egg Geodes
Suck an egg into a bottle
Make "Mood" Easter Eggs
Walk on Eggs
Make Water Marble Easter Eggs

·         “Silky Science: Tie-Dyeing Eggs.” Scientific American. 21 March 2013. 26 March 2017.
·         Stewart, Brian. “Egg Cetera #6: Hunting for the world’s oldest decorated eggs.” University of Cambridge. 10 April 2010. . 26 March 2017.


Picture Credits:
Bunny and eggs: Superbass, CC BY-SA 4.0, via wikimedia commons
Basket of Bulgarian Orthodox Easter Eggs: lkonact via wikimedia commons
Egg in Vinegar: Yat-Long Poon, in Experimenting with Science, Wiley Publishing


The Genetics of the Luck o’ the Irish

by Ana Wang, Graduate Student at The Scripps Research Institute

With St. Patrick’s Day around the corner and a tumultuous start to 2017, most of us probably hope for a little of that fabled Luck o’ the Irish, and what’s more hopeful this time of year than finding a four-leaf clover? The myth of the four-leaf clover bringing good fortune has cultural origins that may be as simple as the fact that these clovers are rare, so finding one can make you feel special – or lucky. And they are pretty uncommon – on average, you’d have to search through 10,000 clovers to find one four-leaf clover! More rare still are clovers with five, six, seven, or more leaves – but they do exist. Currently, the world record is at 56 leaves on a clover found in Japan!

 Four-leaf clover

Four-leaf clover

Have you ever wondered why some clovers have four (or more) leaves? Or maybe you’ve wondered why more clovers don’t have four leaves. Well, look no further as we are going to delve into the science behind this lucky charm.

Whether or not a clover has the fortuitous fourth leaf – (or, more accurately leaflet) – is largely based on the code in the clover’s genetic material.  That being said, the exact cause of the fourth leaflet is hard to study and largely unknown, due to some quirks of the clover’s DNA. The common clover in North America is the white clover* which has four copies of each gene.** For reference, humans and most other organisms only have two copies of each gene. To add to the white clover’s genetic complexity, each chromosome (which contains the genes) in an individual clover often comes from a different species. You can imagine how hard it is to study lineage and inheritance with essentially four different parents!

 Five-leaf clover

Five-leaf clover

It is hypothesized that many genes, rather than a single gene, contribute to the determination of whether a clover is a trifoliate (three leaflets) or multifoliate (more than three leaflets). The Parrott Lab at the University of Georgia shed some light on this issue by studying three-leaf and four-or-more-leaf clovers in separate, but identical, surroundings. This set-up allowed the researchers to zero in on differences that stemmed from only genetics, as it kept the environmental influences of the two groups the same. Studying the DNA from the clovers showed that the multifoliate trait is recessive to the trifoliate trait. This means that even when a clover contains genes for both traits, it will have a trifoliate morphology. This is predominantly why the multifoliate variants are much more rare than the traditional three-leaf shamrock.

Genes are not the end of the four-leaf-clover story, however. The Parrott Lab also did some work on environmental influences. They ran their studies in both summer and winter and found more four-leaf clovers grew in the summertime, showing that genes AND the environment influence the number of leaves on a clover. Many suspect that chemicals and radiation may also increase the occurrence of four-or-more leaf clovers – but that has yet to be proven.

 Three-leaf shamrock   

Three-leaf shamrock


The four-leaf clover has become an international symbol of good luck. It is said that St. Patrick used the shamrock – the clover symbol of Ireland - to explain the Holy Trinity, with each leaflet representing one hypostasis . It is also said that the three leaflets represent hope, faith, and love. To many today, the fourth leaflet on a four-leaf-clover represents luck. To many in the Middle Ages, it was believed to bestow the carrier with the magical power to see fairies. To  plant biologists, though, it can represent the amazing complexity and infinite possibilities that lie within even a seemingly simple and common weed.


*The scientific name for the white clover is Trifolium repens, where trifolium refers to three leaves.

**Organisms with four copies of each gene are called allotetrapoloids.


·         “Most Leaves on a clover.” Guinness World Records. Web. 15 March, 2017.
·         Tashiro, Rebecca M., et al. Leaf Trait Coloration in White Clover and Molecular Mapping of the Red Midrib and Leaflet Number Traits. Crop Science 50, 1260-1268 (2010).


Many clovers: By JPS68via Wikimedia Commons
Four-leaf clover: By Calignano via Wikimedia Commons                                            
Five-leaf clover: By 本人 - 本人, via Wikimedia Commons
Three-leaf Shamrock: via Wikimedia Commons



Science Delivered on The Radio Show Esoterica!

Did you know Marie Curie had a daughter, Irene Joliot-Curie who won a Noble Prize in Chemistry? Get a run down of some of the early women pioneers in STEM in this Esoterica podcast! We are happy to say that Science Delivered gets a shout-out at the end. It's a short program so we highly recommend listening to the whole thing, but if you MUST skip ahead our piece starts around 2:47.

Thanks to Chris Kenna and Esoterica for this great piece!

*Esoterica is weekly radio program in Maine.

Book Announcement: "Experimenting with Science" is published!

Science Delivered founder "Dr. Olivia" has authored her first book! "Experimenting with Science" is published by Wiley and the For Dummies people. It's part of a new Dummies series for kids, aimed at ages 7-11, but we think grown-ups can enjoy it too.

Inside you'll find some of our favorite experiments! All experiments are done with simple and mostly household materials. We take on: Forces, Air Pressure, Sound, Chemistry, Plants and Animals, Perception and Art and Science. Check out the bonus material too!

Time for Credits! Our models were Teke Helms and Annika and Avery Pitts. Sam Poon did much of the photography work. Cynthia Mullins did several of the art and science experiments and inspiration for using recycled materials for Magnet Monsters can from Erin Pennell from ArtFORM. Paul Bonthius and Charles Toth did the technical editing, and Oliver Mullins helped with some Chemistry. Stephanie Mullins helped edit some of the "layman" pictures we had. Thanks everybody for your great efforts!

14 Definitions of Critical Thinking

Here at Science Delivered an important part of our mission is promoting confidence and critical thinking. Kids and adults possessing these attributes are well prepared to pursue their goals and navigate life’s obstacles. But while the words ‘critical thinking” gets thrown around quite a bit, we rarely see a critical analysis of the term itself. So what does 'critical thinking' really mean?

The dictionary definition is:

"The objective analysis and evaluation of an issue in order to form a judgment.”

But this definition isn’t overly helpful. So, in order to define this skill that we aim to cultivate, we’ve come up with 14 of our own definitions. Here it goes!

What does 'critical thinking' really mean?

  1. Critical thinking means being willing to change your position or beliefs as you collect more data.

  2. Critical thinking means being open to (quality) data that contradicts your previous beliefs.

  3. Critical thinking can mean ignoring an emotional or “gut” reaction to new information; our guts can make mistakes!

  4. Critical thinking means taking into account the source of the information.

  5. BUT critical thinking also means never (or rarely) dismissing information out of hand simply because of the source.

  6. Critical thinking means understanding that presented facts can be technically true but the manner in which they are presented can be skewed or misleading.

  7. Critical thinking means understanding that people, companies, ads and politicians often rely on authoritative sounding “science” and “statistics” to change your beliefs or behavior. Sometimes the facts they present are legitimate, but often they are not. Learning how to tell the difference makes navigating the world easier.

  8. Critical thinking means viscerally understanding that you don’t know everything.

  9. Critical thinking means resisting believing things solely because they fit in with your worldview.

  10. Critical thinking means understanding that others have had truly different experiences than you and may have different values and expectations of the world. This doesn’t (usually) mean one person’s values are right and another’s are wrong.

  11. We can’t be experts on everything, so we have to trust experts to inform our beliefs and ideas. But experts are not infallible – they can be wrong! In our opinion critical thinking means trusting the experts around 80-85% of the time.

  12. Critical thinking means being skeptical, especially when things seem somewhat unbelievable, but not being dismissive out of hand of new ideas.

  13. Critical thinking is often described as removing emotion from your ideas and decisions, but we only partially agree with that. Sometimes emotions and empathy are needed for sound critical thinking.

  14. Critical thinking means knowing that just because you have believed something all your life, doesn’t necessarily mean it’s true! Sometimes beliefs and ideas need to be reevaluated as we grow.


Teaching and engaging in critical thinking is helpful for the individual student and helpful for society. Critical thinking helps counteract bias and lets us evaluate what our biggest needs are and where our energy is best spent. We hope we can help our students obtain these lofty goals!

We’d love to hear from you – is there a definition of critical thinking that you'd like to add to our list?


Oobleck and Non-Newtonian Fluids

Move like crazy - or sink!

Recently at Science Delivered, we created an Oobleck Pool. Never heard of this before? Watch the video below and see if you see anything unexpected.



"Oobleck" is the popular name given to a corn starch and water mixture. This mixture has the fascinating property of being a solid or a liquid depending on the pressure, or shearing force, exerted upon it. More on this down below, but in practical terms, it means that smacking the Oobleck Pool with your feet temporarily turns the surface into solid. But if you place you feet (or hands, or elbow etc) into the Oobleck slowly, you'll get sucked right in.


Where does the name "Oobleck" come from?

           The original Oobleck from Dr. Seuss

          The original Oobleck from Dr. Seuss

The term "Oobleck" comes from an early work of Dr. Seuss, Bartholomew and the Oobleck. Magicians make a green gooey substance come down from the sky; it creates havoc in the land and look quite similar to the cornstarch and water mixture when you play with small amounts of it and let it drip. Our Oobleck can create havoc too - if you get stuck in it!


What is a non-Newtonian Fluid?

This might be best answered by defining a "Newtonian" fluid, which is an ideal liquid. In lay terms, the flow of a Newtonian fluid will not change no matter what you do (assuming constant temperature). If you consider water, you can pour water our slowly, or stir it really fast, or shake it up in a bottle and flows remains the same in all conditions. The viscosity does not change.

In contrast, consider trying to get ketchup out of a glass bottle. The ketchup will sit, clumped, requiring you to bang the bottle to get it out . . . at which point it would all come out at once. The applied force (hitting the bottle) causes the viscosity of the ketchup to change. The Oobleck is a mixture of corn starch and water. When you apply force to this mixture, the mixture hardens, enough so that you can walk on a pool of it. But if the force is too weak, the substance will act as a liquid and you will sink right in.


Are all non-newtonian fluids the same?

No! Non-Newtonian fluids can be classified as shear-thinning or shear-thickening. Meaning, fluids can either decrease or increase their viscosity in response to force. Remember how the ketchup flowed quickly out of the bottle once you hit it? That means it is sheer-thinning, it flows more easily in response to force. Other shear-thinning fluids are paint, blood, whipped cream and lava. The Oobleck corn starch and water mixture, on the other hand, is shear-thickening. This mixture becomes a solid with increased force, and acts as a liquid otherwise, as you can see from the video above and this one here.


It is interesting to note that the Oobleck is often compared to quicksand, however, according to this article, quicksand is shear thinning, and therefore behaves in an opposing manner to the Oobleck. In quicksand, it is the force of walking on it that liquifies the substance, which is why frantic struggling will only get you deeper. See the powerful effects of quicksand, and how to escape here.


So How do you make an oobleck pool?

Oobleck is easy to make in small quantities - just add a cup of water to ~ 3/4 cups of cornstarch and kneading it with your hands until the cornstarch is mixed in and not clumpy. More detailed instructions can be found here or here.

Making a pool is a whole other story. It's messy and expensive, and a difficult clean up, but if you are really hankering to do it we will give you instructions!

You will need:

200 pounds corn starch (can be modified for different size pools)

20 gallons of water

Kiddie pool

Cement mixture

Tarp to protect the ground

~15 heavy duty trashbags for disposal.

We started by using this kiddie pool and finding a wholesale food company who generously allowed us to open an account even though we wouldn't be making regular purchases. 500 pounds of cornstarch delivery later and we were ready to go! You can order large quantities of corn starch off Amazon, although it's not cheap.

We then rented a cement mixer. Do not even attempt to mix this by hand! Ours fit one 50 pound bag of cornstarch at a time. We used roughly 5 gallons of water for every 50 pound bag. Even with the cement mixture we would get clumps of unmixed cornstarch stuck to the sides and have to scrape them off. Test the mixture with your hands, if you move your hand slowly through the material (with the mixer off of course) it should be relatively clump free.

We ended up getting a pretty decent pool with "only" 200 pounds of cornstarch, so it took four cycles in the cement mixture. I'd recommend leaving at least an hour for set up assuming you have several strong adults.

If the pool is left untouched for a few hours the cornstarch will separate from the water and settle at the bottom - this pool is good for one-day use only.

Put down a tarp! This is an extremely messy project. The cornstarch billows everywhere and it does not come off the ground easily. The ground protection we used was inadequate and after several sweeping and hitting our patio with a hose there is still cornstarch stuck in cervices.

Disposal is another issue. We let the cornstarch sit for a couple days in an attempt to let it dry out, but it will start to rot so you can't let this go on for too long. We then double bagged heavy duty trash bags and picked it up in clumps into the bag. The trash can was extremely heavy but luckily the city still took it away.

There you have it! Everything you wanted to know about Oobleck Pools. For the unique chance to try this yourself, come to Science Fest 5K. [edit: Science Fest 5K has passed]