April 2015 will be the fourth anniversary for Common Science®. In each of the past three Decembers I have published a hyper-linked index for the columns from that year. This year I decided to do something different. Below is an index with links to all 185 columns I have published.
I have some new ideas for Common Science® for 2015. I’ve been writing for 3.5 years, doing the radio spot (Mondays at 4:32 on 1360 AM/97.9 FM WCHL, Chapel Hill, NC), and have been running a Twitter Feed, @commonscience, for about a year. Lately, I have been evaluating where to go next. I’ve written an outline for a book and also started to develop some materials to teach a class or workshop on some of the topics I have covered. My friend Robert has suggested that I start up a companion website for my columns on Chapelboro.com. I’m also developing a logo.
This comprehensive index has helped me to sort through my thoughts on possible new directions. For you, I hope it can serve as a bit of a reference e-book of easy-to-understand science explanations accompanied by my (hopefully) interesting, insights and commentaries.
I particularly enjoy receiving correspondence from readers at firstname.lastname@example.org. With rare exceptions, I respond to all of them. So if you have a comment or question on something I have written about or want to suggest a topic for a future column, shoot me a note.
Common Science Comprehensive Index
1 April 25, 2011 An Introduction to Your Host
2 April 25, 2011 Photosynthesis Part I: Oxygen Gets All the Press
3 April 27, 2011 Nothing Matters More than Oil, Nothing
4 May 5, 2011 Local Deal: 60% Off Hot Water
5 May 10, 2011 Dating an Engineer
6 May 16, 2011 Photosynthesis Part II: Glucose Needs a New Agent
7 May 20, 2011 Shelter from the Storm
8 June 1, 2011 Petroleum: 300 Million Years of Sunlight
9 June 5, 2011 Is Your Cell Phone Trying to Kill You?
10 June 11, 2011 Farewell to Brood XIX
11 June 18, 2011 Peak Oil in Five Paragraphs or Less
12 June 27, 2011 Lessons for Chapelboro from George Washington
13 July 4, 2011 Gas Prices and the Dow Jones
14 July 10, 2011 A Science Question for Michele Bachman
15 July 17, 2011 Fun with Fritz and Carl
16 July 29, 2011 Welcome to the Greenhouse
17 August 8, 2011 Electricity Production 101
18 August 14, 2011 To Frack or not to Frack
19 August 22, 2011 The World’s Greatest Cheat Sheet
20 August 24, 2011 Earthquake!
21 September 5, 2011 It’s a Theory that’s Out There
22 September 11, 2011 Everything Comes from Oil, Everything
23 September 19, 2011 Flu Season Primer Part I: The Virus
24 September 25, 2011 Flu Season Primer Part II: The Immune System
25 October 2, 2011 Flu Season Primer Part III: The Flu
26 October 9, 2011 The Flu: Epilogue
27 October 16, 2011 Entropy and the Local Economy
28 October 20, 2011 The Saudi Arabia of Denial
29 October 30, 2011 iPads, Priuses, and Neodymium
30 November 7, 2011 It’s Getting Crowded in Here
31 November 13, 2011 Your Mother the Plant
32 November 21, 2011 Carbon Monoxide – The Silent Killer
33 November 28, 2011 Advice to My Nephew on Whether to Study Science or Engineering
34 December 5, 2011 Biofuels Part I: Biodiesel Basics
35 December 12, 2011 Biofuels Part II: The Secret Life of Vegetable Oil
36 December 18, 2011 Biofuels Part III: Ethanol, It’s not Just for Breakfast Anymore
37 December 27, 2011 “A Year from Now You Will Wish You Had Started Today”
38 January 9, 2012 Chapelboro 2050 Part I: Life on Two Wheels
39 January 16, 2012 Chapelboro 2050 Part II: A Farewell to Lawns
40 January 22, 2012 Yes, We Have no Bananas
41 January 29, 2012 Chapelboro 2050 Part III: Get into the Zone
42 February 6, 2012 Chapelboro 2050 Part IV: The Good Dirt
43 February 12, 2012 2012 The Year Without Winter
44 February 20, 2012 Keystone Controversy
45 February 27, 2012 What a Fracking Mess
46 March 5, 2012 Follow the Bouncing Rubber Ball
47 March 12, 2012 Water Part I: Is God a Mathematician?
48 March 19, 2012 Lessons from the Explosion in the iPad Factory in China
49 March 26, 2012 Water Part II: Water, Water Everywhere, Nor Any Drop to Drink
50 April 1, 2012 Water Part III: Get the Salt Out
51 April 9, 2012 Water Part IV: When the Well Runs Dry
52 April 23, 2012 Another Piece of the Fracking Puzzle
53 April 30, 2012 Water Part V: When Oil and Water Mix
54 May 7, 2012 Getting Ready for Summer with SPF
55 May 14, 2012 Yes This Really is a Column about Phosphorous
56 May 21, 2012 Fracking, What NPR Left Out
57 May 28, 2012 Gravity, Still a Mystery
58 June 4, 2012 The Transit of Venus
59 June 11, 2012 Bronze Age Part I: Intelligence versus Accumulated Knowledge
60 June 18, 2012 Bronze Age Part II: The Case of the Missing Copper
61 June 24, 2012 High Fructose Corn Syrup, One Lump or Two?
62 July 2, 2012 Don’t Know Much Biology
63 July 9, 2012 The God Particle
64 July 16, 2012 Don’t Sweat It
65 July 22, 2012 Welcome to the Greenhouse: Reprise
66 July 29, 2012 To Frack or not to Frack: Reprise
67 August 6, 2012 When the Lights Go Out
68 August 12, 2012 Don’t Let the Bed Bugs Bite
69 August 20, 2012 Marriage Advice from Common Science
70 August 26, 2012 The Science Behind WCHL, Your News, Talk, and FM Station
71 September 3, 2012 West Nile Virus
72 September 10, 2012 If We Mine it or Drill It, We’re Going to Burn it
73 September 17, 2012 Nuclear Power Part I: The Science
74 September 24, 2012 Nuclear Power Part II: Waste, No Solution So Far
75 September 30, 2012 Nuclear Power Part III: Safety and Conclusion
76 October 8, 2012 Why This is an Important Year to Get Your Flu Shot
77 October 15, 2012 Deep Sea Vents, The Key to the Biggest Question in the Universe?
78 October 22, 2012 Political Non-Science Part I
79 October 28, 2012 Political Non-Science Part II: Calling Dr. Holdren
80 November 4, 2012 Nanotechnology
81 November 6, 2012 Why Ohio is not Close
82 November 12, 2012 Risky Business
83 November 19, 2012 Methane Hydrate Part I: The Science
84 November 26, 2012 Methane Hydrate Part II: All You Really Need to Know About Global Warming
85 November 30, 2012 Common Science Flash Post: Flu Season Update
86 December 3, 2012 The Greatest Invention of the 21st Century
87 December 10, 2012 An Ode to President Carter
88 December 16, 2012 The Lesson of Nylons
89 December 31, 2012 Common Science: The Year in Review
90 January 7, 2013 A Follow-Up Question for Mr. Skvarla
91 January 14, 2013 Hemp, George Washington Grew It
92 January 20, 2013 In Which I Reveal Myself to be a Luddite, At Least Partly
93 January 27, 2013 Perils of a Hyper Hygienic Existence
94 February 4, 2013 Bananas Will Never Grow in Barrow
95 February 10, 2013 Dear God What is that Smell?
96 February 18, 2013 Food Part I: Three Book Recommendations
97 February 24, 2013 Food Part II: The Science of the Stomach
98 March 4, 2013 Food Part IIIA: Wonder Bread is not Wonderful
99 March 11, 2013 Food Part IIIB: An Apple a Day Really Did Used to Keep the Doctor Away
100 March 18, 2013 Common Science Column 100
101 March 24, 2013 Food Part IV: The Chicken and the Egg
102 March 31, 2013 Food Part V: Conclusion and Some Politics
103 April 15, 2013 National Helium Shortage
104 April 21, 2013 Want to Grow the Local Economy? Hire More Engineers
105 April 29, 2013 Advice for Opponents to the Keystone XL Pipeline
106 May 6, 2013 Depleted Uranium
107 May 12, 2013 Cougars in Chapel Hill in 2035?
108 May 19, 2013 Ten Things You Should Know about CO2 Topping 400 PPM
109 May 26, 2013 Mentors
110 June 3, 2013 Hurricanes Part I: Hurricane Barry
111 June 10, 2013 Hurricanes Part II: Storm Surge
112 June 16, 2013 Hurricanes Part III: Frequency and Global Warming
113 June 23, 2013 Voyager I: Off to Interstellar Space
114 July 1, 2013 Empire of the Ants
115 July 8, 2013 No Where Else for the Rain to Go
116 July 21, 2013 The Power of Backpacking
117 July 29, 2013 Monkey Pox . . . Seriously?
118 August 5, 2013 Something is Rotten in the Province of Alberta
119 August 11, 2013 The Caterpillar Effect
120 August 19, 2013 Could Caesar Eat Peanuts?
121 August 25, 2013 The Rise and Fall of U.S. Infrastructure Part I: The Rise
122 September 1, 2013 The Rise and Fall of U.S. Infrastructure Part II: The Fall
123 September 8, 2013 The Rise and Fall of U.S. Infrastructure Part III: Conclusion
124 September 16, 2013 The Butterfly Effect
125 September 23, 2013 A World without Fossil Fuels
126 September 29, 2013 Bacteria and Obesity, A Surprising Link
127 October 6, 2013 Your Sister the Mushroom
128 October 13, 2013 Fungi of the Future
129 October 20, 2013 How Engineers Spend Their Spare Time
130 October 27, 2013 The Uncommon Core of the New Math
131 November 3, 2013 The Physics of Your Fireplace
132 November 10, 2013 Sudden Cardiac Arrest Part I: The Heart
133 November 17, 2013 Sudden Cardiac Arrest Part II: Heart Attack or Cardiac Arrest
134 November 24, 2013 Sudden Cardiac Arrest Part III: First Aid
135 December 1, 2013 It’s the Extraction, Not the Emissions, That Matter
136 December 8, 2013 Sudden Cardiac Arrest Part IV: The Frozen Man
137 December 15, 2013 Smog, The Desolation of Shanghai
138 December 22, 2013 Common Science 2013 Index
139 January 5, 2014 2014 Predictions Part I: The Positive
140 January 12, 2014 2014 Predictions Part II: The Negative
141 January 19, 2014 We Can Afford More Math Textbooks
142 January 26, 2014 West Virginia Chemical Spill
143 February 2, 2014 My First PC Weighed 25 Pounds
144 February 10, 2014 Keystone Pipeline Update
145 February 16, 2014 A Tale of Two Spills
146 February 23, 2014 The Case of the Missing Propane
147 March 3, 2014 Checking In on Peak Oil
148 March 16, 2014 China, The Canary in the Coal Mine
149 March 23, 2014 3D Printing Part I: The Technology
150 March 31, 2014 The Birthday Problem
151 April 6, 2014 3D Printing Part II: The Future
152 April 13, 2014 3D Printing Part III: A UNC Connection
153 April 20, 2014 The Vanishing of the Bees Part I: Psychology
154 April 27, 2014 The Vanishing of the Bees Part II: Local Efforts
155 May 4, 2014 My Conflicting Thoughts on Beekeeping
156 May 12, 2014 Meanwhile, In the War on Science
157 May 18, 2014 Renewable Energy is Sort of like the Internet
158 May 26, 2014 Fracking Gag Rule Part I: Trade Secret?
159 June 1, 2014 Fracking Gag Rule Part II: The Real Reasons
160 June 8, 2014 Fracking Gag Rule Part III: Wastewater
161 June 29, 2014 Brazil and BBQ
162 July 6, 2014 Hello, Arthur
163 July 13, 2014 Chikungunya is Coming: Part I
164 July 20, 2014 Chikungunya is Coming: Part II
165 July 27, 2014 Soil Part I: Seaweed Fertilizer
166 August 3, 2014 Meanwhile in the Arctic
167 August 10, 2014 Soil Part II: An Optimistic Global Warming Column
168 August 17, 2014 Methane in the Water Part I: Toxicity
169 August 24, 2014 Methane in the Water Part II: Fires and Explosions
170 August 31, 2014 Why Solar Roads Are a Bad Idea
171 September 7, 2014 How to Teach an Engineer to Play Guitar
172 September 14, 2014 All About Electricity
173 September 21, 2014 Chikungunya Part III: The Epidemic Continues
174 September 28, 2014 Of Minerals and Men
175 October 5, 2014 Mercury Rising
176 October 12, 2014 The Case of the Disappearing Lakes
177 October 20, 2014 How Chemical Engineering is Like Calculus
178 October 26, 2014 Common Science Grab Bag
179 November 2, 2014 Spinal Cord Miracle?
180 November 9, 2014 Is the Toilet the Greatest Public Health Invention Ever?
181 November 16, 2014 Why are the Norwegians Burning Trash?
182 November 23, 2014 An Engineer on a Diet: Part I
183 November 30, 2014 An Engineer on a Diet: Part II
184 December 7, 2014 Fracking: A Raleigh-Riyadh Connection
185 December 14, 2014 Results of My 2014 Predictionshttp://chapelboro.com/columns/common-science/common-science-comprehensive-index/
Below is my third annual index for Common Science on Chapelboro.com. I’d like to thank my readers for their support and for all of the interesting questions I have received from you at email@example.com. Just follow the hyperlinks below to read any of this year’s stories. And if there is a topic you would like me to cover in 2014, send me an email.
Happy Holidays from Common Science!
1. A Follow-Up Question for Mr. Skvarla 1/6/13
An evaluation of the North Carolina Secretary of the Department of Environmental and Natural Resources’ view that global warming is still an open question.
2. Hemp, George Washington Grew It 1/13/13
A review of the remarkable properties of the hemp plant and the history of why we stopped growing it.
A personal confession regarding my affection for hand tools.
4. Perils of a Hyper Hygienic Existence 1/27/13
Some of the health challenges presented by trying to keep all bacteria out of our lives.
5. Bananas Will Never Grow in Barrow 2/3/13
An explanation of why plants will not be able to migrate fast enough to keep pace with global warming and the implications of this for the world’s food supply.
6. Dear God What is That Smell? 2/10/13
The science behind women’s superior sense of smell.
7. Food Part I: Three Book Recommendations 2/17/13
Book reviews on three recent books about our food supply.
8. Food Part II: The Science of the Stomach 2/24/13
How the digestive system deconstructs our food and conveys needed nutrients to the rest of our body.
A review of the aspects of the U.S. industrial food system which are making our diets less and less healthy.
The conclusion of Part III.
11. Common Science Column 100 3/17/13
A thank you column to my readers to mark my 100th column.
12. Food Part IV: The Chicken and the Egg 3/24/13
The shortcomings of factory chicken farms in providing us with healthy and nutritious food.
13. Food Part V: Conclusion and Some Politics 3/31/13
The conclusion of my series on food with advice for the individual, our local region, and our nation on how to improve our food system and live healthier lives.
14. National Helium Shortage 4/15/13
Reasons why elements do not obey the law of supply and demand, and the politics behind our helium shortage.
An argument that the foundation of value creation is the transformation of raw materials into finished goods, and that more engineers are needed to boost this process.
16. Advice for Opponents of the Keystone Pipeline 4/29/13
An argument that the focus on pollution of water supplies by pipeline leaks is the wrong focus for those trying to stop the pipeline project.
17. Depleted Uranium 5/6/13
An explanation of what depleted uranium is, what it is used for, the health problems it creates, and the challenges of cleaning it up in Iraq.
18.Cougars in Chapel Hill in 2035 5/13/13
Using the data for the expansion of the range of the cougar from the Rockies to the Mississippi in conjunction with Fick’s Law of Diffusion, I predict that Cougars will return to Chapel Hill, NC in 2035.
An explanation of the significance of the concentration of carbon dioxide in the atmosphere reaching the 400 ppm milestone and the implications for the future.
20. Mentors 5/27/13
The story of three important mentors in my life and the lessons they gave me.
21. Hurricanes Part I: Hurricane Barry 6/3/13
The science behind hurricanes.
22. Hurricanes Part II: Storm Surge 6/10/13
An explanation of why most of the damage and loss of life from Hurricanes is the result of storm surge.
An explanation of why warmer oceans may result in stronger hurricanes but not more frequent storms.
24. Voyager I: Off to Interstellar Space 6/23/13
After decades of travel, the first man-made object will be leaving our solar system and sending back data from interstellar space.
25. Empire of the Ants 7/1/13
The invasion of the Southeastern United States by the Tawny Crazy Ant.
26. No Where Else for the Rain to Go 7/8/13
An explanation of how outdated storm water systems contributed to the Great Chapel Hill Flood of 2013.
27. The Power of Backpacking 7/15/13
After returning from a recent hike on the Appalachian Trail, I calculate the power consumption required to lug a 30 pound backpack up hills over uneven ground.
28.Monkey Pox . . . Seriously? 7/22/13
Now that we have stopped giving the smallpox vaccine, monkey pox is on the rise.
The details behind a “spill” from a tar sands well in Alberta and an explanation of why this type of event will continue to occur.
30.The Caterpillar Effect 8/12/13
We all plant flowers to attract butterflies, but what we are not doing is giving their caterpillars anything to eat.
31. Could Caesar Eat Peanuts 8/19/13
The surprising correlation between Caesarian birth and food allergies.
The history of the great investments in U.S. infrastructure from the 1800s through the 1970s.
The rapid deterioration of U.S. infrastructure which occurred since 1980, after investment as a function of gross domestic product significantly declined.
A plan for building the infrastructure we need to succeed in the 21st Century.
35. The Butterfly Effect 9/15/13
An explanation of the difference between the Butterfly Effect and Chaos Theory.
36.A World Without Fossil Fuels 9/22/13
My vision of the state of the world today if the earth did not have fossil fuels.
37.Bacteria and Obesity, A Surprising Link 9/29/13
Use of antibiotics in young mammals limits the diversity of gastrointestinal tract bacteria for life, a key factor in the obesity epidemic.
38.Your Sister the Mushroom 10/6/13
An exploration of the commonality between humans and mushrooms due to their relationship on the tree of evolution.
39.Fungi of the Future 10/13/13
Some predictions on the key role that fungi will play in our lives during the 21st century.
40.How Engineers Spend Their Spare Time 10/20/13
My project to install a solar water heating system in my green house to grow tomatoes all year.
41. The Uncommon Core of the New Math 10/27/13
My critique of the new Common Core math curriculum.
42.The Physics of Your Fireplace 11/3/13
The surprising scientific sophistication of the gas fireplace.
43.Sudden Cardiac Arrest Part I: The Heart 11/10/13
The beginning of a series on the science of sudden cardiac arrest and the story of my father’s remarkable survival of one.
The differences between a heart attack and a cardiac arrest and their symptoms.
45.Sudden Cardiac Arrest Part IV: First Aid 11/24/13
First aid for sudden cardiac arrest.
Stories about carbon dioxide emissions from individual countries are inherently misleading. What truly matters in terms of global warming is global extraction of below-ground carbon atoms.
Conclusion of the Sudden Cardiac Arrest series, including the story of how and why therapeutic hypothermia saved my father’s life.
48.Smog, The Desolation of Shanghai 12/15/13
The science behind the devastating smog in Shanghai, China.
Since personal obligations have kept me busy this week over Thanksgiving, I will not be publishing the conclusion of the “Sudden Cardiac Arrest” series until December 8th. This week, I am reprising a column from September, 2012, with this new introduction, which I hope will help to shed some light on two recent, but seemingly contradictory news stories. In 2013, carbon dioxide emissions in the United States were down by 3.7% compared to 2012. In stark contrast, gloggbal emissions, at a staggering 10 billion tons, were 2.1% higher than in 2012.
As I explained in “If We Mine it or Drill it, We’re Going to Burn It,” news stories which focus on carbon emissions are inherently misleading. Since the air in the atmosphere is all mixed together, it does not matter from which country the emissions originate. The parameter that truly matters is the rate at which we are extracting carbon, in the form of coal, oil, and natural gas, from below the ground.
The widespread utilization of hydraulic fracturing (fracking) combined with horizontal drilling in the U.S. has resulted in a significant increase in extraction of natural gas. Natural gas is difficult and expensive to export, so nearly all of this increased supply is being burned in domestic power plants to make electricity. As more electricity in the U.S. is being generated from natural gas, the amount produced by burning coal is decreasing. Generating an equivalent amount of electricity from natural gas rather than coal releases less carbon dioxide. Therefore, the shift towards natural gas for electricity production in the U.S. is the primary reason that carbon dioxide emissions from the U.S. have been reduced. As nice as this may sound, it doesn’t really matter.
To understand why it doesn’t matter, one need look no further than Appalachia, the heart of the U.S. coal mining industry, rumors of whose death have been greatly exaggerated. Despite the loss of a portion of the electricity market, U.S. coal extraction is at an all-time high. Since coal is easy to transport, it is being shipped all over the world, particularly China and India, to generate electricity there.
The end result of the natural gas “boom” from fracking and the increase in coal exports is an increase in the extraction of underground carbon from the U.S. This is the story that matters about the U.S. contribution to carbon dioxide emissions and global warming. We are making it worse, not better.
For more detail and the underlying science, follow the link above to my previous column. If you have a comment or question use the interface below or send me an email to firstname.lastname@example.org://chapelboro.com/columns/common-science/extraction-emissions-matters/
I recently had the chance to read through my stack of the last several months of Scientific American® magazine. My curiosity was piqued a story in one of the issues about a study conducted by the Henry Ford Hospital in Detroit. The study reported that babies who had been born via Caesarian section (C-section) were five times more likely to develop food allergies than those born vaginally. Like many parents I know, I have a strong impression that childhood food allergies are far more prevalent now than in the 1970s when I grew up. I have no childhood memories of peanut-free classrooms or EpiPens.
A search of the CDC and NIH websites provided the data for the graph below.
C-section rates have been steadily rising in the United States, from around 5% of births in 1970 to nearly 33% today. The data for childhood peanut and overall food allergies show that not only are childhood food allergies on the rise, but the rate of rise is nearly identical to the rate of increase of C-sections.
We’ll get back to the correlation been allergies and C-sections in a moment, but first permit me a brief aside to do a little math. I read several news reports on the Henry Ford Hospital study which all included the “five times more likely” statement, but omitted any absolute numbers. This is a key gap. For example, if C-sections increased the chance of developing a food allergy from 0.01% to 0.05%, it would probably not be significant enough to factor childbirth decisions.
However, using the data from the graph above and little algebra, it is not difficult to quantify the risks. If the 33% of children born via C-section are five times more likely to develop food allergies, and the total rate of allergies for all children is 5.1%, then the chance that a child born by C-section will develop a food allergy is 11.0% versus just 2.2% for a child born vaginally. This is a noteworthy difference and likely worthy of some consideration by expectant parents.
Getting back to the graph, we can see that childhood food allergies and rates of Caesarian births are closely correlated, but correlation does not necessarily demonstrate causation. The study at the Henry Ford Hospital addressed this issue and developed a convincing case for causation. While in-utero, the gastrointestinal (GI) tract of a child is bacteria free. Beneficial bacteria in your GI tract are essential both to digest food and to ward of disease. Therefore, newborn babies need to rapidly develop a large and diverse population GI tract bacteria.
During a vaginal birth, the baby’s GI tract becomes populated with the mother’s bacteria from the ingestion of fluids through the mouth. This “inoculation” of bacteria from the mother gives the child a tremendous head start towards developing a healthy digestive system. Babies born by C-section only start to populate their GI tract with bacteria from breast milk and/or from sticking their fingers in their mouths. This less efficient approach to establishing a healthy bacteria population appears to dramatically increase the incidence of food allergies. Food allergies may lack a scary-sounding name, but they are by no means a trivial circumstance. Sufferers can experience reduced quality of life, severe reactions, and, in extreme cases, death.
The parallels between this column and the issues I discussed in my recent column entitled “The Perils of a Hyper Hygienic Existence” are striking. Through the use of antibiotics some people have the population of healthy bacteria in their GI tract dramatically reduced in a sustained manner. This circumstance can bring about debilitating diarrhea and a variety of other serious GI tract problems. Recent studies have shown that these patients can experience remarkable improvement by introducing the bacterial flora from a healthy donor by a process rather unfortunately named fecal transplant.
When considering the correlation between Caesarian birth rates and food allergies I thought a similar solution might be appropriate. When Caesarian births are performed, I thought that a methodology might be considered which would introduce the mother’s bacterial flora to the child’s GI tract to help fend off food allergies. I found a recent study conducted in Venezuela which did just that. They gave the child the bacteria she needed with a simple mouth swab after the C-section. This simple procedure could dramatically reduce the incidence of food allergies in C-section babies.
Have a comment or question? Use the comment interface below or send me an email to email@example.com://chapelboro.com/columns/common-science/could-caesar-eat-peanuts/
You may recall some excitement in Chapel Hill in December of 2008 when there was a reported cougar sighting near the UNC golf course. Like many cougar sightings in North Carolina, this one was not confirmed by state wildlife officials. But cougars are on the move eastward from the Rockies and are likely to return to the area some day. The question is when? Common Science is here to try to answer that question.
The discussion of cougars gets complicated by the many names given to the species including puma, mountain lion, and catamount. They are all the same. Prior to European colonization, cougars ranged through most of the United States and Canada, feeding primarily on deer, elk, and moose. Cougars, males in particular, are solitary, territorial, and nocturnal. Their maximum population densities average only four cougars for every 40 square miles, or 0.1 per square mile, a number to which we will refer back later. Therefore, even when cougars are at their normal population densities, sightings are usually rare.
When U.S. and Canadian settlers pushed westward, they considered the cougar to be a menace and a nuisance and killed them indiscriminately. Additionally, even though the losses of livestock were statistically low, farmers and ranchers successfully lobbied their respective state governments to pay bounties for dead cougars. By the 1950s, with the exception of a an isolated population in the Florida Everglades, all cougars east of the Mississippi river had been eliminated and the population between the Mississippi and the Rocky Mountains was nearly wiped out as well. By the 1960s and 1970s, most states repealed the bounties and imposed regulations against indiscriminate killing of cougars, allowing the populations to begin a slow rebound. At present, it is estimated that the cougar population in the U.S. is somewhere between 30,000 and 50,000.
The vanguard of a cougar migration consists of juvenile males who need to find available territories to avoid conflicts with older males. Occasionally a lone male will travel hundreds of miles out of range, which accounts for the infrequent but intriguing reports of cougars along the eastern seaboard, including a recent confirmed sighting in Connecticut. However, the re-establishment of a stable population in a new area must await the arrival of both genders. The eastward migration of the cougar is being tracked via confirmed sightings in midwest states, including Oklahoma, Missouri, Illinois, and Arkansas. Cougar sightings in these states grew from just two in 1990 to 34 in 2008, suggesting a noteworthy increase in population density during this time interval.
This brings me to the reason I find the phenomena of animal migrations to be interesting, and which will usher in the section of this column which is almost certain to differentiate it from any other column you encounter covering the return of the cougar to the eastern United States. The movement of animal populations can be modeled with diffusion equations, a tool often used by engineers like me. Diffusion equations are used to determine the rate of movement of materials from an area of high concentration to one of low concentration. If you’d like to run your own diffusion experiment, put a drop of food dye into a glass of water and watch. Initially, the area where the drop landed will have high concentration of dye. With time, molecules of the dye will migrate away from the area of high concentration to zones of water in the glass which have low or no concentration of dye.
The dynamics of this simple kitchen experiment have a lengthy and elegant mathematical explanation which culminates in Fick’s Law of Diffusion. I’m tempted to include a thorough explanation of the underlying mathematics of Fick’s Law, but I’m not so sure you’d be tempted to read it. What I would like you to consider however, is that the migration of the cougar and the diffusion of the food dye are quite similar. In the case of the cougars, the area near the Rocky Mountains which contains 0.1 cougars per square mile is like the drop of food dye, and the area bereft of cougars east of the Rockies is like the rest of the water in the glass. Therefore, we can use Fick’s Law to try to predict when the cougar will return to the southern part of heaven.
If you look at the map below, the western most dashed line runs approximately along the north-south axis of the Rocky Mountains. About 500 miles to the east, shown by the vertical dashed line called D1 (distance 1), the cougar population density was such that there were just 2 sightings in 1990. We don’t know the exact population density of cougars along D1 in 1990, but we know it was low. In my calculations, I assigned it a value of 0.002 cougars per square mile. I can’t know if this is correct, but as long as I am consistent with the assumption that a population density of 0.002 cougars per square mile will result in 2 sightings per year, the subsequent predictions will still work. (I need you to trust me on that one.) The line D2 on the map indicates the location of Chapel Hill, which is approximately 1400 miles east of the Rockies.
Now that I have the population density of cougars for two locations in 1990, the Rockies and the line D1, I can model the population density of cougars as a function of distance using Fick’s Law. This is shown by the blue line on the graph below. By 2008, the number of sightings in the D1 area rose to 34 per year. Since sightings increased by a factor of 17, from 2 to 34, it is reasonable to assume that the population density increased by a factor of 17 as well. Using this assumption, the population density as a function of distance for 2008 is shown with the purple line. The curve for 2008 suggests that by this time cougars should have begun recapturing western Tennessee as part of their range. News reports conflict as usual, but there is strong anecdotal evidence that they did return to the Volunteer State around that time.
Using this model, I can calculate how long it should take for the population density in Chapel Hill to reach 0.002 cougars per square mile, the level at which we could expected to begin to see confirmed sightings from a resident population consisting of both males and females. This is shown on the graph with the green line, suggesting that in addition to jaguars, tigers, and wildcats (our high school mascots in case you missed the reference), Chapel Hill will have cougars in 2035. If we ever need to build a fourth High School, then the choice for a mascot is obvious.
Have a comment or question? Use the interface below or send me an email to firstname.lastname@example.org://chapelboro.com/columns/common-science/cougars-in-chapel-hill-in-2035/