Monday, 17 October 2016


pitch drop
15 of the Longest-Running Scientific Studies in History
By Austin Thompson,
Mental Floss, 15 October 2016.

Most experiments are designed to be done quickly. Get data, analyze data, publish data, move on. But the universe doesn’t work on nice brief timescales. For some things you need time. Lots of time.

1. The Broadbalk Experiment - 173 Years

In 1842, John Bennet Lawes patented his method for making superphosphate (a common, synthetic plant nutrient) and opened up what is believed to be the first artificial fertilizer factory in the world. The following year, Lawes and chemist Joseph Henry Gilbert began a series of experiments comparing the effects of organic and inorganic fertilizers, which are now the oldest agricultural studies on Earth. For over 150 years parts of a field of winter wheat have received either manure, artificial fertilizer, or no fertilizer. The results are about what you’d expect: artificial and natural fertilized plots produce around six to seven tons of grain per hectare, while the unfertilized plot produces around one ton of grain per hectare. But there’s more. They can use these studies to test everything from herbicides to soil microbes and even figure out oxygen ratios for better reconstruction of paleoclimates.

2. The Park Grass Experiment - 160 Years

Lawes and Gilbert started several more experiments at around the same time. In one of these experiments with hay, Lawes observed that each plot was so distinct that it looked like he was experimenting with different seed mixes as opposed to different fertilizers. The nitrogen fertilizers being applied benefited the grasses over any other plant species, but if phosphorus and potassium were the main components of the fertilizer, the peas took over the plot. Since then, this field has been one of the most important biodiversity experiments on Earth.

3. The Broadbalk and Geescroft Wildernesses - 134 Years

Geescroft Wilderness. Image credit: Forestry Commission.

Yet another one of Lawes’ experiments: In 1882 he abandoned part of the Broadbalk experiment to see what would happen. What happened was that within a few years, the wheat plants were completely outcompeted by weeds - and then trees moved in. In 1900, half of the area was allowed to continue as normal and the other half has had the trees removed every year in one of the longest studies of how plants recolonize farmland.

4. Dr. Beal’s Seed Viability Experiment - 137 Years

Image credit: Wikimedia Commons

In 1879, William Beal [pictured above] of Michigan State University buried 20 bottles of seeds on campus. The purpose of this experiment was to see how long the seeds would remain viable buried underground. Originally, one bottle was dug up every five years, but that soon changed to once every 10 years, and is now once every 20 years. In the last recovery in 2000, 26 plants were germinated, meaning slightly more than half survived over 100 years in the ground. The next will be dug up in 2020, and (assuming no more extensions) the experiment will end in 2100.

Even if it is extended for a while, there will probably still be viable seeds. In 2008, scientists were able to successfully germinate a circa-2000 year old date palm seed, and four years later, Russian scientists were able grow a plant from a 32,000 year old seed that had been buried by an ancient squirrel.

5. The Pitch Drop Experiment - 86 Years

If you hit a mass of pitch (the leftovers from distilling crude oil) with a hammer, it shatters like a solid. In 1927, Thomas Parnell of the University of Queensland in Australia decided to demonstrate to his students that it was actually liquid. They just needed to watch it for a while. Some pitch was heated up and poured into a sealed stem glass funnel. Three years later, the stem of the funnel was cut and the pitch began to flow. Very slowly. Eight years later, the first drop fell. Soon the experiment was relegated to a cupboard to collect dust, until 1961 when John Mainstone learned of its existence and restored the test to its rightful glory. Sadly, he never saw a pitch drop. In 1979 it dropped on a weekend, in 1988 he was away getting a drink, in 2000 the webcam failed, and he died before the most recent drop in April 2014.

As it turns out, the Parnell-initiated pitch drop experiment isn’t even the oldest. After it gathered international headlines, reports of other pitch drop experiments became news. Aberystwyth University in Wales found a pitch drop experiment that was started 13 years before the Australian one, and has yet to produce a single drop (and indeed is not expected to for another 1300 years), while the Royal Scottish Museum in Edinburgh found a pitch drop experiment from 1902. All of them prove one thing though: With enough time, a substance that can be shattered with a hammer still might be a liquid.

6. The Clarendon Dry Pile - 176-191 Years

Image credit: DavidCWG/Wikimedia Commons

Around 1840, Oxford physics professor Robert Walker bought a curious little contraption from a pair of London instrument makers that was made up of two dry piles (a type of battery) connected to bells with a metal sphere hanging in between them. When the ball hit one of the bells, it became negatively charged and shot towards the other positively charged bell where the process repeats itself. Because it uses only a minuscule amount of energy, the operation has occurred ten billion times and counting. It’s entirely possible that the ball or bells will wear out before the batteries fully discharge.

Although we don’t know the composition of the battery itself (and likely won’t until it winds down in a few hundred years), it has led to scientific advancements. During WWII, the British Admiralty developed an infrared telescope that needed a battery capable of producing high voltage, low current, and that could last forever. One of the scientists remembered seeing the Clarendon Dry Pile - also referred to as the Oxford Electric Bell - and was able to find out how to make his own dry pile for the telescope.

7. The Beverly (Atmospheric) Clock - 152 Years

Image credit: Mysterious snapper/Wikimedia Commons

Sitting in the foyer of the University of Otago in New Zealand is the Beverly Clock. Developed in 1864 by Arthur Beverly, it is a phenomenal example of a self-winding clock. Beverly realized that, while most clocks used a weight falling to get the energy to run the clock mechanism, he could get the same energy with one cubic foot of air expanding and contracting over a six-degree Celsius temperature range. It hasn’t always worked; there have been times it needed cleanings, it stopped when the Physics department moved, and if the temperature is too stable it can stop. But it’s still going over 150 years later.

8. The Audubon Christmas Bird Count - 116 Years

Since 1900, folks from across the continent have spent time counting birds. What began as an activity to keep people from hunting our feathered friends on Christmas Day, has turned into one of the world’s most massive and long-lasting citizen science projects. Although the 2015 results aren’t ready yet, we know that in 2014, 72,653 observers counted 68,753,007 birds of 2106 species.

9. The Harvard Study of Adult Development - 78 Years

One of the longest running development studies, in 1938 Harvard began studying a group of 268 sophomores (including one John F. Kennedy), and soon an additional study added 456 inner-city Bostonians. They’ve been followed ever since, from World War II through the Cold War and into the present day, with surveys every two years and physical examinations every five. Because of the sheer wealth of data, they’ve been able to learn all kinds of interesting and unexpected things. One such example: The quality of vacations one has in their youth often indicates increased happiness later in life.

10. The Terman Life Cycle Study - 95 Years

Lewis Terman. Image credit: Wikimedia Commons.

In 1921, 1470 California children who scored over 135 on an IQ test began a relationship that would turn into one of the world’s most famous longitudinal studies - the Terman Life Cycle Study of Children with High Ability.  Over the years, in order to show that early promise didn’t lead to later disappointment, participants filled out questionnaires about everything from early development, interests, and health to relationships and personality.  One of the most interesting findings is that, even among these smart folk, character traits like perseverance made the most difference in career success.

11. The National Food Survey - 76 Years

Image credit: Daily Mail

Starting in 1940, the UK’s National Food Survey tracked household food consumption and expenditure, and was the longest lasting program of its kind in the world. In 2000 it was replaced with the Expenditure and Food Survey, and in 2008 the Living Costs and Food Survey. And it’s provided interesting results. For instance, earlier this year it was revealed that tea consumption has fallen from around 23 cups per person per week to only eight cups, and no one in the UK ate pizza in 1974, but now the average Brit eats 75 grams (2.5 ounces) a week.

12. The Framingham Heart Study - 68 Years

Image credit: Framingham Heart Study

In 1948, the National Heart, Lung, and Blood Institute teamed up with Boston University to get 5209 people from the town of Framingham to do a long-term study of how cardiovascular disease developed. Twenty-three years later they also recruited the adult children of the original experiment and in 2002 a third generation. Over the decades, the Framingham Heart Study researchers claim to have discovered that cigarette smoking increased risk, in addition to identifying potential risk factors for Alzheimer’s, and the dangers of high blood pressure.

13. The E. Coli Long Term Evolution Experiment - 26 Years

Image credit: Brian Baer and Neerja Hajela/Wikimedia Commons

While this one might not seem that impressive in terms of length, it has to be the record for number of generations that have come and gone over the course of the study: well over 50,000. Richard Lenski was curious whether flasks of identical bacteria would change in the same way over time, or if the groups would diverge from each other. Eventually, he got bored with the experiment, but his colleagues convinced him to keep going, and it’s a good thing they did. In 2003, Lenski noticed that one of flasks had gone cloudy, and some research led him to discover that the E. coli in one of the flasks had gained the ability to metabolize citrate. Because he had been freezing previous generations of his experiment, he was able to precisely track how this evolution occurred.

14. The BSE Experiment - 11 Years

A cow with BSE. Image credit: Dr. Art Davis/Wikimedia Commons.

Sadly, sometimes things can go terribly wrong during long-term experiments. Between 1990 and 1992, British scientists collected thousands of sheep brains. Then, for over four years, those prepared sheep brains were injected into hundreds of mice to learn if the sheep brains were infected with BSE (mad-cow disease). Preliminary findings suggested that they were, and plans were drawn up to slaughter every sheep in England. Except those sheep brains? They were actually cow brains that had been mislabeled. And thus ended the longest running experiment on sheep and BSE.

15. The Juneau Icefield Research Program - 68 Years


Attention to glacier retreat and the effects of global warming on the world’s ice fields has rapidly increased over the course of the last few decades, but the Juneau Icefield Research Program has been monitoring the situation up north since 1948. In its nearly 70 years of existence, the project become the longest-running study of its kind, as well as an educational and exploratory experience. The monitoring of the many glaciers of the Juneau Icefield in Alaska and British Columbia has a rapidly approaching end date though - at least in geological terms. A recent study published in the Journal of Glaciology predicts that the field will be gone by 2200.

Top gif image: The Pitch Drop Experiment. Credit: Image created from ThePitchDrop/YouTube.

[Source: Mental Floss. Edited. Some images and videos added.]

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