Science World

Fatter Population Threatens World Food Supply

Turns out obesity isn’t just a health issue;  all of that overeating could seriously cut into the future world food supply.

According to a new study from Great Britain, if the current worldwide obesity epidemic continues unabated, maintaining enough food to feed the world could actually become a much more serious challenge.

Right now, the world’s population is over seven billion, and growing.  The more people there are, the more food and resources are needed.

According to the London School of Hygiene & Tropical Medicine,  the weight of the human population should be taken into consideration – in addition to the number of people in the world –  when determining future food security and environmental sustainability.

Using data from various studies, researchers determined the world’s adult population weighs 287 million metric tons, or 287 billion kilograms.

Separately, we each weigh an average of 62 kilograms, but that average varies from country to country.

Researchers estimate 15 million of that 287 metric tons is due to those who are overweight, while 3.5 million metric tons are due to obesity.

North Americans have the highest body mass of any continent, according to the study, with an average body mass of 80.7kg.

While North America has only about six percent of the world’s population, it contributes 34 percent of the world’s biomass.

Asians, on the other hand, whose average weight is 58 kilograms, make up around 61 percent of the world’s population, but they’re only responsible for roughly 13 percent of the world’s biomass.

Among nations,  the United States came in as the “heaviest” country, while Eritrea was the “lightest”.

The researchers also looked at how those who are overweight and obese impact the total weight and averages.

Keep in mind that there is a difference between being overweight and obese.

You’re considered to be overweight when you weigh more than the weight that is appropriate for your height and bone structure or have a Body Mass Index (BMI) of 25 or greater.

If you have BMI of 30 or more, medical experts consider you to be obese.

Experts say that up to half of all food that is eaten is burned up by various physical activities.  But as your weight rises, your energy requirements increase as well, because it takes more energy to move a heavy body.

Even when at rest, those who have a bigger body mass burn more energy.

So, the bigger you are, the more energy you’ll need; the more energy you need means you must eat more; the more food eaten by a growing world population could  then, in turn, impact affect food supplies and future food security.

Soybeans being harvested (Photo: Jake was here via Wikimedia Commons)

Soybeans being harvested (Photo: Jake was here via Wikimedia Commons)

The domino effect of a heavier populace can also affect environmental sustainability.  Because in order to feed, cool or warm and transport a heavier population, more natural resources, such as fossil-fuels, will be needed and consumed.

Sarah Walpole, a practicing medical doctor who co-authored the study,  worries people from developing nations, who tend to be thinner than those in developed countries, will be most at risk of food insecurity.

“If our global consumption for food or our demand for food are increasing, it going to be those poor populations that feel the impact most,” she says.

One of the areas researchers want to study next is the impact the global child population has on the world’s total human biomass.

Dr. Walpole joins us on this week’s radio edition of “Science World.”  Check out the right column for scheduled air-times or listen to the interview with Dr. Walpole below.

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NASA Launches Online Game for Would-be Rocket Scientists

(Photo: NASA, M.Masetti)

(Photo: NASA, M.Masetti)

If you think you have what it takes to build a satellite, NASA has just introduced an online game that might appeal to you.

With “Build It Yourself: Satellite!” the US space agency offers users the chance to act as engineers and astronomers who conceive and build their own special virtual satellite.

“It’s fun to play,” says Maggie Masetti, a NASA webmaster who created the game. “And users will learn something about satellite instrumentation and optics and how they are used to make scientific discoveries, as well about a large range of different existing astronomical missions.”

The game lets players choose what kind of science their satellite will study. They can then customize the sophisticated technical aspects of their satellite – such as what wavelengths their creation will operate at and what kind of tools, instruments and optics will give them the best opportunity to learn as much as possible about their chosen science.

Artist conception of James Webb Space Telescope (Image: NASA)

Artist conception of James Webb Space Telescope (Image: NASA)

A number of astronomical missions, some dating back to 1980s, are available to game players.  You can go from rather small x-ray telescopes, like NASA’s Rossi X-ray Timing Explorer, to the much larger and popular  Hubble Space Telescope.

The game is available in two sizes so players can choose the one better suited to their monitor.  If you’re stuck with a slower computer, the game offers a special toggle button that will reduce the quality of the graphics but will make the game run faster.

The new gaming experience was inspired by the James Webb space telescope, which is being built now and is scheduled for launch in 2018.

Said to have the latest cutting-edge technology, the Webb space telescope will help scientists expose the secrets of the universe by taking them far back in time, toward the Big Bang.  Webb will be the most powerful telescope ever built by the space agency.

Who knows, maybe after playing “Build It Yourself: Satellite!” you’ll realize you have the talent and ability to become a real-life rocket scientist!

Time-lapse of the construction of the giant structural steel frame that will be used to assemble the mirrors and instruments of the James Webb Space Telescope.

Stonehenge Mystery Solved?

Stonehenge (Photo: Rupert Jones via Flicker/Creative Commons)

Stonehenge (Photo: Rupert Jones via Flicker/Creative Commons)

As crowds converged on Stonehenge last week for the summer solstice, a new study based on 10 years of archaeological investigations revealed the ancient monument was built to unify all of the people of Britain.

For years, experts have tried to uncover the many mysteries of Stonehenge, one of the world’s most famous prehistoric sites, which was built about 4,500-to- 5,000 years ago in South Central England.

Stonehenge has long been thought to be a prehistoric observatory, a sun temple, a place of healing and a temple of the ancient druids.  But a team of archeologists, working on the Stonehenge Riverside Project, rejected all those possibilities.

Summer Soltice Sunrise at Stonehenge (Photo: AP Photo/Lefteris Pitarakis)

Summer solstice sunrise at Stonehenge (Photo: AP Photo/Lefteris Pitarakis)

According to the research team, the Neolithic and Bronze Age structure was built after years of struggle and conflict between the people of eastern and western Britain.

The stones symbolize the ancestors of different farming communities in Great Britain, according to the researchers.

The building of Stonehenge also corresponded with a shift of identity for the British.

“When Stonehenge was built, there was a growing island-wide culture – the same styles of houses, pottery and other material forms were used from Orkney to the south coast,” said Mike Parker Pearson,  a member of the Stonehenge Riverside Project.  “This was very different to the regionalism of previous centuries. Just the work itself, requiring everyone literally to pull together, would have been an act of unification.”

The construction of Stonehenge required thousands of laborers to move the monolithic stones from as far away as west Wales.  Many more people were needed to shape and erect the stones after such a long journey.

Crowd gathers for 2012 Summer Solstice at Stonehenge (AP Photo/Lefteris Pitarakis)

Crowd gathers for 2012 Summer Solstice at Stonehenge (AP Photo/Lefteris Pitarakis)

Archeologists believe Stonehenge was built in stages from about 3000 BC to 2000 BC.

The location for Stonehenge wasn’t a random choice,  according to researchers.  The spot had a long-held, special significance to the prehistoric people of Britain.

The research team found that Stonehenge’s collection of stones, which are aligned with the solstices, actually sits on a series of natural landforms that form an axis between the directions of midsummer sunrise and midwinter sunset.

“When we stumbled across this extraordinary natural arrangement of the sun’s path being marked in the land,” says Parker Pearson, “we realized that prehistoric people selected this place to build Stonehenge because of its pre-ordained significance. This might explain why there are eight monuments in the Stonehenge area with solstitial alignments, a number unmatched anywhere else. Perhaps they saw this place as the center of the world”.

NASA Makes Surprise Discovery in Arctic Ocean

One of the most common kinds of phytoplankton, as seen through a microscope. These tiny oceanic plants were in a sample of water collected about 5 feet below the ice during the 2011 ICESCAPE campaign. (Photo: William M. Balch/Bigelow Laboratory for Ocean Sciences)

One of the most common kinds of phytoplankton, as seen through a microscope. These tiny oceanic plants were in a sample of Arctic water collected about five feet below the ice during the 2011 ICESCAPE campaign. (Photo: William M. Balch/Bigelow Laboratory for Ocean Sciences)

NASA has discovered phytoplankton are much more abundant in Arctic waters than any other ocean region on Earth, which could have a huge impact on our understanding of the region’s ecology.

Space agency officials say the revelation is as dramatic and unexpected as finding a rainforest in the middle of a desert.

The microscopic, one-celled aquatic plants are known as essential primary-producers, which form the base of the food chain for sea life.

NASA’s  ICESCAPE expedition made the discovery after punching through nearly 31 centimeters of thick ice.

Scientists found concentrations of the microorganism that were  “almost two orders of magnitude greater than any other concentration of phytoplankton ever found on the Earth,” according to Dr. Paula Bontempi, NASA’s Ocean Biology and Biogeochemistry program manager.

Like other forms of plant life, phytoplankton need water, nutrients and sunlight to grow and flourish.

NASA researchers think these unexpected concentrations of phytoplankton could be due to Arctic ice melting at a very fast rate.

The thinning of the ice, according to Bontempi, causes melt ponds – pools of open water in what is normally solid ice – to form, which allows sunlight to shine through the water.

Since sunlight levels are usually low in the Arctic waters, it may be like “having this blast of sunlight where you didn’t have it before and then all of a sudden the plants just take off,” Bontempi says.

This expedition marks the first time the phenomenon has been observed,  so Bontempi and her colleagues don’t know if it’s something that’s been happening every year, or if it is just starting to occur.

If this large phytoplankton bloom in the Arctic is a totally new phenomenon, Bontempi says she and her colleagues will have to figure out what it all means.

The shallow but extensive ponds that form on sea ice when its snow cover melts in the summer act as windows, letting light penetrate the ice cap. (Photo: Don Perovich/U.S. Army Cold Regions and Engineering Laboratory)

The shallow but extensive melt ponds that form on sea ice when snow cover melts in the summer act as windows, letting light penetrate the ice cap. (Photo: Don Perovich/U.S. Army Cold Regions and Engineering Laboratory)

“This could have huge impacts for our understanding of Arctic ecology and, for that matter, carbon cycling [allows carbon to be recycled and reused] because, as you know, phytoplankton or plants take up carbon dioxide and give off oxygen. So, it’s quite possible that the Arctic carbon cycle models will be impacted as well.”

The large blooms of phytoplankton in the Arctic Ocean could also have huge impacts on other forms of life higher up in the food chain, such as fish and polar bears, which feed and depend on the phytoplankton to find their food.

According to Bontempi, it will probably take a few years to do a full analysis of  the data gathered over two seasons by the ICESCAPE expedition.

Dr. Paula Bontempi joins us on this week’s radio edition of “Science World,” to talk about where scientists go from here after the discovery of  these huge blooms of phytoplankton in the Arctic.  Check out the right column for scheduled air-times or listen to the interview with Dr. Bontempi below.

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Insects Use Plants as Telephones to Communicate, Leave ‘Voicemail’

Like humans, insects communicate with each other by “telephone” and can even leave messages, according to Dutch researchers.

No special electronics are needed because the bugs literally use green technology – plants – to communicate.

According to the new study from the Netherlands Institute of Ecology and Wageningen University, insects which live in and above the ground use a plant as a telephone by eating its roots. That changes the chemical composition of its leaves, which in turn causes the plant to release alarm signals into the air.

These signals tell other insects not to eat that plant and move along, in order to avoid any competition between insects. The signals also warn others of possibly-dangerous chemical compounds in the plant.

If a bug isn’t around to immediately receive the message, the study shows another insect can leave a ‘voicemail’ message in the soil itself, through various soil fungi, by leaving specific remains in the soil after eating from the plant.

In the greenhouse of the Netherlands Institute of Ecology plants and plant-feeding insects are put together to assess their ability to store 'voicemail messages' in the soil. (Photo: Olga Kostenko/NIOO-KNAW)

In the Netherlands Institute of Ecology greenhouse, plants and plant-feeding insects are put together to assess their ability to store ‘voicemail messages’ in the soil. (Photo: Olga Kostenko/NIOO-KNAW)

Unlike our own ‘voicemail’ messages which disappear at a push of a button, these warning messages live on to serve future generations of insects.  Any new plants that happen to grow on the same spot, according to the research, can grab these same signals from the soil and again communicate the message to other insects.

The messages left in the soil can be rather specific . The new plant could warn bugs that its predecessor suffered from conditions that could be harmful to insects.

In their experiments, the researchers grew ragwort plants in a greenhouse and then left the plants open to threatening insects, such as leaf-eating caterpillars or root-feeding beetle larvae.  They later replaced those plants by growing new ones in the same soil and again the plants were left open to the hungry insects.

“What we discovered is that the composition of fungi in the soil changed greatly and depended on whether the insect had been feeding on roots or leaves,” explains researcher and study author, Olga Kostenko. “These changes in fungal community, in turn, affected the growth and chemistry of the next batch of plants and therefore the insects on those plants.”

The researchers are working to find an answer to how long the warning messages remain in the soil and just how widespread this occurrence is throughout nature.

Scientists Move Closer to Predicting Volcanic Eruptions

Map showing some of the new lava flows erupted at Axial Seamount in 2011. Dark blue areas are where there is no depth change, light blue indicates a lava thickness of 3-5 meters, and orange areas show where the lava thickness is as much as 15 meters. (Image: Dave Caress, Monterey Bay Aquarium Research Institute, Copyright 2011 MBARI)

Map showing some of the new lava flows erupted at Axial Seamount in 2011. Dark blue areas are where there is no depth change, light blue indicates a lava thickness of 3-5 meters, and orange areas show where the lava thickness is as much as 15 meters. (Image: Dave Caress, Monterey Bay Aquarium Research Institute, Copyright 2011 MBARI)

Oregon scientists who correctly predicted the 2011 eruption of the Axial Seamount underwater volcano years before it occurred, now say another underwater volcano off the Oregon coast gave off signals just hours before it erupted.

Underwater hydrophones showed a sudden increase in seismic energy about 2.6 hours before the eruption started about 400 kilometers off the Oregon coast, according to the scientific team. The development signals that it might eventually be possible to forecast eruptions of undersea volcanoes.

The scientists noticed a cyclic pattern of ground deformation measurements – which measures the changes in ground shape which can occur before, during and after an eruption – that suggests the Axial Seamount could also erupt again, perhaps as soon as 2018.

For four years before the 2011 eruption, marine geologist Bob Dziak and other team members noted that, while there was a gradual build up in the number of small earthquakes, there was only a small increase in the overall seismic energy produced from those earthquakes.  But, just a few hours before Axial erupted on April 6, 2011, that began to change.

“The hydrophones picked up the signal of literally thousands of small earthquakes within a few minutes, which we traced to magma rising from within the volcano and breaking through the crust,” Dziak said. “As the magma ascends, it forces its way through cracks and creates a burst of earthquake activity that intensifies as it gets closer to the surface.

Using seismic analysis, the team was able see just how the magma rose within the volcano about two hours before the eruption.

The chain is all that is visible of an ocean-bottom hydrophone buried in about six feet of new lava from an April 2011 eruption of Axial Seamount. (photo courtesy of Bill Chadwick and Bob Dziak of Oregon State University; copyright Woods Hole Oceanographic Institution)

The chain is all that is visible of an ocean-bottom hydrophone buried in about six feet of new lava from an April 2011 eruption of Axial Seamount. (photo courtesy of Bill Chadwick and Bob Dziak of Oregon State University; copyright Woods Hole Oceanographic Institution)

“Whether the seismic energy signal preceding the eruption is unique to Axial or may be replicated at other volcanoes isn’t yet clear,” said Dziak, “but it gives scientists an excellent base from which to begin.”

To make their findings, the Oregon team had some other unique tools at their disposal, including a one-of-a-kind robotic submersible used to bounce sound waves off the seafloor, allowing scientists to map the topography of the Axial Seamount before and after the eruption.  Having a before-and-after map allowed geologists to clearly distinguish the lava flows from the 2011 eruption from the flows of previous eruptions in the area.

Over the next few years, the researchers will install a number of new underwater instruments and cables around Axial Seamount, which they say will help scientists monitor the ocean and seafloor off  the Pacific Northwest.

European Scientists Hope to Send Humans Back to the Moon

December 1972 - Apollo 17 Astronaut Eugene "Gene" Cernan was the last human being to set foot on the Moon (Photo: NASA)

December 1972 - Apollo 17 Astronaut Eugene 'Gene' Cernan was the last human on the Moon (Photo: NASA)

A team of European scientists wants to send people back to the moon, ending the 40-year break from human lunar exploration.

The group not only wants to see a resumption of lunar exploration, but it recommends those efforts be dramatically stepped-up.

In a report to be published in “Planetary and Space Science,” the authors argue sending humans back to the moon, placing new scientific instruments on, and returning additional samples from the surface of the moon, will help us better understand the history of the Solar System, the origin and evolution of the Earth-Moon system, the geological evolution of rocky planets, and the near-Earth cosmic environment throughout Solar System.

The last time a human walked on the moon was during the Apollo 17 mission in December 1972.

The USSR's Luna 24 unmanned lunar explorer was the last to go and return from the moon in August 1976 (Image: NASA)

The USSR's Luna 24 unmanned lunar explorer was the last to go and return from the moon in August 1976 (Image: NASA)

The scientists believe a renewed emphasis on exploration of the moon would also provide a number of research opportunities in astronomy, astrobiology, fundamental physics, life sciences, human physiology and medicine.

Over the past decade, there’s been something of a renaissance in lunar exploration. A number of unmanned spacecraft – from the European Space Agency (ESA), Japan, China, India and the U.S. – have orbited the moon, but none have performed a controlled landing on its surface.  The last spacecraft to touch down on the moon and return to Earth was Russia’s Luna 24 robotic mission in August 1976.

However, a portion of the US Lunar Crater Observation and Sensing Satellite (LCROSS) and India’s Chandrayaan-1 Moon Impact Probe (MIP) were deliberately crashed into the moon’s surface in order to perform experiments required by their missions.

Although some of their objectives can still be achieved robotically,  the European science team says lunar exploration would benefit significantly from renewed human operations on the moon.

Artist Concept of the unmanned Lunar Reconnaissance Orbiter currently orbiting and mapping the moon at 50 kilometers from lunar surface. (Image: NASA)

Artist Concept of the unmanned Lunar Reconnaissance Orbiter currently orbiting and mapping the moon at 50 kilometers from lunar surface. (Image: NASA)

They recommend current and future non-manned lunar exploration missions be developed in the context of future human exploration, similar to what’s outlined in 2007’s Global Exploration road map which recommends an expansion of human presence throughout the Solar System and human exploration missions to the surface of Mars.

Following the framework of a 1992 study by the European Space Agency, the paper’s authors propose their lunar science objectives can logically be divided into three categories:

  • Science of the moon (study of the moon itself)
  • Science on the moon (studies that use the moon’s surface as a platform for experiments, not related to the moon itself.
  • Science from the moon (using the lunar surface as a base to conduct astronomical observations).

New Web-based Program Helps Doctors Save Lives

Patient getting emergency room treatment for cardiac emergency (Photo: US Navy via Wikimedia Commons)

Patient getting emergency room treatment for cardiac emergency (Photo: US Navy via Wikimedia Commons)

Heart failure is one of the most common causes of hospitalization and is among the most expensive chronic diseases to treat.  When a patient comes in to the emergency room complaining about having difficulty breathing, shortness of breath, fatigue, or chest tightness, the health care professionals must decide then and there if the patient is at a high or low short-term risk of dying within the next seven days.

Admission to the hospital is often required for patients who were determined to have a high or intermediate-risk.  But, for those who were considered to be low-risk patients, the doctors may just send them home after receiving some medical care at the emergency room.

If a bedside clinical assessment of a heart failure patient isn’t clearly apparent, this could lead to an uncertain prognosis which may cause the doctor to either overestimate or underestimate the risk of death.  This results in some very low-risk patients being hospitalized when they could have been sent home or, conversely, with very high-risk patients who were thought to be safe for discharge being sent home where they soon die.

(Photo: KOMU Photos/Eric Staszczak via Flickr/Creative Commons)

(Photo: KOMU Photos/Eric Staszczak via Flickr/Creative Commons)

Determining whether a heart failure patient is high or low risk is often very challenging, even for the best physicians.  But now, a new web based computer algorithm developed in Canada may help doctors make better decisions on whether the patient stays or is sent back home.

“Doctors estimate the risk of heart failure patients in the emergency department based on best clinical judgment which may include different factors depending on their prior experience,” says Dr. Douglas Lee, a cardiologist at Toronto’s Peter Munk Cardiac Centre, scientist at the Institute for Clinical Evaluative Sciences and Associate Professor of Medicine at the University of Toronto.

Dr. Lee led a team of doctors and scientists to develop the “Emergency Heart Failure Mortality Risk Grade” or EHMRG.  It’s a risk model or algorithm that uses 10 simple predictors such as blood pressure, heart rate, and levels of troponin (an enzyme that’s normally only found in the heart) all of which can indicate potential heart trouble.

Dr. Douglas Lee led team to develop "Emergency Heart Failure Mortality Risk Grade" or EHMRG. (Photo: Peter Munk Cardiac Centre)

Dr. Douglas Lee led team to develop 'Emergency Heart Failure Mortality Risk Grade' or EHMRG. (Photo: Peter Munk Cardiac Centre)

After entering all of the required medical information into the program, available on the web, the program performs calculations and produces an individual probability report on whether that patient could die within the week.

Along with the web-based application Dr. Lee and his team is also developing a version of this program for the smartphone.  Dr. Lee’s goal with this system is to collect data from individual physicians and hospitals that would be used to make comparative studies that would improve the quality of care and also help doctors and hospitals become more cost efficient.

Dr. Lee invites any physician who may be reading this to try their new system. It’s available on the web. The address is ccort.ca.

On this week’s radio edition of “Science World” Dr. Lee joins us to talk about this new system and the countless number of lives it could save every year.  Check out the right column for scheduled air-times or listen to the interview with Dr. Lee below.

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See Jupiter’s Newly-discovered Tiny Moon in Motion

S/2010 J 1 in motion Sept. 8, 2010. Animation is sped up by a factor of 2000. The actual time between each image in the animation is roughly 38 minutes. (Photo:Canada-France-Hawaii Telescope)

S/2010 J 1 in motion Sept. 8, 2010. Animation is sped up by a factor of 2000. The actual time between each image in the animation is roughly 38 minutes. (Photo:Canada-France-Hawaii Telescope)

Astronomers have found that one of two recently-discovered moons of Jupiter is just two kilometers in diameter and may be the smallest of Jupiter’s 67 satellites.

Back in September 2010, scientists discovered two unknown distant satellites of Jupiter while conducting routine tracking observations of the planet’s previously identified moons.

To confirm that these were indeed new satellites of Jupiter, and not asteroids, the scientists re-observed them several more times during the autumn of 2010.

The International Astronomical Union’s Minor Planet Center designated the two new moons as S/2010 J 1 and S/2010 J 2.

S/2010 J 1 was discovered in September 2010 from images taken with the Palomar Observatory’s 200-inch Hale Telescope.  At its furthest, this moon is about 30,774,922 kilometers from Jupiter.

The second moon, S/2010 J 2, about 26,541,445 kilometers from the giant planet, was discovered the same month on images taken with the MegaCam mosaic CCD camera by the 3.6m Canada-France-Hawaii telescope (CFHT).  After checking observational data, astronomers also later found that the satellite was weakly visible, on Sept 7, 2010, at the Palomar Observatory.

It’s interesting to note that the moon that would come to be called S/2010 J 1, was first detected back in 2003, but was never classified as a satellite because it couldn’t be found in required follow-up observations.

The astronomers say the size of the two moons can be estimated on factors that are based on their brightness.  S/2010 J 1 is estimated to be around three kilometers in diameter. S/2010 J 1, the faintest and probably smallest Jovian moon, has been estimated to be about two kilometers in diameter.

Red diamonds show the 2010-11 observed locations of S/2010 J 1, while blue triangles show the locations of S/2010 J 2. The predicted positions of the satellites for the best fit orbits from JPL are plotted at 48-hour intervals, shown by the red and blue dots for S/2010 J 1 and S/2010 J 2, respectively (Courtesy: Mike Alexandersen)

Red diamonds show the 2010-11 observed locations of S/2010 J 1, while blue triangles show the locations of S/2010 J 2. The predicted positions of the satellites for the best fit orbits from JPL are plotted at 48-hour intervals, shown by the red and blue dots for S/2010 J 1 and S/2010 J 2, respectively (Courtesy: Mike Alexandersen)

S/2010 J 1 and S/2010 J 2 are designated as irregular satellites, or provisional moons, and are not given actual names by the International Astronomy Union (IAU) because their discoveries have not been confirmed.

Moons such as the S/2010 J 1 and S/2010 J 2 have been found to be clustered in families of other satellites with similar colors and orbits. Scientists believe these families may have formed as a result of ancient collisions with comets or asteroids with former larger moons.

S/2010 J 1 appears to belong to the Carme group, or family, while S/2010 J 2 appears to belong to the Ananke group.

Birds Ended Reign of Super-sized Insects

The ancient giant griffinfly Meganeura monyi had a wingspan of up to 75 centimeters (Artwork: Dodoni)

The ancient giant griffinfly Meganeura monyi had a wingspan of up to 75 centimeters (Artwork: Dodoni)

Some 300 million years  super-sized insects – some as large as  hawks – swarmed the Earth.  The largest of these mega-insects was a predatory dragonfly-like creature with a wingspan of up to 75 centimeters.

That was during the late Carboniferous– early Permian periods, when the atmosphere was rich with oxygen. But then, 150 million years ago, birds showed up and the downsizing of insects began.

Scientists at the University of California, Santa Cruz believe high concentrations of oxygen in the atmosphere – over 30 percent of the air was 02 versus the 21 percent we have in today’s atmosphere – were responsible for the insects’ large size.

Insects have small breathing tubes instead of lungs, so the higher oxygen levels allowed them to take in and use more of the life-sustaining gas which encouraged their super sizes.

This fossil insect wing (Stephanotypus schneideri) from about 300 million years ago measures 19.5 centimeters. For comparison, the inset (left) shows the wing of the largest dragonfly of the past 65 million years. (Photo: Wolfgang Zessin)

This fossil insect wing (Stephanotypus schneideri) from about 300 million years ago measures 19.5 centimeters. For comparison, the inset (left) shows the wing of the largest dragonfly of the past 65 million years. (Photo: Wolfgang Zessin)

To reach their findings, the scientists examined data from more than 10,500 fossil wing lengths taken from various published records.  They checked the size of the insects versus oxygen levels as they evolved over a period of hundreds of millions of years.

“Maximum insect size does track oxygen surprisingly well as it goes up and down for about 200 million years,” said Matthew Clapham, an assistant professor at UC Santa Cruz, who c0-authored a study published online in Proceedings of the Academy of Science. “Then right around the end of the Jurassic and beginning of the Cretaceous period, about 150 million years ago, all of a sudden oxygen goes up but insect size goes down. And this coincides really strikingly with the evolution of birds.”

With all over those hungry birds around, insects needed to become more maneuverable.  Survival was a driving force in the evolution of flying insects.  As result, the insects became smaller, which allowed them to survive and thrive, while their giant relatives died off.

Another transition in insect size took place more recently, at the end of the Cretaceous period some 90 and 65 million years ago, according to  Clapman and Jered Karr, a UCSC graduate student who co-authored the study.  They think several factors, such as the continued specialization of birds, along with the evolution of bats, and a mass extinction at the end of the Cretaceous period, may be behind this evolutionary transition.  A shortage of fossils from that period has made it difficult for scientists to track insect sizes.

Drawing of the Ichthyornis dispar, a bird from the Late Cretaceous of North America (Artwork: ArthurWeasley via Wikimedia Commons)

Drawing of the Ichthyornis dispar, a bird from the Late Cretaceous of North America (Artwork: ArthurWeasley via Wikimedia Commons)

“I suspect it’s from the continuing specialization of birds,” Clapham said. “The early birds were not very good at flying. But by the end of the Cretaceous, birds did look quite a lot like modern birds.”

Clapham emphasizes their study wasn’t about determining average insect size during this time period, because the fossil records tended to favor the larger sized insects over the smaller ones, but instead concentrated on changes in the maximum size of insects over time.

“There have always been small insects,” he said. “Even in the Permian when you had these giant insects, there were lots with wings a couple of millimeters long. It’s always a combination of ecological and environmental factors that determines body size, and there are plenty of ecological reasons why insects are small,” said Clapman.