Bees are important pollinators for a number of crops. (Photo credit: B.A.E. Inc./Alamy)

The Importance of Bees

Bees do much more than produce honey. In fact, bees are an essential part of the pollination process for more than 100 food crops. These insects are particularly important pollinators for nut, fruit, and vegetable crops. The California almond industry alone requires the importation of more than 50 percent of the entire honeybee population in the United States! Due to their important agricultural role, the loss of bees could potentially decimate crop production and the agricultural industry that depends upon them. According to the United States Department of Agriculture (USDA), bees add more than $15 billion in value to a variety of crops they pollinate.

Though the colony loss in late 2006 was astonishing, bee colonies have actually been on the decline since the 1980s. Scientists point to the introduction of new pathogens and pests as explanations for the decline in bee colony health. When a high number of bee colonies are imported to pollinate a crop such as almonds in California, it is quite easy for pathogens and other ailments to pass from one colony to another. Stresses from moving a colony from one place to another has also been implicated in increased colony losses since the 1980s as well.

Colony Collapse Disorder

“Colony Collapse Disorder,” or CCD, is the name scientists have given to the current situation faced by bee colonies. When the initial collapse became apparent in 2006, scientists weren’t quite sure what was behind the disorder. In fact, multiple hypotheses abounded. According to the Agriculture Research Service (ARS) Bee Research Laboratory in Beltsville, Maryland, there were four possible explanations. These causes included pathogens, parasites, environmental stresses such as pesticides, and management stresses, such as a lack of proper nutrition sources for the bees.

In 2007, ARS scientists began testing these various hypotheses. In their research (which is on-going), the scientists collected bees from both healthy colonies and CCD-affected colonies. They then screened the collected bees for the presence of both new and known pathogens. The scientists discovered that bees from the colonies affected by CCD had a higher rate of infection by Nosema ceranae, a fungal pathogen. However, this higher rate was not considered statistically significant—meaning that Nosema could not be implicated as the sole explanation for colony decline. Further analysis showed that the incidence of bees that had high fungal-pathogen loads combined with infection by several RNA viruses from the Dicistroviridae family was a clear indicator of imminent colony collapse.

Nosems ceranae infects bees through the fecal-oral route. When bees ingest the fungal pathogen, it embeds itself into the bee’s gut lining. Scientists hypothesize that a greater number of fungal pathogens in the bee’s gut lining compromises the bee’s health, and allows subsequent RNA virus infections to overwhelm the bee, thus killing it.

However, a new study from the Harvard School of Public Health indicates that the likely culprit in worldwide honeybee colony declines is actually imidacloprid, a popular pesticide. The results of the study, led by Chensheng Lu, an associate professor of environmental exposure biology at Harvard, will be published in the June issue of the journal Bulletin of Insectology.

Imidacloprid is a neonicotinoid, a class of insecticides that was developed in the 1980s and introduced into common use in the early 1990s. Imiadocloprid is one of the most widely-used insecticides and is utilized to combat soil, timber, seed, and animal pests. It is also used as a treatment against pests that attack cereal, cotton, grain, potato, rice, fruit, and vegetable crops. The impact of neonicotinoids on bee colonies has actually been known for quite a while. Several European countries have banned or limited the use of this class of insecticides—due to its observed effects on honeybees—soon after it was introduced in the 1990s.

According to the Harvard researchers, honeybees can be exposed to imidacloprid in two ways: either through nectar from plants that have been treated with imadocloprid or through the high-fructose corn syrup that beekeepers use to feed their honeybees. (Imadacloprid is found in corn syrup because most of the corn grown in the United States has been treated with this insecticide since 2005.)

“The significance of bees to agriculture cannot be underestimated,” Lu said in a press release about the new study. “And it apparently doesn’t take much of the pesticide to affect the bees. Our experiment included pesticide amounts below what is normally present in the environment.”

More to Explore

• Questions and Answers: Colony Collapse Disorder
• Use of Common Pesticide Linked to Bee Colony Collapse
• Microbial Team May Be Culprit in Colony Collapse Disorder

Ambergris is a valuable substance that originates in a sperm whale's digestive system. (Photo credit: Michael Freeman/Corbis)

“Who would think, then, that such fine ladies and gentlemen should regale themselves with an essence found in the inglorious bowels of a sick whale!” – Moby Dick

When a “strange and mysterious” object washed ashore on a public beach in Wellington, New Zealand, rumors began to spread that it was ambergris. Soon after, fortune hunters arrived and tore the mysterious substance apart with shovels, collecting pieces in plastic bags. At $10-$20 per gram, even a small portion could reap a large reward. However, not long after its discovery, it was found that the mysterious object was actually just a large block of lard.

Before this event, molecular biologist Christopher Kemp had never even heard of ambergris. But after seeing the frenzy that the faux-ambergris had incited, he became “obsessed with ambergris and the idea of stumbling over something on the beach that might be a worth thousands of dollars.” He recently documented this obsession in his book Floating Gold: A Natural (and Unnatural) History of Ambergris.

So, what exactly is ambergris, anyway? Ambergris is a solid, waxy substance that is produced by the digestive system of sperm whales. Scientists hypothesize that ambergris is used by the whale’s digestive system to ease the passage of sharp objects from the things they eat, such as squid beaks. Hardened pieces of ambergris often contain bits of squid beak and other sharp objects.

Though often referred to as “whale barf,” it is thought that ambergris actually exits the whale through the, uh, other end of the digestive tract. Although ambergris at first smells as one would expect something to smell after being ejected from the body, over time it acquires a sweet, earthy scent, which some liken to the smell of fresh mulch.

“Like lots of other strange natural substances, ambergris is valuable because of its rarity," Kemp explains. “It is only produced by sperm whales, and only by an estimated one percent of them. Once expelled by a whale, it must float for years. Then it must make landfall, avoid being broken into pieces by rough seas, and someone must find it. In other words, the odds of finding ambergris are extremely small. All these factors make it very valuable.”

Most perhaps identify ambergris with the perfume industry, where it is used as a fixative for other scents. Ambergris “fixes” the other scents in the perfume, allowing them to be more pronounced and last longer than they would otherwise. Other uses for ambergris include as an incense, as a food flavoring (purportedly as an aphrodisiac), and as a medication for headaches, colds, epilepsy, and other physical ailments. During the Middle Ages, some thought ambergris could protect people from contracting the Black Death if they held a piece of it beneath their nose.

Originally, ambergris was taken from whales as a part of the harvesting process. During the late 1700s to mid-1850s, the whaling industry especially targeted sperm whales as a source of spermaceti—an oily substance contained in its head and used to make smokeless candles—and ambergris. Estimates indicate that as many as 5,000 sperm whales were killed each year during that time period. As recent as the 1960s, 30,000 sperm whales were harvested in one season. In 1986, the International Whaling Commission instituted a moratorium on commercial whaling.

Because it is sourced from an endangered species, international regulatory agencies banned the use of ambergris in the 1970s. In 2005, it again became legal to use ambergris. However, it can only come from distributors that can ensure that the ambergris was collected only after it had washed ashore and wasn’t harvested by any other method. But today many fragrance companies have phased out the use of ambergris, and instead use synthetic versions to avoid any legal ambiguity. American fragrance companies are especially careful, as the sperm whale is listed as endangered by the U.S. Fish & Wildlife Service. The Endangered Species Act (ESA) of 1973 prohibits the sale or trade of parts or products from any endangered species.

“Whether or not perfumers still use ambergris is a bit of a mystery,” Kemp said. “It’s not something an established and successful perfumer like Chanel will discuss.”

Recently, researchers at the University of British Columbia discovered a potential alternative to ambergris. Joerg Bohlmann, a professor of Botany and Forest Sciences, worked with Philipp Zerbe, a postdoctoral research associate, to identify a gene in balsam fir trees that could be used by the fragrance industry to produce an inexpensive fixative and scent.

“The use of ambergris in the fragrance industry has been controversial,” Bohlmann said in a press release about the discovery. “First of all, it’s an animal byproduct and the use of such in cosmetics has been problematic, not to mention it comes from the sperm whale, an endangered species.”

“We’ve now discovered that a gene from the balsam fir is much more efficient at producing such natural compounds, which could make production of this bio-product less expensive and more sustainable,” Bohlmann said.

More to Explore

• How to Make High-End Perfumes without Whale Barf
• Floating Gold: The Romance of Ambergris
• Strange but True: Whale Waste Is Extremely Valuable
• Ambergris, Treasure of the Deep
• Floating Gold: A Natural (and Unnatural) History of Ambergris by Christopher Kemp
• Sperm Whale

Organic household wastes such as egg shells and non-meat food leftovers can be composted. (Credit: Andrew Walters/Alamy)

What is Composting?

Composting refers to the process of controlled decomposition of organic materials. In composting, organic material decomposes into a nutrient-rich material called humus. The resulting humus can be added to soils to improve its nutrient and moisture content.

Using a compost bins also keeps organic materials out of landfills, where they take up unnecessary space. In addition, when organic materials decompose in landfills, they produce methane gas and acidic leachate. If not dealt with correctly, the production of methane gas can lead to explosions and leachate can pollute the local water supply.

On a large scale, composting is used in landscaping to stifle pest and weed growth, prevent the need for chemical fertilizers, and promote crop yield. In addition, compost has been used to help remediate polluted soils by aiding in the removal of heavy metals, pesticides, and both chlorinated and nonchlorinated hydrocarbons. On a smaller scale, compost can be used as potting soil for houseplants and as a soil enhancer for home gardens.

Building An Indoor Compost Bin

To make a compost bin for indoor use, initially you will need a plastic storage bin with a iid, shredded newspaper, and red worms. You can purchase red worms from many garden centers or from online retailers. The rule of thumb is to use two pounds of worms for one every pound of waste you plan to compost.

Your storage bin will ideally be longer than it is deep. It is more important to have more surface area than depth. An ideal bin size is 2' x 3' x 1'. After procuring your container, poke holes in the lid and along the sides of the bin, about 1 to 2 inches from the top.

Next, gather some black-and-white newsprint and shed it into 2 inch-width pieces. Wet the paper in the sink and wring out the excess water. Place the moistened paper along the bottom of the container until the container is about half-full. Add your worms onto the newspaper layer and cover them with another two inches of moistened newspaper. Place the lid on top of your container.

Let your worms acclimate to their new home for about a week before adding scraps (see the lists below) to the bin. Before adding the scraps, chop them into small piece if necessary. Bury the scraps within the bedding layer; don't just pile the scraps on top. Don't overload the bin with too much food at one time as this can lead to spoilage. After about three months, move the compost over to one side and add food and newspaper to the other side. After about two weeks, all the worms should have moved over to the new bedding area. You can now remove the compost and use it in your gardening projects.

Building an Outdoor Compost Bin

Some composting bins are kept outside. (Credit: Cultura/Alamy)

If you have the space outside, you can make an outdoor compost bin. Bins suitable for composting can be bought at garden centers (such as the one shown here), or you can build one yourself. See the resources below for instructions on how to make your own outdoor compost bin. Place a layer of wood chips, saw dust, or straw in the bottom of the bin to absorb any excess moisture. Similar to your indoor compost bin, you can place food scraps into your outdoor bin. In addition, the larger-sized outdoor bin is an ideal location for yard clippings (such as cut grass or raked leaves). To help with oxygenation, use a shovel to turn over the contents in your compost bin every week or so.

What Can and Can't Be Composted

Not everything can be put into your compost bin. The following items can be composted:

• black-ink newsprint
• cardboard rolls
• coffee grounds and filters
• eggshells (washed clean of egg residue
• nut shells
• vegetable and fruit peels
• tea bags

These items should not be put in your compost bin:

• dairy products
• fats, grease, lard, or oils
• meat, fishbones, or scaps
• pet waste
• colored paper or newsprint with color ink

Troubleshooting Your Compost Bin

Your compost bin should not smell. There are several reasons why your compost may develop an odor. First, make sure that you are burying your food scraps underneath the bedding. If there is too much moisture in your bin, add more newspaper scraps to soak up the excess. Some food items are naturally stinky when they decompose—you may want to avoid composting broccoli and onion scraps, and never compost dairy, meat, fat, or oil products. If you notice that your compost is too moist, add more dry bedding (newspaper scraps). If fruit flies seem to be gathering around your bin, make sure that you are properly burying the food. Also, wash off vegetable or fruit peels before you add the scraps to your bin to remove any fruit fly eggs that may be present.

A Perfect Earth Day Activity

As you have learned, starting your own compost bin is a fairly easy process. Composting is a fun way to make use of much of the organic waste that you produce each day that would otherwise take up space in a landfill. Building your own compost bin is just one way that you can live a greener life. You may even want to consider making a compost bin to help celebrate Earth Day on April 22! Are you doing anything special to celebrate Earth Day? Leave a comment below about any special activities you or your classmates are doing in celebration of Earth Day.

More to Explore

• The Care and Keeping of Worms (PDF)
• Constructing a Garbage Can Compost Bin
• Worm Man Composting Worms
• Worm Composting
• US EPA: Composting
• Composting 101

Researchers led by Evgeny Katz, the Milton Kerker Chaired Professor of Colloid Science at Clarkson University, have implanted a biofuel cell in a living snail. (Photo courtesy of Clarkson University)

Imagine a world inhabited by tiny insects outfitted with cameras, microphones, or other sensors. Though it might sound like a scene straight out of a science fiction novel, researchers are edging ever closer to making this scenario a reality.

Recently, researchers at Clarkson University in Potsdam, New York successfully implanted a biofuel cell into a living snail. This biofuel cell extracts energy from glucose and oxygen found within the snail’s hemolymph (blood). Electrical energy is generated when electrodes are attached to an external circuit. The amount of electrical energy produced by the snail is limited to the size of the implanted electrode. On average, the snails produced about 7.45 microwatts of power, though after a period of 45 minutes, the snail’s ability to produce electrical energy dropped by 80 percent. The researchers found that in order to produce a continuous amount of power, the electrical energy must be extracted at a level of 0.16 microwatts. The snails are able to regenerate the glucose lost to energy production by normal processes such as eating and resting.

Research conducted by scientists at the University of Michigan is focusing on harnessing an insect’s own energy from either its body heat or movements. Recently, engineers developed a device that converts the kinetic energy from a June beetle’s wing movements into electrical energy. This electrical energy can be used to power small sensors implanted into the insect’s body.

The U.S. Department of Defense has funded similar cyborg insect (or “cybugs”) research endeavors for a number of years. The intention of this research is to develop insects that can be outfitted with cameras, microphones, and other sensors, which could be used to gather intelligence for military functions. Initial research attempted to control insects by attaching machinery onto their backs. However, this method proved to be impractical and unreliable. In 2006, the Hybrid Insects Micro Electromechanical Systems (HI-MEMS) program was instituted through the Defense Advanced Research Projects Agency (DARPA) to sponsor research that involves the implantation of microchips directly into insects. As the insects grow, the circuitry becomes embedded in their nerves and muscles. The thought is that researchers can use this embedded circuitry to control the insects movements. Since its inception, HI-MEMS has invested more than $12 million into this research. In addition to their use by the military, cyborg insects could also be potentially used in environmental applications as well. Cameras and gas sensors could be used to monitor or determine the severity of environmental hazards such as chemical spills.

More to Explore

• Clarkson University Scientists Implant Biofuel Cell in Living Snail
• Cyborg Snails Power Up
• Insect Cyborgs May Become First Responders, Search and Monitor Hazardous Environs
• Cyborg Search-and-Rescue Insects’ Power Source Unveiled
• Military Developing Robot-Insect Cyborgs
• Powerful Ideas: Military Develops 'Cybug' Spies
• Defense Advanced Research Projects Agency (DARPA)
• Hybrid Insect Micro Electromechanical Systems (HI-MEMS)

The appendix is a pinky-finger sized organ located just below the junction between the small and large intestines. Though its function has been debated over the years, scientists have known for a while that the appendix is formed from immune system tissue.

The appendix is a pinky-finger sized organ located just below the junction of the large and small intestines.

According to Dr. Bill Parker, the appendix serves as a natural reserve for beneficial bacteria in our guts. Parker, an associate professor of surgery at Duke University’s School of Medicine, has spent a portion of his career studying the role of immunity in the gut, and through this research formed his hypothesis about the function of the appendix.

Our guts are full of beneficial bacteria. These bacteria help us to digest the food we eat by helping to break down food particles into nutrients our bodies can absorb. They also help to prevent the growth of harmful bacteria. The relationship between these bacteria and our gut is not one-sided; in return for their role in helping to maintain overall gut health, the bacteria have a safe place to live and get the nutrients they need to survive.

Parker’s initial studies related to the function of the appendix were theoretical, given that it is difficult to study the appendix’s function in situ (and any such experiment would have serious ethical issues). In addition, though some other animals, such as great apes, rabbits, wombats, and opossums also have appendixes, their appendixes are significantly different from the human appendix, and would not make a valid substitution in an experiment.

However, a recent study appears to corroborate Parker’s hypothesis. A team of researchers, led by Dr. James Grendell, chief of the Gastroenterology, Hepatology and Nutrition division at Winthrop University Hospital, studied the histories of 254 patients known to have experienced gut infections caused by Clostridium difficile. This bacterium, commonly referred to as C. diff, is a particularly deadly pathogen that is known to infect hospital patients who have been put on extended courses of antibiotics. Such long courses of antibiotics are known to completely deplete all of the good bacteria from a patient’s gastrointestinal tract. As a result, C. diff can infect the patient’s gut, causing severe gastrointestinal distress.

According to Parker’s hypothesis, if the patient’s appendix is still intact, it should be able to replenish the gut’s population of good bacteria after a case of C. diff, preventing a recurrence. If a patient has had their appendix removed, they would likely be more susceptible to a recurrence of C. diff infection. Grendell and his colleagues found exactly these results—patients who lacked an appendix had nearly double the chance of a recurrence of a C. diff infection, while those patients who still had their appendix has less than a 20 percent chance of infection recurrence.

Parker thinks that the appendix evolved for a lifestyle that was much less sanitary than the one many of us experience today. In parts of the world where clean water is a luxury and cholera is still a problem, the appendix is likely a vital organ that helps to repopulate the gut with good bacteria after such an infection occurs. In fact, in the developing world, appendix removal is much less common than it is in developed countries.

Though far from conclusive, the results of Grendell’s study indicate that Parker’s hypothesis may be correct. Up until recently, appendixes were routinely removed during abdominal surgeries given their supposed uselessness as a measure to prevent complications or a possible future bout of appendicitis. However, given the appendix’s apparent role as a reservoir of good bacteria, such removals may soon be a thing of the past.

More to Explore

• Your Appendix Could Save Your Life
• Is the Mystery of the Appendix Close to Being Unraveled?
• The Appendix - Good For Something After All
• Vestigial Organs Not So Useless After All, Studies Find
• Appendix Isn't Useless At All: It's A Safe House For Good Bacteria
• Interactive Digestive System Guide
• Digestive Disorders: The Appendix

The deer mouse is just one type of mouse that is known to sing. (Photo credit: Thomas Kitchin and Victoria Hurst/Design Pics Inc./Alamy)

You are likely quite familiar with the sound of birds singing. You might have also heard the sounds of frogs singing a chorus around a pond or lake. But did you know that some mice sing too? What is the reason behind this unusual behavior?

Bret Pasch, a doctoral student at the University of Florida, is researching that question. He and his colleagues study a rodent called the Alston’s singing mouse (Scotinomys teguina). This insectivorous mouse is native to montane cloud forests that are found throughout Central America.

Pasch’s research indicates that males are primarily the singers in this mouse species. Not unlike birds and frogs, he thinks that these mice sing in order to attract mates and repel potential rivals. Hormones play an important role in a male’s ability to sing. In one experiment, a set of males were neutered. One group received synthetic hormones, while the control group did not. The males that did not receive the hormones were found to be poor singers—their songs had slower trill rates and were limited to a small range of frequencies.

A second experiment tested females’ interest in different songs. When female Alston’s singing mice were presented with two songs, one of which was played at normal speed, and one of which was enhanced to play at a higher speed, and thus a faster trill, the females overwhelmingly preferred the enhanced song. Researchers believe that a more complex song indicates to the female that the male is a better-quality mate. According to Pasch, males that are better singers have better control over their nervous, neuromuscular, and cardiac systems, which would serve as an excellent indication of their overall good health.

The results of Pasch’s research were published in the June 2011 edition of the journal Animal Behaviour. Other scientists who contributed to the research included Andreas S. George, Polly Campbell, and Steven M. Phelps.

More to Explore

• Androgen-Dependent Male Vocal Performance Influences Female Preference in Neotropical Singing Mice [pdf]
• Squeaking Up A Storm: Yes, That Mouse Is Singing
• The Mystery of the Singing Mice
• Deer Mouse Singing [audio/video]
• Male Alston's singing mouse (S. teguina) [video]
• Female Alston's singing mouse (S. teguina) listening to male song [video]
• UF Study: When Singing Mice Choose A Mate, A Skillful Song Gets the Gal

A jumping spider uses its principal forward-facing eyes to perceive depth. (Credit: Kam Yee Fong / Alamy)

Blurry vision in humans often results in a prescription for glasses, contacts, or even surgery to restore a person's vision to 20/20. For jumping spiders, however, blurry vision is an asset. Research by a team of scientists at Osaka City University in Japan indicates that the key to a jumping spider’s leaping prowess is its unusual method of depth perception. The research, led by Akihisa Terakita, Mitsumasa Koyangi, and Takashi Nagata, utilized a variety of techniques to study the connection between jumping spiders’ vision and leaping acuity, including molecular biology and electrophysiology.

Humans and some other animals use binocular stereoscopic vision to perceive depth. Other species utilize far less sophisticated methods to perceive changes in depth. For example, most insects use motion parallax, or the movement of their heads in a side-to-side motion, to determine changes in depth. Blurry vision, or image defocus, does have a place in depth perception, however. Research has shown that humans use image defocus as a way to roughly estimate the relative depth of objects. Interestingly, jumping spiders use image defocus as an absolute measure of depth.

Jumping spiders use their two pairs of larger forward-facing eyes and smaller anterior lateral eyes to approach and successfully pounce on potential prey. By covering up the spiders’ anterior lateral eyes, the researchers found that the spiders’ principal forward-facing eyes were most important for depth perception. Through their studies, the scientists discovered that a jumping spider’s retina is made up of four layers. The first two layers are most sensitive to green light, while the second and third layers are most sensitive to ultraviolet (UV) light. Green light that enters the retina is only clearly focused on the first layer. The second layer only receives a blurry, defocused image. The amount of defocus is proportional to the distance of the object to the lens. In other words, the larger the amount of defocus, the farther away the object is. Conversely, the smaller the amount of defocus, the closer the object is to the spider. This use of defocus to perceive depth makes a jumping spider’s vision unlike any other animal.

The researchers tested their hypothesis by observing the spiders’ ability to jump under a variety of different lighting conditions. When exposed to red light, the spiders jumped short of their prey. This is because the retinal images were less-fuzzy under red light, which made the spiders think their prey was closer than it really was. However, under green light, the spiders nearly always successfully pounced on their prey.

According to the researchers, the spiders’ principal eyes are a “real-life example of ‘depth from defocus,’ a notable depth measurement technique that is being developed for computer vision.” The scientists think that gaining an understanding of how jumping spiders see may inform the development of this form of vision in computers and also have implications for the development of related technologies as well.

Results from the scientists' research were published in the January 27, 2012 issue of the journal Science. Scientists who contributed to this research included Takashi Nagata, Mitsumasa Koyanagi, Hisao Tsukamoto, Shinjiro Saeki, Kunio Isono, Yoshinori Shichida, Fumio Tokunaga, Michiyo Kinoshita, Kentaro Arikawa, and Akihisa Terakita.

More to Explore

• Depth Perception from Image Defocus in a Jumping Spider [abstract]
• Jumping Spiders Focus Like a Camera to Hunt
• How a Blurry-Eyed Spider Pounces on Target
• Spiders Hunt with 3-D Vision
• Jumping Spiders Use Blurry Vision to Pounce
• Jumping Spiders Use Blurry Vision to Catch Quick Prey with Precision [video]

There are more than 640 species of cone snails. The shells of these snails range in size from just a few centimeters to more than 20 centimeters in length. Most cone snails live in the tropical waters of coral reefs, primarily in the western Indo-Pacific region. Some cone snails are also found in temperate waters around South Africa and in cooler waters near southern California.

The geographic cone snail shown here is the most venomous of the 500 known species of cone snails. (Photo credit: Jeff Rotman / Alamy)

These stealthy snails bury themselves beneath the sand and lie in wait for their prey. They use their siphon, a tube-like organ, to sense chemicals emitted by other aquatic animals, and their eye stalks to detect changes in light. When a suitable species happens by, the cone snail loads a hollow tooth-like “harpoon” into its proboscis. It fills the harpoon with venom and shoots it into its prey. The venom contains a mixture of chemicals that acts as a neurotoxin. The toxin quickly affects the victim’s nervous system, paralyzing it and ultimately leading to its death. Soon after, the snail uses its proboscis to engulf its victim, and suck it into its shell where it is digested. Each harpoon is used only once, as the snail produces additional ones in an internal tooth sac.

Each cone snail species has on average 100 different toxins. This means that there are more than 50,000 different toxins expressed across the more than 600 species of cone snails. Scientists are interested in learning how each toxin affects the victim of a cone snail sting. Results from experiments with cone snail toxins, or conotoxins, are helping scientists understand how cells, particularly those cells found in the nervous system, interact and communicate. This information is highly valuable to those in the biomedical research field, as these toxins could prove to be important for the development of medicines and treatments for human ailments. Conotoxin research has already led to the development of a pain medication for those suffering from cancer. This new pain treatment offers the same pain relief as morphine but lacks the addictive side effects of many traditional painkillers. Biomedical researchers also think conotoxins may have a role to play in the development of treatments for epilepsy, Alzheimer’s, and Parkinson’s.

However, like many species that inhabit tropical reefs, cone snails are vulnerable to habitat loss and human actions. These snails, though dangerous to handle, are attractive to shell collectors and the shells of rare species can fetch up to $5,000. Some scientists worry that the snails’ importance to biomedical research may also harm populations living in the wild. Some biomedical researchers are using new techniques that allow them to “milk” captive snails for their venom, rather than dissecting the venom sacs from dead snails. In addition, scientists are currently studying cone snail populations around the world to determine which species are vulnerable or are already under threat of extinction. Scientists hope that putting proactive conservation measures into place now will help protect populations in the wild and prevent cases of overharvesting for either recreational or scientific pursuits.

More to Explore

• The Cone Snail
• The Geographic Cone Snail (Conus geographus)
• How A Venomous Cone Snail Catches and Kills Fish
• Venomous Snails: One Slip, and You're Dead...
• Toxic Snail Venoms Yielding New Painkillers, Drugs
• The Venom Cure
• Killer Cone Snails [video]

Before we delve too far into the topic, let’s discuss some terminology. An introduced species, also called an alien or non-native species, is any organism that was brought to an ecosystem as the result of human actions. In some cases, the introduced species may die out or is able to coexist with native species. In other cases, the introduced species may pose a threat to the stability of an ecosystem by preying on or outcompeting native species for resources. Additionally, introduced species may cause economic damage, particularly in terms of lost revenue resulting from the damage to agricultural crops. When an introduced species causes ecosystem instability or economic harm, it is referred to as an invasive species.

Though the introduction of non-native species to some ecosystems was not intentional, that is not always the case. For example, starlings and house sparrows were first introduced into the United States in the 1890s after an eccentric drug manufacturer named Eugene Scheiffelin from the Bronx decided that all of the songbirds mentioned in Shakespeare’s plays should be imported from England into New York. In the case of the starlings, what initially began as a population of 100 birds released into Central Park has since turned into a population of over 200 million, which can be found across the entire continent of North America, and even up into Alaska. Other species of plants and animals have been intentionally introduced for a variety of reasons including uses for agricultural, recreational, and ornamental purposes.

Though many decry the spread of colony-collapse disorder that is affecting honeybee colonies across North America, and researchers are rushing to find its cause and cure, nobody talks about the fact that honeybees are in fact a non-native species to North America. English settlers introduced honeybees to the New World in the 1600s. Since that time, additional colonies of bees have been introduced from Europe, Asia, and Africa. However, no one argues that since their introduction, honeybees have taken on a significant role as pollinators to a variety of plants, including many important crop species. The loss of honeybees at this point could have a devastating effect on crop production that depends on them, such as the Californian almond industry.

Clearly, not all non-native species are perceived of as being “bad.” But when should a non-native species be considered to be good, and when should it be considered to be bad? Can such a distinction be made? Three scientists recently published a review article in the journal Conservation Biology that calls into question the practice of thinking that non-native species are inherently bad. The article, written by Martin Schlaepfer (State University of New York-Syracuse), Dov Sax (Brown University), and Julian Olden (University of Washington), suggests that non-native species can, and do, contribute to conservation objectives. These contributions include:

• providing habitat or food resources to rare or endangered species,
• serving as functional substitutes for extinct species, and
• providing desirable ecosystem functions.

According to the authors, “Non-native species might contribute to achieving conservation goals in the future because they may be more likely than native species to persist and provide ecosystem services in areas where climate and land use are changing rapidly and because they may evolve into new and endemic taxa.”

Conservation biologists are not so sure non-native species, such as the tamarisk plants shown here, are as bad as they were once considered to be. (Credit: James Steinberg / Photo Researchers, Inc.)

One example of an often-maligned non-native (and invasive) species that is providing ecosystem services is the tamarisk, or saltcedar, tree. This tree is of particular concern in the southwestern United States, where it is commonly found alongside rivers. Concerns about this species include its ability to outcompete local plant species and its ability to draw a significant amount of water from the water table. Conservation biologists worry that if left unchecked, the tamarisk tree could replace native species, thus affecting those species that depend on native plants as sources of food or shelter. However, recent research suggests that the plant’s ability to draw down the water table have been exaggerated. In addition, these trees now serve as habitat for the southwestern willow flycatcher. Eradicating tamarisk trees now would result in reduced habitat available for this endangered bird species.

Research conducted by scientists at Princeton University found that in some cases, non-native species take over the roles once held by native species. The scientists compared the health of plant populations on New Zealand’s North Island, where most native vertebrate pollinators have gone extinct, and the health of plant populations on the remote Little Barrier Island, just off the coast of New Zealand, where native species thrive. In their study, published in the journal Proceedings of the Royal Society B, the scientists found that on the North Island, non-native species, such as rats, have taken on the role as pollinators once held by the now-extinct native species. These results indicate that just removing the non-native species could cause significant harm to the North Island plant population. Instead, in such cases, conservation biologists need to take into consideration the role that non-native species have in an ecosystem before taking action to eradicate them.

According to David Wilcove, co-author of the New Zealand study, “…our findings show that eliminating an invasive species for the benefit of native species could actually harm an ecosystem, a surprising dynamic that could frustrate ecosystem restoration efforts.”

Clearly, non-native species are not always the evil-doers that they are often portrayed to be. In fact, the longer a non-native species is in an ecosystem, the more it may become entangled in the ecosystem’s functions. Over time, a non-native species may even prove to be a benefit to the ecosystem in which it was once reviled.

According to the authors of the Conservation Biology article, “We predict the proportion of non-native species that are viewed as benign or even desirable will slowly increase over time as their potential contributions to society and to achieving conservation objectives become well recognized and realized.”

More to Explore

• Harm not those strangers that pollinate, study warns
• Rethinking the War on Invasive Species
• The Potential Conservation Value of Non-Native Species [pdf]
• Alien Species Reconsidered: Finding a Value in Non-Natives

Northern leopard frogs leap with the help of a catapult-like mechanism in their tendons. (Photo credit: Oxford Scientific)

Many species of frogs are excellent jumpers. Members of the order Anura are known for their particularly powerful jumps. In fact, jumps made by members of this amphibian order are an example one of the most powerful accelerations in vertebrate movement. However, the acceleration of a frog’s jump requires more energy than its muscles are capable of producing. Scientists have hypothesized that these animals use a catapult-like mechanism to store and quickly let go of energy to produce powerful leaps that far exceed the capacity of their leg muscles. Researchers at Brown University recently conducted an experiment to determine if such a mechanism was behind the frog’s incredible ability to jump.

The research was conducted by Brown University scientists Henry Astley, a doctoral student studying biomechanics, and Thomas Roberts, an associate professor of ecology and evolutionary biology. In their experiment, the scientists implanted metal beads into the shin bone, ankle bone, and leg muscle of four northern leopard frogs (Rana pipiens). The researchers then used three-dimensional X-ray video technology to track the movements of each frog before, during, and after a jump. The film was recorded at 500 frames per second, which allowed the scientists to view the jumps 17 times slower than normal.

In viewing the resulting videos, the scientists determined that the catapult-like mechanism hypothesis was correct. The video footage showed that as the frog prepares to jump, its calf muscle shortens. Once 100 milliseconds has passed, the calf muscle stops moving. This indicates that the stretched tendon, which is wrapped around the ankle bone, is fully loaded with energy. When the frog leaps, the tendon lets the stored energy go, which causes a quick extension of the ankle joint, thrusting the frog forward. In real time, the frog jump takes about a fifth of a second.

"Our research offers the first complete picture of the muscle-tendon-joint system during jumping," Astley said in email correspondence. "Prior work led us to this, but was never able to definitively prove the existence of the catapult mechanism."

The scientists believe that this research has implications beyond just understanding the mechanism that powers jumping in frogs. "The biggest implication is that these catapult mechanisms may be much more common than previously thought," Astley said. "[It] may exist in many more animal species than presently known."

The results of this research were reported on November 16, 2011 in an online edition of the journal Biology Letters. The National Science Foundation funded this research.

More to Explore

• Evidence for a vertebrate catapult: elastic energy storage in the plantaris tendon during frog jumping [abstract]
• Frogs’ amazing leaps due to springy tendons
• Fluoroscopic View of Frog Jumping [video]
• Frog’s Leap A Marvel of Muscle Mechanics [video]
• The Anuran Life Cycle
• Northern Leopard Frog

Yellow stripes are just one example of the body patterns found on members of the poison dart frog species Ranitomeya imitator. (Photo credit: Dennis Flaherty/ Photo Researchers, Inc.)

An interesting aspect of Ranitomeya imitator is that the species has 10 different body patterns, or morphs. Marcel Chouteau, an evolutionary biologist at the University of Montreal, was interested in finding out why there were so many different body patterns within the same species.

To conduct his experiment, Chouteau enlisted the help of his girlfriend to help him make 3600 frog models out of modeling clay. Each model was life size and measured 18 millimeters in length. One-third of the clay models were painted to resemble frogs with a yellow stripe pattern on its back; another third were painted to resemble frogs with green patches on its back; and a final third were used as a control for weight selection and were painted brown to resemble the coloring of non-poisonous frogs in the area.

Three hundred of each model type (striped, patchy, and control), for a total of 900 models, were placed at two sites within the Amazon rain forest. One site was located in the lowland plains. The second site was located 10 kilometers away at a mountainous location. After the models were placed, Chouteau returned to check on them every 24-hours over a span of three days. Chouteau repeated his three-day experiment on three different occasions.

Due to the malleable nature of the model’s clay bodies, predation marks from bites were clearly visible. Chouteau found that at each site, the frogs that looked least like the local frog had the most bite marks. Accordingly, when predators see targets of a different species, they attack. However, he also found that the predators learn quickly to avoid the novel prey. After the first 24 hours of the study, the number of bite marks significantly decreased for the non-typical frogs.

The results of this research indicate that predators play an important role in the selection of multiple body patterns within the same species of poison dart frog. It appears that avian predators are just as geographically-specific as are their frog prey. The unrecognized frog phenotypes are more easily detected by predators, and hence do not last long in a new territory. In other words, predators keep each pattern going by selecting against any frogs that do not match the skin pattern they have learned to avoid. These results support the idea that natural selection plays an important role in the development of the many different skin patterns found among members of Ranitomeya imitator.

The results of this research were published in the December 2011 issue of the journal The American Naturalist.

More to Explore

• Predators drive the evolution of poison dart frogs' skin patterns
• The Role of Predators in Maintaining the Geographic Organization of Aposematic Signals [abstract]
• One Species, Ten Patterns? Why Poison Dart Frogs Dress Differently
• Ranitomeya imitator

Research indicates rising global temperatures may result in smaller plant and animal species. (Photo credit: Evgeny Dubinchuk/Fotolia)

Plants and animals are already beginning to change their behavior due to a warmer climate. Animals are beginning to migrate earlier, plants have changed their flowering periods, and many plants and animals have shifted their distribution away from the equator and closer to the cooler north and south poles. Recent research indicates that these modified behaviors are not the only change that species will undergo if the climate continues to warm as expected. These studies show that plant and animals may actually shrink in size as the climate continues to change.

Jennifer Sheridan, a professor of conservation biology at the University of Alabama, and David Bickford, a professor of environmental science at the National University of Singapore collaborated together on an article published in the journal Nature Climate Change. In the article, the scientists evaluated data from the fossil record, as well as modern-day studies to hypothesize what might happen if plant and animal sizes shrink due to a warming climate.

Their studies of the fossil record indicate that animals such as beetles, spiders, and pocket gophers significantly shrank in size during the Paleocene-Eocene Thermal Maximum, which occurred around 55.8 million years ago. Modern-day observations indicate that over the last 100 years, a variety of plant and animal species have decreased in size as average global temperatures have increased.

In addition to synthesizing data from the fossil record and current literature, the scientists also conducted two experiments. In one experiment, the scientists exposed ocean-dwelling creatures such as scallops, oysters, and scallops to conditions mimicking ocean water with increasing levels of acidity. As the acidity of the water increased, the marine animals’ ability to form their shells decreased, leading to an overall decrease in size. In a second experiment in which plants were grown under controlled climate conditions, the scientists found that for every 2 degrees that the temperature was increased, fruit size decreased by 3 to 17 percent. Similarly, when a variety of animals, including fish, beetles, marine invertebrates, and salamanders were exposed to increasing temperatures, they decreased in size, too. Fish, in particular, decreased between 6 and 22 percent in size.

Some species of salamanders are decreasing in size due to increased temperatures. (Photo credit: Carsten Meyer/Fotolia)

Research published in the journal The American Naturalist corroborates this data. This study focused on ectotherms, also known as cold-blooded animals, and how increased temperatures affect their growth rate and development. Experiments conducted with copepods, which are tiny aquatic crustaceans, showed that when exposed to warmer temperatures, the copepods go through their life stages at a quicker pace, meaning they reach adulthood at a smaller size than normal. This observation held true for a range of copepod species.

Why are species shrinking? Scientists point to a few explanations. Smaller plant size is linked to warmer and drier conditions and scarce water supplies. In addition, drought conditions often lead to forest fires, which diminish the amount of nitrogen, a nutrient necessary for plant growth, in the soil. These smaller plants in turn provide less of a satisfying meal for the herbivores that eat them. If the herbivores are unable to eat enough of their plant food source, or cannot find a replacement plant to eat, they will likely be unable to grow to their full size. Smaller herbivores in turn require predators to find more prey to eat to maintain their body size, or they too, will shrink in size.

Though not much is yet known about how worldwide food webs will be affected by a potential decrease in size across species, scientists hypothesize that changes in one species could have a ripple-effect on other species within their food web. They also foresee some species not feeling any affects due to a changing climate, which could also lead to imbalances within a food web, as some species thrive while others decline. Though computer models can help to show how shrinking species’ size may affect ecosystems in the future, only time will tell the actual impact these changes. As described above, current research indicates that shrinking species size could have a significant impact, though more research is necessary.

More to Explore

• Shrinking Body Size as an Ecological Response to Climate Change [abstract]
• Growth and Development Rates Have Different Thermal Responses [abstract]
• Climate Change Is Shrinking Species, Study Warns
• How Climate Change May Shrink Species

Turkey is a common sight on Thanksgiving. (Photo credit: Photodisc/Getty Images)

The centerpiece of many Thanksgiving dinners in the United States is a roasted turkey. According to the United States Department of Agriculture (USDA), it is expected that over 248 million broad-breasted white turkeys—the standard turkey found in your local supermarket—will be raised in the United States. This Thanksgiving alone, according to the National Turkey Federation, it is estimated that Americans will consume 46 million turkeys. However, a growing number of small-scale poultry producers across the United States are eschewing modern industrial farming practices and instead are raising unique and rare breeds of turkeys that have been around since the very first Thanksgiving feast in 1621.

An Introduction to Heritage Turkeys

According to the Heritage Turkey Foundation, heritage turkeys were originally bred for fine flavor, beauty, and thriftyness, a quality that referred to the amount of meat produced from the quantity of food fed to the turkey. Turkeys are a quintessential American food—all domesticated turkeys in the United States are descendants of wild turkeys native to North and South America.

There are three criteria a turkey must meet to qualify as a heritage turkey, according to the American Livestock Breeds Conservancy (ALBC). These qualities include the following:

This male turkey (commonly called a 'tom') is an example of the Bourbon Red heritage breed. (Photo credit: Keith J Smith/Alamy)

• The turkeys must reproduce naturally by mating. In order to qualify as a heritage turkey, the turkey must be the result of naturally mating pairs of both grandparent and parent stock.
• The turkeys must have a long productive outdoor lifespan. Breeding hens most be productive for five to seven years. Breeding toms must be productive for three to five years. It is imperative that the turkeys have the genetic ability to withstand the rigors of living outdoors.
• The turkeys must have a slow, natural growth rate. The birds should reach marketable weight in about 28 weeks. This long period of growth lets the birds develop strong skeletal structures and healthy organs prior to putting on muscle mass.

There are a number of different breeds of heritage turkeys. Many of the turkeys were originally bred for qualities such as productivity or specific color patterns. Among the breeds that are named by the American Poultry Association as standard breeds are Black, Bronze, Narragansett, White Holland, Slate, Bourbon Red, Beltsville Small White, and Royal Palm. Two other popular varieties of heritage turkeys include the Jersey Buff and White Midget. Over the past ten years, populations of heritage breeds of turkeys have been on the rise. According to Marjorie Bender, ALBC research and technical program director, in 1997 there were 1328 breeder birds; just four years ago, that number had grown to 10,404 breeder birds. Though most heritage turkey breeds are still endangered, there populations are much more secure than they were ten years ago.

Comparing Heritage Turkeys to Standard Turkeys

Over 99 percent of the turkeys raised in the United States are of the broad-breasted white variety. (Photo credit: INSADCO Photography/Alamy)

What makes heritage turkeys different from the standard turkeys you might find in your local supermarket? The standard turkey you most often find in the supermarket is a breed called the broad-breasted white turkey. These turkeys have been bred to provide a large amount of breast meat. Because of their abnormally large breast-size, the turkeys are unable to reproduce naturally. Instead, artificial insemination is necessary. Without human intervention, these turkeys would go extinct after just one generation.

In addition, while heritage turkeys must be free to roam, most broad-breasted white turkeys are raised in confined conditions. Due to these confined conditions, the turkeys are given antibiotics and other supplements to prevent the spread of disease. Heritage turkeys are certified antibiotic-free. The diets of both types of birds are also different. Since heritage turkeys are allowed to roam freely in the outdoors, they feed on a natural diet of insects, seeds, and grasses. Industrial turkeys are fed a steady diet of grains. According to research conducted by the USDA Sustainable Agriculture and Research Education Program, meat from turkeys that spent some portion of their lifetime outside had 21 percent less total fat, 30 percent less saturated fat, 28 percent fewer calories, 50 percent more vitamin A and 100 percent more omega-3 fatty acids.

One of the biggest differences between a standard turkey and a heritage turkey is the length of time it takes for each to reach maturity. Standard turkeys reach an average weight of 32 pounds over a period of 18 weeks. This length of time to maturity is 10 weeks earlier than it takes for heritage turkeys to reach maturity. To put this value into perspective, a market-ready standard turkey is the equivalent of an 11-year-old child weighing 300 pounds.

Drawbacks and a Look to the Future

One of the benefits of industrially-raised turkeys is their low cost in the marketplace. Raising a large amount of turkeys in a small space under standardized conditions lets producers sell them at the supermarket for a lower price. Because heritage turkeys require more space and take longer to grow to maturity, they are more expensive to raise. This added expense is passed on to the consumer. Compared to a standard supermarket turkey, heritage turkeys are often exponentially more expensive.

Because most heritage turkeys are produced by small-scale farms, they are often fairly difficult to procure. Most heritage turkeys are accounted for long before the Thanksgiving holiday. Although the production of heritage turkeys remains a niche industry, a growing interest in organic and sustainably-produced food products is helping to bring the breeds to the forefront. Without the farmers' intervention, many of the breeds of heritage turkeys would go extinct. By continuing to raise these rare and unique breeds of turkeys, poultry farmers help to maintain the genetic diversity of turkey species.

"Endangered breeds are a significant part of biological diversity in agriculture," Ms. Bender said. "These breeds are important to conserve because they provide options for the future. Agriculture will change, [and] the animals will be able to meet the new demands only if we assure their survival."

More to Explore

• Definition of a Heritage Turkey
• American Livestock Breeds Conservancy
• Heritage Turkey Foundation
• National Turkey Federation
• Thanksgiving Day Facts

Research indicates that yawning helps to cool down your brain. (Photo credit: Will & Deni McIntyre/Photo Researchers, Inc.)

These results support the thermoregulatory theory of yawning, which suggests that yawning is caused by brain temperature increases. The act of yawning is therefore used to cool the brain down. Scientists think that this cooling effect occurs due to an increase in blood flow to the brain caused by the stretching of the jaw as well as the countercurrent heat exchange that is associated with the deep inhalation of a yawn.

Andrew Gallup, a post-doctoral research associate at Princeton University, collaborated with Omar Eldakar, a post-doctoral fellow at the University of Arizona, on this research study, which was published in the September 2011 issue of the online journal Frontiers in Evolutionary Neuroscience. Their field-observational experiment involved measuring the incidence of yawning among a group of 160 randomly-chosen young adults in Arizona. Eighty of the participants were tested during the summer months and the remaining 80 participants were tested in the winter months. In their study, the scientists showed each participant an image of someone yawning (since yawning is “contagious”— perhaps looking at the photo that accompanies this article made you
yawn?) and measured the number of times each participant yawned.

Results from their research show that there is a higher incidence of yawning when ambient air temperatures were lower than human body temperature. They found that study participants yawned less frequently (around 25 percent of the time) during the summer months, when air temperatures often exceeded human body temperature and humidity was lower. During the winter months, when air temperature was mild (around 71 degrees Fahrenheit) and humidity was slightly higher, participants yawned more frequently (nearly 50 percent of the time). Their results also indicate that yawning is related to the amount of time a person spends outside exposed to the elements. The scientists found that though nearly 40 percent of the participants yawned within the first five minutes of being outside, in the summer months, this number drastically reduced as time outside increased. During the winter months, yawning occurred at a slightly higher frequency after more than five minutes outdoors had passed.

The results of this research support previous non-human animal studies. For example, a study involving rats found that the rats' brain temperatures decreased immediately after a yawn. A second study using rats found that the incidence of yawning increased as air temperature increased. However, when the air temperature became too warm, the frequency of yawning decreased. Similar results occurred in a study involving parakeets. In one such study, parakeets were exposed to three different conditions: moderate air temperature, high air temperature, and increasing air temperature. Though yawning did not increase in the first two situations, the birds yawned at a significantly greater frequency when the air temperature increased over time.

So why do you yawn you are tired? Research indicates that both exhaustion and sleep deprivation are both associated with higher brain temperatures. These increased brain temperatures in turn trigger yawning to help the brain to cool down. Additionally, brain research also shows that yawning helps with the transition from sleeping to waking states, and vice versa.

The results from these studies have many practical implications. For example, studying the mechanism behind yawning could help researchers improve their knowledge about neurological diseases such as multiple sclerosis and epilepsy, both of which are associated with frequent yawning. The occurrence of excessive yawning could also be used as a diagnostic tool for thermoregulatory impairments.

More to Explore

• Contagious Yawning and Seasonal Climate Variation
• More Than A Sign of Sleepiness, Yawning May Cool the Brain
• Why We Yawn
• Yawn

Research indicates that aerobic activity promotes brain health. (Photo credit: Rubberball/Getty Images)

You probably know that physical activity is an important part of obtaining and maintaining a healthy body weight. But, research shows that a consistent aerobic exercise regimen has a number of other positive effects on your health, too. These positive effects include a decreased risk for type II diabetes, cardiovascular-related disease, osteoporosis, and mental disorders. Recent research also indicates that physical fitness is also important when it comes to brain health and development.

Connecting Exercise to Brain Health in Children and Teens

Studies show that only 50 percent of children and only 8 percent of teens are physically active for the government-recommended 60 minutes per day. If 60 minutes of exercise sounds like a lot to you, consider that the average 8 to 17 year old spends 7.5 hours doing passive activities such as watching TV, using a computer, playing video games, or texting on their phone.

Childhood and adolescent years are associated with rapid development of the brain. During this time period, structural and functional circuitry necessary for higher-level thinking, form in the brain. This circuitry allows for the brain’s executive functions, such as the ability to regulate behavior, multi-task, and avoid distraction. Several studies have shown that physical activity is particularly important during early childhood. For example, one study found that an aerobic exercise regimen followed for three months improved the executive function abilities of overweight children. The results of another study linked inactivity during childhood to poorer academic performance and lower performance on standard neuropsychological tests.

Connecting Exercise to Brain Health in Older Adults

Unlike in the childhood and teenage years, during young adulthood, not much change occurs in the brain. Instead, the years between the ages of 19 and 35 are associated with stability in brain structure and function, as well as peak cognitive performance. Researchers have found mixed results in studies relating physical activity to brain health in this age group. However, once older adulthood is reached, exercise once again becomes important for brain health and function.

Aerobic exercise helps to prevent cognitive impairment in older adults. (Photo credit: Keith Brofsky/Photodisc/Getty Images)

During old age, the hippocampus normally shrinks 1 to 2 percent in size every year. The loss of hippocampus volume is associated with an increased risk for the development of cognitive impairment, such as dementia or Alzheimer’s disease. Multiple studies have shown that adding a consistent aerobic exercise program increases hippocampus volume. Studies show that aerobic training results in the generation of new neurons in the hippocampus, and these new neurons are connected with an improvement in hippocampus function.

Research also indicates that weight-training is also important for maintaining or enhancing brain function in older adults. One six-month study found that a three-time weekly program of moderate- to high-intensity resistance training led to improved memory performance and verbal concept formation. Another study that focused on older women found that those who lifted weights performed better on cognitive tests than those women who just did toning exercises.

Connecting Exercise with Improved Brain Function

In addition to strengthening the heart, aerobic exercise also results in a significant increase in the movement of blood to the brain. Researchers think this rapid influx of blood to the brain is required for the growth of new neurons. Research using mice as the test subject corroborate this hypothesis. Several studies using mice as a test subject indicate that aerobic exercise increases the growth of new blood vessels as well as new neurons in the brain, actions that are both associated with improved learning and memory.

Adding Exercise to Your Day

How can you get in the recommended amount of exercise every day? It may not be as hard as you might think. First, the 60 minutes of exercise do not have to be continuous—just try to incorporate at least 60 minutes worth of physical activity throughout your day. The important thing is to integrate aerobic, muscle-strengthening, and bone-strengthening exercises to your daily routine. Examples of aerobic exercise include dancing, running, bike riding, martial arts practice, and playing sports. Muscle-strengthening exercises include push-ups, sit-ups, and lifting weights. Bone-strengthening exercises include activities that apply force to your joints, such as jumping rope, running, and gymnastics.

As the research shows, exercise is not just important for maintaining a healthy body. Adding physical exercise to your daily routine is also quite important for maintaining a healthy and well-functioning brain. It seems that Thomas Jefferson was right when he said that “A strong body makes the mind strong.”

More to Explore

• Physical Activity for Everyone
• Let's Move!
• Exercise Helps Overweight Children Think Better, Do Better in Math
• Exercise May Help Prevent Brain Damage Caused by Alzheimer's Disease
• Moderate to Intense Exercise May Protect the Brain
• Exercise Has Numerous Beneficial Effects On Brain Health and Cognition, Review Suggests