It's no secret that greenhouse gases warm the planet and that this has dire consequences for the environment whole islands swallowed up by rising seas, animal and plant species stressed by higher temperatures, and upsets in ecological interactions as populations move to cooler areas. However, carbon dioxide has another, less familiar environmental repercussion: making the Earth's oceans more acidic. Higher levels of carbon dioxide in the atmosphere mean that more carbon dioxide dissolves in the ocean. This dissolved carbon dioxide forms carbonic acid the same substance that helps give carbonated beverages their acidic kick. While this process isn't going to make the ocean fizzy anytime soon, it is introducing its own set of challenges for marine organisms like plankton and coral.
The pork chops you buy in the supermarket neatly packaged in plastic and styrofoam may look completely sterile, but are, in fact, likely to be contaminated with disease-causing bacteria - and not with just any old bugs, but with hard-to-treat, antibiotic resistant strains. In a recently published study, researchers with the National Antimicrobial Resistance Monitoring System bought meat from a wide sampling of chain grocery stores across the country and analyzed the bacteria on the meat. Resistant microbes were found in 81% of ground turkey samples, 69% of pork chops, 55% of ground beef samples, and 39% of chicken parts.
The next time you are in the kitchen, try this experiment: pick up a box of butter (four sticks) in one hand and a box of saltines (four packets) in the other. Which is heavier? If you said the butter, you are not alone. Most people would identify the box of butter as the heavier object even though, if you look at the labels, you'll see that they both weigh exactly one pound! This is an example of the size-weight illusion, and it is incredibly common. Read more to see the evolution (and baseball) connection ...
If you'd visited Tuolumne Meadows in Yosemite National Park 100 years ago, you probably would have encountered the alpine chipmunk, Tamias alpinus. Today, however, park visitors will have to hike up a nearby mountain to see one of these critters. That's because this species is sensitive to temperature and over the last hundred years of global climate change, Yosemite has warmed by about 5.5 degrees Fahrenheit. As the temperature increased, the chipmunks retreated to higher and higher elevations where it was cooler. Today, they occupy a fraction of their original range. If climate change continues, they could be squeezed right off the tops of their mountains and out of existence.
Swarms of tiny robots have given up their selfish ways and started sharing resources for the greater good. Though this might sound like the plot of a bad summer blockbuster, it is real news. This month, a team of Swiss researchers announced that they've used robots to simulate biological evolution. The simple, mobile robots - each a little larger than a sugar cube - began their lives directionless, meandering aimlessly into walls. But after a few generations of natural selection, their computer programs evolved so that they became efficient foragers, purposefully collecting disks that represent food. None of that is particularly surprising. Scientists have long been able to simulate evolution through computer programs that mimic the processes of genetic inheritance, mutation, recombination, and reproduction. What is noteworthy is that many of these robots eventually evolved to help one another, sacrificing personal success to aid other robots in their group.
Back in the Jurassic, dinosaurs may have dominated terrestrial ecosystems, but they were not alone. Scurrying around their feet and clinging to the trees above them were the fuzzy ancestors of their successors. When most of the dinosaurs perished, the surviving mammals diversified into the dinosaurs' niches, where they remain today. Last month, scientists reported on the discovery of a fossil mammal from China that would have lived alongside the dinosaurs and that, at 160 million years old, represents one of the earliest mammals known.
Scientists discover new species all the time, but usually these new species are microbes, plants, insects, and other forms of non-vertebrate life. Few vertebrate species have thus far evaded the curious gaze of biologists intent on understanding the diversity of life on Earth - that is, unless the vertebrate in question happens to be very, very tiny. Last month, scientists announced the discovery of not one, but four miniscule lizard species. The smallest of these new chameleons, which live in the far north of the African island of Madagascar and inhabit leaf litter, reaches an adult body size of just two centimeters.
The evolutionary tree presented focuses on relationships among the ray-finned fishes (Actinopterygii). You can click on the colored logos to read about evolutionary innovations and see lists of characteristics that evolved in different lineages. Note that this tree has been pruned to focus on certain groups of interest.
This month, biologists reported that a bacterial infection has run rampant in populations of a major crop pest in the Southwest. The bacterium (called Rickettsia) is a close relative of the species that causes typhus in humans. Its host is the sweet potato whitefly, a tiny bug that can occur in large enough numbers to form visible clouds. Whiteflies suck the sap from plants and spread crop diseases, causing hundreds of millions of dollars of damage in a single season. In just a few years, the percentage of southwestern whiteflies infected with Rickettsia has skyrocketed from 1% to more than 90%. Unfortunately, this is not the boon for local farmers that it might seem.
Whizzing down the interstate, the sounds that concern most of us include the radio's tuning, conversation with our fellow passengers, and, of course, the ominous howl of a siren approaching from behind. But just outside the car door, the soundscape is quite different. On busy thoroughfares, traffic noise approximates a non-stop, low-pitched roar that necessitates shouting to communicate if one is unlucky enough to need to change a tire at the side of the road. Now, new research shows that it is not just humans who strain to be heard over the din of a highway ...
Last month, biologists announced the discovery of hybrid sharks in Australian waters. The new sharks may not warrant a marine park attraction they look much like their closely-related parent species but do represent an unexpected twist of biology and evolution. This is the first time that scientists have found evidence of shark hybridization an event that was thought to be rare because, unlike the many fish that simply release eggs and sperm into the water, sharks mate. Clearly, though, the widely-distributed common blacktip shark and the Australian blacktip shark (which is restricted to northern and eastern Australia) have few qualms about each other: 57 apparently healthy hybrid individuals were discovered in the first investigation of these animals. What does this mean for the future evolution of blacktip sharks?
It's that time of year again. Coughing coworkers, student absences, and reminders to get your shot are sure signs that flu season is upon us. This year's epidemic seems to have struck earlier and harder than usual all amid concerns over shortages of the flu vaccine. While some vaccines provide lifelong protection with one or a few doses (e.g., measles, mumps, and polio), the flu requires a new shot every year. And in some years, the flu shot is hardly effective at all. Why is the flu vaccine different from so many other vaccines? A look at the evolution of the flu virus can explain the weaknesses of current vaccines and points the way towards a vaccine that could provide long-lasting, universal protection.
Investigating a Deep Sea Mystery is based on Deep-sea mystery solved: astonishing larval transformation and extreme sexual dimorphism unite three fish families by Johnson, et al. (2009)* published in Biology Letters, Royal Society. The deep sea fishes at the heart of the investigation and this activity were historically classified into three families or clades based on the obvious morphological differences between the members of each group. Over time, as new data was accumulated, a new hypothesis was generated; the three fish clades were really one. Johnson, et al. found patterns in collection data that supported an alternative relationship; that they are the males, females, and larvae of a single family or clade, and that the morphological differences are the result of extreme ontogenetic (developmental) metamorphosis and sexual dimorphism. In this activity students follow the steps of the science team to unravel the mystery of the fishes' classification by analyzing some of the same morphological and phylogenetic data as the science team.
If you follow environmental news at all, you'll be familiar with the most common cause of extinction in the world today: habitat loss. Habitat destruction threatens the survival of some the world's most charismatic organisms animals like the giant panda, the Sumatran tiger, and the Asian elephant. Humans have encroached on the wilderness in order to farm, mine, log, and build, and in the process, we've pushed the natural inhabitants of those areas into smaller and smaller refuges. Making matters worse, global climate change caused by our production of greenhouse gases is altering the environments within those refuges, forcing species to contend with new challenges. While these might seem like entirely modern problems, recent research indicates that's not the case and that current levels of habitat loss and climate change could have devastating consequences.
Unfortunately, many people have persistent misconceptions about evolution. Some are simple misunderstandingsÅƒideas that develop in the course of learning about evolution, possibly from school experiences and/or the media. Other misconceptions may stem from purposeful attempts to misrepresent evolution and undermine the public's understanding of this topic.
Last month, paleontologists from Canada, the U.S., and Japan announced an exciting discovery: feathered dinosaur fossils in North America. When Ornithomimus edmontonicus was first studied in the 1930s, its ostrich-like skeleton earned it a name that translates to "bird mimic." Now new fossils and a re-evaluation of old ones have revealed that its body covering also fits the moniker. A newly unearthed, year-old juvenile specimen is covered in downy, hair-like feathers, and re-examination of an adult specimen turned up traces of standard feathers with a central shaft. While most popular reporting has focused on the idea that these shafted feathers may have been used to attract mates, the real news in this research lies elsewhere
Diners sitting down to enjoy a burger couldn't be faulted for wondering, "Where's the beef from?" After all, just a few months ago, European consumers were dismayed to discover that many products marketed as beef actually contained large quantities of horse meat. Genetic fingerprinting, which was used to detect the imposter beef, can identify meat as a particular species or even a particular population. However, other analyses of genetic data can trace the source of a patty, McNugget, or filet, not just to a particular breed or population, but back in time. Using these techniques, scientists have uncovered the deep evolutionary origins of domesticated animals (such as sheep) and major crop plants (such as corn). Now, they've applied those techniques to cattle as well. This month, a team of researchers from the Universities of Texas and Missouri announced the results of a study focusing on the origins of breeds specific to the Americas, like the Texas Longhorn. The story told by the cows' genes crisscrosses the trajectory of human evolutionary history from wild aurochs that lived alongside Neanderthals, to Christopher Columbus and, ultimately, the American West
Science has now provided an excuse for those of us used to being chided by our dentists for not brushing often enough: blame your cavities on the Industrial Revolution. New research suggests that the dietary changes associated with the Industrial Revolution 150 years ago (and with the invention of agriculture 10,000 years ago) caused an epidemic of tooth decay and gum disease. The culprits are oral bacteria. The human mouth is the native home of a wide variety of microbes, some helpful species and some harmful. Over the course of human history, eating more starch and sugar seems to have tipped the balance in favor of the disease-causing bacteria. Even without ultrasonic toothbrushes and mouthwashes, our ancestors may have had healthier teeth than we do!
This list of conceptual understandings regarding evolution are aligned across grade levels to help instructors identify age-appropriate learning goals for their students and understand how concepts taught at one grade level lay the groundwork for more sophisticated concepts later on. The Framework is divided into five strands: History of life; Evidence of evolution; Mechanisms of evolution; Nature of science; and Studying evolution
Understanding Evolution provides a large collection of images and illustrations you may download and use in lectures and presentations to help explain the concepts of evolution.
Extinction is a fact of modern life. Humanity's relentless encroachment on the wilderness has marred the diversity of life with conspicuous gaps where the Tasmanian tiger, the Passenger Pigeon, the Ivory-billed Woodpecker, and countless others used to be. As these extinctions accumulate, the Earth inches closer and closer to its sixth mass extinction. We are all too familiar with the concept of mass extinction - a disaster strikes and sets off a chain of events that result in a massive die-off. But you may not have considered what comes next: what happens to surviving species in the wake of a massive extinction event? Recent research suggests that mass extinctions shake up life on Earth in surprising ways.
In the next few months, college students across the country will be offered the chance to save a life by swabbing cells from the insides of their cheeks and registering as a potential marrow donor with Be The Match The Give A Spit About Cancer campaign, which launched in October, helps college students organize marrow donor registry drives. The cells collected in these drives are used to figure out who might be able to donate marrow or blood stem cells to a patient with a life-threatening disease like leukemia. While ethnicity is irrelevant to most medical procedures, marrow and blood stem cell transplants are an exception to this rule.
This month, the World Health Organization announced that tuberculosis cases are on the decline for the first time in at least 20 years. We seem finally to be winning what has been a very long battle. Tuberculosis bacteria have been attacking us since modern humans began to migrate out of Africa around 40,000 years ago. If you enjoy classic literature, you'll be familiar with the cough, fever, and weight loss of consumption (the old-fashioned term for tuberculosis), which used to be a near certain death sentence. That changed when the aminoglycoside antibiotic streptomycin was discovered in 1943.
Though we often think of evolution as occurring at a snail's pace, one fish species is highlighting just how quickly evolution occurs in the right circumstances. Between 1947 and 1976, General Electric released more than a million pounds of PCBs into the Hudson River. PCBs can kill fish and seabirds and have been linked to cancer and other serious health problems in humans. PCBs were banned in 1979, but the toxins have remained at high levels in the Hudson because they settle into the sediments on the bottom of the river and don't break down. Now, scientists have discovered that, over the past 60 years, one bottom-feeding fish species, the Atlantic tomcod, has evolved resistance to PCBs.