Understanding Evolution: your one-stop source for information on evolution
Resource library Teaching materials Evolution 101

What's new at Understanding Evolution

Here are the latest updates to Understanding Evolution. You can also sign up to receive alerts about updates via our monthly email newsletter or RSS feed.

Why the Y is here to stay - May, 2014
The Y chromosome is finally getting the respect it deserves. Since the early 1900s, we've known that the Y chromosome is responsible for making males — XX embryos develop into girls and XY embryos develop into boys — but the Y was thought to do little else. After all, at just one quarter the length of the X chromosome, the Y is relatively puny. Biologists hypothesized that the few genes it does carry contribute to processes like sperm production and testes development by helping turn on and off other genes. In fact, the Y had such a bad rap that many researchers suggested that it was on its way to evolutionary extinction. However, now, new research suggests that the Y chromosome is here to stay. Its function goes far beyond triggering maleness...

Genetic engineering vs. evolution - April, 2014
In the late 1990s, a new weapon in the fight against agricultural pests was introduced: Bt corn. The new maize variety was genetically engineered to carry genes from the bacterium Bacillus thurinigiensis (hence the moniker "Bt") that cause the crop to produce an all-natural pesticide. This meant that growers could get good yields from their cornfields without spraying on so many toxins. Since then, many farmers have jumped on this bandwagon. In 2012, more than 69 million hectares were planted with Bt crops — an area about the size of Texas! There has been much debate over the risks of this technological advance, but now it appears that the downfall of Bt corn might be the very problem that it was supposed to solve in the first place: agricultural pests, in particular the western corn rootworm. These beetle larvae eat the roots of corn plants potentially ruining the crop. In recent years, more and more larvae that are resistant to the effects of the Bt toxin have been showing up in fields and chewing their way into plants. How and why did this happen? It all comes down to evolution.

Evolutionary history is more than skin deep - March, 2014
Many of the marks that evolutionary history has left on our bodies are invisible. Lactose tolerance, a predisposition towards diabetes, genes that contribute to breast cancer, and many other inconspicuous traits are legacies of the paths that our ancestors took as they left or stayed in Africa between 60 and 125 thousand years ago. However, other markers of these unique evolutionary histories are perfectly obvious, perhaps most notably skin color. It's clear that people whose ancestors hail from different parts of the earth have differently colored skin and that this is related to how much of the sun's radiation hits that part of the planet. The less radiation, the lighter the native population's skin color tends to be. This is a great example of recent evolution in human populations. But what if we go back deeper in our evolutionary history, back to when all of humanity lived in Africa? At that time, all humans had darkly pigmented skin. A new study sheds light on how and why this skin pigmentation evolved.

The deep roots of diabetes - February, 2014
The modern diabetes epidemic is caused, not by a virulent pathogen, but by the spread of an even stealthier invader: the Western lifestyle. As people around the world have begun to eat less healthily, lead more sedentary lives, and live to older ages, adult onset diabetes (type 2 diabetes) has become common in places where the disease was previously unknown. Between 1985 and 2002, the number of people with diabetes grew from 30 million to 217 million, and this figure is expected to exceed 366 million by 2030. But the epidemic has not been even-handed. Even accounting for differences in lifestyle, some populations have been hit particularly hard. Mexicans and Latin Americans, for example, have nearly twice the chance of developing diabetes that non-Hispanic white Americans do. New research addresses these disparities. Last month, scientists announced that they'd discovered a gene that helps explain the difference in diabetes risk among many populations. In a strange twist, the gene version in question traces its ancestry back to Neanderthals! What exactly is going on here?

Bottlenecks, BRCA, and Breast Cancer - December, 2013
As tests for genes that contribute to more diseases become available and, in many cases, become cheaper, we will increasingly be faced with decisions about how much we want to know about our future health prospects. Would you want to know if you carried a gene that conferred a 60% chance of developing Huntington's disease by age 65? Or that multiplied your chances of having a stroke by five—even though the risk of having a stroke in any given year would still be extremely low? How much would you pay for a test that, for more than 99.5% of women will reassure them that nothing is wrong, but in the other cases will reveal that one's odds of developing ovarian cancer are 39%? A prime example of this situation made the front page of the New York Times last month—and highlighted the deep connections that genetic testing has to the evolutionary history of human populations...

Lumping or splitting in the fossil record - November, 2013
Rarely does pure science take top billing in the news, but this past month saw a notable exception. The front page of the New York Times was occupied by the image of an ancient hominid skull caked in dirt. This 1.8 million-year-old fossil, excavated in the Republic of Georgia, represents the oldest complete adult cranium of a hominid yet discovered. That alone would be significant news, but the context in which the fossil was preserved adds even more weight to the discovery...

Anniella The legless lizards of LAX - October, 2013
Last month, biologists announced the discovery of four new species of lizard, not in an exotic tropical jungle, but right under our noses. The new-to-science animals (from the genus Anniella) were found at several unlikely locations — including in an abandoned lot in Bakersfield, California, and near the runway at Los Angeles International Airport. But don't count on catching sight of one of these critters the next time you have a layover at LAX. First, they are small — less than 8 inches long. Second, they live mostly underground (the researchers had to tempt them out of hiding by leaving pieces of cardboard and plywood on the ground). And third, even if you did see one, you might not recognize it as a lizard. The four new species have no legs and could easily be mistaken for snakes! So why aren't these sleek, scaled creatures snakes, and how did they avoid detection for so long? The answers are evolutionary ones.

velvet worm A new old animal - September, 2013
Eoperipatus totoro doesn't look much like a fearsome predator. In fact, this two-inch long critter resembles nothing so much as a plush, candy-colored caterpillar with wriggly antennae. But this little known animal is no caterpillar. It is a velvet worm — a.k.a. an onychophoran, a group of organisms that today live in tropical regions and trap their insect prey using jets of sticky slime, a-la Spider-Man. Discovered in Vietnam and officially described just last month, this particular species may be new to science, but the onychophorans as a group have long been of interest to biologists for their important role in evolutionary history...
meat Antibiotic resistant bacteria at the meat counter - May 2013, updated June 2014
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.

A fisheye view of the tree of life A fisheye view of the tree of life - April 2013
Explore our interactive fish evolutionary tree to learn about amazing innovations that have evolved in the different lineages.

where's the beef No more mystery meat - April 2013
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 …

fossil teeth The recent roots of dental disease - March 2013
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!

flu Influenza, an ever-evolving target for vaccine development - February 2013
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.

Jackson Njau CSI: Olduvai Gorge. The work of Jackson Njau
Follow paleoanthropologist Jackson Njau as he examines fossil evidence for clues of crocodile predation on early hominids.

grasshopper Grasshoppers change their tune. Is it evolution in action? - December 2012
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 ...

Kim Bostwick How boogieing birds evolved: The work of Kim Bostwick
When ornithologist Kim Bostwick goes hunting with her binoculars, she's not just looking for birds; she's looking for untold evolutionary stories.

Satish Pillai Using trees to uproot HIV: The work of Satish Pillai
See how scientist Satish Pillai uses phylogenetics to investigate the possibilities of developing an effective vaccine and of curing HIV.

Ornithomimus A new look at dinosaur fossils pushes back the evolution of feathered wings - November 2012
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.

marine algae Acidic oceans prompt evolution - October 2012
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.

passenger pigeon What comes after mass extinctions? - September 2012
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.

DNA Evolution at the scene of the crime - updated August 2012
The tests confirm, beyond a shadow of doubt, that Roger Keith Coleman did it, but Alan Crotzer did not. In 1992, Coleman was executed for the rape and murder of his sister-in-law. In 1981, Crotzer was sentenced to 130 years in prison for a robbery and pair of rapes. Though the crimes themselves are old, judgments long since rendered, and punishments already meted out, for many observers, the actual guilt or innocence of these two defendants for two different crimes was only just settled by an increasingly important test: the DNA fingerprint. Recent DNA tests revealed that it was, indeed, Coleman's semen in the body of his victim, and that he had actually committed the crime for which he was executed more than 10 years ago. And recent DNA tests revealed that Krotzer is not a rapist and has spent 24 years in prison for crimes he did not commit.

mosquito Fighting the evolution of malaria in Cambodia - updated July 2012
Malaria infects more than 250 million people a year and kills almost one million — most of them children. The disease is curable with the right treatment, but this year scientists announced that it may not be curable for long. Strains of malaria that have evolved resistance to our most effective drug, artemisinin, have been discovered in western Cambodia and could spread to the rest of the world. Understanding the environment that contributed to this worrisome evolutionary step is helping scientists, doctors, and policymakers develop effective strategies for keeping resistant strains of malaria in check.

chicks Evolution and the avian flu - updated June 2012
The warnings are dire. The economic cost for developed countries alone is estimated at 550 billion dollars, and the projected worldwide death toll ranges between 2 million and 150 million people. The very real specter behind these warnings is, of course, avian flu. As the virus spreads through bird populations, governments have heeded the warnings of health officials and begun to cull infected flocks. More than 150 million birds have been killed so far, with further control efforts looming. However, less than 200 human cases of avian flu have been identified thus far. Why the global concern over localized outbreaks?

trilobite and tiger Lessons for today in ancient mass extinctions - May 2012
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.

chipmunk Climate change causes loss of genetic diversity - April 2012
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.

chameleon Evolutionary history in a tiny package - March 2012
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.

blacktip shark Hybrid sharks aren't "trying" to adapt - February 2012
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?

cheek swabbing When fighting leukemia, evolutionary history matters - December 2011
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.

tuberculosis patient An antibiotic that exploits evolutionary history - October 2011
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.

Juramaia The evidence lines up in early mammal evolution - September 2011
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.

cichlid Sex, speciation, and fishy physics - updated July 2011
For the summer holidays, Evo in the News will be revisiting past news items to bring you up-to-date on recent research and developments. In March of 2009, we reported on how the physics of light seems to have spurred speciation in Lake Victoria's cichlid fish. This summer, we report on new evidence that backs up this hypothesis — and that highlights the threat posed to these fish by pollution that clouds the lake's waters.

cricket Quick evolution leads to quiet crickets - updated June 2011
For the summer holidays, Evo in the News will be revisiting past news items to bring you up-to-date on recent research and developments. In December of 2006, we reported on a bizarre case of evolution in action. Crickets on the Hawaiian island of Kauai were being parasitized by flies that track the crickets down by following their mating chirps. When a new mutation arose that caused male crickets to develop silent wings, it swept through the population since it helped male crickets avoid being eaten alive by the flies' larvae. In June of 2008, we reported on new research into the genetics of this mutation. This year, we continue to follow the story of the silent crickets. Researchers recently announced that they've looked more closely at the crickets' genetics in order to learn how crickets arrived on Hawaii in the first place and how the mutation might have gotten a foothold in the island population.

robot "Error. Greed does not compute." - May 2011
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.

whiteflies Gender-biased bacteria throw off an evolutionary balance - April 2011
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.

Warning Toxic river means rapid evolution for one fish species - March 2011
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.

pitcher Evo in the news: Bad at estimating? Blame evolution - February 2011
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.

panther Evo in the news: Genetic variation helps rescue endangered panthers - December 2010
This fall, biologists announced the apparent success of a last-ditch conservation effort: the Florida panther, once slated for extinction, has been given a second lease on life by the infusion of genetic variation. In the 1900s, this population nosedived because of hunting and habitat loss. By the 1990s, there were fewer than 30 Florida panthers left. Find out about the evolutionary basis of this successful conservation plan.

gorilla Evo in the news: Spreading disease on evolutionary timescales - November 2010
If you are trying to stay healthy this cold and flu season, you may find yourself washing your hands frequently and avoiding crowded places like schools and airports. That's because most infectious diseases that we are familiar with are passed from human to human — and the more human germs you come into contact with, the more likely you are to have one make its home in your body. However, on evolutionary timescales, pathogens don't necessarily respect species boundaries. Find out how a deadly strains of malaria jump between chimp, gorilla and human hosts.

Tibetan woman Evo in the news: Evolving altitude aptitude - October 2010
If you live in the lowlands, you may have experienced the huffing and puffing that typically accompany a trip to higher altitudes. That's because oxygen levels go down as one goes up. Travelling to Denver from sea level means a 17% decrease in available oxygen. Our bodies compensate for even this small change with faster breathing and a higher heart rate — at least until we acclimate to the thinner atmosphere. And a loftier vacation spot (for example, La Paz, Bolivia at 11,942 feet) could bring on serious altitude sickness with insomnia, nausea, and swelling — but not for everyone. Read more about the adaptations of the Tibetan highlanders.

bedbug Evo in the news: Bed bugs bite back thanks to evolution - September 2010
Bed bugs might sound like an old-fashioned problem, but now they are back — and with a vengeance. Fifty years ago, the blood-sucking pests were nearly eradicated in the United States thanks in part to the use of pesticides like DDT. Today, they are creeping over sheets — and tormenting hapless sleepers — across the country. Read about how bedbugs evolve to overcome control measures.

cave Evo in the news: Making sense of ancient hominin DNA - May 2010
In the last two months, news outlets have been abuzz with the announcement of what many suggested was a new hominin species. In 2008, a 40,000 year old pinky bone from a child was discovered in a Siberian cave. The bone was not enough to identify the species of its possessor, but since both Neanderthals and humans are known to have lived in the area at the time, scientists assumed it belonged to one of these two species. That all changed in March of this year, when German researchers announced that they'd managed to extract DNA from the fossil — and it didn't match up to the known genetic sequences of either humans or Neanderthals. Find out more.


Subscribe to Understanding Evolution!
Get free updates and news stories via email or RSS.

 

This site was created by the University of California Museum of Paleontology with support provided by the National Science Foundation (grant no. 0096613) and the Howard Hughes Medical Institute (grant no. 51003439).