2016 Stories
Black widow virus results from evolution, not genetic engineering
This fall researchers announced a surprising discovery: a virus carrying genes for a toxin from black widow spider venom. While that conjures up frightening thoughts (a flu that causes a breakout of festering welts!), rest assured that this virus cannot infect humans. In fact, it infects only a particular type of bacterium that itself only infect insects, spiders, and their close relatives (i.e., arthropods). How did this creepy mash-up occur in the first place? A black widow virus might sound like the product of genetic engineering — like strawberries bearing fish genes or goats that make spider-silk proteins – but it is actually the result of evolution…
Read more »GMOs struggle to stay one step ahead of evolution
While strawberries containing fish genes make big news, they haven’t actually made an appearance at your local grocery store. In fact, few genetically modified organisms are currently sold as food in the US, but the exceptions are doozies: about 85 percent of the corn and soybeans grown in the US are genetically engineered. Most of those crops are engineered for two particular traits — to resist herbicides like Roundup (which is useful because it allows growers to use the substance against weeds in the same fields as their crops) and, in the case of corn, to kill the Western Corn Rootworm, a beetle larva that eats cornstalks from the ground up. Genetically modified corn kills rootworm with a gene originally found in the soil bacterium, Bacillus thuringiensis (i.e., Bt). This gene produces a protein that is toxic to rootworms, but not to humans and many other animals. So-called Bt corn has been on the market for a little over a decade; however, in recent years, the benefits of using this variety have dwindled as rootworm populations have evolved resistance to the Bt toxin. Now, scientists working for DuPont have announced the discovery of another gene from a different soil bacterium that could replace Bt once resistance is so prevalent that the Bt toxin is no longer effective.
Read more »The mutations that make us human
When we imagine what made early modern humans unique, it’s tempting to imagine a caveperson, brandishing a lit torch against the night, using fire to eke out a better living from a hostile environment. However, humans were not alone in their use of fire. Neanderthals, which inhabited the planet at the same time as the first modern humans, were using fire at least 175,000 years ago, and there is evidence that Homo erectus used fire in Africa more than a million years ago. Now, new research suggests that part of what distinguished early humans from their close relatives was not their use of fire, but how the human lineage evolved in response to fire. This past summer, a group of biologists and anthropologists announced that they’d discovered a mutation that may have allowed our early ancestors to better deal with breathing in the toxic chemicals produced by open fires.
Read more »A field guide for the new Tree of Life
If you are a science news junkie, perhaps you saw it while scrolling through your news feed: the new Tree of Life. Last month, researchers announced that they’d used genetic sequences to build a much more inclusive picture of the Tree of Life. The tree is unique because it includes many microbial species that researchers have never even seen, let alone figured out how to grow in a lab. We know these lineages exclusively from broken up bits of DNA that the researchers culled from a wide variety of environments — from California meadows to geyser systems. Some of the DNA was even collected from the inside of dolphins’ mouths! The researchers fit those DNA bits together like a puzzle until they got the complete genomes of these mystery organisms and used that information to locate their branches on the tree. All of that is fascinating — but when you dig down and start looking at this new tree, you wouldn’t be faulted for wondering, “Uh, where’s the tree here?” The new Tree of Life, in fact, looks more like an exploding firework than an oak or an elm. Here, we’ll explore a tool that can help you interpret different styles of evolutionary trees (i.e., phylogenies) that you might see online, in textbooks, or in museum exhibits.
Read more »Super-Mendelian mosquitoes may fight malaria
A recent outbreak of the Zika virus in the Americas has brought mosquitoes buzzing onto the front pages of newspapers. With a bite, infected mosquitoes can transmit Zika to humans. While most adults will experience only mild symptoms from the virus, the results can be devastating for a fetus carried by an infected mother. Evidence suggests that the Zika virus is likely responsible for a surge of birth defects in Brazil, and nearby countries are on high alert as the virus spreads. Of course, Zika is in the news now, but mosquito-borne diseases are nothing new. Malaria, in particular, threatens human health on an even wider scale than Zika. The malaria protozoan kills hundreds of thousands each year despite our efforts to snuff it out. Campaigns to fight malaria have tackled the problem on many fronts — treating the disease with new drugs, helping people protect themselves from insect bites, and reducing mosquito populations. With advances in genetic technology, scientists are investigating a new approach: genetically engineering mosquitoes to resist the malaria parasite. In fact, in 2012, researchers showed that mosquitoes engineered to carry two different malaria resistance genes, could not transmit the disease at all! But in order to actually combat malaria with this exciting discovery, we’d need to figure out how to get the resistance genes to spread through mosquito populations…
Read more »Unmuddying the Cambrian waters
Any scholar of history knows that the further back in time you go seeking answers, the more sparse and unreliable the clues. Paleontology is the study of the history of life, and its clues — for the most part — take the form of fossils. The fossil record is notoriously incomplete, but in general, we have more direct evidence of life in the recent past than we do of life in the most distant past. It should therefore not be surprising that one of the most studied events in evolution, the Cambrian “explosion” (which started about 542 million years ago and lasted — unlike most explosions — over 10 million years), is also one of the most enigmatic and passionately debated. Can new research bring the life of the Cambrian into focus?
Read more »Will evolution doom the cheetah?
Few people will disagree: cheetahs are impressive creatures. These majestic cats are the bold sprinters of the Serengeti, propelling themselves at bursts of speed that are estimated to reach 75 mph, and accelerating from 0 to 60 mph as fast as a Ferrari 458 Italia or Porsche 911. Evolutionary changes to this species’ heart, respiratory system, muscles and limbs have landed them the title of fastest land animal. Unfortunately, this beautiful animal is at risk of extinction. Though the cheetah’s numbers have been depleted in recent history from poaching, habitat loss and the illegal pet trade, their vulnerability goes back even further than this. So who or what is the culprit? It may surprise you to learn that the answer is none other than evolution…
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