As they scrub the smeared ink from their wrists yet again, left-handed people must sometimes wonder what the point of all this is. Why do we have a dominant hand, anyway? However arbitrary it seems, we’re not alone in favoring one side over the other—there are all kinds of animals with a preferred paw, claw, or swimming direction. Now flying birds have flapped into the club. In at least one species, birds tend to veer one direction over the other when faced with an obstacle. More than just a pointless impediment to scissors use, “handedness” in birds might keep their flocks flying.
The birds in question are budgerigars, or budgies. Better known to Americans as ordinary pet parakeets, in Australia these birds travel the desert and scrubland in dense flocks. University of Queensland neuroscientist Mandyam Srinivasan says that flying this way without crashing isn’t a trivial task. “Whilst landing on a tree, for example, it would be important to find a clear path,” he says, “as well as avoid collisions with other birds.”
You might say the benefit of staying alive is an actual no-brainer: even brainless lifeforms do their best not to die. For the most part, anyway. When they’re under stress, single-celled organisms may opt to cut up their DNA and neatly implode. A new study hints that by committing suicide in this way, an organism helps its nearby relatives to stay alive—and hurts its rivals at the same time.
In animals with many cells like us, cellular suicide happens all the time, and it helps keep the whole organism in tip-top shape. As embryos, for example, the cells that form our little paws kill themselves off to make fingers. We’re born with a brain that’s too densely connected, and as we grow the superfluous brain cells die to get things in order. Even as adults, our bodies’ regular upkeep includes constantly adding new cells and commanding older ones to die.
If your entire body consists of one cell, the benefit of killing it is less obvious. Yet various single-celled organisms—from fungi to parasites to bacteria—have been shown to off themselves under stress.
Pierre Durand, an evolutionary biologist at the University of the Witwatersrand in Johannesburg, has been trying to figure out why. In an earlier study with a single-celled algae called Chlamydomonas reinhardtii, Durand grew cells in the liquid where other cells had previous killed themselves (in response to heat stress). The algae grew faster than usual in the suicide liquid. But liquid where cells had been killed from the outside (the researchers tore them apart with sound waves) was harmful to living cells. A cell that dies suddenly leaks toxic contents into its surroundings, but cells that commit suicide apparently don’t—and even leave behind something healthy for other cells to eat. Read More
It was a battle fought in the mountains of southwestern China, where patchy forests sustain the last shreds of the wild giant panda population. All at once, intruders began marching in and helping themselves to the pandas’ food. The incursion happened far from most human eyes, and the pandas that witnessed it likely didn’t know what to think. It’s not often that one sees a horse in a bamboo forest.
In these woods, the Wolong National Nature Reserve is an important refuge for pandas. About a tenth of the entire wild panda population lives there—although that amounts to only 150 or so animals. They share the space with around 5,000 humans, most of whom are farmers who graze their livestock in designated areas.
A new trend emerged among these farmers in the 2000s as they began to do more business with an adjacent township where horses are reared. Though the Wolong farmers had previously raised cattle, pigs, goats, and yaks, they now began buying horses too.
“We first realized the problem while we were hiking in panda habitat and conducting habitat sampling for our research in 2009,” says Vanessa Hull, a graduate student at Michigan State University. Large areas of forest were “mowed down by horses,” she says. “It was honestly a shock to me.” Read More
Learning to walk would be even harder if babies had to do it in jello. This is roughly the problem faced by young Humboldt squid. They start out life at one one-thousandth of their adult size and have to fight against the sticky water molecules surrounding them as they learn how to swim. They deal with it by sometimes swimming like jellyfish instead of squid (and hoping they survive long enough to grow).
Danna Staaf and her colleagues at the Hopkins Marine Station of Stanford University studied the swimming styles of newly hatched Humboldt squid. With a mantle (the bell-shaped part) less than a millimeter long, these might be the tiniest squid in the sea. The researchers picked apart their subjects’ swimming motions in high-speed videos, one frame at a time—sort of like a TV sports commentator analyzing Michael Phelps’s backstroke, if Phelps quadrupled his number of arms and was transparent. Read More
Pretty blossoms aren’t immune to the body-morphing, plague-spreading powers of a good microbe. Some of the flowers you admire on a spring day might only be blooming, for example, because they’re hostages of a disease. Plant diseases can’t scatter in sneeze droplets like a human virus can. But they can change the look and behavior of their hosts to make sure they travel as widely—and dangerously—as possible.
1. Replacing pollen with disease bombs
In a new review of flower diseases (title: “Arranging the bouquet of disease”), Scott McArt of the University of Massachusetts at Amherst and his colleagues examined the ways that infectious microbes can alter their host plants. One such microbe is a fungus called Microbotryum violaceum, which infects plants in the carnation family.
Plants are infected with the fungus when pollinating insects visit, carrying spores another infected plant has dusted onto their bodies. The fungus burrows down into the new plant, finds the site of developing pollen, and destroys it. Then it replaces the flower’s packets of pollen with its own spores. Read More
No need to start from scratch. Here, someone else already took a wolf and made you a perfectly serviceable sea-level dog. With some genetic tweaking, you can craft a powerful pet that isn’t bothered by living on an oxygen-starved mountaintop. A few of the same tweaks to your DNA will even let you live there with it.
This is no cockapoo or schnoodle. The Tibetan mastiff and the dog it was bred from, called the Chinese native dog, are ancient breeds, thousands of years old. Tibetan mastiffs live comfortably on the Tibetan Plateau, which with an average elevation of over 4,500 meters is nearly three times as high as Denver. Residents keep the bulky, athletic beasts as guard dogs.
Chinese geneticist Ya-Ping Zhang, along with an international group of coauthors, wanted to know what mutations in canine DNA had created this altitude-loving breed. They gathered DNA from 32 Tibetan mastiffs, along with 20 Chinese native dogs and 14 wolves—the starting material. Read More
Scott MacIvor has cracked open hundreds of artificial bee nests. But two he peered inside in Toronto gave him pause. Within their containers, the bees he studies had carefully built homes for their young out of plastic debris. Mixed in with the usual construction materials of leaves and mud, MacIvor could clearly see bits of shopping bag.
These aren’t the hive-dwelling honeybees you know from your backyard. For his PhD research at York University, MacIvor studies so-called solitary bees. Megachile bees live on their own, feeding from and pollinating flowers. Females find a cozy space they can fit into—maybe a hole in a tree, or the inside of a plant stem—and begin building a nest inside it. They lay one egg at a time, tucked away with a little ball of food for when it hatches. Then they wall off the egg and food into a compartment, or cell, and start work on the next one. The adults don’t live long, so the baby bees will be on their own when they hatch.
MacIvor uses pieces of PVC piping to lure solitary bees and study the nests they build inside. It was while observing these traps such as these, which he’d set up around Toronto to study how an urban setting affects the bees, that he discovered some nests that were not exactly traditional. Read More
It’s not the reason you’d guess. They make perfectly pleasant-smelling neighbors. Yet skunks and other animals that use projectile stink as a weapon are apparently destined by evolution to be loners—not because of who they are, but because of who preys on them.
Ted Stankowich, who studies the intersection of evolution, animal behavior and ecology at California State University, Long Beach, promises skunks aren’t offensive to each other. “They try not to get it on themselves,” he says; they spray directed streams of foul liquid only at their attackers. “There’s no social repulsion from other members of [their] species.”
Yet when Stankowich and his coauthors scrutinized the lifestyles of 181 carnivorous mammal species, they found that the stink sprayers are loners. None of these animals—which included stink badgers, grisons, and zorillas as well as skunks—live in groups, the way social animals such as otters, hyenas or foxes do. Read More
In a dirt-floored room in Austria, a puppy sniffed and pawed at a wooden box with a treat inside. It circled the box over and over, unable to find a way in. Finally it sat at the feet of a nearby human and looked up at her appealingly, swishing its tail. The woman stared at the ceiling, ignoring the puppy. The answer wouldn’t come from her—if the dog wanted the treat, it would have to imitate the way it had seen another dog open the box earlier.
The puppy ultimately failed, as did most other dogs in this experiment. But all of the wolves that tried it succeeded easily. The reason may be that in creating domestic dogs that pay attention to us, we robbed them of the ability to learn from each other. Read More