ScienceAdviser: Mice employ aggressive first aid to resuscitate unresponsive companions

You don’t even realize you’re doing it: The person you’re talking to blinks and you blink back. This subtle nonverbal exchange apparently helps humans and other primates bond. And according to a new study, dogs, too, may unwittingly use quick eye closing to connect.

It’s known that domestic dogs tend to blink more around other dogs. They also appear to blink to keep the peace with their canine companions—and humans as well—when tensions rise. To find out if dogs engage in reciprocal blinking, researchers created videos of dogs blinking, staring ahead without blinking, or licking their noses—a gesture that can signal  eagerness or frustration. When the researchers showed these videos to 54 adult pet dogs, the animals blinked about 16% more on average when watching the other dog blinking than during the two other kinds of scenes, the team reported this week  in Royal Society Open Science.

Like people, the dogs probably aren’t aware of these reactions. But the work “raises fascinating questions about how [dogs] communicate,” says Martina Francesconi, an ethologist who was not involved in the study. “They might be more in tune with one another than we realized.”

When a person collapses in public, folks nearby will often rush to revive them with CPR and other emergency measures. But humans aren’t the only animals with an instinct for first aid: Elephants, chimpanzees, and dolphins can recognize when an individual is incapacitated and will respond with behaviors like touching, grooming, and nudging. Now, scientists have discovered that mice also have an innate urge to rescue unconscious companions.

In a new Science study, researchers report that rodents increased the time they spent sniffing and grooming a peer when the mouse was drugged into unconsciousness. As the drugged animal became more and more unresponsive, the “bystander” turned to more... aggressive first aid tactics. “They start with sniffing, and then grooming, and then with a very intensive or physical interaction ,” study co-author Li Zhang tells New Scientist. “They really open the mouth of this animal and pull out its tongue.” The team found that this intense form of mouth-to-mouth resuscitation actually helped enlarge the animal’s airway, allowing it to recover faster. The study authors traced these behaviors to a part of the brain called the paraventricular nucleus, where neurons produce oxytocin—a hormone that promotes empathy-like behavior in rodents. The authors of a second Science study, however, found similar results when they examined the medial amygdala, which plays a role in a variety of innate social behaviors.

“These findings add to the evidence that an impulse to help others in states of extreme distress is shared by many species and highlight neural mechanisms that drive instinctive rescue,” neuroscientists William Sheeran and Zoe Donaldson write in a related Science Perspective.

Read the science papers on THE BEHAVIOR and the Neural Basis

When it comes to evolution, some species are simply better than others. No matter what challenges the world throws at them, they seem to effortlessly adapt. But does such evolvability, well, evolve?

To find out, researchers grew Pseudomonas fluorescens bacteria under two sets of conditions: one that favored mat-making, cellulose-producing bacteria, and one that favored ‘cheating’ mat-colonizing, non-cellulose-producing bacteria. The cultures were then swapped, and any bacteria that failed to evolve the other phenotype within 6 days were tossed. While most lineages died out eventually, some evolved the ability to switch between the two forms with ease—thanks in part to mutation rates in a certain part of the genome that were up to 350 times higher than seen in the original bacteria , they report in this week’s issue of Science.

The findings run counter to the idea that evolution is random, the team explains. “Natural selection amplifies traits beneficial in the present environment and is ‘blind’ to future contingencies,” they write, so it shouldn’t lead to changes that facilitate future adaptation. And yet, it did. “I don’t know of another experiment that has demonstrated the de novo origin of this phenomenon,” evolutionary biologist Richard Lenski tells New Scientist.

The results have “powerful implications,” writes Edo Kussell in a related Perspective, “given the huge metapopulations with billions of parallel lineages that exist in nature.” 

Quick: Name something venomous.

If I had to guess, you probably said “snake” or “spider.” As someone who wrote a book on venomous creatures, I’ll give you bonus points if you said box jelly, blue-ringed octopus, or platypus (really!). All of those are correct answers—but they also reveal our bias when talking about venoms. That is, there is a general sense that these potent chemical cocktails are the evolutionary inventions of animals. But in a new review, Loma Linda University venom scientist William Hayes and colleagues point out that there are myriad venomous branches throughout the tree of life—and by studying oft-overlooked  venomous organisms, we can learn much more about the biology, ecology, and evolution of venoms, as well as how to use that knowledge to our own benefit.

Hayes says the paper, published this month in Toxins, was inspired by his students. More than a decade ago, he began teaching a graduate course on the biology of venoms, which initially focused on the various definitions of venom that existed in the literature. Class discussions led to a paper laying out straightforward definitions for the various kinds of toxic lifeforms : Those that are venomous—meaning they introduce toxins via some kind of wound—as opposed to poisonous (those with toxins that enter passively, via ingestion, absorption, or inhalation) or toxungenous (those that actively fling toxins, even though those toxins themselves act like poisons). But the class also got Hayes and his students thinking about what other living things might fit under such classifications. That “forced us to contemplate examples among non-animals,” he tells me. “The deeper we dug into those examples, the more convinced we became that venom wasn't invented solely by animals. It's a remarkable adaptation that is far, far more widespread and ubiquitous than currently recognized.”

When writing Venomous, I did decide to focus on animals, though like anyone who has encountered a stinging nettle, I was well aware of venomous plants. Still, even I didn’t appreciate the diversity of members of the green venomous club that Hayes et al . highlight in the review. Hundreds of plant species are myrmecophytes, meaning they partner with ants; the flora provide food and a place to live, while the fauna defend their live-in dining viciously. That makes them functionally venomous, says Hayes. “The plants can actually increase the size of their ant colonies in response to grazing by herbivores and even manipulate the ants to preferentially frequent the younger leaves,” he explains. “These strategies resemble the decision-making of snakes, scorpions, and other animals that can control how much venom they deliver during a bite or sting, a trait we call venom-metering.”

I also hadn’t realized that the third kingdom of complex life—the fungi—also boasts venomous members in addition to poisonous ones. Not only do their root-like hyphae sometimes puncture plants or animals to deliver toxins, some have evolved specialized structures specifically for injecting awful stuff. “One group of fungi that parasitizes plants can enter their tissue by forming a specialized penetrating structure (an appresorium) that allows a portion of the fungus to squeeze in and secrete toxins that destroy the plant’s cells,” Hayes points out. “The fungus then feeds on the dead cells”—not entirely unlike how a spider slurps up the remains of a liquified bug.

And venomous lifeforms come in even smaller sizes, Hayes and colleagues note. There are single-celled protists and even bacteria with specialized structures for injecting toxins into other cells. By that standard, many viruses might count as venomous, though whether they’re considered “lifeforms” is debatable. Bacteriophages inject bacteria with chemicals and the genetic instructions for their own making, for instance. “By the consensus criteria for a venom delivery system, viruses could be regarded as the most abundant venomous life form on this planet,” Hayes et al. write.

Ultimately, Hayes says, the diversity of examples of venomous organisms should have toxinologists rethinking their basic assumptions about venom. What we know now is based on “a mere fraction of the evolutionary events that have culminated in its usage,” he and his colleague write. “No rational reason exists to exclude these entities from dialogue regarding the evolution and nature of venoms, venom delivery systems, and venomous organisms.”

And welcoming these toxic entities into the venomous fold will only add to our scientific understanding of venoms, the team says. “We can expect to learn many new and exciting things about the evolutionary pathways of venom divergence … the ecological benefits and costs of venom use… the behavioral aspects of strategic venom deployment … and potential applications for biotechnology and human therapeutics,” they conclude.

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