Entries Tagged "natural security"

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Self-Domestication in Bonobos and Other Animals

Self-domestication happens when the benefits of cooperation outweigh the costs:

But why and how could natural selection tame the bonobo? One possible narrative begins about 2.5 million years ago, when the last common ancestor of bonobos and chimpanzees lived both north and south of the Zaire River, as did gorillas, their ecological rivals. A massive drought drove gorillas from the south, and they never returned. That last common ancestor suddenly had the southern jungles to themselves.

As a result, competition for resources wouldn’t be as fierce as before. Aggression, such a costly habit, wouldn’t have been so necessary. And whereas a resource-limited environment likely made female alliances rare, as they are in modern chimpanzees, reduced competition would have allowed females to become friends. No longer would males intimidate them and force them into sex. Once reproduction was no longer traumatic, they could afford to be fertile more often, which in turn reduced competition between males.

“If females don’t let you beat them up, why should a male bonobo try to be dominant over all the other males?” said Hare. “In male chimps, it’s very costly to be on top. Often in primate hierarchies, you don’t stay on top very long. Everyone is gunning for you. You’re getting in a lot of fights. If you don’t have to do that, it’s better for everybody.” Chimpanzees had been caught in what Hare called “this terrible cycle, and bonobos have been able to break this cycle.”

This is the sort of thing I write about in my new book. And with both bonobos and humans, there’s an obvious security problem: if almost everyone is non-aggressive, an aggressive minority can easily dominate. How does society prevent that from happening?

Posted on February 17, 2012 at 6:25 AM • View Comments

Feeling vs. Reality of Security in Sparrows

Sparrows have fewer surviving offspring if they feel insecure, regardless of whether they actually are insecure. Liana Y. Zanette, Aija F. White, Marek C. Allen, and Michael Clinchy, “Perceived Predation Risk Reduces the Number of Offspring Songbirds Produce per Year,” Science, 9 Dec 2011:

Abstract: Predator effects on prey demography have traditionally been ascribed solely to direct killing in studies of population ecology and wildlife management. Predators also affect the prey’s perception of predation risk, but this has not been thought to meaningfully affect prey demography. We isolated the effects of perceived predation risk in a free-living population of song sparrows by actively eliminating direct predation and used playbacks of predator calls and sounds to manipulate perceived risk. We found that the perception of predation risk alone reduced the number of offspring produced per year by 40%. Our results suggest that the perception of predation risk is itself powerful enough to affect wildlife population dynamics, and should thus be given greater consideration in vertebrate conservation and management.

Seems as if the sparrows could use a little security theater.

Posted on December 14, 2011 at 1:22 PM • View Comments

Security Systems as a Marker for High-Value Targets

If something is protected by heavy security, it’s obviously worth stealing. Here’s an example from the insect world:

Maize plants, like many others, protect themselves with poisons. They pump their roots with highly toxic insecticides called BXDs, which deters hungry mandibles. But these toxins don’t come free. The plant needs energy to act as its own pharmacist, so it distributes the poison to the areas that deserve the greatest fortification—its crown roots.

Maize seedlings grow roots either from the embryo itself (embryonic roots), or from the growing stem (crown roots). Christelle Robert found that the crown roots are especially important. They contain the most nutrients, and their loss matters more to the seedlings. As such, they receive the greatest investment of BXDs; they contain five times more of one particularly toxic compound called DIMBOA.

So, if plant-eating insects want to nibble on the most nutritious roots, they also swallow the highest amount of poison. Instead, they target the more lightly defended embryonic roots, which are less valuable to the plant. But the Western corn rootworm ignores these rules of engagement.

The larva of this beetle eats the roots of maize, corn and other cereals and it’s a significant pest that can ravage entire crops. Its success stems from its ability to turn maize’s defence against it. Robert found that the rootworm, unlike other insects, ignore the embryonic roots and head straight for the crown ones.

When Robert gave rootworms a mutant plant that couldn’t produce BXDs, it lost its interest in the crown roots. Rather than being deterred by the plant’s poisons, the rootworm actually uses them to track down the most nutritious meals.

The rootworms are immune to the poison, of course. Otherwise the trick wouldn’t work.

Paper, behind a paywall.

Posted on November 29, 2011 at 2:13 PM • View Comments

Spider Webs Contain Ant Poison

Shichang Zhang, Teck Hui Koh, Wee Khee Seah, Yee Hing Lai, Mark A. Elgar, and Daiqin Li (2011), “A Novel Property of Spider Silk: Chemical Defence Against Ants,” Proceedings of the Royal Society B: Biological Sciences (full text is behind a paywall).

Abstract: Spider webs are made of silk, the properties of which ensure remarkable efficiency at capturing prey. However, remaining on, or near, the web exposes the resident spiders to many potential predators, such as ants. Surprisingly, ants are rarely reported foraging on the webs of orb-weaving spiders, despite the formidable capacity of ants to subdue prey and repel enemies, the diversity and abundance of orb-web spiders, and the nutritional value of the web and resident spider. We explain this paradox by reporting a novel property of the silk produced by the orb-web spider Nephila antipodiana (Walckenaer). These spiders deposit on the silk a pyrrolidine alkaloid (2-pyrrolidinone) that provides protection from ant invasion. Furthermore, the ontogenetic change in the production of 2-pyrrolidinone suggests that this compound represents an adaptive response to the threat of natural enemies, rather than a simple by-product of silk synthesis: while 2-pyrrolidinone occurs on the silk threads produced by adult and large juvenile spiders, it is absent on threads produced by small juvenile spiders, whose threads are sufficiently thin to be inaccessible to ants.

Posted on November 28, 2011 at 12:55 PM • View Comments

Rat that Applies Poison to its Fur

The African crested rat applies tree poison to its fur to make itself more deadly.

The researchers made their discovery after presenting a wild-caught crested rat with branches and roots of the Acokanthera tree, whose bark includes the toxin ouabain.

The animal gnawed and chewed the tree’s bark but avoided the nontoxic leaves and fruit. The rat then applied the pasty, deadly drool to spiky flank hairs. Microscopes later revealed that the hairs are actually hollow quills that rapidly absorb the ouabain-saliva mixture, offering an unpleasant surprise to predators attempt to taste the rat.

Posted on August 12, 2011 at 11:13 AM • View Comments

Zombie Fungus

The security connection is pretty tenuous, so I figured I’d blog this on a Saturday.

Once it infects an ant, the fungus uses as-yet-unidentified chemicals to control the ant’s behavior, Hughes told LiveScience. It directs the ant to leave its colony (a very un-ant-like thing to do) and bite down on the underside of a leaf—the ant’s soon-to-be resting place. Once it is killed by the fungus, the ant remains anchored in place, thanks to its death grip on the leaf.

Ultimately, the fungus produces a long stalk that protrudes from the ant’s head, shooting spores out in the hopes of infecting other ants. Two of the four newly discovered species also sprouted smaller stalks elsewhere, including from the victim’s feet and lower leg joints – the equivalent of knees.

Posted on March 19, 2011 at 9:12 AM • View Comments

Ant Warfare

Interesting:

According to Moffett, we might actually learn a thing or two from how ants wage war. For one, ant armies operate with precise organization despite a lack of central command. “We’re accustomed to being told what to do,” Moffett says. “I think there’s something to be said for fewer layers of control and oversight.”

Which, according to Moffett, is what can make human cyberwar and terrorist cells so effective. Battles waged on the web are often “downright ant-like,” with massive, networked groups engaging in strategic teamwork to rise up with little hierarchy. “Such ‘weak ties’ ­ wide-ranging connections that take us beyond the tight-knit groups we interact with regularly—are likely of special importance in organizing both ants and people,” Moffett notes in his book.

Posted on August 9, 2010 at 7:12 AM • View Comments

Security Trade-Offs in Crayfish

Interesting:

The experiments offered the crayfish stark decisions—a choice between finding their next meal and becoming a meal for an apparent predator. In deciding on a course of action, they carefully weighed the risk of attack against the expected reward, Herberholz says.

Using a non-invasive method that allowed the crustaceans to freely move, the researchers offered juvenile Louisiana Red Swamp crayfish a simultaneous threat and reward: ahead lay the scent of food, but also the apparent approach of a predator.

In some cases, the “predator” (actually a shadow) appeared to be moving swiftly, in others slowly. To up the ante, the researchers also varied the intensity of the odor of food.

How would the animals react? Did the risk of being eaten outweigh their desire to feed? Should they “freeze”—in effect, play dead, hoping the predator would pass by, while the crayfish remained close to its meal—or move away from both the predator and food?

To make a quick escape, the crayfish flip their tails and swim backwards, an action preceded by a strong, measurable electric neural impulse. The specially designed tanks could non-invasively pick up and record these electrical signals. This allowed the researchers to identify the activation patterns of specific neurons during the decision-making process.

Although tail-flipping is a very effective escape strategy against natural predators, it adds critical distance between a foraging animal and its next meal.

The crayfish took decisive action in a matter of milliseconds. When faced with very fast shadows, they were significantly more likely to freeze than tail-flip away.

The researchers conclude that there is little incentive for retreat when the predator appears to be moving too rapidly for escape, and the crayfish would lose its own opportunity to eat. This was also true when the food odor was the strongest, raising the benefit of staying close to the expected reward. A strong predator stimulus, however, was able to override an attractive food signal, and crayfish decided to flip away under these conditions.

It’s not that this surprises anyone, it’s that researchers can now try and figure out the exact brain processes that enable the crayfish to make these decisions.

Posted on June 25, 2010 at 6:53 AM • View Comments

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Sidebar photo of Bruce Schneier by Joe MacInnis.