Entries Tagged "natural security"

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Risk Preferences in Chimpanzees and Bonobos

I’ve already written about prospect theory, which explains how people approach risk. People tend to be risk averse when it comes to gains, and risk seeking when it comes to losses:

Evolutionarily, presumably it is a better survival strategy to—all other things being equal, of course—accept small gains rather than risking them for larger ones, and risk larger losses rather than accepting smaller losses. Lions chase young or wounded wildebeest because the investment needed to kill them is lower. Mature and healthy prey would probably be more nutritious, but there’s a risk of missing lunch entirely if it gets away. And a small meal will tide the lion over until another day. Getting through today is more important than the possibility of having food tomorrow.

Similarly, it is evolutionarily better to risk a larger loss than to accept a smaller loss. Because animals tend to live on the razor’s edge between starvation and reproduction, any loss of food—whether small or large—can be equally bad. That is, both can result in death. If that’s true, the best option is to risk everything for the chance at no loss at all.

This behavior has been demonstrated in animals as well: “species of insects, birds and mammals range from risk neutral to risk averse when making decisions about amounts of food, but are risk seeking towards delays in receiving food.”

A recent study examines the relative risk preferences in two closely related species: chimanzees and bonobos.


Human and non-human animals tend to avoid risky prospects. If such patterns of economic choice are adaptive, risk preferences should reflect the typical decision-making environments faced by organisms. However, this approach has not been widely used to examine the risk sensitivity in closely related species with different ecologies. Here, we experimentally examined risk-sensitive behaviour in chimpanzees (Pan troglodytes) and bonobos (Pan paniscus), closely related species whose distinct ecologies are thought to be the major selective force shaping their unique behavioural repertoires. Because chimpanzees exploit riskier food sources in the wild, we predicted that they would exhibit greater tolerance for risk in choices about food. Results confirmed this prediction: chimpanzees significantly preferred the risky option, whereas bonobos preferred the fixed option. These results provide a relatively rare example of risk-prone behaviour in the context of gains and show how ecological pressures can sculpt economic decision making.

The basic argument is that in the natural environment of the chimpanzee, if you don’t take risks you don’t get any of the high-value rewards (e.g., monkey meat). Bonobos “rely more heavily than chimpanzees on terrestrial herbaceous vegetation, a more temporally and spatially consistent food source.” So chimpanzees are less likely to avoid taking risks.

Fascinating stuff, but there are at least two problems with this study. The first one, the researchers explain in their paper. The animals studied—five of each species—were from the Wolfgang Koehler Primate Research Center at the Leipzig Zoo, and the experimenters were unable to rule out differences in the “experiences, cultures and conditions of the two specific groups tested here.”

The second problem is more general: we know very little about the life of bonobos in the wild. There’s a lot of popular stereotypes about bonobos, but they’re sloppy at best.

Even so, I like seeing this kind of research. It’s fascinating.

EDITED TO ADD (5/13): Response to that last link.

Posted on April 17, 2008 at 6:20 AMView Comments

Security Arms Races in Duck Oviducts and Phalluses

Interesting research at Yale:

Dr. Brennan argues that elaborate female duck anatomy evolves as a countermeasure against aggressive males. “Once they choose a male, they’re making the best possible choice, and that’s the male they want siring their offspring,” she said. “They don’t want the guy flying in from who knows where. It makes sense that they would develop a defense.”

Female ducks seem to be equipped to block the sperm of unwanted males. Their lower oviduct is spiraled like the male phallus, for example, but it turns in the opposite direction. Dr. Brennan suspects that the female ducks can force sperm into one of the pockets and then expel it. “It only makes sense as a barrier,” she said.

To support her argument, Dr. Brennan notes studies on some species that have found that forced matings make up about a third of all matings. Yet only 3 percent of the offspring are the result of forced matings. “To me, it means these females are successful with this strategy,” she said.

Dr. Brennan suspects that when the females of a species evolved better defenses, they drove the evolution of male phalluses. “The males have to step up to produce a longer or more flexible phallus,” she said.

Posted on May 3, 2007 at 7:45 AMView Comments

Friday Squid Blogging: Steganographic Squid

Seems that some squid can hide messages in their skin:

In the animal world, squid are masters of disguise. Pigmented skin cells enable them to camouflage themselves—almost instantaneously—from predators. Squid also produce polarized skin patterns by regulating the iridescence of their skin, possibly creating a “hidden communication channel”? visible only to animals that are sensitive to polarized light.


Mäthger and Hanlon’s findings present the first anatomical evidence for a “hidden communication channel”? that can remain masked by typical camouflage patterns. Their results suggest that it might be possible for squid to send concealed polarized signals to one other while staying camouflaged to fish or mammalian predators, most of which do not have polarization vision.

My favorite security stories are from the natural world. Evolution results in some of the most interesting security countermeasures.

Posted on September 29, 2006 at 2:59 PMView Comments

Ants Staging Ambushes

From Nature via BoingBoing:

Using a home-made trap, a tiny species of ant is capable of ensnaring prey much larger than itself and tearing it to pieces.

The ants (Allomerus decemarticulatus), which live in Amazonian plants called Hirtella physophora, construct a honeycomb-like structure out of their host plant’s fibres from which they can stage an ambush.

The worker ants hide in the holes of this death trap with their mouths open wide, waiting for locusts, butterflies or other insects to land. When prey arrives they quickly seize its extremities, pulling on legs, arms and antennae until the hostage is rendered immobile. Once trapped, other ants from the colony arrive to sting and bite the prey until it is paralyzed.

Posted on April 26, 2005 at 9:52 AMView Comments

Camouflage in Octopodes

From Nature.com:

Two tiny species of tropical octopus have demonstrated a remarkable disappearing trick. They adopt a two-armed “walk” that frees up their remaining six limbs to camouflage them as they slink away from trouble.

I have a fondness for security countermeasures in the natural world. As people, we try to figure out the most effective countermeasure for a given attack. Evolution works differently. A species tries different countermeasures at random, and stops at the first one that just barely works.

(I found this on BoingBoing.)

Posted on March 28, 2005 at 12:38 AMView Comments

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Sidebar photo of Bruce Schneier by Joe MacInnis.