Game theory models based on repeated interactions between two individuals have often been the framework for understanding cooperative interactions in humans, but these models rarely apply in nature. Non-human animals, after all, rarely find themselves in situations like the “prisoner’s dilemma.”

Instead, partner choice and competition are emerging as the framework for understanding cooperation in the natural world. Some mutualisms (biological interactions between organisms where each individual derives a fitness benefit) can be described as “biological markets,” where organisms exchange goods or services. These markets and the animals that participate in them share some similarities with humans and our markets: animals preferentially interact with partners that provide the highest-quality goods or services; animals sometimes cheat each other; competition is often a good thing, and threatening to take your business elsewhere can lead to more cooperative behavior from your partner.

In many cleaner mutualisms among fish, cleaner fish occupy cleaner “stations” where they remove parasites from cooperating client fish. Buyer beware, though, because clients often have to wait for service from a cleaner and when it’s finally their turn, they may be cheated by cleaners that feed on tissue or mucous instead of parasites. Clients don’t have many options for ensuring good service. They can’t demand their mucous back or complain to management. What they can do is go get cleaned somewhere else.

Thomas C. Adam, a graduate student at the Department of Ecology, Evolution, and Marine Biology at the University of California, Santa Barbara, investigated cleaner-client interactions involving the territorial butterflyfish Chaetodon ornatissimus . In the Maharepa lagoon on the north shore of Moorea, French Polynesia, C. ornatissimus (at left) is the preferred client of bluestreak cleaner wrasse (at right), but has the option of partnering with several other species of cleaners common to the area. Snorkelers mapped the territorial boundaries of C. ornatissimus and conducted hour-long observations of their interactions with their cleaners (in total, individual fish in 32 territories were observed for 43 hours).

The results of the study indicate that not only do bluestreak cleaner wrasse compete for access to their butterflyfish clients (the amount of time cleaners had access to clients was negatively associated with the number of cleaner stations in a territory and individual butterflyfish with access to multiple cleaner stations did, indeed, shop around and were less likely to return to a cleaner station for their next cleaning than individuals with access to just one cleaner station), but the ability of butterflyfish to take their business elsewhere got them higher-quality service from cleaners. To wit, (1) the observed clients were never ignored by cleaners (at left) when they had more than one cleaner station in their territory (in contrast, five of 11 fish with a single cleaner station in their territory were observed being ignored), (2) while there was no evidence that clients with access to multiple cleaner stations were cheated less frequently than clients without access, the clients with their choice of partners were less likely have interactions terminated early by cleaners and were inspected for significantly longer during each cleaning session.
See? The free market does work sometimes.

Reference: Adam, T. (2010). Competition encourages cooperation: client fish receive higher-quality service when cleaner fish compete Animal Behaviour, 79 (6), 1183-1189 DOI: 10.1016/j.anbehav.2010.02.023

KJZ2QQZUA2N6

I recently took part in what social scientists call a “vacancy chain” (a social structure through which vacancies in discrete, reusable, and limited resources propagate through a population) and all I needed was a moving truck, a few helpful relatives, a case of beer and a few pizzas. You see, when my girlfriend and I moved into a new house in May, we filled a vacancy left by the previous tenants. When we moved, someone moved into our old apartment and filled the vacancy we left. Their apartment, in turn, was filled by someone else, and their apartment was moved in to by someone else and so on and so forth. Somewhere (further up the chain than me), a vacancy was created and propagated down the socioeconomic order through a series of interdependent events and resulted in many individuals acquiring new, sometimes better (we have a patio, but no central air, so the jury is still out), resources and benefiting from them.

Hermit crabs, for whom really nice shells to call home are a scarce commodity, have evolved their own sorts of vacancy chains as way for optimizing shell acquisition and occupancy. While these shell vacancy chains have been described (and shown to provide aggregate benefits that are distributed across many participants) for several hermit crab species in previous research, not much was known about the behaviorial and ecological factors that lead to and influence them.

Cue the arrival of Randi Rotjan, Jeffrey R. Chabot and Sara M. Lewis (from the New England Aquarium in Boston, the Pfizer Research Technology Center in Cambridge, MA and the Department of Biology at Tufts University, respectively) at Carrie Bow Cay, a ¾-acre island located near the Belizean barrier reef that is home to Eighty-four palm trees and 1,084 purple-clawed hermit crabs of the terrestrial species Coenobita clypeatus.While the biologists were there study parrotfish, bad weather made the water too rough for diving, so they used their time to better understand shell vacancy chains. The researchers marked 20 locations around the island, set out a single vacant shell at dusk at each one and monitored them. Over the course of 24 hours they observed a total of 16 vacancy chains of two different types, asynchronous and synchronous.

An asynchronous chain occurs when one crab moves into a new, empty shell and abandons its old one to be found by another crab, which abandons its own for another crab to find, etc. With this type of chain, shell switching is sequential and the crabs experience little to no interference or competition. They have the opportunity to investigate any vacant shells they find and can directly compare their current shell with a new shell by switching back and forth between the two. The down side is that individual crabs aren’t very likely to just stumble upon a vacant shell that meets their specific size and quality requirements. It’s like if I told you that you could wander around your town, go into any unoccupied houses you wanted, check them out and pick your dream home, but you’d have to find the one with two bedrooms, a dishwasher and a fireplace on your own by chance, without the aid of Craigslist.

Synchronous shell vacancy chains are more social and much more interesting. They start off with “waiters,” crabs that hang around a shell that’s too big for them, and wait for a bigger crab to come along so that if the big crab moves in to the vacant shell, the waiter can grab their more appropriately-sized hand-me-down shell (the researchers note that the decision to wait, and how long to wait, based on previous experience, provides some evidence that the crabs are smarter than we thought). The chains that the researchers observed began with one to 20 waiters who spent anywhere from a few minutes to an hour-plus loitering around empty shells. As a crowd gathers, the crabs queue up by size, from largest to smallest, and once largest crab switches into the vacant shell, each crab climbs into a new shell as it’s vacated by the slightly larger crab ahead of it, quickly shuffling vacancies (literally) down the chain. In both chain types, the fun stops when the last shell vacated is so low in quality (too small or damaged) that all the crabs reject it.

A Synchronous Chain in Action

In addition to the waiting that kicks off synchronous chains, the researchers observed other unique shell acquisition behaviors that the crabs only exhibited in social contexts and appeared to be associated with the vacancy chains. At almost half of the observed locations, when the waiting crabs were all too small for they vacant shell they had gathered around, some would “piggyback,” or form lines with each crab grasping the shell of another crab from behind and frequently moving in and out of the line to jockey for a better positions. The researchers hypothesize that piggybacking may be help establish a dominance hierarchy among the waiting crabs and/or allow them to investigate some of the shells they might be able to move into. Theses piggyback lines often transformed into queues upon the arrival of crabs that were appropriately sized for the vacant shell.

At some of the locations, multiple queues formed when there were many similarly sized waiters, and the crabs in these queues appeared to engage in a “tug-of-war” for control of the vacant shell. The smallest crabs, positioned at the end of each queue, frequently switched back and forth between the lines in a possible attempt to stake its place in the winning line.

So what sets these theatrics off in the first place? Population density seems to be a key factor determining the length and type of vacancy chains. Using modeling software, the researchers created a simulated habitat space and a population of crabs of varying sizes. Rules for shell switches that realistically reflected hermit crab behavior were established and, after a while, a vacant shell appropriately sized for the largest crab in the population was placed the center of the habitat and the simulation was continued. During 100 model runs were at each combination of 2 parameters: population density (8 levels, from 10 to 900 crabs) and maximum waiting times for the waiters (2 levels), vacancy chain lengths increased along with population density at the highest population density, almost half of the shell switches that occurred were part of synchronous vacancy chains. How word about an available shell gets out among the crabs in the first place is still unknown, though. The researchers plan to address the question in a future study and speculate that the waiters may use aural or chemical signals to draw attention to the vacancy.

Reference: Rotjan, R., Chabot, J., & Lewis, S. (2010). Social context of shell acquisition in Coenobita clypeatus hermit crabs Behavioral Ecology, 21 (3), 639-646 DOI: 10.1093/beheco/arq027

Image: “Caribbean hermit crab (coenobita clypeatus)” by ZooFari, via Wikimedia.

How you think you assess and explore new things? You might assume that you do it primarily through sight, right? If I have a cool new gadget, the first words out of your mouth would likely be, “Can I see it?” Chances are, though, that when you say that, you’ll also extend your arm and open your hand. Seeing isn’t all there is. You want to touch, feel, hold and manipulate unfamiliar things.

The way those objects feel in your hands have a significant influence on the judgments you form about them. Past research has shown that shoppers understand and form impressions more readily about products with which they can physically interact and that tactile sensations can influence their perceptions and opinions of products’ quality. This happens even when touching a product doesn’t give any clues about its quality, like when shoppers said that water from a firm bottle seemed to taste better than water from a flimsy bottle. Findings like this have led psychologists to suggest that touch experiences might create a “scaffold” for the development of conceptual knowledge. In other words, mental action may be grounded in physical action, and sensory and motor processes are fundamental to some aspects of cognition.

In a study recently published in Science, researchers tested how three tactile sensations – weight, texture and hardness – influence perceptions, judgments and decisions of and about unrelated situations, people and objects. They found that touching objects can trigger a “haptic [relating to or based on the sense of touch] mindset” and cause people to apply concepts related to those sensations (texture and someone being “rough around the edges,” for example) to interpersonal interactions.

Joshua Ackerman, Christopher Nocera and John Bargh (from MIT, Harvard and Yale, respectively) conducted six experiments to see how weight, texture and hardness affected decision making and the formation of social impressions in people they met on the street. In one of the weight-related experiments, 54 passersby were asked to evaluate a job candidate by reviewing resumes on either light (3/4 lb) or heavy (4 1/2 lb) clipboards. Weight is associated seriousness and importance, a la “weighty matters” and the “gravity of the situation.” Sure enough, the people who reviewed the resume on the heavy clipboard 1) rated the the candidate as better suited for the position 2) said the candidate displayed more serious interest and 3) rated their own accuracy on the task as more important than the participants using the light clipboard did.

In the texture experiment, 64 people read a description of an ambiguous social interaction and were asked about the nature of the interaction, specifically, whether it was adversarial or friendly. Before they read the story, though, the participants completed a puzzle, the pieces of which were covered either with sandpaper or left bare. The participants who completed the sandpaper-covered puzzle rated the interaction as more adversarial and harsh than the participants who completed the smooth puzzle, consistent with rough textures’ metaphorical relationship harshness and difficulty (“a rough day,” “coarse language”).

To see if texture affected people’s social decisions, 42 participants first completed either the smooth or rough puzzle and then played an Ultimatum game where they received 10 tickets for a $50 lottery and could choose any of the tickets to an anonymous participant. If the other person accepted the ticket offer, great; if not, all the tickets were forfeited. Participants who completed the rough puzzle offered more lottery tickets than those who did the smooth puzzle, suggesting that they were primed for difficult social interaction and hence used compensatory bargaining behavior.

The last two experiments focused on hardness, which is associated with stability and rigidity (“he’s my rock” and “hard-hearted”). In one experiment, 49 people were asked to watch a magic act and then guess the secret. First, though, they got to examine the object to be used – either a soft piece of blanket or a hard block of wood – and verify that there wasn’t anything odd unusual about them. The act was then postponed indefinitely while the participants read a description of an interaction between a boss and an employee and evaluated the employee’s rigidity/strictness. Those who felt the wooden block rated the employee as more rigid/strict than those who felt the blanket.

The final experiment tested whether or not passive touch experiences could affect decision-making like active manipulation of objects had. Eighty-six participants were “primed by the seat of their pants” and sat in either hard wooden chairs or soft cushioned one while completing an impression formation task similar to the previous experiment and a negotiation task. This negotiation had participants pretending to shop for a new car (sticker price $16,500) and making two offers on the car (the second assuming that the dealer rejected the first offer). Comparable to the previous experiment, people who sat in the hard chairs said the employee was more stable than did participants who sat in the soft chairs. In the negotiation, hard chair participants changed their price between the two offers by a lesser amount than the soft chair participants did, suggesting that a haptic mindset can be triggered even when touch occur in body parts beside the hands and even when an object is not being actively manipulated.

It’s sort of the opposite of what Funkadelic would have you believe: free your ass and your mind will follow. While the idea of your butt or your hands or your feet having such power over your brain might seem a little odd, researchers in the field of embodied cognition have spent decades chipping away at the idea that mind and body are so separate from each other. Past studies have demonstrated that kids who use their hands while solving math problems have an easier time of it, that actors can remember lines more easily when moving and that holding a warm cup of coffee makes you more generous.

If physical sensation and movement has such a strong influence on our thoughts, though, is manipulating the mind as easy as buying heavier clipboards and upholstering the furniture? While the study might provide some lessons for job candidates, pollsters and car salesmen on manipulating their environment to bend social interactions in their favor, the authors note that this sort of exploitation is only easy when people are distracted and that paying attention to your surroundings diminishes the effects of these tactile cues. In other words, you’d do well to watch where you sit.

Reference: Ackerman JM, Nocera CC, & Bargh JA (2010). Incidental haptic sensations influence social judgments and decisions. Science (New York, N.Y.), 328 (5986), 1712-5 PMID: 20576894

Image: Anthony Redmile Carved Armchair with Malachite Bone and Horn via Boing Boing

“All you need is a cow and a centrifuge to harvest enough oocysts to infect a small city.”

- Brandeis University biochemist Liz Hedstrom, on the prevalence of calves infected by cryptosporidium, a protozoan parasite that is spread through contaminated water and causes diarrhea.

via.

It wasn’t too long ago that we (Homo sapiens) thought we were pretty special, far above and beyond the other animals. Then, one, by one, by one, the boundaries that supposedly kept us separated from the rest of the animal kingdom revealed themselves to be less than solid. We can’t even claim a monopoly on mourning anymore, and if this photo wasn’t enough to convince you of that, then two studies in the new issue of Current Biology provide close-up looks at the ways chimpanzees deal with death.

In the first study, researchers from the University of Stirling, witness and describe the final hours of Pansy, a 50-year-old female at the Blair Drummond Safari and Adventure Park in Stirlingshire, England, and the response of group-mates at the moment of her death. While the traumatic death of an adult chimp is usually with noisy, sometimes aggressive responses, the dying chimp’s group-mates remained mostly calm before and after her death. For several days before her death, the other chimps stayed very quiet and groomed and caressed her. At what the researchers presume was the moment of death, they closely inspected her face and tested her for signs of life. After she died they left the body alone, except for her adult daughter, who remained by her mother’s body through the night. When park staff removed the body the following morning, the group remained calm and for several days after avoided in the area where female had died (though it was normally a favored spot).

In this video from the study (tilt your head, as it’s more or less upside-down), three adult chimps gather around the dying female, nudge her, inspect her face and manipulate her head and shoulders. After not seeing any signs of life, two chimps leave and the third follows not long after.

In this video, taken the day after the chimp’s death, an adult male acts aggressively toward the body (the third display by that male observed by the researchers), but proceeds to remove straw from the body and grooms it. He is joined by an adult female, who also removes straw from the deceased’s face.

In the second study, researchers observed two infants in a semi-isolated chimpanzee community near Bossou, Guinea die from a flu-like respiratory ailment. For weeks afterward, the mothers of the dead infants continued to carry their children’s bodies around, groom them and take them to their nests during periods of rest. During this time, as the bodies mummified completely, the mothers began to “let go” of their babies. They gradually tolerated longer periods of separation from the bodies and eventually allowed other chimps in the group to handle them. Group members showed interest in the bodies and other infants and juveniles attempted to play with them.

In this video, one of the grieving mothers, Vuavua, keeps flies away from the body of her dead infant, Veve. Vuavua carried, groomed and cared for Veve’s body for a total of 19 days after death.

In this video, a juvenile chimp in the group, Fokayé, plays with the body of one of the dead infants, Jimato. Fokayé’s mother, Fotaiu (middle), appears to be a little uneasy about being touched by the corpse. This was the only time the researchers observed any of the chimps reacting to the bodies in that way. Eventually, Jimato’s mother, Jire (left), takes the Jimato’s body away. Jire carried the body for 68 days after death.

Dora Biro, lead author of the second study, says that her team’s observations confirm a mother-child bond powerful enough to persist even after death and provide all the more reason to learn more about the extent to which chimpanzees understand death in order to better understand both how chimps interpret their world and the evolutionary origins of our own perception of death.

Reference:

Anderson et al. (2010). “Pan thanatology.” Current Biology 20: 8

Biro et al. (2010). “Chimpanzee mothers at Bossou, Guinea carry the mummified remains of their dead infants.” Current Biology 20: 8

Last week Gourmet magazine was euthanized at the ripe old age of 68 by its masters at Condé Nast. Christopher Kimball, founder/publisher/editor of Cook’s Illustrated and third-rate Garrison Keillor’s  impersonator, promptly started mourning on the New York Times Op-ed page and sussed out who was really to blame for the magazine’s death: the internet, and everyone on it, seemingly. Certainly the instant pundits, anonymous Twitter users and poor “CM,” author of the recipe that is Google’s first return for “broccoli casserole,” which Kimball guarantees will be disappointing.[1]

According to Kimball, when the barrier of entry is lowered and more folks have an opportunity to peddle their wares in the marketplace of ideas, the room available to “thoughtful, considered editorial”‘ is severely diminished, because “everyone has an equal voice” on “this ship of fools.”

Hamilton Nolan countered the notion on Gawker, saying, “the democratic aspect of the internet that’s so terrifying to the old guard is not one that means that every opinion is equal; it just means that every opinion can be equally heard.” And that’s what makes it so easy to find thoughtful, considered editorial in the wilderness of the Web: the fact that people who have thoughtful, considered things to say about a topic and may very well be experts on that topic -  but might not have had the means, the time, or the inclination to speak on that topic in a traditional media outlet – can go ahead and talk about it.

Of course, there’s plenty of bullshit on the Internet, too, but it’s hardly like the apocalyptic vision Kimball has running through his head, because the shit isn’t just flowing freely. The trick is that on the Internet, every reader is their own gatekeeper. We don’t have to rely on any Christopher Kimballs to tell us which information is worth our time which experts and pundits pass muster and which editorial is thoughtful and considered. A reader keeps pointing and clicking and hunting and pecking, and the wheat is eventually separated from the chaff and the cream rises to the top.

Now, the best part of all of this is that only a few days before the Gourmet news broke, I received a sample issue of Cook’s Illustrated in the mail. If you want thoughtful, considered editorial of the type that Kimball talks about, I suggest you run screaming in the other direction. Keith Dresser’s (obviously an expert created from the top down and with a lifetime of experience, otherwise he would not have made it onto Mr. Kimball’s hallowed pages) “How to Pan-Sear Shrimp,” insists that shrimp can be caramelized. This is wrong and happens to be a pet peeve of mine. The browning that happens when you pan sear shrimp, or a burger, or grill a steak, etc. isn’t caramelization at work, but the Maillard reaction, a complex series of chemical reactions that occur when the carbonyl group of a reducing sugar reacts with the amino group of an amino acid, usually in the presence of heat. This non-enzymatic browning results in an array of molecules and compounds responsible for positive and negative flavors and odors. In layman’s terms, it’s the chemical reaction that gives your meat that wonderful brown, flavorful crust.

The results of the Maillard reaction (named after Louis-Camille Maillard, the French physician and chemist who was the first person to describe it) often look and taste the same as those of caramelization, but they’re two very different processes. The Maillard reaction involves both reducing sugars and amino acids, while caramelization involves only sugars undergoing various chemical reactions (among them, sucrose inversion, intramolecular bonding, isomerization and dehydration, condensation, fragmentation and polymerization reactions).

It’s a mistake that’s easy enough to make (even celebrity chef Robert Irvine talks about caramelizing meat in an episode of Dinner: Impossible), but the facts are easy enough to find on various food science web sites. Maybe Kimball should make sure is own house is in order before blaming the Internet for anyone’s woes.

[1] The first comment on the recipe reads: “I found this website from a New York Times article I read today and I am so happy I did! This was the best broccoli casserole ever and my family devoured it and they will not even eat broccoli most of the time.” There’s a special place in heaven for smart asses like that.

Images: Maillard Reaction diagram – Foodmate.net, Louis Camille Maillard – The Louis Camille Maillard organisation via Wikimedia Commons

Researchers at the University of Illinois recently published the results of an experiment that spanned 20 years and involved several generations of largemouth bass and an untold of amount of bait. Their conclusion: The apple doesn’t fall far from the tree, even, apparently, if you’re a fish.

The study started in 1975 at Ridge Lake, an experimental study lake in Fox Ridge State Park in Charleston, Illinois. Over the course of four years of controlled fishing, the bass from the resident population of the lake were caught, measured and tagged to keep track of how many times each fish had been caught, and then released.

The researchers recorded thousands of catches and found that some fish went for the bait more often than others, a lot more. One fish was caught three times in the first two days of the experiment, and another was caught 16 times in one year. When the lake was drained, the researchers also found some 200 fish that had never been caught during the study.

A total of 1,700 fish were collected from the drained lake. Male and female fish that had been caught four or more times in the study were designated High Vulnerability (HV) parents, and those that had never been caught were designated Low Vulnerability (LV) parents. The HV and LV groups were placed in separate university research ponds, where they spawned and produced lines of HV and LV offspring. These two lines were marked, raised in common ponds until they were big enough to be fished and then the anglers were let loose, starting the process over again.

Through three generations, the fish in each group followed closely in their parents footsteps (finsteps? finswims?) of either getting caught, or not (the difference in vulnerability between the HV and LV lines grew even larger with each generation), confirming that vulnerability to being caught by fishermen is a heritable trait in largemouth bass.

While that fact might make for great trivia, the study gives us more than just gee-whiz science. It suggests that recreational fishing can cause evolutionary changes the same way commercial fishing can.

The researchers found that most of the selective pressure is occurring on the LV fish, making fish that are already unlikely to be caught even less vulnerable. On the other hand, there was only a small increase in vulnerability to being caught in the HV group[1].

The researchers aren’t sure which inherited behavior causes these differences (it may be a wariness of anglers’ hooks and general lack of aggression that are passed on to offspring), but both these changes, they suspect, have implications for the bass’ reproductive success. Female largemouth bass swim away from their eggs after laying them, while the males stay with the eggs and until they hatch and guard the fry for the first month of their lives. The LV males may go after anglers’ hooks less often, or not at all, but their lack of aggression may also mean that they provide less protection from predators for their young. More aggressive HV males likely have higher mating success and are good protecting their fry from predators, but that aggression also makes them more likely to go after lures, get caught and leave their offspring vulnerable to predators.

During spawning season (in Illinois, this is from about April 1-June 15), males are caught the most, which causes concern for the HV males. Most bass anglers practice catch-and-release fishing, and the research team says that perception is that this has no negative impact on the fish, but during spawning season, if a male bass caught and kept away from their nests for more than even a few minutes, that may be enough time for predators to find the nest and eat the eggs or fry (a previous study by other researchers showed that, if a smallmouth bass is away from the nest for 1.4 minutes, as many as 1,100 eggs can be eaten).

The researchers suggest that wildlife management agencies set aside portions of lakes as bass spawning sanctuaries, where all fishing would be prohibited, and makes catch-and-release mandatory in the rest of the lake during the spawning season. They also recommend immediate catch-and-release regulations in fishing tournaments held during the bass’ reproductive period.

Reference: Philipp, David P., Cooke, Steven J., Claussen, Julie E., Koppelman, Jeffrey B., Suski, Cory D., Burkett, Dale P. Selection for Vulnerability to Angling in Largemouth Bass. Transactions of the American Fisheries Society 2009;138:189–199. DOI: 10.1577/T06-243.1

Image:”Largemouth Bass – Micropterus salmoides.” Trisha M Shears.

The Batronaut, a free-tailed bat whose age was unknown, passed away on Sunday, March 15 near his perch on the north side of the Space Shuttle Discovery’s external fuel tank at the Kennedy Space Center in Cape Canaveral, Florida. The cause of death is believed to be the 1400°C exhaust of the shuttle’s rocket boosters.

The Batronaut is believed to have been a resident of the Merritt Island National Wildlife Refuge and enjoyed sleeping upside down and eating bugs.

The Batronaut will be fondly remembered by America as the bat that almost made it into space. An account of his final hours, “Interim Problem Report 119V-0080,” has been written by NASA’s Systems Engineering and Integration team.

In lieu of flowers, please build a bat house.

Only about 10 percent of the world is left-handed, and with good reason. My southpaw brethren and I are at an extreme disadvantage in the evolutionary race. We’ve been shown to have greater risk of schizophrenia, autism, epilepsy and learning disabilities, and are shorter lived, just plain shorter and more likely to be homosexual than righties. All that makes it difficult for lefties to attract mates, reproduce and pass on their genes, so scientists have been wondering for a long time why left-handedness persists.

A team of researchers at the Institute of Evolutionary Sciences at the University of Montpellier, France who surveyed the existing literature on the evolutionary perspectives of left-handedness, including its mechanisms and the costs and benefits acting as selective forces on the left-handed, say they may have found the secret to southpaw survival. We lefties simply had a tactical advantage in one-on-one competition.

The team’s study suggests that because lefties are in the minority, right-handed opponents may not have been used to the way they fight, and the element of surprise gave lefties an advantage. Their very uncommonness, and a good left hook jab, gave them an edge.

Because the advantage allowed them to survive physical confrontation and win resources and mates, left-handedness became more frequent over the generations through natural selection.

We can see sort of the same thing happening in the success of left-handed boxers like “Gentleman Jim” Corbett and Oscar de la Hoya and left-handed tennis players like John McEnroe and Jimmy Connors. Death isn’t on the line at Wimbledon, but everyone loves a winner, so they attract more sex partners and are more likely to reproduce.

The researchers also noted that lefties in many European countries have higher average incomes and are well represented among gifted children with high IQs. Although an advantage in fist fighting doesn’t explain that, a place at the top of the socio-economic ladder certainly promotes reproductive success, so smarts and cash should result in higher birth rates for lefties and the passing along of left-handedness.

Reference: Llaurens, V., Faurie, C. and Raymond, M. 2009 : Why are some people left-handed? An evolutioanry perspective. Philosophical Transaction of the Royal Society B. doi:10.1098/rstb.2008.0235