Wednesday, November 28, 2012

Mr. Nanny Makes Mr. Right

Quick! Introduce yourself to this guy before
his baby-high wears off! Photo by David
Castillo Dominici at FreeDigitalPhotos.net
What happens if you take a wrestler or action star and force him to babysit obnoxious but lovable kids? Well, if you’ve seen movies like The Pacifier with Vin Diesel, The Tooth Fairy with Dwayne ‘The Rock’ Johnson, Kindergarten Cop with Arnold Schwarzenegger, or The Spy Next Door with Jackie Chan, you know that he will fall madly in love both with his young charges and with the closest available woman. Hollywood is so sure of this phenomenon that they have based a whole genre of family movies on it. Now, scientists are finding that Hollywood may be on to something.

Prairie voles are one of the only 3-5% of mammals that are monogamous and in which both parents help take care of young. In females, maternal care is regulated in part by the hormones associated with pregnancy, birth and lactation. The fact that males don’t do those things and they still provide paternal care is curious. The fact that male prairie voles will often provide care to offspring that aren’t even their own is even more curious.

Will Kenkel, Jim Paredes, Jason Yee, Hossein Pournajafi-Nazarloo, Karen Bales, and Sue Carter at the University of Illinois at Chicago recently explored what happens to male prairie voles when they are exposed to unfamiliar vole pups. Male voles without any experience with females or pups were placed in a new clean cage. Then the researchers put either a pup (that was not related to the male), a dowel rod (an unfamiliar object), or nothing into the cage with them for 10 minutes. Afterwards, they measured oxytocin (a hormone associated with bonding between mothers and their offspring) and corticosterone (a stress hormone) in the males’ blood at different time points. In another study, they also looked at the activity of brain neurons associated with the production of these hormones.


video
A male prairie vole is startled to find a baby in his cage...
But then he takes care of it. Video by Will Kenkel.

Both adult and juvenile males exposed to a pup for 10 minutes had higher oxytocin and lower corticosterone compared to the males not exposed to a pup. But this effect was short-lived, as male hormone levels quickly evened out again. Most of these males that were exposed to a pup showed alloparental care (care of a baby that is not their own), like approaching the pup, cuddling with it and grooming it. Males with higher oxytocin and lower corticosterone levels were more attentive towards the pups. Additionally, alloparental males exposed to pups had more activity of oxytocin-producing neurons and less activity of neurons associated with corticosterone-production in a specific brain region called the paraventricular nucleus (or PVN for short).

Oxytocin is strongly associated with pair bonding in prairie voles, particularly in females, and corticosterone affects pair bonding too (generally increasing pair bonding in males and preventing it in females). If exposure to a pup affects these hormones, maybe it affects how the male would interact with adult females. To test this, the researchers put male voles in a new clean cage and put a pup, a dowel rod, or nothing into the cage with them for 20 minutes. Then they put the males with an unfamiliar adult female for 30 minutes. After getting acquainted with the female, the males were put in a “partner preference apparatus”, which has three connected chambers: a neutral center chamber, a connected chamber with the familiar female tethered into it, and a connected chamber with an unfamiliar female tethered into it. The researchers measured how much time the males spent in each of the three chambers and with each of the two females over the next 3 hours.


A prairie vole pair snuggles. Photo from Young,
Gobrogge, Liu and Wang paper in
Frontiers in Neuroendocrinology (2011)
Males that were exposed to a dowel rod or to nothing before they were introduced to a female spent equal amounts of time with each of the two females. But males that were exposed to a pup before they were introduced to a female spent nearly 4 times as much time with that female than with the unfamiliar one. In other words, hanging out with a random pup acted like Love Potion #9 on these bachelor males and made them fall for the next female they encountered! Interestingly, this effect was true not only for the males that acted in an alloparental way towards the pups, but it was also true of males that attacked the pups (The researchers quickly rescued the pups if this occurred). Perhaps, males that were alloparental with the pups had increased oxytocin and males that were aggressive with the pups had increased corticosterone, either of which would make it more likely for them to form a preference for the female they were with.

Hmm… Got your eye on a special someone? Try volunteering him to babysit before your next date.

Want to know more? Check this out:

Kenkel, W., Paredes, J., Yee, J., Pournajafi-Nazarloo, H., Bales, K., & Carter, C. (2012). Neuroendocrine and Behavioural Responses to Exposure to an Infant in Male Prairie Voles Journal of Neuroendocrinology, 24 (6), 874-886 DOI: 10.1111/j.1365-2826.2012.02301.x

Wednesday, November 21, 2012

Competitive Females

Paula Broadwell, the aggressive competitor.
Photo from her Facebook page.
By now, you’ve probably heard all about Paula Broadwell, the woman that seduced the notoriously disciplined CIA director, four-star US Army general, husband and father, General David Petraeus. What kind of a woman might be able to sway a man that has such admirable self-control? Broadwell was Petraeus’ biographer, a West Point graduate with a Harvard graduate degree, an Army Reservist thrice recalled to active duty, a fitness champion, Ironman triathlete and even a machine gun model. Her accomplishments are clearly impressive, but maybe the key comes down to her competitive nature. I mean, she did send several threatening e-mails to an attractive socialite and Petraeus family friend, warning her to stay away from her (other) man.

When we think about competing for mates, we generally think about males competing for females and breeding territories with horns to duke it out, or elaborate feathers to show off, or dance-offs to demonstrate their physical abilities. But females often have to compete for the high-quality males and breeding territories too. And many of the concepts that apply to males competing for females have been found to also apply to females competing for males.

A dark-eyed junco thinking
"What you lookin' at?".
Photo by Kristal Cain.
As much as we know about males competing with one another, we know surprisingly little about females competing with one another, although they clearly do. Kristal Cain and Ellen Ketterson at Indiana University sought out to shed light on female competition and its effect on breeding success. They did this with female Carolina dark-eyed juncos, a socially monogamous songbird species in which both parents care for the young. They were curious whether more aggressive females would also have other competitive traits, like large body size. They also wondered whether aggressive females would have better breeding success.

The researchers caught female juncos to measure and put identifying leg bands on them. They then released them and spent their nesting season looking for their nests. When they found a nest, they identified whose nest it was by the female’s leg bands. The researchers tested how aggressive females were towards competing females by placing a caged female within 3 meters of a subject’s nest and watching to see if she swooped at the caged female. Then they kept an eye on the nest to see if the chicks all survived until they fledged (left the nest on their own) or if the nest was destroyed (usually by a predator) before the chicks fledged.

A female junco in full-on attack mode. Photo by Kristal Cain.
Females that were more aggressive towards “competing” females tended to be bigger and had chicks that were more likely to fledge. Now, if this were a story about competitive males, we might think big aggressive males with more successful chicks might have higher testosterone. Alternatively, low testosterone is often found in males that are better fathers. But these are females… Does it even make sense to talk about testosterone in females? Of course it does! Turns out, males don’t have a monopoly on testosterone; females have it too.

The researchers drew blood from the females and then gave them a “testosterone challenge” by injecting them with a hormone called gonadotropin-releasing hormone (or GnRH for short). GnRH is a trigger that causes a series of biological events that result in the gonads producing more hormones, including testosterone. The researchers then drew a second blood sample to measure how much testosterone levels changed in response to the GnRH injection.

More aggressive females produced more testosterone in response to the GnRH injection than did less aggressive females. This same effect has also been shown to be true of males behaving aggressively towards each other. I guess males and females really aren’t all that different, eh? But interestingly, females that produced more testosterone in response to the GnRH challenge also had more successful nests.

It’s important to keep in mind that these results are correlational. Maybe testosterone makes females bigger and more aggressive and better mothers. Or perhaps having a temper increases your testosterone production. Or maybe some other hormone that increases in response to GnRH (there are many) is responsible for the effects. In any case, females that are bigger and more aggressive and have more successful offspring also produce more testosterone in response to a GnRH injection.

Paula Broadwell shows off her aggressive abilities in this KRISS ARMS video
(gif'd by Michael Pakradooni).
As far as we know, no one has given Paula Broadwell a testosterone challenge, but she undoubtedly has a number of correlated competitive traits. Paula Broadwell is a competitive, physically fit, attractive parent who has shown that she can out-compete the spouses of high-quality mates… But then again, so is David Petraeus.

Want to know more? Check this out:

Cain, K., & Ketterson, E. (2011). Competitive females are successful females; phenotype, mechanism, and selection in a common songbird Behavioral Ecology and Sociobiology, 66 (2), 241-252 DOI: 10.1007/s00265-011-1272-5

Wednesday, November 14, 2012

Battle of The Grad Programs

Graduate school is an intense time peppered with qualifying exams, botched experiments, difficult advisors, and sleepless nights… Sometimes, grad students just need to vent and let loose, sometimes even at the same time. (Singing relieves pain, you know). And when they put their creative minds to it, we are gifted with gems like these:

Engineering Students:




Neuroscience Students:



Medical Students:



Vote for your favorite in the comments section below. If you are in the thick of the academic grind, don’t forget to take a moment to let your hair down once in awhile. And if you feel so inspired, make a video of your own, upload it on YouTube and send me a link to include in a future battle!

Wednesday, November 7, 2012

Political Animals

Now that we are finally on the other side of one of the longest, most expensive political campaign seasons of United States history, we find ourselves with a new mixed-bag of leaders. Our nation’s decision-makers include career politicians and new freshman politicians; they include lawyers, military members, doctors, businessmen, farmers, ministers, educators, scientists, pilots, and entertainers; they include Protestants, Catholics, Jews, Quakers, Mormons, Buddhists and Muslims; they include white Americans, African Americans, Asian Americans, and Hispanic and Latino Americans; they include men and women; they include straight and gay people; and oh yeah, they include Republicans and Democrats. With so many differences that generate so many viewpoints, how will they ever find common ground to make the kind of decisions that will move our nation in a positive direction?

Hey, Look guys! We make a peace sign! Image from Wikimedia.
Research into group decision-making in social animals has shown that ants, fish, birds, and bees have all discovered strategies to make intelligent group decisions. If they can do it, we can do it, right? What can we learn from these critters about harnessing the knowledge in all of us to move our whole group in the best possible direction? We will explore these insights in this post, which is a mash-up of two previous posts. To see the originals, check out Can a Horde of Idiots Be a Genius? and Why This Horde of Idiots Is No Genius.

Jean-Louis Deneubourg, a professor at the Free University of Brussels, and his colleagues tested the abilities of Argentine ants (a common dark-brown ant species) to collectively solve foraging problems. In one of these studies, the ants were provided with a bridge that connected the nest to a food source. This bridge split and fused in two places (like eyeglass frames), but at each split one branch was shorter than the other, resulting in a single shortest-path and multiple longer paths. After a few minutes, explorers crossed the bridge (by a meandering path) and discovered the food. This recruited foragers, each of which chose randomly between the short and the long branch at each split. Then suddenly, the foragers all started to prefer the shortest route. How did they do that?

This figure from the Goss et al 1989 paper in Naturwissemschaften shows (a) the design of a single module, (b) ants scattered on the bridge after 4 minutes (I promise they’re there), and (c) ants mostly on the shortest path after 8 minutes
You can think of it this way: a single individual often tries to make decisions based on the uncertain information available to it. But if you have a group of individuals, they will likely each have information that differs somewhat from the information of others in the group. If they each make a decision based on their own information alone, they will likely result in a number of poor decisions and a few good ones. But if they can each base their decisions on the accumulation of all of the information of the group, they stand a much better chance of making a good decision. The more information accumulated, the more likely they are to make the best possible decision.

In the case of the Argentine ant, the accumulated information takes the form of pheromone trails. Argentine ants lay pheromone trails both when leaving the nest and when returning to the nest. Ants that are lucky enough to take a shorter foraging route return to the nest sooner, increasing the pheromone concentration of the route each way. In this way, shorter routes develop more concentrated pheromone trails faster, which attract more ants, which further increase pheromone concentration of the shortest routes. In this way, an ant colony can make an intelligent decision (take the shortest foraging route) without any individual doing anything more intelligent than following a simple rule (follow the strongest pheromone signal).

Home is where the heart is. Photo of a bee swarm by Tom Seeley
Honeybee colonies also solve complicated tasks with the use of communication. Tom Seeley at Cornell University and his colleagues have investigated the honeybee group decision-making process of finding a new home. When a colony outgrows their hive, hundreds of scouts will go in search of a suitable new home, preferably one that is high off the ground with a south-facing entrance and room to grow. During this time, the house-hunters will coalesce on a nearby branch while they search out and decide among new home options. This process can take anywhere from hours to days during which the colony is vulnerable and exposed. But they can’t be too hasty: choosing a new home that is too small or too exposed could be equally deadly. Although each swarm has a queen, she plays no role in making this life-or-death decision. Rather, this decision is made by a consensus among 300-500 scout bees that results after an intense “dance-debate”.


If a scout finds a good candidate home, she returns to the colony and performs a waggle dance, a dance in which her body position and movements encode the directions to her site and her dancing vigor relates to how awesome she thinks the site is. Some scouts that see her dance may be persuaded to follow her directions and check out the site for themselves, and if impressed, may return to the hive and perform waggle dances too. Or they may follow another scout’s directions to a different site or even strike out on their own. Over time, scouts that are less enthusiastic about their discovered site stop dancing, in part discouraged by dancers for other sites that bump heads with them and beep at them in disagreement. Eventually, the majority of the dancing scouts are all dancing the same vigorous dance. But interestingly, few scouts ever visit more than one site. Better sites simply receive more vigorous “dance-votes” and then attract more scouts to do the same. Like ants in search of a foraging path, the intensity of the collective signal drives the group towards the best decision. Once a quorum is reached, the honeybees leave their branch as a single united swarm and move into their new home, which is almost always the best site. 
Each dot represents where on the body this dancer was head-bumped by a
dancer for a competing site. Each time she's bumped, she's a little less enthusiastic
about her own dance. Figure from Seeley, et al. 2012 paper in Science.
But groups can develop better solutions than individuals even without communication. Gaia Dell’Ariccia at the University of Zurich in Switzerland and her colleagues explored homing pigeon navigation by placing GPS trackers on the backs of pigeons and releasing them from a familiar location either alone or in a group of six. Because they were all trained to fly home from this site, they all found their way home regardless of whether they were alone or in a group. But as a flock, the pigeons left sooner, rested less, flew faster, and took a more direct route than did the same birds when making the trip alone. By averaging the directional tendencies of everyone in the group, they were able to mutually correct the errors of each individual and follow the straightest path.

What can we learn from these examples? Like individual congressmen and senators, in each of these examples each individual has limited and uncertain information, but each individual has information that may be slightly different than their neighbors’. This diversity can be our congress’ greatest asset, if they use it in the same way so many animals naturally do. Tom Seeley summarized these approaches based on his insights from years of watching honeybees:

Tom Seeley’s Five Habits of Highly Effective Hives

1. “Group members share a goal”.
This is easy for honeybees, but not as much for us. All of the honeybees in a swarm share the same goal: Find the best possible home as quickly as possible. People are not always similar in our goals, needs and wants and one person’s goals are sometimes in direct conflict with another person’s goals. The trick here is finding common ground.

2. “Group members search broadly to find possible solutions to the problem”.
Seek out information from as many sources as you can. Be creative. Use your personal experience. And if the group is diverse, there will be a broader range of personal experience to harness. Diversity increases the ability of a group to make the best decisions.

3. “Group members contribute their information freely and honestly”.
This requires a welcoming and supportive environment that withholds judgment of the individuals for the ideas expressed. You don’t have to agree with an idea to respect and listen to the person expressing it.

4. “Group members evaluate the options independently and they vote independently”.
Just as scout bees don’t dance for a site they have not visited and assessed themselves, we should not advocate possible solutions or candidates that we have not ourselves looked into and thought critically about. A group can only be smarter than the individuals in it if the individuals think for themselves.

5. “Group members aggregate their votes fairly”.
Everyone gets a vote and each one counts equally. ‘Nuff said.

We can learn a lot from these honeybees. Even when the stakes are high, we can make good decisions for our group if we are open, honest, inclusive, fair and think independently.

Want to know more? Check these out:

1. Couzin, I. (2009). Collective cognition in animal groups Trends in Cognitive Sciences, 13 (1), 36-43 DOI: 10.1016/j.tics.2008.10.002

2. List, C., Elsholtz, C., & Seeley, T. (2009). Independence and interdependence in collective decision making: an agent-based model of nest-site choice by honeybee swarms Philosophical Transactions of the Royal Society B: Biological Sciences, 364 (1518), 755-762 DOI: 10.1098/rstb.2008.0277

3. Seeley, T., Visscher, P., Schlegel, T., Hogan, P., Franks, N., & Marshall, J. (2011). Stop Signals Provide Cross Inhibition in Collective Decision-Making by Honeybee Swarms Science, 335 (6064), 108-111 DOI: 10.1126/science.1210361

4. Dell'Ariccia, G., Dell'Omo, G., Wolfer, D., & Lipp, H. (2008). Flock flying improves pigeons' homing: GPS track analysis of individual flyers versus small groups Animal Behaviour, 76 (4), 1165-1172 DOI: 10.1016/j.anbehav.2008.05.022

5. Honeybee Democracy by Thomas Seeley

6. The Smart Swarm by Peter Miller

7. The Wisdom of Crowds by James Surowiecki

Friday, November 2, 2012

Donate To Student Science Projects And Your Money Will Double!

There are just a few days left for the Science Bloggers for Students drive to raise money for science education and we have exciting news! The DonorsChoose.org Board of Directors has made available up to $50,000 for matching funds for anyone that donates to a Science Bloggers for Students page! But for the teachers to get access to this generous donation for their student projects, we all have to donate something ourselves (and the DonorsChoose.org Board of Directors will match dollar-for-dollar for the first $100 per donor). Just think, if you donate $5 for a student project you are excited about, the teacher will get $10 towards making that project happen. And you would be amazed at what a dedicated and creative teacher can do with $10 (In fact, 3 of the projects I am promoting need less than $300 to provide an unforgetable learning experience for their students).


At The Scorpion and The Frog Giving Page, listed under Proudly Independent Science Bloggers, I chose to promote four projects in high poverty areas across the country that teach students about animals in creative and inspiring ways.
  • Help Ms. Bakker’s high school class in Chicago, Illinois build Carnivore Scent Stations (areas with loose dirt on top and animal scent in a hole beneath to attract wildlife) and track the prints of animals that visit the stations.
  • Or help Mrs. Westphal’s elementary students in Astatula, Florida study food webs by dissecting owl pellets.
  • Or help Mrs. Maruri’s class in Pleasant Grove, Utah get dissection kits to study animal anatomy.
  • Or help Mrs. Scherer’s students in Detroit, Michigan study the life cycles of chickens, ducks, ladybugs, crayfish, guppies, tadpoles and butterflies by bringing the animals into the classroom to care for and to study.
Check out these awesome projects here. And if you prefer to give to a different project, the matching gift will apply to any project listed under Science Bloggers for Students! To use the matching code, type in the word SCIENCE as the match or gift code when you check out. It'll look something like this (minus the red box that is pointing out where to type SCIENCE):


Donate to help passionate teachers have the resources they need to inspire our next generation of biologists! Donations of any amount make a difference and are appreciated...Now Twice As Much!

The Science Blogger Challenge and the matching funds run through November 5th, so donate right now before you forget.