Wednesday, March 27, 2013

Those Aren’t Chocolate, Easter Bunny!

The Easter Bunny has a dirty secret. When he’s not hopping around in his pristinely white fur hiding beautifully colored eggs and decorated baskets full of treats…he’s eating his own poo. Gross!

Never trust a rabbit. Photo by the Mosman Library at Wikimedia.
But don’t judge him before you understand him. It’s not that he chooses to eat poop, but that he has to for his own health. In fact, all rabbits do.

Rabbits are herbivores, which means that they only eat plant material. Plant material is very difficult to digest, although it may not seem like it (I mean, we eat plants all the time with no problem, right?). But when it comes to digestion, it’s not what you put in your mouth and swallow that matters, but what your body can break down.

This process of breaking down food depends on digestive enzymes, a group of chemicals that break down food. Each type of digestive enzyme is specific for breaking down a particular type of food chemical. Plant material is so hard to digest because it is largely composed of cellulose, a sugar that we vertebrates don’t have an enzyme for.

Herbivorous animals that lack this enzyme have developed an alternative strategy to get the nutrients they need out of these plants – They have microbes that live in their guts and ferment the plant material. Many of these microbes, which include bacteria, protists, yeast and fungi, produce the enzyme needed to break down cellulose. But these microbes are slow-acting (which means herbivores with longer guts get more nutrients), and they are sensitive (which means herbivores with special microbe gut chambers get more nutrients).

Rabbits have a special gut chamber called a cecum (or caecum) that houses many of their gut microbes. The cecum is so important to rabbit digestion, it’s even bigger than their stomach! When a rabbit eats something, the food is broken down by chewing, swallowed, and passed on to the stomach (follow along with the diagram below). The stomach stores and sterilizes the food while breaking down some of the nutrients before it passes the food on to the small intestine. The small intestine absorbs the nutrients it can before the remaining food gets sorted at a fork in this digestive road. The fibrous food parts move on to the colon, where it is converted into little hard turd-balls. The non-fibrous parts go to the cecum, where the microbes living there work their magic, breaking down the remaining food into absorbable nutrients.

This diagram of the rabbit digestive system was posted by Sunshineconnelly at Wikimedia. Trace through it as we talk about where each digestive step happens.
The trouble is, this food has already passed the part of the digestive tract that absorbs most of these nutrients: the small intestine. Now, it has nowhere to go but out. So the cecum pushes these remaining nutrients into the colon, which turns them into cecotropes (or caecotrophes): mucus-covered, nutrient-rich, moist turds shaped like a bunch of grapes (and according to the Easter Bunny, just as delicious). And the only way rabbits can get the nutrients (and remaining microbes) out of these little nuggets is to send them through the digestive tract all over again by eating them. So that is what they do.

Eating poo sounds gross and unusual, but it is actually fairly common in the animal kingdom. So common, in fact, that there is a term for it: coprophagia. Hamsters and capybaras have similar digestive tracts to rabbits and eat their own poo for the same reasons. Other animals, like elephants, hippos, pandas, and koalas, are born without the necessary microbes to digest the food available, so the babies obtain these microbes by eating their mothers’ poo. And many coprophagous insects, like flies and dung-beetles, subsist on diets composed of the poo of large animals.

So don’t hate on the Easter Bunny for his repulsive ways. He can’t help what he is. Just appreciate him for all the chocolate eggs he brings you every Easter. Wait… Those are chocolate eggs he brought you, right?

Wednesday, March 20, 2013

How To Get Into An Animal Behavior Graduate Program: Getting Good Recommendation Letters

It’s hard to feel strong and confident when
asking for recommendation letters leaves
you feeling like this. Photo by Jan Mehlich
at Wikimedia.
You’re applying to graduate schools and you’ve been fretting about your grades, your test scores, and your essays for months. And then you remember about the recommendation letters – How many did they want? Three?! Ugh… Why do they make people jump through these hoops, anyway?
Turns out, the recommendation letters are a critical component of the graduate school application and they can make the difference between acceptance and rejection. You don’t just want 3 rec letters - You want 3 awesome rec letters. And although it may feel like the quality of letters written by other people is out of your hands, there are several things you can do to maximize the quality of the letters people write for you.
Before you start asking people to write rec letters, it’s important to think about how these letters are used. Generally, an admissions committee will go through applications to filter out those applicants that don’t meet the minimum standards with respect to grades, test scores, and prerequisites. Those applications that make it through the first pass are then sent on to the researchers the applicants have requested to work with. If the researcher you would like to work with is looking for graduate students that year, he or she will assess your full application. The rec letters are used to get a feel for your initiative, dedication, maturity, intelligence, creativity, ability to work with others, leadership skills, and communication skills. The better a letter can highlight these attributes about you in a personalized and detailed way, the more effective the letter will be in convincing the researcher to welcome you as a new lab member.
The most important step of getting good rec letters is asking the right people. When someone writes a rec letter for you, they can only talk about what they know about you. You may have had the most incredible and respected professor in the world, but if your only interaction with her was as a student in her 200-student lecture, she’s probably not going to have much to say about you other than what your grades were in her class. Even if you got an ‘A’ in that class, she probably won’t be able to write about the personal attributes a researcher would want to know about you. You want to request rec letters from people who know and think highly of you and your abilities (which means you must have been awesome in their presence). Secondarily, you want to ask people who hold respected positions. Some examples of good people to ask are research supervisors (if they know you well enough, a professor’s letter would typically be considered more highly than a graduate student’s letter), work supervisors (the more your work related to animal behavior or biology, the better), and professors that personally interacted with you (especially if they could write about your involvement in class projects).
Once you’ve chosen the people you would like to ask, there is a lot you can do to increase the likelihood that that their letters will be great (and submitted on time). Chances are, the people you are asking for rec letters already have a lot on their plate. The easier you make it for them, the less they will forget. Prepare a packet for each person who will write a rec letter for you. This packet should include:
  • An organized list of all the schools/programs you are applying to, their deadlines, and directions for submitting letters. Include a stamped and addressed envelope for each school that wants your references to mail their letters.
  • Your current résumé. This should include your major(s) and minor(s), current GPA, a list of science courses you’ve taken, extracurricular activities, jobs, internships, volunteer positions, honors and scholarships, and research projects.
  • A list of your accomplishments with the person writing the letter. This may include what you have contributed to projects and your memories of what you gained from your experience with that person. Include details like dates and project names. This might jog the letter-writer’s memory so he or she can write a more personalized letter.
  • Any forms the schools require. Check to see if they require your signature before you include them in the packet.
  • All this should be in a folder with your name and e-mail address on it.

Now comes the slightly awkward part: actually asking for a recommendation letter. If you chose your preferred letter-writers correctly, they should know you personally and have an idea of your career interests already, which will make this process less awkward. You can ask if someone would be willing to write you a letter either in person or by e-mail, ideally at least a month before they are due. In this first broach of the topic, you want to communicate your ultimate career goals, what types of programs you are applying for, and how many programs there are. Then you ask if they are willing and able to write recommendation letters for you. Mention that you have more information on the programs and your experiences to provide them if they would like and offer to meet with them to talk more about your goals and experiences.
Sometimes, the person you ask will decline because they feel they do not know enough positive things about you to write a strong letter for you (which would indicate that you chose the wrong person to ask or you failed to be awesome in the right people's presence) or because they simply do not have enough time. Just in case, you should have a few extra potential letter-writers in mind. But in most cases, if you chose the right people, they will be happy to write the letters for you. Bring them your prepared packet and chat with them about yourself and your goals. One or two weeks before each deadline, e-mail each reviewer a reminder of the deadline (unless they told you the letters have already been submitted).
If your letter-writers know and are impressed by you and your abilities, they should have plenty of good things to write about. If you are organized, you can make sure they remember all those wonderful things about you in time to put them in your rec letter and submit them before the deadlines. The way you approach this request can make the difference between ho-hum letters and door-opening letters.
For more advice on applying to graduate programs, go here.

Wednesday, March 13, 2013

How To Get Into An Animal Behavior Graduate Program: An Outline

Do you dream about a career of studying animals?
Image by
**NOTE: Although this advice is written for those interested in applying to graduate programs in animal behavior, it applies to most programs in the sciences.**

So you want to go to grad school to study animal behavior… Well join the club! It is a competitive world out there and this is an increasingly competitive field. But if every fiber of your being knows this is the path for you, then there is a way for you to follow that path. With hard work, dedication and persistence, you can join the ranks of today's animal biologists to pursue a career of trekking to wild places to study animals in their native habitats, testing questions about the physiology of behavior in a lab, or exploring the genetics of behavioral adaptation.

This is an outline of advice on how to get into a graduate program in animal behavior. More details on the individual steps will follow, so leave a comment below or e-mail me if you have any particular questions you would like me to address or if you have any advice you would like to share.

  1. Get good grades, particularly in your science and math courses. And make sure you take all the science and math prerequisites for biology graduate programs.
  2. Prepare well for the GREs.
  3. Get research experience. This can come in many forms (such as volunteering in a lab, working as a field technician, or doing an independent project for credit), but as a general rule, the more involved you are in a project, the more it will impress those making acceptance decisions.
  4. Choose the labs you are interested in, not just the schools. As a graduate student, you will spend most of your time working with your advisor and the other members of your advisor’s lab. This means that the right fit is imperative. Figure out what researchers you may want to work with, then see if they are at a school you would like to attend.
  5. Be organized in your application process. There will be a lot of details to keep straight: due dates, recommendation letters, essays, communication with potential advisors… The more organized you are, the less likely you are to miss a deadline or make an embarrassing mistake.
  6. Write compelling essays. Most schools will ask you to write two short essays: a Statement of Purpose and a Personal History. This is your place to set yourself apart. They need to convey your experience with animal behavior research and passion for working with that particular advisor. They also need to be very well written, so expect to write multiple drafts.
  7. Be organized and prepared when you ask for your recommendation letters. The easier you make it for your references to write a thoughtful recommendation letter for you, the better the letters will be.
  8. Apply for funding. This isn’t essential: Most first-year graduate students do not have their own funding. But the ability of a school and a specific researcher to accept a graduate student depends on what funding is available to support them. If you have your own funding, it is more likely you will to be able to write your own ticket.
  9. Be prepared for each interview you are invited to.
  10. If at first you don’t succeed, try and try again. Although heartbraking at the time, it is very common in animal behavior graduate programs to not be accepted anywhere in your first year of applications. If you are rejected, it doesn’t necessarily mean you are not a good candidate. Often it means there is no funding available to support you in the labs you would like to join. Spend the year participating in research and applying for funding so you can reapply next year.
The submission of a successful application takes a lot of planning and preparation. Getting good grades is a continuous effort. Plus, the most successful applicants often have two or more years of research experience. Ideally, you are working on these two things at least by your sophomore year of college. But if you waited too long and you haven’t taken enough science or math prerequisites, your grades are not where they need to be, or you don’t have enough research experience, you can take some extra time after you graduate to take community college courses and volunteer or work in a lab. Persistence and dedication are key to following a challenging path.

Wednesday, March 6, 2013

Hey Hey! We’re The Monkeys!

A tamarin rock star
(photographed by Ltshears at Wikimedia)
Our moods change when we hear music, but not all music affects us the same way. Slow, soft, higher-pitched, melodic songs soothe us; upbeat classical music makes us more alert and active; and fast, harsh, lower-pitched, dissonant music can rev us up and stress us out. Why would certain sounds affect us in specific emotional ways? One possibility is because of an overlap between how we perceive music and how we perceive human voice. Across human languages, people talk to their babies in slower, softer, higher-pitched voices than they speak to adults. And when we’re angry, we belt out low-pitched growly tones. The specific vocal attributes that we use in different emotional contexts are specific to our species… So what makes us so egocentric to think that other species might respond to our music in the same ways that we do?

A serene tamarin ponders where he placed
his smoking jacket (photographed by
Michael Gäbler at Wikimedia)
Chuck Snowdon, a psychologist and animal behaviorist at the University of Wisconsin in Madison, and David Teie, a musician at the University of Maryland in College Park, teamed up to ask whether animals might respond more strongly to music if it were made specifically for them.

Cotton-top tamarins are squirrel-sized monkeys from northern Colombia that are highly social and vocal. As in humans (and pretty much every other vocalizing species studied), they tend to make higher-pitched tonal sounds when in friendly states and lower-pitched growly sounds when in aggressive states. But tamarin vocalizations have different tempos and pitch ranges than our tempos and pitch ranges.

Chuck and David musically analyzed recorded tamarin calls to determine the common attributes of the sounds they make when they are feeling friendly or when they are aggressive or fearful. Then they composed music based on these attributes, essentially creating tamarin happy-music and tamarin death metal. They also composed original music based on human vocal attributes. They played 30-second clips of these different music types to pairs of tamarins and measured their behavior while the song was being played and for the first 5 minutes after it had finished. They compared these behavioral measures to the tamarins’ behavior during baseline periods (time periods not associated with the music sessions).

An example of happy tamarin music (Copyright by David Teie and available through Biology Letters) can be found here.
An example of aggressive tamarin music (Copyright by David Teie and available through Biology Letters) can be found here.
As the researchers had predicted, tamarins were much more affected by tamarin music than by human music. Happy tamarin music seemed to calm them, causing the tamarins to move less and eat and drink more in the 5 minutes after the music stopped. Compared to the happy tamarin music, the aggressive tamarin music seemed to stress them out, causing the tamarins to move more and show more anxious behaviors (like bristling their fur and peeing) after the music stopped.

The tamarins also showed lesser reactions to the human music. They showed less anxious behavior after the happy human music played and moved less after the aggressive human music played. So, human voice-based music also affected the tamarins to some degree, but not as strongly. This may be because there are some aspects of how we communicate emotions with our voice that are the same in tamarins. (How did the tamarin music make you feel?)

Can you imagine what we could do with this idea of species-specific music? Well, David and Chuck did! They have since developed music for cats using similar techniques. Although they're still working on the paper, they have said that the cats prefered and were more calmed by cat music compared to human music. You can find samples and get your own copies here.

We often think of vocal signals conveying messages in particular sounds, like words and sentences. But calls seem to do much more than that, making the emotions and behaviors of those listening resemble the emotions of those calling.

Want to know more? Check this out:

Snowdon, C., & Teie, D. (2009). Affective responses in tamarins elicited by species-specific music Biology Letters, 6 (1), 30-32 DOI: 10.1098/rsbl.2009.0593