Wednesday, March 31, 2010

Family matters

If you’re a pet owner, chances are you believe your pet has a personality, recognizes you, loves you, feels your pain. Who hasn’t heard a story about a girl who’s crying over a heart break, and her dog comes over to cuddle with her and lick her tears away? On the other hand, many firmly believe that animals are just friendly when they want food, and that they don’t have the kind of intelligence needed for emotions such as empathy. For example, my dad likes to claim that cats have a “smooth brain”, a reference to the fact that the brains of cats are not folded as much as those of humans, and therefore, the 16 pounds of fluff sleeping in my living room can’t possibly experience more than “hungry”, “sleepy” and “farty”. The thing is, it’s hard to tell, because we can’t ask animals how they feel. Faced with this difficulty, a team of researchers recently devised a method to determine if the lowly mouse is capable of complex emotions.

The researchers initially wanted to see if mice could learn to fear something without experiencing it. They put two mice in a cage and separated them by a see-through wall. The researchers then proceeded to give mild electrical shocks to the feet of one of the mice. Interestingly, the observing mouse (who wasn’t getting shocked) also displayed signs of fear (which is expressed mostly by a freezing behavior). What’s more, when the observing mouse was put back in the same experimental cage later, it still displayed signs of fear, meaning it remembered the experience of watching the other mouse get shocked. However, if you put the observer mouse in a different cage or different environment, it behaved normally. These results indicate that the observing mouse learned to fear a specific context without experiencing the pain it fears.

So what, you say? The mouse could just be mimicking the fear behavior, or experiencing “emotional contagion”. But there’s more. The researchers tried the same experiment, but this time, they used a pair of siblings instead of two random mice. Surprisingly, the effect they observed in the first experiment was now much stronger: the observer mice displayed significantly more freezing behavior, as if they could relate more to the pain of a sibling mouse than to that of a random mouse. The freezing effect was also stronger when the two mice were unrelated but had been sharing a cage for more than 10 weeks (mice in common-law). Overall, the more familiar the observer mouse is with the mouse getting the shocks, the better the observer mouse can feel the pain of the other mouse.

Are the mice really feeling empathy, or are they simply sensing a danger? While this study can’t tease those two possibilities apart, the fact that the response is much stronger when the mice are related definitely raises the interesting hypothesis that, pardon the cliché, “animals have feelings too”. What is your experience with animal intelligence? Share in the comments!

Reference: Observational fear learning involves affective pain system and Cav1.2 Ca1+ channels in ACC. (2010) Jeon et al. Nature Neuroscience 13(4):482-8.

Sunday, March 21, 2010

Males taking pregnancy to a whole new level

There’s an interesting debate going on in the science communication community over whether it’s more valuable to talk about relevant science news or cool science news. If you read my tagline, you’ll know which side I’m on (though my preference is for science news that are both relevant and cool). But just for today, I’d thought I’d switch roles and share the findings of a recent article on a topic that definitely doesn’t seem relevant for us: male pregnancy.

Male pregnancy occurs only in seahorses and their relatives, and happens when females deposit their eggs in a pouch located on the male. The pouch serves a similar function as the human uterus and provides nutrition and protection for the offspring while they develop. In a recent study published in Nature, researchers looked at how male pipefishes manage these pregnancies and find surprising behavior.

First, the researchers confirmed that the male pipefish prefers to mate with larger females. This maximizes evolutionary fitness (survival of the fittest) because larger females lay more eggs and their eggs have a greater chance of surviving. Interestingly, the shorter the male, the stronger the preference for a large female. I’m going to let you draw your own conclusions as to the origins of Little Man Syndrome.

Second, the researchers found that the chances of survival of the offspring depend on previous pregnancies. If a male really invested himself in a previous pregnancy and spent a lot of energy caring for the offspring of a larger female, the chances of survival of a later pregnancy from a smaller female are much lower. This essentially means that the male can gauge the “attractiveness” of a female and distribute his resources accordingly. In some cases, when forced to reproduce with a small female, males can partly or even completely abort the offspring (by not spending energy for their nutrition and care) to conserve their reproductive potential for when they hit the jack pot chunky female. Kind of a blow to the supermodels of the pipefish world, if you ask me.

Overall, the study suggests that male pipefishes have much greater control over reproduction that we initially thought, and certainly much greater control over reproduction when compared to the standard female mammal pregnancy scheme.

Now let’s see if we can find some relevance to this study and make it a two-for-one. Can you find any relevance for us in this study, in aspects of the study, or even in questions it raises? Contribute your thoughts in the comments!


Reference: Post-copulatory sexual selection and sexual conflict in the evolution of male pregnancy. (2010) Paczolt KA, Jones AG. Nature 464(18):401-4.

Sunday, March 14, 2010

It's my blogiversary!

Scientific Chick is one year old today!

I prefer cookies to cake, so I give you the best science cookies I could find:

Thanks for reading!

Saturday, March 13, 2010

Pesticides for macho frogs

The increasing demand for organic food sends a pretty clear message that we are starting to realize that pesticides and herbicides are bad. We are concerned that pesticide exposure may be linked to cancer, decreased fertility rates, etc. Unfortunately, the majority of living organisms can’t choose their level of exposure to these chemicals, and a recent study describes a most unusual consequence of pesticide exposure in frogs.

The researchers looked at the effects of exposure to atrazine, the most widely used pesticide in the world, and the most common pesticide contaminant in water. The study shows that when male frogs are exposed to atrazine they become demasculinized, meaning they lose male characteristics. This happens both at the physical, or “looks” level (the male frogs look like female frogs), and at the physiological, or “function” level (the male atrazine-exposed frogs have reduced testosterone levels and sperm count compared with control male frogs).

All this isn’t exactly new. For years, we have been aware that pesticide exposure interferes with normal hormonal function in a variety of organisms (salmon, frogs, rodents). What sets this study apart is that the researchers observed that in 10% of the atrazine-exposed male frogs, a complete reversal to a female frog happened. Everything about these initially male frogs now identified them as female, with the only exception of their genetic code (the equivalent of their Y chromosome). They looked 100% female, had female reproductive organs, and were able to mate with other males and produce eggs. If you’re in the market for an amphibian sex-change, look no further.

I know what you’re thinking. Surely the researchers exposed the frogs to crazy high levels of atrazine? No. They used a concentration of 2.5 parts per billion, which is consistent with what you can find in the environment. But frogs can be hermaphrodites, right? So it’s not a big stretch that they would switch over from hermaphrodite to female and just lose their “half male”? No. While these frogs can be hermaphrodites, the researchers only looked at genetic males, meaning males that could not be or become hermaphrodites. But the researchers looked at early stages of development, right? When the tadpole can go either way? Again, no. These were adult frogs.

Can we extrapolate these results to humans? Unlikely. Frogs absorb chemicals like atrazine through their skin, something mammals don’t do. Therefore, you would need exposure at a much higher concentration to achieve the same amount of atrazine in our system. Does this mean the study is not relevant to human health? Again, no (I’m so negative today!). The fact that atrazine is so potent at interfering with the frog’s hormonal system is definitely cause for concern. Interestingly, atrazine is banned in the European Union. The United States, on the other hand, slathered 76 million pounds of the stuff on cropland in 2003. (Organic) food for thought…

Reference: Atrazine induces complete feminization and chemical castration in male African clawed frogs (Xenopus laevis). (2010) Hayes TB, Khoury V, Narayan A, Nazir M, Park A, Brown T, Adame L, Chan E, Bucholz D, Stueve T, Gallipeau S. Proc Natl Acad Sci 107(10):4612-17.

Saturday, March 6, 2010

Oms for ouches

In North America one in three people struggle with chronic pain. Old sports injuries, carpal tunnel syndrome, migraines, the causes are varied, and the treatments are few. In my case, too many hours of swimming have done a number on my shoulders, and I’m left popping Advils like they’re jelly beans. Forced to quit swimming, I now took up cycling, to make sure I wreck my knees and get the full body experience. In any case, chronic pain can be debilitating, and to the sufferers, it often seems like there is no way out. Interestingly, a new study suggests that a little open mindedness in the form of mediation can be a huge help.

The study looks at the effectiveness of a technique called mindfulness mediation for the reduction of chronic pain in various conditions ranging from arthritis to fibromyalgia. Mindfulness meditation aims at paying close attention to the moment, at accepting thoughts and sensations for what they are, without judging them and without reacting to them. It takes practice, and commitment, but an increasing number of people swear by it for improving their quality of life.

The researchers studied over 100 participants with chronic pain before and after an 8-week regimen of mindfulness meditation, performed both in weekly classes and at home. The outcome survey assessed a number of parameters such as body pain, vitality and fatigue, limitations due to physical health problems (try washing your hair when both your shoulders feel broken), and so on.

Overall, mindfulness meditation lead to a significant improvement of all the parameters studied. Not only that, it lead to clinically relevant changes in measures like bodily pain and general health perception. Interestingly, when you divide the group by specific health condition, some conditions show a much greater improvement than others. For example, arthritis and back/neck pain sufferers benefited from meditation more than headache/migraine sufferers.

So how does mindfulness meditation work? Because we are just beginning to understand the impact of meditation in the brain, we can only take educated guesses. It is possible that meditation can regulate sensory and affective aspects of pain itself (i.e. you actually hurt less). It is also possible that meditation acts to reduce distressing thoughts that come with pain and usually amplify the pain feeling (i.e. you still hurt, but you stress out about it less, so the pain doesn’t seem as bad). It may also be a combination of both (isn’t it always?).

The study is very convincing, but it’s not perfect. Without a proper control group (i.e. a cohort of people who have chronic pain but don’t meditate), it’s not possible to rule out that everyone just had a spontaneous improvement in their pain. However, given that most participants had been experiencing pain for several years, this seems unlikely. In addition, the sample sizes for individual condition groups were pretty small (27 to 53 individuals per group), which limits statistical power. Finally, the participants in the study were not very heterogeneous, being mostly well-educated Caucasian women, so who knows if this applies to everyone.

Mindfulness meditation is obviously no miracle cure for chronic pain, but it sure seems like it can help people cope with the pain. In my humble opinion, it can only be a good thing to take some time to breathe correctly and relax. It would be extra nice if the researchers also recommended daily naps, though.

Mr. Minou is also an adept of meditation.

Reference: Mindfulness-based stress reduction for chronic pain conditions: variation in treatment outcomes and role of home meditation practice. (2010) Rosenzweig S, Greeson JM, Reibel DK, Green JS, Jasser SA, Beasley D. J Psychosom Res. 68(1):29-36.

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