Choosy mates

Zach and I have finally completed our move and I will hopefully be able to update at least semi-regularly again. 

I’ve been noticing a lot of articles in the news lately which report on the “surprising” result that human men and women are about equally choosy when picking a mate (in this article, for example).  The articles claim that the result is surprising because of a long-standing belief that women are choosier because they invest more energy into reproduction (larger gametes, gestation, etc.) then men.

Because reproductive investment is low in men, they could potentially produce hundreds of offspring at little cost to themselves. This high potential for reproductive success means that men should mate with lots of females to maximize their fitness. On the other hand, females are only capable of producing a fixed number of offspring during their lifetime and mating is often costly, so females should only mate with a few, carefully choosen males. The main point here is that males have a greater reproductive potential than females. 

That’s all well and good, but it completely ignores the fact that, in monogamous systems, a male will only end up with as many offsprings as his female partner is capable of producing. Males should therefore be choosy because they want to find a female that will produce as many healthy offspring as possible and females should still be choosy for the same reasons as before.  

Of course, few if any species are completely monogamous.  Genetic studies have revealed that many of the bird species we’ve written songs and poems about because we consider them to be shining examples of monogamy are actually fooling around behind each other’s backs fairly often. So we shouldn’t be surprised when we find that females are willing to sneak around with males of a higher quality than their social partner and males should be willing to sneak around when they get the chance too.  But the point still remains that both sexes in mainly monogamous systems they should be as choosy as possible about the social partner with which they’ll be producing the bulk of their offspring.  

Most human cultures are monogamous (to some degree) and so it doesn’t seem to me that we ought to be too surprised to find that males and females are equally choosy about their partners. The studies examining human mating behavior are certainly interesting, but (despite their claims) they aren’t producing results that are particularly surprising. 

Should scientists be better public servants?

In an earlier blog I chastised parents for taking advice from celebrities like Jim Carrey and Jenny McCarthy on important health topics.  In the days since I wrote that blog I’ve been wondering about the scientist’s role as a public servant.  Could the scientific community have done more to counter this misinformation, perhaps preventing the decrease in vaccine use that we’re currently witnessing?

I believe that the answer is yes, we could have done more.  Vaccines aren’t the only area where greater scientist involvement could make a difference.  I’m confident that just about every scientific subdiscipline has something important to offer the public.

So how do we get this information to the public?  It won’t be easy, but I think we need to be proactive.  We could contact newspapers, TV stations and radio stations, for starters.  We could contact local high schools and offer to give special lectures to students during their scheduled science classes. 

But the question remains, “Are we obligated to do anything?”  It likely depends on which scientific position you hold, but the contracts that most of us have signed in no way state that we’re obligated to educate the public.  That being said, I think it’s important to remember that taxpayers pay our bills.  Whether you’re funded by NSF, NIH, the university or college that you work for or some other government agency, it’s likely that state and federal tax monies are going towards funding your projects and paying your bills. 

Despite this, it is the case that what we’re actually being paid to do is to either teach courses or conduct research.  Our bills are also being paid by the students sitting in the courses that we teach.  In fact, in academia at least, too much public service could be detrimental to your career.

Why don’t scientists spend more time engaging the public?

The answer, in my mind, is because it’s often detrimental to our careers.  It’ll probably take a lot of time and effort to really get the public’s attention (especially when we’re going up against celebrities) and many of us are in a system where we can’t afford to offer that kind of a time commitment.

If you’re a professor going up for tenure, then you’re going to be judged on a set of predetermined criteria.  I have yet to go through the tenure process myself (I’m still a graduate student), but I believe I have a pretty good understanding of what the criteria are for achieving tenure.  The tenure committee focuses on how many papers you’ve published and where you published them, how many courses you taught and how well you taught them, how capable you were at establishing your lab, and how much service you provided to the department and the institution as a whole. 

 

Carl Sagan

If you’re going to excel in all of these areas in the space of 7 years, then just about any activity you engage in that isn’t focused on achieving these ends is going to set you back.  I know people who have even put off having the children that they eventually want until after they’ve received tenure because they don’t even feel like they have time any spare time at all.  During the years when you’re really getting into the groove of what kind of a scientist you’re going to be, you’re keenly aware that you don’t have time to spend communicating with the public.  This is critical because, as far as I can tell, not making tenure is devastating to one’s career.

 

Once tenure has been reached, there is still no incentive to spend one’s time with the public.  Professional scientific societies and the scientific community as a whole primarily praise and award achievements in research, not public education.  So again, time spent communicating with the public is time that you’re taking away from advancing your career. 

So what is the solution?

I don’t think that change is going to come without a push from research institutions and professional societies.  For example, I think it would be absolutely fantastic if universities hired scientists who were paid to spend all of their time finding ways to communicate with the public.  They should be required to stay on top of important public issues (swine flu, vaccines, etc.) and should then disseminate this information through public media as well as more direct avenues (public lectures, etc.).

Alternatively, universities could offer professors limited teaching loads for a semester every couple years in return for time spent educating more publicly.  They would be charged with discussing whatever topics are pertinent in their field and would be required in some way to show that they had made a strong effort to get this information out.

The problem with both of these solutions is that they require even MORE taxpayer money to get them accomplished.  Hiring a scientist whose sole job it is to educate the public wouldn’t be cheap, nor would paying a professor who wasn’t teaching (as college students sitting in a classroom are paying tuition which keeps the university running).

E.O. Wilson

Until we figure out another solution, our hopes rest on the few scientists who really do try to reach out to the public.  There are and have been a few greats.  My personal favorites are Carl Sagan and E.O. Wilson. 

Many others have good intentions, but end up preaching to the choir.  Some choose channels that have a tendency to reach people who are already science minded.  Others close out those that they need to educate by insulting them for holding different beliefs or for not understanding the concepts that we’re trying to get across.  I guess my point here is that, if you’re a scientist interested in public education, please please please stay patient and don’t fuel the growing stereotype that scientists are assholes.  This makes it difficult for us to get the public to listen when it’s really important.

In conclusion….

I look forward to reading your comments in regard to this post.  I’m sure that there’ll be controversy over whether or not we should feel obligated to spend our time communicating with the public.  I’m not suggesting that all scientists should be obligated to do this, but simply that we could probably make a big difference if we did find ways to spend at least some of our time correcting misunderstandings and spreading new information.  What do you think?

Philadelphia’s Mütter Museum

A few years ago, my favorite technical writer/biologist and I traveled halfway across the country to visit the Mütter Museum in Philadelphia, PA.  The museum is associated with The College of Physicians of Philadelphia and was originally intended as a way to teach its aspiring doctors about medical anomalies.  It’s now open to the public and aims to educate visitors about medical anomalies and how the practice of medicine has evolved over time.  Currently, they have an exhibit on the impact of lead on human health. 

It’s a fairly small museum, but has a number of really neat displays.  Among the displays you’ll find a cancerous growth removed from Grover Cleveland, vertical sections of the human head and a 9-foot long human colon.  It’s a pretty neat way to learn about human anatomy.  Some great pictures from the museum can be found here. 

My favorite display is the skeleton of Harry Eastlack found in one of the downstairs corners of the museum.  Harry had a disease known as FOP (fibrodysplasia ossificans progressiva), a rare disease of the connective tissues (muscles, tendons and ligaments).  When a person with FOP injures his connective tissue, his body ossifies (turns to bone) the region instead of repairing it normally.  People with this disease often lose coordination over time as various parts of their body become bone and fuse together. 

By age 20, Harry’s vertebrae had fused together and by the end of his life so much of his body had been ossified that he was pretty much incapable of movement. Fortunately for the scientific community, Harry was selfless enough to be thinking about other sufferers of FOP and donated his body to science in the hope that it would increase our understanding of the disease.  Unfortunately for FOP sufferers, there is still no cure.  

My favorite thing about the museum was that there was a real air of curiosity and respect amongst the visitors.  An environment like this could easily lend itself to lots of crude jokes, but I didn’t overhear even one.  So if you’re genuinely interested in human anatomy, then I would suggest dropping in on the Mütter Museum the next time you’re in the Philly area.

Bacteria communicate more efficiently than I do

Some things are just better done in groups.  For example, it’s better to wait until you have a large group of allies before going to war.  People know this, and apparently bacteria do as well.

If a lone bacterium where to “decide” that it was time to launch an attack on its host, then the host’s immune system would probably be able to hone in on this individual and remove it rather quickly.  The bacterium’s chance of success increases dramatically when it’s acting in conjunction with lots of other bacteria at the same time.  Bacteria figure out how many of their allies are present through a system known as quorum sensing.

When a bacterium’s receptors detect a sufficient number of allies close by, a series of important genes related to accomplishing specific tasks are switched on or off.  By this mechanism, everyone goes into attack mode together. 

Bacteria use quorum sensing in other ways too.  My favorite example involves a bioluminescent bacteria called Vibrio fischeri.  Bioluminescent bacteria produce a glowing light, similar to the lights emitted by fireflies.  Vibrio fischeri have an unusual symbiotic relationship bobtail squids. 

During the day, these bacteria reside in a portion of the squid’s mantle, where they’re provided with ample resources for growth and reproduction.  By night, when the squid is ready to hunt, the bacteria have sufficiently multiplied to the point where they reach quorum.  At this point, they begin bioluminescing as a group.

So why would the squid want to be carrying around a bunch of brightly lit bacteria? Well, on moonlit nights the squid casts a distinctive shadow on the sea floor as it hunts, attracting the attention of predators. 

The light produced by the bacteria cancels out the squid’s shadow.  The squid’s bacteria pouch contains a filter, which the squid uses to dim the light to the point that the amount of light emitted from the pouch matches the amount of light shining on the side of the squid facing the sky.  In return for a good meal and a safe place to call home, the bacteria help the squid hide from its predators.

At the end of the night, the squid squeezes most of the bacteria out of the pouch, leaving enough so that quorum will be reached again the following night.

Current quorum sensing studies are attempting to better understand mechanisms bacteria use to coordinate attacks on the human body.  By figuring out how bacteria communicate with one another, it may be possible to disrupt their communication efforts and less the efficiency with which they attack.

If you’re interested in learning more, the Bassler Lab  does a lot of awesome work on quorum sensing.

You are what you eat

One of the most interesting parasites is the protozoan Toxoplasma gondii. This sucker is everywhere and capable of some pretty amazing behavioral host manipulations.

 Nearly all warm-blooded organisms can be an intermediate host for this parasite. The parasite reproduces asexually in this host and forms cysts in its muscles and brain tissues. The parasite “wants” (in an evolutionary sense) its intermediate host to be consumed by its definitive host (wild and domestic cats) and has evolved elaborate mechanisms for altering its host’s behavior to make this happen. For example, infected mice become more active and more willing to spend time in open areas.

 Studies in rats have produced even more surprising results. Rats have an innate aversion to cat urine because it is usually a very good indicator that a predator is in the area. A study comparing rats infected with Toxoplasma gondii to uninfected controls discovered that not only do infected individuals lack the characteristic aversion response, but they actually seem to be drawn TO cat urine, a behavior which is certainly risky for a rodent.

 So parasites seem pretty capable of modifying the behaviors of rodents. But what about people?

 For many years, infection by Toxoplasma gondii in people wasn’t thought to be serious. Infected individuals would exhibit flu-like systems for a few days to a month or so, but after that would no longer feel “sick.” However, we now know that individuals remain infected because the parasite forms antibiotic resistant cysts that continue to reside in muscle and brain tissues.

 Recently, some labs have begun looking at whether or not Toxoplasma gondii has subtle behavioral effects that may have been overlooked in the past. Research is accumulating to suggest that this is indeed the case.

 Personality surveys have yielded mixed results, but the majority of surveys reveal that Toxoplasma gondii infected individuals exhibit significantly different behaviors than uninfected controls. For example, personality inventory results suggested that infected males are more vigilant, frugal, suspicious, jealous and less rule-following than male uninfected controls (any other women finding themselves wondering if particular ex-boyfriends were carrying heavy parasite loads??). Infected women, on the other hand, show a higher “superego strength,” meaning that they’re more moral, warm, persistent, rule-conscious and outgoing. These behavioral differences are more noticeable as time goes on.

 But that’s not all! Both infected men and women show higher apprehension, greater insecurity, and a decrease in novelty-seeking behaviors. Importantly, infected individuals appear to have slower reaction times than uninfected individuals. If you’re wondering whether or not the difference in reaction times is enough to matter, then consider the finding that infected individuals are 2.65 times more likely to be in a traffic accident than an uninfected individual.

 Finally, and perhaps most perplexing, is the finding that infected females are pregnant for a longer and are more likely to give birth to a son than a daughter.

 An important disclaimer should be made here. Because purposefully infecting people would be unethical, we can’t scientifically compare human behaviors before and after infection with Toxoplasma gondii. This means that it’s currently impossible to figure out whether this parasite induces the behavioral changes or whether individuals with a certain personality type are simply more likely to become infected.

 The jury is still out on the mechanism the parasite uses to induce these manipulations. Promising research suggests that manipulation of the dopaminergic system is to blame, but I’m not yet aware of anything conclusive.

 So how do people become infected in the first place? One common way to come in contact with the parasite is through the consumption of uncooked meats. Lots of warm-blooded animals contain infective Toxoplasma gondii cysts in their muscles, so countries in which people often enjoy undercooked meats have a higher occurrence of infection.

 Additionally, having cats around can increase infection risks. Toxoplasma gondii offspring are passed into the environment with a cat’s feces, where they become infective a few days later. Consuming the parasite and becoming infected can occur after changing a litter box or gardening (if cats have been defecating in the garden), for example.

 Infection rates in a population depend on diet and feline exposure, and infection rates have been reported to be as high as 80% in some areas. In the United Kingdom, for example, a report revealed that up to 38% of stored meat samples contained Toxoplasma gondii.

 These results have interesting implications! First of all, it’s almost scary to ponder whether or not some of the behavioral attributes that you consider to be quintessentially “you” are subtly modified by parasites. Second, how much of the differences between cultures can be explained by differences in infection rates? Might it be more dangerous to drive in countries where people eat a lot of uncooked meat, for example? Also, can information about how parasite behavioral manipulations tell us about how our brain works? Hopefully, the future holds more answers!

 Read more(!):

 Lots of work on this topic have been done by the Flegr lab and a review of their work on how Toxoplasma gondii effects human behavior can be found here.

 A review of the rodent literature by Joanne Webster can be found here.

 A paper on how Toxoplasma gondii may affect human culture by Kevin Lafferty can be found here.