Today we have a special Q & A from Kelly Allen and her East Chapel Hill HS Biology II (Human Biology) students. Each year Allen’s students participate in Biology Book Clubs and this year they read Rob Dunn’s The Wild Life of Our Bodies. Without further ado, questions asked by high school juniors and seniors to Rob Dunn:
Amanda: Why did humans lose their ability to detect who a person is by their scent, while other primates and mammals still are able to do so? Since its something needed for survival, I would have thought that our ability to smell would have improved, so why did it get worse?
Rob: This is a fascinating question. Our smell is still good, just not as good as that of our ancestors (a few important genes are actually broken). One possibility is that as we began to become more vocal that the cues provided by language replaced those provided by odor. We are a “I think therefore I am,” sort of species rather than a “I stink therefore I am,” one. But the truth is this is a good mystery you should study.
Morgan: What is the most important “good bacteria species” on our bodies, if one exists?
Kristen: Are people from different countries affected by different face mites?
So far it looks as though people whose ancestors are from different regions have different face mites. Mites on people of Thai ancestry are different, it seems, than those on people of Irish ancestry. But humans are incredibly diverse and so we have only seen a small part of the global story so far. If you have ideas about how to sample people from every country on Earth in one place, let us know. We are ready to go for it and, in doing so, to finally answer your question well.
Evy: Could human activities (like washing faces, lotion, etc.) affect the types of face mites we have?
On the one hand, you would think that these behaviors must. On the other hand, mites can go deep into your pores and so it is also possible that they are able to ride out these assaults on their well-being like prairie dogs waiting for a coyote to walk away.
Alex: You mentioned that thousands of species remain unnamed because of the lack of knowledge about them. At what point is the information about a species sufficient enough to call for a name?
If the species is, say, an animal, we need to compare the features of what has been found (say a mite on your face) to those of other similar organisms in museum collections. This requires scientists to travel to those museums. It requires detailed drawings. It requires a lot of time and fastidiousness. There are so many new species out there that there just aren’t enough scientists around to do this. There is a scale insect living in my backyard that is probably a new species, but there aren’t really that many scale insect biologists around and so I suspect it will take a long time for anyone to name it. For bacteria, things are even more difficult. To really name a new bacteria species one has to grow it. To grow it we have to figure out what it eats. For most bacteria species on Earth that have been discovered so far this business of knowing what they eat is very, very difficult. No one can yet grow in culture most of the species found on your body Alex, for example.
Cassie: How many of the thousands of unnamed species that live on/in our bodies do you believe are beneficial to us? Or do you believe that most just have a fairly commensalistic relationship with us?
Great question. My sense is that the majority are having little negative or positive effect but that there are probably several hundred with benefits (on the average person). But that is just a wild guess. I’ll give you a wild and specific guess—238.
Wenyu: How do our bodies deal with all the different mites, worms, etc. in the air that we breathe in?
That is interesting. Sometimes your lungs get inflamed and generate an immune response. This is part of what is happening when you get phlem in your lungs. In other cases, the organisms just hang out there, peacefully bumping around as you inhale and exhale. Nearly all of us have large populations of fungi in our lungs. I think those fungi are mutualists and help to increase the surface area of our lungs. No one really studies them though.
Caroline: Do the hair mites reproduce on our head and continue to grow in numbers as we age?
Yes. But not just on your head.
Aatia: You mentioned how science can tie into other things. I’m an English person, so how can science contribute to what I want to do later in life?
Well, as someone who loves to read and/or write, you have a potentially great role to play in helping others to understand science. Just as with anything else, we understand science best in the context of stories. But let’s assume the extreme case and assume you hate science. It makes you crazy. You took Biology II because your mom said you have to. Even then, science will shadow your life, shadow your writing. Chekhov wrote, “show me a room with a man and woman and a teacup and the story is always about the man and the woman.” Great writing is usually about people, but people are biological, their bodies and narratives obey the laws of science. To be a great writer you need to understand people well, to understand people well you have to understand biology, to understand biology, you need to understand something of chemistry, to understand chemistry really well, well, you need to have a sense of the history of the universe.
Abby: When people get infected with toxoplasmosis, does it make them love cats more in addition to making them more likely to be in a car crash?
That is an awesome question. As far as I know no one has ever asked it. But, as you intuit, it is what we would predict based on studies of mice and rats. Actually, what we would predict is that people infected by Toxoplasma gondii are attracted to the smell of cat pee. You should study this, Abby!
Ella Biestek: If you get facials regularly, do the mites actually remain on your face…even with chemical peel facials?
Well, we know that they don’t disappear entirely from your body. They may just hunker down and wait it out. How awful it must be for them! Or maybe what happens is that the mites on your face die when you get a facial and are replaced by the ones that survived on, say, your back.
Ellis: Are the bacteria that reside on your skin, the ones that are the first to protect your body against infection, the same ones that determine your tastiness appeal to mosquitoes?
We don’t know yet. My prediction is that people whose ancestors have lived with malaria are likely to have bacteria on their skin that is less attractive to mosquitoes. The logic goes like this… Those of their ancestors that were more attractive to mosquitoes died. As a result, anyone who was a little less attractive to mosquitoes was more likely to pass on their genes. Those genes, we can speculate, were ones associated with the ability to “garden” hard to detect skin microbes. I guess my sense is that there are many potentially beneficial skin microbes and a subset of those is attractive to mosquitoes. That subset, it appears, is the same subset that we tend to favor when we use antiperspirant.