Stupid Eustachian tube tricks

From Wikipedia:

Some people are born with an ability to voluntarily contract just these muscles called Voluntary Tubal Opening, similar to the ability of those who can wiggle their ears. Those who have this ability can hear "pop" or "click" sound in the middle ear when actuating these muscles, and are able to hold the muscle contraction (some refer to this as 'clicking your ears to equalize the pressure').[citation needed] Doing so will make one's voice sound louder to oneself. This ability allows such people to voluntarily equalize pressures at will when making rapid ascents or descents, typically in aircraft flights or large elevation changes in either tall buildings or mountainous treks.

I am one of these people, although clearing my ears without swallowing wasn't something I was aware I could do until I took SCUBA classes some years ago. When I do this it makes a click loud enough that my wife can hear it if she puts her head close to mine. Unfortunately this doesn't seem to help in clearing a lingering ear infection, as I can't currently get my left ear to click.

Studies in current evolution

Research Question:
To what extent is the number of children people choose to have in developed nations heritable (in the genetic sense)?

Importance:
If it is heritable, this is most likely the largest determiner of fitness outcomes, as the great majority of children survive to adulthood, no matter how many siblings they have. This implies potentially rapid Darwinian selection for those who choose larger families. Over the course of a few centuries this selection could have important impacts on human demography and population. Given an estimate of heritability, this effect could be quantified.

Method:
The old twins/siblings separated at birth databases?

Ethical considerations: many

Likelihood I will actually get around to this:
small

Hobbits had big odd looking feet.

Well, duh...

Next they'll discover that Homo floresiensis were fond of tea cakes and lived in holes with circular green doors.

The Free Encyclopedia and 'Hairless' Apes

Without having done extensive checking, I would guess that Wikipedia is the only encyclopedia in the world in which the section on primate taxonomy includes nude photos of male and female humans with all their body-hair removed.

I suppose one could argue that body hair would obscure some portion of our typically primate anatomy, or make the photos appear less clinical. That said, none of the other primates pictured are shaven, so why the humans? And honestly, human's body hair doesn't hide that much anyway. As humans are naturally the least hairy of any primate, the clean shaven models seem to me to unduly exaggerate our distinctness from other primates. I don't approve.

On further consideration of the nature of Wikipedia, the inclusion of these photos could be intended purely to annoy social conservatives who object on religious grounds to the placement of humans among the primates. In that case the hairlessness would presumably be intended to emphasize the nudity of the models.

A conjecture on the link between babies and lack of sex

I am told by those who have children that one of the many sacrifices couples make to raise a baby is opportunity for sexual intimacy. I don't have kids, so don't know from personal experience, but it certainly makes sense. Between exhaustion, vehement interruptions and company in the house, it can be hard for a couple to find the time, privacy and energy to maintain their pre-parental levels of activity. I have had friends say that it seems very much like the baby is plotting to destroy its parents' sex lives. It has just occurred to me that in a sense, this could be very true.

Evolutionarily, there are many ways in which the interests of the parent and the interests of the offspring are aligned. The fitness of both are improved if the baby grows, thrives and go on to produce its own offspring. They share many genes, and anything that is good for the one is at least a little bit good for the other. But some things that are good for the fitness of the parents are a net selective loss for the baby. Such as having another baby come along too soon. The parents of course are equally closely related to all their offspring, and therefore will tend to distribute care and resources between their children in a way that maximizes the number of future grandchildren. But the baby is twice as closely related to herself as she is to her full sibling; she is much better off monopolizing her parents' time and resources for longer than they might desire. The parents' fitness is maximized by having an interbirth interval just long enough to get a good return on their investment in this offspring, without unduly diminishing their opportunity to have more children in the future. The child's fitness is maximized by having the parents wait somewhat longer, until the diminishment of their future reproductive chances for each additional day waited is twice the per day increase in her own fitness gain. The technical term for this disalignment of interest, appropriately, is parent-offspring conflict.
At first glance, the advantage in the conflict over the length of the interbirth interval would seem to be distinctly on the side of the parents, rather than the sessile, pre-sentient, altricail lump of chub, digestive organs and breathing apparatus. But oh, those breathing bits can very easily be used to make sounds. Sounds that communicate desperate dire need to protect and nourish the baby. Sounds that cannot easily be ignored. What harm if one screams just a little bit louder, a little more frequently, screams and cries with slightly less provocation, and makes the parents increase their interbirth interval just a little while longer?

Before you label me a conspiracy theorist, let me be clear. I am not implying that the babies of the world are 'trying,' in any intentional way, to deprive their parents of sex. They don't have to try. It comes naturally to them.

One foot in this world...

From my perspective as an evolutionary biologist, all of the social sciences are parts of the study of human behavior, which is a part of the study of animal behavior, which is a part of biology. I don't generally bring this up to the social scientists I know.

I recently attended a talk, in which the speaker was an historical economist, studying the marriage market in post-WWI France. The lack of marriageable men(due to combat fatalities) led to the surviving males having the ability to be much more choosy than they otherwise would. Many men were able to marry women from social classes higher than their own. Many women simply never married. This effect faded away as a new crop of young men got old enough to marry. At the end of his talk I raised my hand, and asked if he was aware of the biological literature on the effect of skewed operational sex ratios on mate choice and assortative mating. I believe that the idea of looking at the literature on the same phenomenon in other species hadn't occurred to him. To a natural scientist this is almost scandalous. To a social scientist, it is the standard and correct way to proceed. It is a very different world view.

But now my field of expertise is becoming evolutionary demography, which draws as much from social science as it does from natural science, and this has begun to affect my thinking. This afternoon I was presenting my research plans to my professor's lab group, and one of the biologists asked why everything I said kept relating back to humans. I told him that as I was studying post-reproductive lifespan, and humans have more PRLS than any other species we know of, and we know more about it in humans, and therefore it was inevitable that most of our questions and methods would relate back to humans. It took me a minute to realize this wasn't the whole truth. The broader answer was that I had started to think a bit like a social scientist, meaning anthropocentrically. In the social sciences one doesn't need an excuse to focus on humans, the social sciences are all about humans. Having a conversation with social scientists requires one to be able to understand anthropocentric thinking, and if one practices this enough, one can start to think like them.

There are times when anthropocentrism is absolutely necessary and proper. Most of human activity revolves around interactions with other humans, and many of the problems we face can only be understood by focusing deeply on understanding humans. Part of the reason I work on problems relating to humans is because that is what society values, and as I've said before, I think this is appropriate. But the reason society (through a grant to an economic demographer) is paying me, rather than an economist or a demographer to do this work, is because it is useful to have your conversation about humans be illuminated by knowledge of other species.

If I stay in this field, which I plan to, I will have to learn how to converse one moment with those for whom humans are almost everything, and the next with those for whom humans are just one very over-studied species.

Non-scatological poo

Biologists not infrequently find ourselves speculating in a purely intellectual way about things that are otherwise not discussed in polite company. Take feces for example. The discussion of feces is so stigmatized as to have its very own adjective. Scatological humor is humor relating to poo. If one's conversation, thinking, humor or complexion is described as scatological, one is generally not flattered. But there are legitimate biological questions to ask about poo.

This afternoon, I was considering the question of why we evolved to have our anus placed such that feces, after leaving the rectum, have ample opportunity to contact the surrounding skin, which then need to be cleaned. And then I began trying to imagine other places a human's digestive tract couple potentially end, and what the advantages and disadvantages would be. What would it be like, for instance if our genitals were behind, rather than in front of, our anuses. And, taking a comparative approach, I thought about what I know about the anal anatomy of other species, and how they clean themselves, or avoid the need to do so. And all in a purely intellectual context, without the slightest feelings of revulsion, shame or titillation. Yet somehow, I knew that one is expected to keep that sort of speculation to one self. Unless one is a biologist. And even so, I probably won't bring it up to my neighbor on the train tomorrow.

Human Oestrus

Iris and I are reading Jared Diamond's book on the evolution of human sexuality, "Why is sex fun?" An interesting read, and in many ways a good introduction to the science of behavioral ecology, except that Diamond falls into his usual habit of making the same point many times and many ways, as if to beat you into agreeing with him. Since I generally start out agreeing with him, this gets tiring. The chapter we were reading last night was primarily his speculations on the evolutionary basis of the lack of obvious oestrus in humans. I was therefore very interested when this evening, browsing the table of contents of ProcRoySoc B, I cam across an article titled "Human Oestrus"

Here is the abstract:

For several decades, scholars of human sexuality have almost uniformly assumed that women evolutionarily lost oestrus—a phase of female sexuality occurring near ovulation and distinct from other phases of the ovarian cycle in terms of female sexual motivations and attractivity. In fact, we argue, this long-standing assumption is wrong. We review evidence that women's fertile-phase sexuality differs in a variety of ways from their sexuality during infertile phases of their cycles. In particular, when fertile in their cycles, women are particularly sexually attracted to a variety of features that likely are (or, ancestrally, were) indicators of genetic quality. As women's fertile-phase sexuality shares with other vertebrate females' fertile-phase sexuality a variety of functional and physiological features, we propose that the term oestrus appropriately applies to this phase in women. We discuss the function of women's non-fertile or extended sexuality and, based on empirical findings, suggest ways that fertile-phase sexuality in women has been shaped to partly function in the context of extra-pair mating. Men are particularly attracted to some features of fertile-phase women, but probably based on by-products of physiological changes males have been selected to detect, not because women signal their cycle-based fertility status.