Wednesday, February 15, 2012
How I got stapled to a live turkey, and other fond memories of California
Sunday, February 12, 2012
Spanning the vastness
Saturday, February 11, 2012
Emissions of the aged
My friend and colleague Emilo Zagheni decided we should make the calculus that much more complicated (and informative) by also asking how the aging of the population will influence carbon outputs. A demographer's demographer, which Emilio surely is, is never happy with any calculation that does not include age-structure in one way or another.
This article in the Economist summarizes what he did and what he found. As people get older, they tend to consume more and more, emitting more and more carbon, until 65ish, at which point consumption tends to start declining. See the graph, and the analysis, in the Economist, or the original in the journal Demography (2011) pp 371-399. The punchline for the carbon-watcher is that the changing age-structure will tend to increase carbon emissions until about 2050, after which point such a large portion of the population will be above 65 (I'll be 73) that the age effect will begin to marginally decrease emissions.
I should finish with a quote from Ron Lee, Professor of both Demography and Economics at UC Berkeley, who both Emilio and I studied under. Ron was one of the inventors of the widely used Lee-Carter method* (1992) for forecasting future mortality patterns. Seventeen years later, I asked Ron how well his forecasts for the first 17 years matched what had actually happened in those years. He cocked his head slightly to the left, sighed sagely and said, "Well, demographers are well aware that our projections don't always fair so well in a complex world. But we console ourselves with the knowledge that we do much better than the economists."
* The original article has been cited more than 1000 times in the peer-reviewed literature, and modifications are used by the US Census Bureau, the UN, and so forth.
Friday, February 03, 2012
Suddenly crustaceans
I've now gotten to the point in my career where I am organizing a research group and serving on people's committees, and suddenly and unintentionally, I'm all into crustaceans. I'm supervising a post-doc and a doctoral student and on the committee of another student all working on different Daphnia projects. Daphnia are the model organism for crustaceans. I've got another post-doc working on barnacles (which despite their outward appearance as adults, are very much crustaceans, and go through not one but two amazing metamorphoses before ending up attached to ships, rocks or whales). This particular barnacle, Balanus improvisus was first described by Darwin (1854) in his giant book on barnacles that he wrote to procrastinate publishing On the Origin of Species (1859).
I've still got projects on Neurospora a fungus best known for ruining your bread, on Hydra, and on primates (including humans) going, but most of my time at the moment is crustacean focused. I suppose I will have to learn the basics of carcinology. Yes, that does come from the same root as carcinogen and carcinoma.
11-hour
One of our laws in the U.S. requires that federal paperwork that people have to fill out be a bit longer than necessary in order to inform us that the federal government is mandated by law to reduce unnecessary paperwork, and to provide an estimate of how long it should take to deal with the particular piece of paperwork.
I'm preparing a grant application to the National Institutes of Health, and have spent the last month trying to figure out the rules, regulations and customs. They provide a helpful 264 page guide to filling out the application form, with links to more information online. This guide estimates it should take me 11 hours to prepare my application, not including the part where I design my research. It also advises me that I should read the whole guide, and the various additional information (including a very necessary glossary) before beginning to fill out the forms. A friend of mine, who recently looked at this instruction book and thereupon decided not to apply for NIH funds, suggested that anyone who could read and comprehend all 264+ pages in under 11 hours with enough time left to fill out the forms should probably just be acknowledged as a genius and given whatever money they need for their work.
I certainly don't blame NIH for having a lot of rules, or putting them in a book. They have a huge number of people asking them for money, the responsibility to make sure all the applications are dealt with fairly, and the need to comply with a very large number of laws on many topics. All sorts of special cases and exceptions arise, and they need to have guidance on everything (although I have already come across several places where one just has to know how it is done, generally by asking people who have done it before). So you can't really blame their helpful but understaffed staff. However the 11-hour estimate should probably be reexamined.
Anyway, I'm learning, and the next time I write an NIH application, it may take me only 11 hours to understand the rules, provided they haven't changed them too much. The sad part is that the proportion of applications funded continues to decline, even as the length of the application instructions increases. I'll distract myself from thinking about that by reading the 33 FAQs about the Modular Grant Application Concept.
Wednesday, January 25, 2012
Can anyone think of model organism genera starting with I,J or Q?
Arabadopsis
Bufo
Caenorhabditis
Drosophila
Escherichia
Felis
Gallus
Hydra
I
J
Klebsiella
Loligo
Mus
Neurospora
Oikopleura
Phodopus
Q
Rattus
Saccharomyces
Trichoplax
Ustilago
Vibrio
Wolbachia
Xenopus
Yersinia
Zea
Thursday, January 05, 2012
A, alligators all around
They say that the distance in inches between an alligator's eyes and its nostrils is equal to the length of the whole animal in feet. This behemoth hangs out by the fishing dock in Loxahatchee National Wildlife Refuge feeding on discarded bait fish and who knows what else. My best guess is 14 inches nose to eyes, which would make it not unheard-of big but certainly exciting-to-canoe-past big.
It is amazing to think such an invulnerable top predator (at least within the refuge) started out nearby as a scared little snack for herons like this:
Authorship code
I'm writing a paper with two of my students. Well, I'm writing it with one of them and another one did a lot of work on the statistics. But today we had to straighten out the order that the authors would be listed in on the paper. This can be a contentious issue, and I know of cases in which papers did not getting written at all because the authors couldn't agree on who got to be listed first. Some big multi-author papers simply list everyone in alphabetical order to avoid the fuss, but then Dr. Aardvark always gets to be first author. Some journals have a little section where each author's contribution is described, but they usually end up saying something uninformative and false like "all authors contributed equally."
I came up with most of the ideas in the current paper, put things together, decided who would do what, etc. My student did much of the lab work and is doing much of the actual writing. Given this, most biologists would propose what I did, and what my student objected to: She (as the person doing the writing) should come first, I (as the senior person on the paper) should come last, and everyone else (in this case meaning the statistics student) gets sandwiched in between. This was very counterintuitive for my student; she thought I was trying to minimize my own role by putting myself last. In fact, it is a step up for me to be writing papers in which I am in that last position. I remember this being counterintuitive for me the first time it was explained to me. I was a college student, and a boss said that he'd make me second author on a paper. I said something to the effect that I'd be glad to be even last author, which I thought was being humble, but he took it as me saying the paper had been my idea. We straightened out the miscommunication but I didn't end up being listed as author on the paper. That the last author spot (at least in biology) signifies the senior author is a code biologists internalize, and I had to think back a long way to figure out why my student objected to me being last author. I explained, she reluctantly believed, and now it is settled.
Tuesday, January 03, 2012
Oh give me a home, where the apple-snails roam
Retirement communities are, by design, fairly sterile places. Much of south Florida is covered in huge gated spreads of nearly identical buildings with neatly trimmed lawns leading down to pleasingly curving shallow canals so that every apartment can have water views. It is uniform, controlled, boring. But all those networks of shallow canals catching lawn fertilizer and Florida sun provide habitat and highways for rapidly growing aquatic plants, which feed aquatic invertebrates and fish. With relatively few retirement community residents catching their own fish, this leaves the fish to grow as big as want.
Or at least it used to. When I was a kid visiting my grandparents in Century Village, I rarely saw any wildlife around the wide place in the canal (referred to as a lagoon because it increases resale values) behind their apartment.
When I was a teenager and my grandmother was widowed, the lawn by the water was occupied by a flock of Muscovi Ducks (plant eaters), Cattle Egrets (which eat mostly insects picked from lawns) and the very occasional Great Blue Heron, which eat only small to medium fish. My aunt inherited the same apartment, and my wife and I brought our baby daughter to visit her this winter. Our first morning there, jetlag woke us early. Standing by the lagoon was a flock of Wood Storks. Walking past them in the water's edge was a flock of White Ibis, trailed by a Tricolor Heron.
On the far bank an Anhinga spread its black wings to the sun. A few feet away lay a huge dead fish, heavily built and probably 80cm long, partly eaten by something. What could kill a fish that big, drag it up on the bank and eat only part of it? Walking the banks we found the shells of numerous Apple Snails, so named because they are as large as the fruit. Apple snails don't come up on land by themselves, so something must have carried them up, presumably to eat them. In back of the next building over, beyond the Great Egret and Little Blue Heron, I could just see something moving on the bank. I thought it might be a dog (not allowed in Century Village) but then I could see it was two long low animals chasing and wrestling with each other. They jumped in the water and swam as no dog could. River otters! A pair of very large river otters chased each other, making circles in the reflected condos. The remains of several large fish, each only partly eaten, attested to the successful hunting they had been having in the canal.
Four Turkey Vultures sat around one such plate of sushi as others circled and swooped, their wing tips almost brushing the screening of enclosed patios. We cajoled my aunt, her bad ankle throbbing, to come out onto the lawn with us for a closer look at the otters. We crept closer to them and the fish they were snacking on until they raised their heads and hissed at me, at which point we backed off.
All this wildlife, carrion, birds and their poo on cars, giant snails, etc. are pretty clearly not what the designers of Century Village, and south Florida's thousands of other retirement communities had in mind. Nevertheless, I think most of the residents are probably happy to have so much nature on their lawns. I doubt all those telescopes and binoculars sitting in the screened patios were for spying on the other retirees.
Is this all good for the wildlife populations? Clearly they would have been better off if the wetlands had not been made into retirement communities, but given that they were, I'd guess that learning to exploit those communities is to their advantage. The water in these canals surely has all sorts of runoff from lawns and parking lots, but if the birds feeding in it can still breed consistently, they are likely to have a feeding habitat that no one will drain, pave or burn. If things get too rough in the nearby Everglades, they will have a retirement home ready.
Sunday, December 18, 2011
The end is neigh!
Wednesday, October 26, 2011
Undermining the Wall of Death
Another field within biology that focuses heavily on understanding aging is biogerontology. Biogerontology focuses on understanding the mechanistic basis of aging at the cellular and molecular level. They describe aging as a process of narrowing of the homeodynamic space, often due to accumulation of damage. Homeodynamic space is a concept related to homeostasis (the tendency of organisms to push their physiological state back to some optimum), but with the recognition that the goal that the individual is pushing towards, and its options for pushing, change over time. For example, as the cells in an organism accumulate mutations, it becomes more dangerous to allow them to continue replicating, because this could spawn a cancer. So the cells are forced to turn down expression of genes that allow for cell replication. But if your cells are replicating less, then you should be more reluctant to allow apoptosis, programmed cell death, because cells that die can't as easily be replaced. But if you've down-regulated the genes involved in apoptosis, this means infected cells will be less likely to kill themselves, so you need to have a stronger inflammation response, so that white blood cells will be brought to areas of infection and kill the infected cells from the outside. But increased inflammation has all sorts of nasty side effects, which themselves need to be compensated for. Note that I am just making this chain up as an example. The point being that the organism, in order to deal with the accumulation of damage, has to adjust various aspects of its physiology, which can cause damage or challenges to the system, which requires further adjustments. The organism gradually loses wiggle room, paints itself into a corner as it were. When this homeodynamic space gets too small, the organism can't respond to whatever insults (internal or external) come along and gets killed.
Reading papers in biogerontology, I am struck by two things. The first is how naive and outdated their evolutionary assumptions tend to be. For example, they still will state that aging is not observed in the wild because no individual lives long enough to grow old in the wild, an opinion that evolutionary biologists began to reject in the 1960s and have now disproved with data from numerous species from plankton to humans and birds to aphids. But I am also struck by how naive they would think our assumptions about age-specific genes are. They state as one of the basic principles of biogerontology that are no genes whose roll it is to cause aging, or which act at a particular age to regulate the chance of death. You will remember I said that such age-specific gene effects, from unspecified genes, are at the center of much of the theory behind evolutionary demography. Yet biogerontologists know such genes not to exist. So our assumptions about the mechanisms are as naive and simplistic as their assumptions regarding the demography.
This lack of communication, with each field basing its thinking on ideas the other has long since rejected, is common in science. There are simply too many journals, papers, conferences, etc., too many fields that may produce important information, for anyone to keep a useful fraction of an eye on most of them. So the lack of communication between fields is to some extent inevitable, but it does have significant consequences.
This is obvious when we introduce the gerontological observation that gene expression is not highly age specific (at least not late in life) to the evolutionary literature on post-reproductive lifespan (PRLS). Much of the study of PRLS has been motivated by the idea that PRLS shouldn't exist unless post-reproductive individuals do something useful for their younger kin. This idea arises from the evolutionary demographic theory of aging I described above. If an individual has reached the age where it can no longer reproduce, the genes it is expressing at that age should be genes that selection doesn't care about at all, because whether she dies at that age has no effect on how many offspring she has. So mutations that kill post-reproductive individuals should accumulate rapidly, unopposed by natural selection. W.D. Hamilton, a preeminent evolutionary theorist of the mid-20th century, wrote in 1966 that “In the absence of complications due to parental care or other altruistic contributions due to post-reproductives, the [mortality] curve should be roughly asymptotic to the age of the ending of reproduction.” By this he means that as the individual approaches the end of her reproductive period, her chance of dying at each instant should approach 100%. This has been dubbed "Hamilton's Wall of Death." Hamilton's work is influential enough, and his basic logic sound enough, that many of my colleagues still believe we should find the Wall of Death. But in fact we can find PRLS in a huge range of organisms where there is no parental care or anything comparable, and the Wall of Death is nowhere to be found. Hamilton's prediction fails because his model is built around high age-specificity of gene expression, which we now know not to exist. Genes which are being expressed at and after the age of reproductive cessation are the same genes being expressed prior to that age, doing the same things they did prior to that age (except of course reproduction) and so they can't just suddenly cause all sorts of lethal effects. This represents a major constraint on the ways selection can shape the pattern of mortality over age, and we evolutionary demographers are just starting to come to terms with the ramifications of this. When I have time to write another longish post, I'll explain how this leads to a major question in evolutionary demography that I have been thinking about but don't yet have any plausible answer to.
Monday, October 10, 2011
Constraints
One type of constraint that is particularly hard to build theory around is that natural selection can only favor those traits that exist. That is, a trait may be drastically suboptimal, but if all individuals in the population have that trait, and the genes which determine it cannot easily be altered by mutation such that they allow a higher fitness solution, the population will continue being far from optimal.
A classic example of this type of suboptimality is known as the 'obstetric dilemma.' This is the problem that humans have narrow pelvises and big heads, and the head has to pass through the pelvis during birth. In a (now somewhat out of date but still sound for our purposes) summary of one hypothesis of how humans diverged from our chimply relatives, Kristen Hawkes (the anthropologist behind the Grandmother Hypothesis) described (in 2003) the central role this obstetric dilemma played in human evolution thusly:
* Drying environments in the late Tertiary constricted African forests, making capacities to use alternative foods more advantageous among ancestral apes.
* Bipedalism was then favored because it freed hands for tool use, which
increased success at hunting big animals, and this put a premium
on larger brains.
* But the mechanics of bipedal locomotion limited pelvic width, so brain expansion created an ‘‘obstetrical dilemma’’ requiring most brain growth to be postnatal.
Consequently, children with developing brains were immature longer and were more dependent, for a longer time, on maternal care.
* The care requirements interfered with maternal hunting, so mothers relied on
provisioning from hunting mates. This help from fathers allowed mothers to produce more surviving offspring.
* Thus, parents formed lasting bonds and nuclear families became the fundamental
units of cooperation in which a sexual division of labor served familial goals of production and reproduction.
Now according to this story, variations of which are still supported by the scientific evidence,much of the distinctness of human life-history comes through:
1. The need for large brains and small pelvises
2. Which explains why our babies are so undeveloped
3. Which explains we take so long to mature
4. Which is an important part in explaining why we end up with our social system.
5. Which explains why we live so long.
So the optimality of a narrow pelvis, the optimality of a large brain and the need for
that brain to pass through that pelvis ends up being a central fact of human evolution. And why, we may ask, is it optimal for the baby's skull to pass through the mother's pelvis? The apparent answer is that if there is only one possible trait, that trait is the best of all possible traits.
The pattern of vertebrates expelling their young through their pelvis dates back to
before vertebrates actually had pelvises.

Note that this fish has its gonads above and in front of its pelvic fin. That is a common trait among fish, including the lobe-finned fish from which all terrestiral vertebrates are descended. The lobe-finned fishes had bony feet with which they could support themselves on the sea floor, and the bones in their pelvic fins would eventually be modified by evolution into the legs and pelvis.
Now the first terrestrial vertebrates were amphibians, and like most frogs and salamanders, laid small soft eggs, so it was probably no problem for them to continue having the gonads in front and running a tube through the pelvis to the cloaca. This system only became problematic when the eggs got large and hard, as they are in reptiles like turtles. Turtle people like to talk about "pelvic consraint" when they discuss why turtles don't make bigger eggs.
The only non-fish vertebrates to escape the need to run the babies through the pelvis are those that no longer have ana full pelvis, like whales and most snakes. To my knowledge nobody has managed to invent an alternative outlet, so everybody, including us, has to find one way or another to get through the pelvis. In fact, the only alternative is a human invention, the cesarian section.
This obstetric dillema is a very obvious contraint of the 'no alternative' type. Whenever I get a chance to write another longish post, I'll give an example of a constraint where the lack of alternatives is less obvious because it is genetic rather than anatomical.
Saturday, October 08, 2011
Sunday, September 25, 2011
Thoughts during a trip to a conference
It took 34 minutes from the time we arrived at Hamburg Hbf until I was sitting in my gate at the Hamburg airport waiting for my flight to Manchester. This without any running, pushing or hurrying, and the airport is not particularly near the Hbf. A single S-Bahn trip stops directly under the security check, so up two escalators I got on one of the many very short lines, and didn't have to remove my shoes or belt, nor get molested. I like to complain about the fact that you can't get a flight from Rostock's small airport to anywhere, but if door to gate takes only two and half hours, this is still better than many trips to JFK I've made. It is frankly slightly disorienting for an American for a transit system to work this smoothly.
As I sat in the gate, two English gentlemen sitting just behind me recognized each other and began to make small talk. The one is the occasional patient of the other, and has an appointment to see him in late December. They kept up a lively conversation about not much of anything, without a single pause, for about 45 minutes. I have heard the English talent for small talk described before, but I must say this was really impressive. They moved purposefully from one genial topic to the next, always with a smooth transition. Football, Christmas Markets, vacation destinations, and so forth. I felt like congratulating them.
As the bus took us from our gate to the plane, we passed a taxiing airplane from Air Tunis. It wonder if flights to Tunis are cheep these days? I've heard they have trouble filling their hotels since the revolution.
As we pass up then down through layers of clouds, I notice how closely defined their surfaces are. The top of my window can be mostly in the cloud, and the bottom mostly out. I wonder vaguely what sort of fluid dynamics allow for such a sharp transition to be stable.
I hope I have the right ticket for this train.
An hour and a half into wandering around Sheffield looking for my accommodation, I'm standing on a corner with three young guys with tattoos on their massive biceps as one of them looks up Edgecliffe Crescent on his iPhone. The guy resting in front of the closed Pakistani restaurant next door says go to the roundabout, take a right, and straight to the top.
Breakfast in the cafeteria is much what you would expect from breakfast in an English University's dormitory cafeteria. The orange juice and eggs are from concentrate, but the sausage is fresh squeezed. I sit across from a young woman who has never been to a conference before. I briefly consider teasing her about the fact that she is nervous despite not having to do anything but listen to other people's presentations. She gives me good directions to the conference hall.
"You can't really understand anything in ecology without thinking about soil biodiversity," says the plenary speaker. I guess what I do isn't ecology.
A couple of people come up to question me further after my talk. One of them is a guy I once emailed for advice on keeping rotifers. I can't remember what the question was, but thank him for how quickly he responded.
There is no way I am going to stay awake through the whole poster session. I get slightly lost on my way back to my room and end up in an OxFam thrift store. I get lost again carrying some used books. I spot an expidition of ecologists and follow them home.
Waking up cold I pass by the Greek place and have peas panner with garlic nann. I happily chew the hard chunks of spices in the sauce. "I'm a womanizer!" announces the old, obese, bald and drunk puddle of English gentleman at the corner table with the off duty waiters. "Yes, Sir, you are!" one of them reassures him.
I consider rehearsing my poster spiel for tomorrow, but instead prepare by sleeping more.
We are joined at breakfast by a conference of dentists (there may be a better term of venery for dentists, but I don't know it). They are easily distinguished by their unecologist-like formalwear.
Lost of people ask questions about my poster, and most of them tell me that while interesting, it has nothing to do with anything they will ever work on. This interesting but not directly relevant feeling is largely mutual.
Thursday, September 08, 2011
Tuesday, September 06, 2011
Dan SMASH!
I am not generally given to violence, but do currently have the urge to break something.

