experimentation

I have discovered that it is actually less effort to unlock the door to my apartment with my pocket knife than with the key. Perhaps it is time to change the lock.

Look Ma, ...

I find myself unable to use my hands for very much of anything, and wondering how to be a productive scientists given this peculiar handicap. The problem is not that I lack hands, I have them and they looked perfectly complete, if slightly blue. The problem is not even I can operate them, I have full control and enough strength to do most simple tasks. Rather my problem is that I mustn't use my hands, for a fight to the swell up become quite painful and remain so for some time. It's not yet entirely clear why this is, so for the time being the blame Levitis Syndrome.

There are many jobs for which not using one's hands would be a greater problem than they are for me as a scientist. A carpenter, a cellist, or a cashier would be much less able to work around this problem and I am. Furthermore, there is extremely little short-term pressure for me to get anything done. In the long term, I have to publish papers to keep my job and move to better jobs in the future. In the short term I want to get things done simply because it is too frustrating to not do so.

I'm using dictation software which, now that I've used for some time, is quite quick and accurate for creating text. Not quite as fast as typing, but a hell of a lot faster than I thought dictation software was before I started using it. I have students to do my lab work for me, I'm not doing any field work, and I have access digitally most of the literature I need. Given all this, why should a small matter like hands make much of a difference?

In practice, there are all sorts of things that I find myself unable to do. The dictation software supposed to make it possible to use many different programs, for surfing the web, analyzing data, sending e-mails and so on; in fact many of these thing are quite difficult to do without moving the mouse or touching the keys. Writing code is extraordinarily difficult. Reading heavy paper books is quite hard. Many software tools are simply inaccessible.

My latest stratagem is to order a mouse controlled by foot. The ability to point and click should solve many of my problems, in combination with this dictation software.

The other challenge of being productive despite my hands, is one of concentration. Doing things so differently requires a lot of thought about how I do them, which distracts me from the ideas and tasks to concentrate on. In addition to that, my hands hurt, tingle, throb and otherwise distract me. I am frankly not so good at ignoring it to the point that I can think deeply.

Ultimately, my hands will probably get better with time and coddling. When that happens, I can add dictation software and foot-controlling a mouse to my long list of random and not particularly useful skills. Until then, I'll be studying the list of available voice commands and wearing slip ons.

Planeless sky

The unpronounceable Icelandic volcano has left my place of work quite empty. This last week was the largest demography conference of the year, and a large portion of my colleagues flew to Dallas for it. They have not been able to return.



This map (from the NYTimes) shows which European airports are currently closed. Rostock is right in the middle of the gray area, half way between Berlin and Copenhagen. The closest operating airports right now are Madrid (2500km), Rome (1700 km including crossing the Alps) or St. Petersburg (2 days by ferry), and they are all booked up. So I may not have many coworkers around until this dust blows over.

The sunsets have been colorful the last couple of days, and the horizon looks hazier than usual, but other than that and the lack of airplanes flying over, I can see no smoke. Also, the grocery stores are out of bananas.

The airlines are starting to question the science behind the flight ban. I am doubtful myself. The concentration of particles (which hasn't actually been measured in most places) must be pretty minute, as the emissions from a small eruption are dispersed over perhaps 100,000,000 cubic kilometers.

I come to that rough estimate because the effected area is about 5000km east to west, 5000km north to south and the cloud is about 4 km top to bottom. I've not seen an estimate for how many tons of ash are up there, or what concentration is dangerous, but I'm guessing the concentration of particulate matter up there is no higher than that over LA or Houston in the summer.

Die Fledermaus

It was only the second warm evening of the year and a Friday no less, so I came home at 5. Iris, having also noticed the weather, was up at Warnemunde, strolling the beach line of the still frigid Baltic with a couple friends, so I decided to go for a walk myself. The riverfront in town, which as been transformed from port to shops and restaurants, had been surrendered all winter to the ice and wind. The brick walkways and cement steps along the riverfront were still strewn with New Year's Eve firecrackers and beer bottles. The ice that had covered the Unterwarnow was gone, and the only remaining snow was nubbins of the huge piles the city had dumped in a parking lot. I strolled along the waterfront, enjoying the presence of other people in a place that for six months had been abandoned, and watching the grebes bring up small wriggling bits of silver from the river. The Institute is on the waterfront and I came to it as the sun went down. I thought about going inside to see if any colleagues wanted to stroll with me, but decided instead to wander through the unoccupied lot next door. That whole section had been a major port and while much of it has been built over, much, including the peace next to the Institute has gone to grass and the occasional tree. A two-story heap of dirt and rocks, dug up to make space for some building's foundation, is all that distinguishes the lot from a small unmaintained park. As I gazed up at this heap in the fading light, something fluttered over and around it. The silhouette of a tiny bat flitted and floated, gliding and diving after nothing I could see. I tried and failed to detect any insects it could be after. yet it repeatedly visited the same spots, just under those exposed tree roots, just over the top of the dirt pile, just past that lighted window of the Institute. closing my eyes and concentrating, I could just barely hear its wings and a rapid ticking at the upper end of audibility, the lowest notes in its echolocation. I could hear no insects flying, calling or crawling. Watching the lightest part of the sky, I spotted a single midge flying a few feet from my head. Moments later it had disappeared into the hunting bat. This qualified me to be added to its circuit; on each subsequent round of the lot, it would make a small circle around me, perhaps a meter way, checking what other insects I may have attracted. I watched it past when I could see anything, and will return on subsequent dusks.

little posting

I"ve been posting not at all for a while; I have carpal tunnel syndrome, and can't easily type. However, over the next several days I will be posting several thing either dictated using dictation software, or copied and pasted.

The following is from the

PLoS Biology Editorial and Publishing Policies

"PLoS Medicine, PLoS Biology and PLoS ONE do not consider for publication papers where any of the research costs or authors' salaries have been funded, in whole or in part, by a tobacco company. "

Discuss

Evolutionary models of evolution

I've been asked to attend an upcoming workshop on modeling the evolution of aging. Modeling in this sense means building a computer model that provides insight into a process. Most of the people who will be there have some experience in modeling, which I don't. So I decided my roll, as the participant most focused on evolutionary theory, should be to make sure that they are doing evolution right. We were asked to each produce a seed, or opening idea, to get the conversation going. Following is a draft of mine. Note that while you can figure out what most of this means, it was written for other scientists and so includes a smattering of jargon and techniquese.



As an evolutionary biologist, I would like to encourage those modeling the evolution of aging to include in their models actual evolution. Optimization models and even Markov Chain models, while very useful, are not evolutionary. By this I mean that they do not include populations changing through descent with modification. To meet a biologist's definition of evolution, a process must include individuals who are reproducing and the offspring must be modified copies of the parents. This requires a population of individuals with heritable traits and mutation rates which modify the parents' traits in the offspring. In order for adaptive evolution to occur, these heritable traits must also influence how many copies of its genome each individual passes on to the next generation.
Markov-chain models, while somewhat closer to evolutionary, still lack the aspect of a population, which is essential for evolution. In many cases the outcome of evolution will depend on having competing or interacting sets of genes within the same population. This cannot be meaningfully understood if the whole population is assumed to have only one set of genes at any one time.
A truly evolutionary model of aging must therefore be fairly complex. It must simulate individuals, who have age-specific mortality and fertility probabilities. These age-specific schedules must be determined by a set of genes. These genes in turn must be determined by a process of inheritance and a process of mutation.
Using such a method, we can address questions that are difficult to get at through optimization. For example, suppose we would like to know why closely related populations have similar patterns of aging, even when they live in different habitats, or occupy different niches. This pattern has been observed in comparative data and comes under the heading of phylogenetic inertia. With an evolutionary simulation, we can impose environments which mediate the relationship between the genes and the demography. We can then ask what characteristics of the environment or what characteristics of the relationship between environment and demography would allow the starting point (that is the initial genes and demography of the population), to influence the ending point (that is the genes and demography the population ends up with).
To take another example, optimization models generally lack any information on the structure of the genome or the process by which that genome changes. However, genomic structure and mutation process are not irrelevant to what demography the population evolves. An evolutionary simulation will allow for modification of the genomic structure or the mutations process. Compare for example, two populations, each of which has a genetically controlled pattern of investment in various tasks such as reproduction, repair, growth or immune function. In population A, as many genes control this at the beginning of life as at the end. In population B, many genes control the pattern of investment early in life, while relatively few are still influencing late life investment. In both populations the genes affecting these investments are subject to mutational pressure and to selection. In each a mutation-selection balance will emerge, but these mutation selection balances will differ between the two populations. The two populations living in the same environment will arrive at different demographies, each nonoptimal.
These are but two of the many complicating factors which can be explored using an evolutionary simulation and are difficult to get at in a model that does not include explicit evolution. Of course models should be simple enough that one can figure out what factor is influencing what outcome. A model cannot include every complicating factor biologists might like to throw in. As such, I propose a modular evolutionary simulation. By this I mean we start with as simple a model as we can which still has real evolution going on and we write it in such a way that one can add more complicated processes. For example, the basic model could have an extremely simple process of mutation, but could be written such that that this process is easy to remove and replace with a more complicated mutational process. Reproduction could be clonal, but again that process of inheritance could be coded such that it could be pulled out and replaced with sexual reproduction by someone who is interested in what effect the mode of reproduction would have on the evolved demography. The environment could be extremely simple and replaceable with a more complicated environment. I am a slow and inexpert programmer but I imagine that it would not be impossible to write such a simulation in a way that genome, inheritance, mutation, environments, and demography are interacting pieces which can be replaced as one replaces the batteries, bulb, wire, switch and casing of a flashlight. One need not modify the casing to replace acid batteries with rechargeables, or replace rechargeables batteries with lithium rechargeables. One can swap a white bulb for a yellow one without modifying the wires or switch. A properly designed base simulation would allow each of us to experiment and still be able to compare our results without any one model becoming unnecessarily complex.

Kudzu Power

For several years I've mused that if only we could find some efficient way to make ethanol from Kudzu (the incredibly fast growing invasive weed that has taken over much of the southeastern US), we could stop importing petroleum, vastly improve many ecosystems and tremendously improve the US economy, all in one swell foop. I didn't take this idea very seriously. It appears that somebody else has. Consider the following abstract from a recent volume of the journal Biomass and Bioenergy:

We determined the amount of standing biomass of kudzu (Pueraria montana var lobata) in naturally infested fields in Maryland and Alabama, USA. At each site, we evaluated the carbohydrate content of roots, stems, and leaves. For a third site from Georgia, we evaluated the carbohydrate content of kudzu roots of varying diameters. Belowground biomass in Alabama exceeded 13 t ha⁻¹, and contained an average of 37% fermentable carbohydrates (sucrose, glucose, and starch). Roots from Georgia of all size classes contained over 60% fermentable carbohydrates. Biomass and carbohydrate levels in roots from Maryland were low compared to plants growing in Alabama and Georgia, producing 5 t ha⁻¹ of roots with 20% non-structural carbohydrate. Stems from Alabama and Maryland contained 1–3% carbohydrates. Based on the yield and carbohydrate content, we estimate wild kudzu stands in Alabama and Georgia could produce 5–10 t ha⁻¹ of carbohydrate, which would rival carbohydrate production from maize and sugar cane fields. If economical harvesting and processing techniques could be developed, the kudzu infesting North America has the potential to supplement existing bioethanol feedstocks, which could be of significance to the rural economy of the southeastern USA.

Further consider this economical processing technique, from next month's PNAS:

Abundant plant biomass has the potential to become a sustainable source of fuels and chemicals. Realizing this potential requires the economical conversion of recalcitrant lignocellulose into useful intermediates, such as sugars. We report a high-yielding chemical process for the hydrolysis of biomass into monosaccharides. Adding water gradually to a chloride ionic liquid-containing catalytic acid leads to a nearly 90% yield of glucose from cellulose and 70–80% yield of sugars from untreated corn stover. Ion-exclusion chromatography allows recovery of the ionic liquid and delivers sugar feedstocks that support the vigorous growth of ethanologenic microbes. This simple chemical process, which requires neither an edible plant nor a cellulase, could enable crude biomass to be the sole source of carbon for a scalable biorefinery.

This will, of course, take longer and be more complicated than anyone currently expects, but I'd be surprised if we don't eventually have industrial scale application of this technology, using many sources, including kudzu.

neologistic challenge

In demography, we spend a lot of time thinking about how the risk of dying increases with age. Economics calls itself the dismal science, demography is the morbid science. Anyway, we call the increase in mortality risk with age in adults "senescence", from the Latin root senex (old). I prefer to think and write about the fact that mortality rate decreases with age in those who are not yet adults. My problem is that there is no word equivalent to senescence that mean this, so I have to invent one.

So I want a word that can be defined as "the decline in mortality risk with age from conception to maturity." A root that means improvement, growth, blossoming, development, growing up, or something along those lines would be best. Twelve points for whoever comes up with the best term.

Cold and Fat

Cold places tend to have fatty cuisines. The usual explanation for this, although I know of no rigorous test, is that cold weather requires us to burn lots of energy to stay warm, and our bodies respond to this greater demand by causing us to eat more rich foods.

This simple idea has several profound implications that I will now proceed to invent.

The first implication is that " burn lots of energy to stay warm" means something very similar to "increase metabolic rate." So people in colder environments should have higher metabolisms. This matches with the current experience of myself and my wife. For the past months the temperature outside our apartment has rarely gotten above freezing, the wind is always blowing and it is generally damp. Our apartment is somewhat difficult to heat, so it is generally cool and sometimes downright cold inside. We have been eating a very rich diet, and rather than gaining weight, I think we are both loosing a bit. And although the short days cause a degree of lethargy, I have been generally quite productive, with fewer problems of concentration than usual.

There is good reason to think, in fact, that colder climates lead to greater productivity. Colder countries are systematically more economically productive than hotter countries, air conditioning raises productivity considerably, and hot countries experience more economic growth in cool years than in warm ones. My preferred speculation is that this is because the experience of coolth induces greater physiological throughput, allowing for greater activity. If one needs to expend energy to keep oneself warm, why not put that energy to some good use, such as thinking, building, or working. Why shiver when I can use the same energy sharpening the knives or generating a hypothesis?

Allow me one further observation and conjecture. Germans, who eat very heavy diets but on the average are less heavy than Americans, are in the habit of opening all the windows whenever it gets warm inside, even if it is below freezing out. Two apparently unrelated stereo-types of modern Americans, both of which have some basis in fact, may in fact be causally related. These are, we are very fat, and we keep our houses very warm in the winter. Perhaps the miracle diet so many have been searching for should include turning down the thermostat. If we burn more calories when we experience cold, and we want to burn more calories, perhaps we should experience more cold.

A month of snow

A cubic meter of fluffy freshly fallen snow weighs about 80kg, while a cubic meter of water weighs a metric ton, 1000kg. This implies that a meter of fresh snow will melt into a paltry 8cm deep layer of water. Enough to make the ground very soggy, but not nearly as impressive as a meter of snow. As ice is slightly less dense than water (about 92% as dense) a meter of snow will squish down into a slightly thicker layer of ice, almost 9cm. A third possibility is to catch a plane to someplace warmer, where the snow never fell at all.

Sprouting collaborations

In the last week I have agreed on two major collaborations (with a Harvard professor and the Director of a Max Planck Institute) ordered some tens of thousands of Euros worth of equipment for my own experiments, hired two lab assistants for those experiments and promised my boss that I would perform a significant reanalysis of a set of data I already have in collaboration with another member of the lab. My wife and I also made some very tasty Brussels sprouts with garlic, soy sauce and lemon juice.

Here's the recipe:

Wash the sprouts, peel off any out leaves that don't look good, and cut each sprout in half.

Cut up a head of garlic.

Juice 2 lemons.

Heat a large cast-iron skillet or other frying surface, large enough to fit all the halved sprouts in a single layer. Put on a fair bit of oil and bring to very hot. Pour in the sprouts and use a spatula or fork to flip them over so that the flat side of each is down. Slide them around some so they all cook evenly. Cook them like that until they are somewhat charred on the bottom. Then flip them over and roll them around so that the other surfaces get cooked. They will still be somewhat too hard inside, so pour in a scant cup of water and cover while the water rapidly boils off, steaming the insides. Once the water cooks off, taste a couple of sprouts and if they are still too hard inside, pour on a little bit more water. Once they are done, remove them to a large bowl and put the garlic on to fry. After a minute, pour some splashes of soy sauce over the garlic, and let it cook down a little bit. Mix this with the lemon juice, salt and pepper, and pour it over the sprouts. Serve hot.

The flapper in winter

It was -10C this morning, and fresh snow on ice made an unbroken expanse of flat whiteness where the harbor usually is. The small ferry constantly crossing back and forth kept one thin line open, and the water birds congregated around that oasis; compared to sub-freezing air, freezing water is relatively warm. A few birds seemed not to have gotten the memo and instead made lumps in the snow at random points on the ice. One large lump the color of dirty ice seemed bird shaped, and I looked at it on and off seeing if it moved. It was the right size and about the right shape and color to be a juvenile swan, but it could also be a pit of trash or a chunk of refrozen slush someone slid out onto the ice.

My colleague, who also watches birds came into my office to ask if I had noticed it, and if so what I thought it was. He said there were footsteps in the fresh snow near it. He was right. Through my binoculars I could see swan prints leading to where it sat. And that lump on top might be a bit of neck leading to a head tucked entirely under a wing. But it must be dead I thought, why else would it sit so still for so long in such a windy spot on the ice?

I glanced at it occasionally though the morning, and it didn't move. Then some people walking their dog passed by, and the dog made like it was going to run out onto the ice to get the swan. A long gray neck snaked out from under the wing and looked straight back at the dog. The dog must have realized the ice was too thin to hold it. As soon as the dog was gone, the head disappeared under the wing again, and there it stayed.

In the early afternoon a fire department rescue truck pulled down the road to the harbor near the swan. Two guys, one holding binoculars, got out and looked at the swan for a while. I wondered if they thought it was a child. They drove away and came back with a third guy, who threw snowballs near the swan and yelled at it until it got up and walked a few steps. They left again, and the swan sat back in its usual spot, head under wing. The snow got heavier and started to pile up on the windward side of the swan, but it stuck to its spot, and still was there when the sun went down.

Almost finished

I'm about ready to submit this paper, and I have very mixed feelings as to its chances of acceptance. I've shown it to two people who told me they thought it was quite good and that I should send it to the high end journal I'm sending it to, and to a third who said he didn't think it would make it past any reviewer without major rewriting including changing which variables I was analyzing and the whole point of the paper. I've worked the paper over so many times I no longer have any idea if is it brilliant and revolutionary or a pile of misconceived hackary. What I do know for certain is that I am not going to start rewriting it at this point, and I'm going to hope that my friend who suggested I needed to do so just missed the point that the other two saw. The paper is methodologically sound, whatever its other flaws, and if the first journal rejects it I'll send it to lower profile journals until someone thinks it is important enough to print.

I really didn't want to get into discussing testis size.

I'm writing a paper on the choice male primates face between caring for the young they already have, and fighting other males for access to mates so they can have more young. There are, of course, other reproductive strategies they could also be investing in, like trying to impress the ladies without fighting, or impressing the ladies by being such good carers. I didn't want to get into all of these, because it just gets to big and complicated, and the relationship between the variables I have is already complicated and interested enough. But my colleague who read the paper for me thinks it is important to include something on investment in sperm competition. Sperm competition occurs when a female mates with more than one male, but only one of them will end up being the father of each baby she produces. The male with the strongest, fastest, healthiest, most numerous sperm will tend to be the father, and as such will tend to pass on his genes for big healthy sperm to the most sons. And to make lots of big healthy sperm, a male needs big testicles. Testicle size turns out to be closely correlated with how much multiple mating the females do, and in highly promiscuous species, males may dedicate a significant portion of their body mass to testes. And this is how I came to be typing search terms like "bush baby testis mass" and "monkey sperm competition" into Google Scholar. You would be amazed what Google is willing to label as a scholarly article.

Lovers in the snow

The UnterWarnow is frozen, and snow is building up on the ice. Sunset will come 7 hours and 45 minutes after sunrise today. The crows and blackbirds are digging in the snow looking for food, and the birds that usually haunt the harbor all winter are gone, perhaps to the south, perhaps out to the Baltic where the water isn’t solid.

But in the tree in front of my office window, two magpies are carrying fresh twigs into a crook between three branches. There is only one reason I know of why they would be doing this: they are building a nest. Most birds, including magpies, only build nests to lay eggs in, and now is not the time to lay eggs. It is too cold for the eggs to develop (even with mom sitting on them), and if they did hatch , there would be nothing to feed them. Any nest built now isn’t even likely to still be in good enough shape to use come spring. The spot where they are putting the twigs is near the top of the tree, on the branch closest to the river, and shakes whenever the wind blows, which it does frequently.

This raises the question of why? When other birds in the neighborhood are struggling just to keep from freezing or starving, why are the magpies wasting their time and exposing themselves to the cold building a nest they can’t use? Perhaps the cold has driven them mad? Maybe they are pulling food out of the dumpster of the near by grocery store, and having plenty of food, think it is time to breed? A genetic disorder?

There may be some perfectly good reason for this (pair-bonding activity?) but I’m not sure I buy that.

When my colleagues and I were writing a paper on the definition of behavior, many of previously published definitions we came across specified that behavior is adaptive, that it will tend to increase the fitness of the individual performing the behavior. We omitted this from our definition, because there are so many behaviors whose adaptive significance is uncertain, or which seem maladaptive. It is certainly true that most behaviors are adaptive, some, like building a nest in a snow storm, probably are not.

Rostock ten day forecast

Snow
Snow
Mostly Cloudy
Snow
Snow
Snow
Snow
Snow
Snow
Snow

I must really love science, as I don't know what else would keep me in this sun-forsaken place.

Picking sources

My work task for this weekend is making me aware of a gap in my education as a scientist. How does one decide which sources to cite when there are many available with the same information?

I and my assistants at Berkeley classified a significant number of primate species based on how much care fathers give to their offspring. For each species we would search the primary literature for sources documenting if fathers in that species provided care to their offspring, and if so how much. We gathered papers, sometimes dozen for a single species, read the relevant pieces and decided that fathers of that species provided no care, little or incidental care, significant care or were, for at least some part of their offspring's lives, the primary caregivers. This compilation allows me to compare the evolution of paternal care with that of other traits, such as the degree to which males fight for access to females in each species (the prediction being that males will tend to either invest heavily in their offspring or fight intensively for mates, but not both).

But what I have to do now is decide, for each species individually, which paper or papers to say I based my decision on when I publish this compilation. I've not actually studied any live primates myself. The many people who have dedicated years of their lives to documenting the behavior of each species, may disagree with my conclusion on their species (some inevitably will, I hope not too many). Those that do will be prone to dismiss the paper as a whole unless I at least give appropriate references to show I wasn't just making my data up. I feel like somehow I've made it this far without really knowing what rules to follow in documenting my sources. One can't just list every paper one consulted, or pick one at random. Should I reference the first paper to suggest that this species had that trait? Or the one with the strongest evidence, or the review article that states that the evidence for that conclusion is overwhelming? Should I include a reference to the dissenting papers, to show that I am aware of them, even if I disagree? Should I try to include references from the journal I plan to submit to?

What I'm actually doing, which may be the wrong approach, is referencing the papers I find most convincing and relevant, regardless of precedence, author or journal. As long as the reviewers don't object, I'll consider this strategy a success.

To survive and reproduce in good times and bad

jte asks:

Is there reason to believe, or evidence to support, that the forms of evolution occurring among species during a period of abundant resources is different from the forms of evolution occurring among species during a period of deficient resources?

It seems that a lot of the argument in evolutionary theory is that it takes a lot of energy to grow extra and useless appendages or what have you, so if they really are useless, you'd expect them to evolve away. But if resources are abundant--energy is not a particularly limiting factor--do you then get a scenario in which all kinds of wacky and useless appendages appear and are not attritioned away? Which gives those appendages time to hang around enough to be available when the environment changes and all of a sudden they are useful and confer an advantage?

Or something like that?

I wouldn't go so far as to say the "forms of evolution" are different. In good times and bad evolution acts through natural selection, genetic drift, mutation and all the same basic mechanisms. Rather I would say that selection acts of different traits, or favors different forms of those traits, depending on if times are good or bad. One excellent example of this has been documented by Peter and Rosemary Grant in long term studies of Darwin's Finches on the Galapagos Islands. The climate in the Galapagos is impacted hugely by the El Nino/La Nina climate cycles. In some parts of the cycle, the islands are cool and damp, vegetation grows lush, and there are lots of big seeds to be had. In other parts of the cycle, it is very hot and very dry and only the desert plants with their tiny little seeds are producing. In the good years, the finches with the big bills can eat lots of big seeds, and reproduce like mad. In only a few years the population of one finch species is dominated by big-billed finches. Then when the rains stop, the population starts to crash, and the finches with the little bills good for extracting and opening small seeds are much more likely to survive. After a few years of that, the population of that same species is again dominated by small billed finches. This isn't individuals developing differently depending on the food supply, this is just massive, cyclical natural selection driving the population's genetic make-up around in circles.

On a much larger time scale, generalists are much more likely to survive large extinction events, while specialists often dominate in habitats that have been very stable for millions of years. Consider which of each of these pairs of species is in greater danger of extinction?

German Cockroaches or Lord Howe Island Woodeating Cockroaches
The Black Rat or the Salt-Marsh Harvest Mouse
The Common Pigeon or the Mariana Fruit Dove
The Common Raccoon or the Cozumel Raccoon
Goats or Alpine Ibex
Humans or Sumatran Orangutans

In each case the generalist are doing fine, while their specialized relatives can't cope with change. The fossil record shows multiple examples of large groups going extinct when the coprolites hit the fan, but one or two very generalized species in those groups making it through and giving rise to many new species. The amazing thing is that over and over most of those new species are specialists, evolving to be increasingly good at dominating increasingly narrow sets of resources. Give Rattus rattus a few tens of millions of years and no other mammals on the planet, and they would evolve into many thousands of separate species, filling a vast array of niches, and most of those species would be specialists. If another great collapse came, the ones most likely to make it through would again be the super generalized rat.

As far as the "useless appendages" argument goes, remember that even when resources are abundant, there is still the race to see who can convert those resources into the most offspring the fastest. Plus, the ideal situation rarely lasts very long. Usually within a few generations the population of predators has increased, the food supply has diminished, or population density has gotten so high that pathogens are spread easily. Exponential growth is not to be underestimated. So with the possible exception of humans over the last couple of hundred years, it is almost never the case that a population goes on growing for many generations without selection knocking back those who spend their energy recklessly.

That said, there are traits that are advantageous in bad time and costly in good times, or the opposite. Sometimes species evolve plasticity, such as the ability to grow a thicker coat when the winter is colder, but not waste the protein in mild winters. And sometimes, like Darwin's finches, they just evolve back and forth. The camel's hump is probably something of a hindrance when water and food are plentiful, but it bears that cost because more often than not things will get dry again, and that hump will save its life. If camels lived in an environment where it didn't get dry for some thousands of years, they might end up sans hump, looking more like big llamas. Or they might just die out, vanquished by cows and goats. Camels, after all, are specialists.

Thrice bitten

There is a class of "getting to know each other" games that organizers like to force upon groups of people meeting for the first time, in order to help them start talking to each other. One of these is called something like "Two truths and a lie" in which each person offers three autobiographical facts, and the group has to guess which one is false. My facts when faced with this game were:

1. I have been stung by a Portuguese Man o'War.

2. I have been poisoned by a black widow spider.

3. I have been bitten by a venomous snake.

The third was the one I intended to be false. I have just found out that all three of these are true. The only snakes I have ever been bitten by are those I have picked up, and the only snakes I have picked up are those which I knew to be non-venomous, primarily garter snakes. It turns out though, that garter snakes are venomous, and my knowledge (shared with most of the rest of the world) of their lack of venom was wrong. Mind you, they almost never actually get any venom into a human, and if they do it is not dangerous. But it turns out garter snakes do have venom glands, and of the dozens I've handled I've twice been bitten by them. Once picking up a tiny individual from under a rock, and once rescuing a larger individual from a road. They don't have fangs, or dental groves, or other efficient venom delivery systems, and their venom isn't strong enough to kill even small prey, but apparently if they chew on a prey item long enough some of the poison will work its way into the wound and perhaps help to subdue the food, easing swallowing. I once watched a small garter snake attempt (for about twenty minutes) to swallow a very large frog, and I must say the poison didn't do the snake much good, despite extensive chewing, because the frog escaped after giving the snake a good kicking about the head.

If I'm ever forced into that game again I will have to change my lie to, "I've been bitten by a venomous mammal." I'm not dumb enough to pick up a shrew.

Convergent crocodilians

This attractive individual lives in the Zoo Basel. It shares a large enclosure with these two:


As we gazed upon their toothy serenity, my wife asked me what species they were. I had to admit I didn't know. There may have been a placard somewhere, but in the crowd of humans I didn't notice it. Clearly crocodillians, and not alligators or caimans, but beyond that I couldn't say. Gharials have longer, skinnier snouts for catching fish, and most crocodiles have thicker, heavier snouts for pulling down large terrestrial animals. These seemed to be somewhere in between.

I've looked up what species of crocodilians have snouts like this, and was pleasantly surprised to find out that there are three candidates: the Slender Snouted Crocodile, the False Gharial and the Freshwater Crocodile. All three have similarly shaped snouts and eat a mixture of fish and terrestrial prey. All three are said to bite humans only when harassed, and all three live in fresh water. Each is found on a different continent and they are not closely related to each other. The African Slender Snouted Crocodile, the South Asian False Gharial and the Austrailan Freshwater Croc have apparently evolved into similar niches and therefore converged on similar morphology. Interestingly, despite its numerous crocodilians, the Western Hemisphere seems to lack a similar species.

I found out that these are Australian Freshwater crocs only by looking up which of these three species the Zoo in Basel keeps.

They also hold three of these, Nile Crocodiles:
That's what the above water part looks like. The below water part of the same individual in the same position looks like this:


Notice the much wider, more typical crocodilian snout.