As usual, it’s not the message, it’s the mere existence of atheists

American Atheists have put up a new set of billboards, with a “go godless” campaign theme.

new-atheist-billboard-split-story-top

What’s interesting, though, is the media response:

Atheists ratchet up rhetoric, use billboards to attack Republican politicians

Hang on there…”Go godless instead” is ratcheting up the rhetoric? It seems like a rather mild suggestion to me — presenting an extremist religious position and then offering an alternative is an entirely reasonable approach.

As for attacking Republican politicians…has CNN noticed that the religious right has staked itself out in the Republican party? If Democrats were saying things as stupid as the Republicans, I’m sure Dave Silverman would be ripping on them just as aggressively. And if the Republicans were not basing bad policy on religious dogma, there wouldn’t be much concern about them and they wouldn’t be appearing on those billboards.

Maybe if they sink a lot of the budget into special effects…

There is no accounting for taste or credulity. Universal Pictures is planning to make Eben Alexander’s book into a movie. You remember Alexander; the Proof of Heaven guy, the surgeon who ‘died’ on the operating table and claimed to have visited heaven?

It might be interesting to see the effort. The whole tone of Alexander’s fantasy is one of vagueness, ineffableness, incomprehending awe — he talks about seeing indescribable beings like birds or angels that he can’t do justice to in words, for instance…I don’t think crisp CGI is exactly going to work in his favor.

What I taught today: the great cis vs trans debate

My students get a full exposure to the Sean Carroll perspective in his book, Endless Forms Most Beautiful, and I’m generally pro-evo devo throughout my course. I do try to make them aware of the bigger picture, though, so today we had an in-class discussion/’debate’ (nothing so formal as a debate, and it was more a tool to make them think about the arguments than to actually resolve a question). Fortunately, there’s one really easy exercise we can do in developmental biology, because some big names in the field have already clearly laid out their positions in a couple of relatively succinct papers, so I had a shortcut to bring the students up to speed on the issues. I split the class on Monday, having half read a paper by Hoekstra and Coyne on “The locus of evolution: evo devo and the genetics of adaptation” (pdf), which argues for the importance of trans-acting mutations in evolution, and another by Wray on “The evolutionary significance of cis-regulatory mutations” (pdf), which argues for the importance of developmental changes through changes in cis regulatory regions.

I drew this little cartoon on the board to illustrate the situation: that changes in the coding regions of genes produce mutations that can have broader effects throughout the cell (trans: they can affect other genes not on the same chromosome), while changes in regulatory DNA will have discrete effects on just the gene on the same strand of DNA they are (cis).

cistrans

Then I asked them put together an argument as a group advocating for the significance to evolution of their ‘side’, cis or trans, which they then delivered to their opponent, with opportunities for rebuttal and counter-rebuttal.

Ah, pitting the students against one another…always the fun part of teaching.

There was good friendly discussion. Both sides had to dig into their respective papers to find the arguments, and then restate them to make their point, both of which are good exercises. The battle waged to and fro, and then our hour was up and I asked them to vote for who ‘won’, in the subjective sense of making a good argument and persuasively advancing their position. The results:

Which position do you think makes the best case for the significance of their phenomenon in evolution?

Team trans: 1
Team cis: 0
Both positions are important: 8

Minnesota mildness for the win!

I did think one student comment was perceptive and exposed the whole argument for a sham. If they were to go off to graduate school in developmental biology, they wouldn’t be picking Team trans or Team cis: they’d be pursuing a phenotype or a pattern of interest, and then analyzing how it worked and came to be, and they’d simply accept the evidence, cis or trans or both, however it turned out. Follow the data, always.

Now that’s a healthy attitude.

I can defend both Lawrence Krauss and philosophy!

Philosophers are still grumbling about Lawrence Krauss, who openly dissed philosophy (word to the philosophers reading this: he recanted, so you can put down the thumbscrews and hot irons for now). This is one of those areas where I’m very much a middle-of-the-road person: I am not a philosopher, at least I’m definitely not as committed to the discipline as someone like Massimo Pigliucci, but I do think philosophy is an essential part of our intellectual toolkit — you can only dismiss it if you haven’t thought much about it, i.e., aren’t using philosophy at all.

So I’m pretty much in agreement with this post about the complementarity of philosophy and science. In fact, I’ll emphatically agree with this bit:

Scientists and mathematicians are really doing philosophy. It’s just that they’ve specialised in a particular branch, and they’re employing the carefully honed tools of their specific shard just for that particular job. So specialised, and so established is that toolkit, that they don’t consider them philosophers any more.

I’ll also agree with the flip side, where he defines philosophy:

Philosophy’s method is bounded only by the finite capacities of human thought. To the extent that something can be reckoned, philosophy can get there. As such, philosophy will never stop asking “why”.

But then I start to quibble (oh, no! I must be infected with philosophy!).

So what this is really saying is that science is a bounded domain of philosophy, while philosophy is unlimited, which sounds like philosophy has the better deal. But I’d argue otherwise: what’s missing in philosophy is that anvil of reality — that something to push against that allows us to test our conclusions against something other than internal consistency. It means philosophy is excellent at solving imaginary problems (which may be essential for understanding more mundane concerns), while science is excellent at solving the narrower domain of real problems. Science has something philosophy lacks: a solid foundation in empiricism. That’s a strength, not a weakness.

I think that’s where philosophers begin to annoy us, when they try to pass judgment using inappropriate referents — which is also how scientists like Krauss can annoy philosophers. And philosophers are so good at rationalizing disagreement away while carping on others. For instance…

Because scientists have a rather poor track record when it comes to doing philosophy.

Sam Harris’s attempt to provide a scientific basis for morality springs to mind, where he poo poos metaethics only to tread squarely in a metaethical dilemma. Or Richard Dawkins and his dismissal of religion as a false belief system, meanwhile dismissing the rather significant psychological and cultural functional roles it has played throughout human history, and may still play today.

Or Krauss, who without a hint of irony, suggests that good philosophers are really just bad scientists, when in fact he’s a good scientist doing philosophy badly. His definition of “nothing” comes not from within science, but is a grope in the dark for a definition that conforms with his particular theoretical predilections. That’s not how one defines things in polite (philosophical) circles, as David Albert pointed out.

After stating that scientists are philosophers and that science is a branch of philosophy, we’re now told that scientists do philosophy poorly. So is he saying that scientists must do science poorly? I know who’s not going to get invited to my next cotillion, that’s for sure.

Rather, scientists do their brand of philosophy very, very well — philosophers seem to be playing a two-faced game here of wanting to claim science as one of their own when they like what it accomplishes, but washing their hands of it when they don’t like it. Nuh-uh, people, you want to call us philosophers, you have to live with the stinking chemicals and the high energy discharges and the reeking cadavers now too.

His examples aren’t persuasive. I’ll skip over Harris, I’m not particularly fond of his efforts to explain morality, but the Dawkins complaint is weird. He does not disregard the immense psychological and cultural roles of religion: in fact, those are reasons why he and I both detest religion, because we’re aware of all the harm it does and has done. That we think the physical and psychological harm is enough that we should change it is not a sign that we’re doing bad philosophy at all; it’s a sign that we scientifical philosophers consider reality and empiricism to be extremely important factors in our thinking…apparently to a greater degree than many non-scientifical philosophers.

As for Krauss, I thought the Albert review was awful — typical unbounded philosophy with no anchor to the truth. Krauss’s definition of “nothing” was not just a grope in the dark. It was a definition built on empirical and theoretical knowledge of what “nothing” is like. Krauss is describing the nothing we have, Albert is describing the nothing he thinks we ought to have. Krauss is being the scientist, Albert is being the philosopher, and the conflict is driven because the philosopher is unable to recognize the prerequisites to doing science well.

I think that appreciating the boundaries of both disciplines as well as their strengths is important for getting along. Krauss may not have appreciated what philosophy has to offer, but a substantial reason for the friction is the smugness of philosophers who disrespect the functional constraints required for doing good science. Scientists don’t get to be “bounded only by the finite capacities of human thought”. We also have to honor the physical nature of reality.

In my head I have the capacity to flap my arms and fly. In the real working world…not so much.

I know this feeling

Maybe you know the feeling, too. You’ve got a career that you work at every day for years, that you take seriously and try to improve constantly, and you’re periodically dragged off to meetings where administrators and bureaucrats tell you what you should be doing — and the information is useless because they’ve never even tried to do it, preferring instead to kibitz professionally. So I felt that familiar sinking pit of despair as I read this article about the current political strategies for ‘fixing’ education. All that saved me from spitting on the screen was the author’s reply.

I’m thinking about the current health care debate. And I am wondering if I will be asked to sit on a national committee charged with the task of creating a core curriculum of medical procedures to be used in hospital emergency rooms.

I realize that most people would think I am unqualified to sit on such a committee because I am not a doctor, I have never worked in an emergency room, and I have never treated a single patient. So what? Today I have listened to people who are not teachers, have never worked in a classroom, and have never taught a single student tell me how to teach.

What I taught today: maternal effect genes

You know I teach the 8am courses every term, right? Every semester for years I get my oddball classes that weren’t present in the curriculum 13 years ago (when I started here) stuffed into the cracks of the schedule. I’m slowly getting to be a little pushier and am gradually making my way into wakier hours with other classes, but so far, developmental biology is still in the darkness. Fortunately, this talk was so jam-packed with excitement and action that they couldn’t possibly sleep through it! Right?

Just a word about the presentation slides: I’m a firm believer that less is more. My goal is not to display my lecture notes, or lists of bullet point slides that make my points for me, but to show complex and interesting illustrations that I talk about and explain — whoa, I know, how radical. I’ve sat through too many talks that flash 60-80 slides at me in an hour, and it’s too much. Take your time, people! That said, I used 18 slides in a 65 minute lecture today, which I felt was a little excessive — I aspire to someday do a lecture with half that number. But I am weak and need the crutch now.

Also, I returned exams today. People asked if I’d post their answers. No way in hell! These are exams and have the privilege of privacy. I will say that in general the students answered well. The goal of that kind of exam isn’t to confront students with a question that has a specific answer, but with a problem that they should explore, defend, or criticise.

So the subject today was maternal effect genes in Drosophila, specifically the prepatterning information that specifies the anterior-posterior and dorsal-ventral axes. Yes! I can tell you’re all excited!

So I gave them the precursor observations to the actual molecular biology, all this lovely modeling of gradients and information domains that was rich with Turing elegance, and then I dashed their optimism with the cold water of reality: molecular biology has shown that instead of beautifully designed systems, we’ve got bits and pieces cobbled together in a functional kludge. Any pretty patterns we do see are the product of brute force coding.

So they got the overall picture of A/P patterning in flies: a gradient of the Bicoid protein, high in front and low in back, is read by cells to determine their location — its the GPS signal of the early fly. The Nanos protein, also found in a gradient but from back to front, is a hack: it’s only purpose is to clear away a leaky remnant of another gene, Hunchback, which isn’t supposed to be expressed yet (although Nanos may be the diminished rump of a more elaborate ancestral posterior patterning scheme). And the Torso related genes are specifically involved in ‘capping’ the front and back ends of the fly.

The main point of interest about the terminal genes like Torso is their mechanism: we sometimes talk about maternal genes as like a paint-by-number system in which Mom lays out the lines for different areas of differentiation in Baby, and then the embryo fills in the details. The terminal genes are like a perfect example of that: in the follicle, cells literally paint the vitelline membrane of the fly with different informational molecules during the construction of the egg, and then as the embryo develops, these molecules trickle across the perivitelline space (a gap between the outer membrane and embryo proper) to bind receptors and trigger regional differentiation.

It’s also a nice segue into the dorsal/ventral patterning genes, because flies do something similar there: proteins imbedded in discrete regions of the vitelline membrane diffuse to Toll receptors, where they selective activate the Dorsal protein by freeing it from the Cactus inhibitor. We go from a paint-by-number kit to a restored gradient from back to belly side of localization of free Dorsal protein to the cell nucleus. By the way, in case they were getting bored with flies, Dorsal is homologous to NF-κB in us vertebrates, using the same nuclear exclusion/inclusion mechanism, and NF-κB is a hot molecule in biomedicine and cancer research right now.

That was my hour. I closed by threatening them with talk of zygotic genes, specifically the gap genes, next week.

Also, Wednesday we’re going to try something a little different. We’ve finished chapter 5 of Carroll’s book Endless Forms Most Beautiful so they should be ready to weigh the importance of various mechanisms, so I split the class in two and told half of them to read Wray’s article on the importance of cis-regulatory mutations in evolution, and Hoekstra and Coyne’s article that argues for a more balanced emphasis. I’d love to have a fight break out in the room.

Actually, I hate the word ‘moron’ used as an insult, thank you very much

As pointed out by several in email, Daniel Fincke, whose last actual direct conversation with me consisted of a defense of his “Chris Christie is fat hur hur” jokes on Facebook some months ago, provides me with an opportunity to clarify something:

Also, I will note that where Chris Clarke completely unfairly attacked civility on the irrelevant grounds that you could order racist internment of people in a way that uses no abusive terms (as though just because bad things can be done civilly, routinized uncivil discourse is our only recourse to prevent that), he has not condemned Pharyngula’s routine use of the word “moron”, a word coined by racist eugenicists to justify equal atrocities against those deemed too intellectually inferior to have civil rights (even though he blogs at Pharyngula). There is an dehumanizing word that coined as part of a movement that did documentable damage to marginalized people and he is indifferent, apparently to the screams of those people while he paints me with no justification as a silencer of the oppressed simply because I advocate reason rather than bullying as the method of persuasion among professed critical thinkers and defenders of reason in the public square.

I’m ignoring the bulk of the paragraph: just shows the guy can’t read for comprehension when he’s upset. Which is an affliction a lot of us have. But he’s right about my not having offered my opinion on the use of the word “moron”.

And here it is: I don’t like it.

For my reasons, you can pretty much take this post and do the obvious find and replace.

I’ll confess I haven’t seen a whole lot of commenters in my threads using the M word, which may be because I don’t read every single comment. I also confess I slip up and use it myself on occasion, and “idiot” more often still.

Still, it’s about goals rather than perfection. I don’t like the word “moron” and wish we would all use something else non-ableist to express our disbelief at a person’s sheer wrongness. Suggestions for alternatives: doofus, fuckwad, jackanapes, buffoon, professional philosopher.

Can I go back to ignoring him now?

What I taught today: induction in worms, early development in flies

Today was the due date for the take-home exam, which meant everything started a bit late — apparently there was a flurry of last-minute printing and so students straggled in. But we at last had a quorum and I threw worms and maggots at them.

The lab today involves starting some nematode cultures so I gave them a bit of background on that. They’re small, transparent hermaphrodites that can reproduce prolifically and will be squirming about on their plates this week. They’re models for the genetic control of cell lineage and also for inductive interactions: I gave them the specific example of the development of the vulva, in which a subset of cells in close proximity to a cell called the anchor cell develop into the primary fate of forming the walls of the vulva, cells slightly further away follow a secondary fate, forming supporting cells, and cells yet further away form the hypodermis or skin of the worm. I had them make suggestions for how we could test that the anchor cell was the source of an inductive signal, and yay, they were awake enough at 8am to propose some good simple experiments like ablation (should lead to failure of the vulva to form) or translocation (should induce a vulva in a different location). I also brought up genetic experiments to make mutants in the signal gene, in the receptors, and deeper cell transduction pathways.

All those experiments work in the predicted ways, and I was able to show them an epistasis map of the pathways. Two lessons I wanted to get across were that we can genetically dissect these pathways in model organisms, and that when we do so, we often find that toolkit Sean Carrol talks about exposed. For instance, in the signal transduction pathway for the worm vulva, there are some familiar friends in there — ras and raf, kinases that we’ll see again in cancers. And of course there are big differences: mutations in ras/raf in us can lead to cancer rather than eruptions of multiple worm vulvas all over our bodies, because genes downstream differ in their specific roles.

Then we started on a little basic fly embryology: the formation of a syncytial blastoderm, experiments with ligation and pole plasm manipulation in Euscelis that led to the recognition of likely gradients of morphogens that patterned the embryos. From there, we jumped to the studies of Nusslein-Volhard and Wieschaus that plucked out the genes involved in those interactions and allowed whole new levels of genetic manipulation. As the hour was wrapping up, I gave them an overview of the five early classes of patterning genes: the maternal genes that set up the polarity of the embryo; the gap genes that read the maternal gene gradient and are expressed in wide bands; the pair-rule genes that respond to boundaries in gap gene expression and form alternating stripes; the segment polarity genes that have domains of expression within each stripe; and the selector genes that then specify unique properties on spatial collections of segments.

And that’s what we’ll be discussing in more detail over the next few weeks.

Slides used in this talk

Scientific morality: an example

Every once in a while, I hear these stirrings from scientists that there can be an objective morality, and that by following reason and evidence we can achieve great advances in ethics and reduce human suffering. I agree, in part. I think reason and science are the only ways we can implement our goals effectively, and that we should be empirically assessing our progress and making changes as necessary in a rational way. But — and this is a huge exception — science is not sufficient. Scientists are flawed, and while you can use science to optimally reach a particular goal, setting that goal in the first place is not determinable by scientific methods.

As a useful corrective to the scientific optimists, I suggest you read Francis Galton’s Memories of My Life, and try to do so with an open mind. That’ll be hard to do, because he says things that we now regard as repugnant, that we learned with hard lessons in the 20th century, lessons he did not experience. I think if Galton had lived through that period, he would have adjusted his opinions accordingly; charitably, I think I can safely assume from his writings that he had a sincere concern for improving the state of humanity, and that all that he proposed would have been for the betterment of individuals.

Man is gifted with pity and other kindly feelings; he has also the power of preventing many kinds of suffering. I conceive it to fall well within his province to replace Natural Selection by other processes that are more merciful and not less effective.

Try to keep that in mind when you read these quotes from his chapter on “Race Improvement”. He’s a scientist with only the highest aspirations for others. But he’s also a flawed scientist with imperfect knowledge, and a human being with a heavy freight of prejudices. He doesn’t realize that he’s paving the road to Hell with his intentions.

Here are the words of an upper middle class Victorian gentlemen who proposes to judge people and determine the value of other lives.

The most common misrepresentations now are that its methods must be altogether those of compulsory unions, as in breeding animals. It is not so. I think that stern compulsion ought to be exerted to prevent the free propagation of the stock of those who are seriously afflicted by lunacy, feeble- mindedness, habitual criminality, and pauperism, but that is quite different from compulsory marriage. How to restrain ill-omened marriages is a question by itself, whether it should be effected by seclusion, or in other ways yet to be devised that are consistent with a humane and well-informed public opinion. I cannot doubt that our democracy will ultimately refuse consent to that liberty of propagating children which is now allowed to the undesirable classes, but the populace has yet to be taught the true state of these things. A democracy cannot endure unless it be composed of able citizens; therefore it must in self-defence withstand the free introduction of degenerate stock.

Note what he considers both undesirable and heritable: Poverty. Crime. Intelligence. He can glibly divide humanity into classes, some of which are “undesirable”. He is looking for humane ways to prevent undesirables from propagating.

He has high moral aims! Keep that in mind; if it were actually true that poor people birthed children who were genetically determined to be poor, shouldn’t we do something about it? Of course, he’s not thinking it through: he can’t legitimately claim that poverty is biologically heritable (it sure is environmentally influenced, though!) and he certainly doesn’t seem to comprehend that poverty is a consequence of an unequal distribution of resources.

He’s also incredibly unaware of his own peculiar biases, biases that leap out to the more modern eye.

Most notabilities have been great eaters and excellent digesters, on literally the same principle that the furnace which can raise more steam than is usual for one of its size must burn more freely and well than is common. Most great men are vigorous animals with exuberant powers and an extreme devotion to a cause. There is no reason to suppose that in breeding for the highest order of intellect we should produce a sterile or a feeble race.

So “great men” are big-bellied men? Where is cause and effect here? Where is the evidence?

One of the dangers of science is that sometimes individuals get so captivated by that heady feeling of success and progress — and let’s not get carried away too far in the other direction, science definitely works and is a far better tool for understanding than any other process — that they forget the limitations, and assume that there every thought is pure and vindicated by scientific triumphalism. Francis Galton seems to have forgotten the meaning of the word humility. Your every opinion is not the same as scientifically-evaluated fact.

Speaking of arrogance and bias:

I may here speak of some attempts by myself, made hitherto in too desultory a way, to obtain materials for a “Beauty-Map” of the British Isles. Whenever I have occasion to classify the persons I meet into three classes, “good, medium, bad,” I use a needle mounted as a pricker, wherewith to prick holes, unseen, in a piece of paper, torn rudely into a cross With a long leg. I use its upper end for “good,” the cross-arm for “medium,” the lower end for “bad.” The prick-holes keep distinct, and are easily read off at leisure. The object, place, and date are written On the paper. I used this plan for my beauty data, classifying the girls I passed in streets or elsewhere as attractive, indifferent, or repellent. Of course this was a purely individual estimate, bat it was consistent, judging from the conformity of different attempts in the same population. I found London to rank highest for beauty; Aberdeen lowest.

I should like to see a complementary set of prick-holes made by the women he so judged, who were then given the opportunity to evaluate the beauty of Francis Galton. Further, I’d like to see a pair of assessments, the first made before the women were told what he’d been doing, and the second after. I think it would be apparent that far from being objective scientific measurement, this was an appalling exercise in subjectivity.

BertillonMugShot

There’s also the bias of the chosen parameters: women were judged for beauty, their most salient characteristic, while Great Men were judged by the size of their guts.

And here’s the dangerous part: that a person can then claim that their views are blessed by Science and Darwin’s Law of Natural Selection. You can’t argue with me; I have the authority of Science, no matter how racist or sexist my views might be.

I venture to offer an explanation of this apparent anomaly which seems perfectly satisfactory from a scientific point of view. It is neither more nor less than that the development of our nature, under Darwin’s law of Natural Selection, has not yet overtaken the development of our religious civilisation. Man was barbarous but yesterday, and therefore it is not to be expected that the natural aptitudes of his race should already have become moulded into accordance with his very recent advance. We men of the present centuries are like animals suddenly transplanted among new conditions of climate and of food; our instincts fail us under the altered circumstances.

My theory is confirmed by the fact that the members of old civilisations are far less sensible than those newly converted from barbarism, of their nature being inadequate to their moral needs. The conscience of a Negro is aghast at his own wild impulsive nature, and is easily stirred by a preacher; but it is scarcely possible to ruffle the self-complacency of a steady-going Chinaman.

Now if you accept these prejudices as true, we cannot avoid Galton’s rational conclusion.

It is known that a considerable part of the huge stream of British charity furthers by indirect and unsuspected ways the production of the Unfit; it is most desirable that money and other attention bestowed on harmful forms of charity should be diverted to the production and well-being of the Fit. For clearness of explanation we may divide newly married couples into three classes, with respect to the probable civic worth of their offspring. There would be a small class of “desirables,” a large class of “passables,” of whom nothing more will be said here, and a small class of “undesirables.” It would clearly be advantageous to the country if social and moral support as well as timely material help were extended to the desirables, and not monopolised as it is now apt to be by the undesirables.

Pretend that there actually was a class of “undesirables,” people destined to be rotten wastrels who would increasingly drain society of its worth (further, suppose they are the poor rather than, say, investment bankers). You could legitimately argue that Galton’s solution is a good one. Wouldn’t that be a dilemma for all us godless liberals; we’d have a logical solution to a real problem, that would require a most illiberal course of action to reach an advantage for our country.

But of course, being a scientist doesn’t mean one is right. Declaring a course of action to be beneficial for society ought to be met with questions about “beneficial for who?” Premises for a claim that seem to do nothing but mirror common social prejudices ought to be questioned, and one good use for science is to test those claims…and perhaps finding that those foundations are rotten ought to be grounds to deny that the authority of science is backing up one’s actions.

And even if every claim was true, it doesn’t necessarily narrow our course as much as some would claim.

Anyway, whenever someone announces that science tells us that particular path is the one true path, or that their arguments are unassailable because they are Scientific, I always turn to high-minded scientist Francis Galton. Imagine a society that tried to actually implement his ideas…oh, wait. Imagine? Read a history book.

What I taught today: Nuffin’!

Nothing at all! I gave the students an exam instead! While I got a plane and left ice-bound Morris to fly to Fort Lauderdale, Florida! Bwahahahahahaha!

Sometimes it is so good to be the professor. And if ever you wonder why my students hate me with a seething hot anger, it’s because I’m such an evil bastard.

Here’s what they have to answer.

Developmental Biology Exam #1

This is a take-home exam. You are free and even encouraged to discuss these questions with your fellow students, but please write your answers independently — I want to hear your voice in your essays. Also note that you are UMM students, and so I have the highest expectations for the quality of your writing, and I will be grading you on grammar and spelling and clarity of expression as well as the content of your essays and your understanding of the concepts.

Answer two of the following three questions, 500-1000 words each. Do not retype the questions into your essay; if I can’t tell which one you’re answering from the story you’re telling, you’re doing it wrong. Include a word count in the top right corner of each of the two essays, and your name in the top left corner of each page. This assignment is due in class on Monday, and there will be a penalty for late submissions.

Question 1: We’ve discussed a few significant terms so far: preformation, mosaicism, regulation, epigenesis. Explain what they mean and how they differ from each other. Can we say that any one of those terms completely explains the phenomenon of development, or is even a “best” answer? Use specific examples to support your argument.

Question 2: Tell me about the lac repressor in E. coli and Pax6 in Drosophila. One of those is called a “master gene” — what does that mean? Is that a useful concept in developmental genetics, and is there anything unique to a gene in a multicellular animal vs. a single-celled bacterium that justifies applying a special concept to one but not the other?

Question 3: Every cell in your body (with a few exceptions) carries exactly the same genetic sequence, yet those cells express very diverse phenotypes, from neurons to nephrons. The easy question: explain some general mechanisms for how development does that. The hard part: answer it as you would to a smart twelve year old, so no jargon or technical terms allowed, but you must also avoid the peril of being condescending.

Wait…I’m going to have to fly back to Morris on Sunday, and then I’m going to have to read and grade all those essays! Aargh — they’re going to get their revenge!