Here’s an excellent case: applying evolutionary principles to cancer improves diagnosis. You are a collection of (mostly) dividing cells, a population moving forward in time, and understanding that explains a great deal about how changes, like cancer, can occur.
As an exercise in futility, The Daily Transcript tries to categorize disciplines of the life sciences. Although there is a general air of truth to what he’s saying, the problem is that, unlike the members of the Tree of Life, academic disciplines are free to hybridize and accumulate and change, so instead of blurry but recognizable terminal branches, you end up with an anastomosing rete, and no one can sort out precisely who is what.
For instance, I’ve got training as a neurophysiologist (electrodes everywhere!), a cell biologist (painting organelles different colors and watching the glowing cells move), and a developmental biologist (which, contrary to Palazzo’s description, is actually the Most Important Discipline in Biology; he’s also wrong about killing fetuses, sometimes we just like to muck ’em up so they’re horribly deformed.) Oh, and I’ve had a smattering of genetics, but it was all developmental—real geneticists are kind of the mathematicians of biology, all very abstract and peculiar and mostly incomprehensible.
I also notice the bench biologist’s bias in his classification scheme. No ecologists? An article on taxonomy with no taxonomists?
Not all the email I get is from cranks and creationist loons. Sometimes I get sincere questions. In today’s edition of “Ask Mr Science Guy!”, Hank Fox asks,
I was thinking recently about the fact that wax collects in one’s ears, and suddenly thought to be amazed that some part of the HUMAN body produces actual WAX. Weird. Like having something like honeybee cells in your ear.
And then I started to think about what sorts of other … exudates the human exterior produces. Mucus, possibly several different types (does the nose itself produce more than one type?). Oils, possibly several different types. That something-or-other that hardens into your fingernails. Saliva, if you wanted to count our frequently-open mouth as sort-of exterior. What else?
Of course I know something about this subject, having taught physiology for a few years. My years of experience have also led me to notice that it is always the guys who ask about disgusting secretions. Why is that?
What has always attracted me to developmental biology is the ability to see the unfolding of pattern—simplicity becomes complexity in a process made up of small steps, comprehensible physical and chemical interactions that build a series of states leading to a mostly robust conclusion. It’s a bit like Conway’s Game of Life in reverse, where we see the patterns and can manipulate them to some degree, but we don’t know the underlying rules, and that’s our job—to puzzle out how it all works.
Another fascinating aspect of development is that all the intricate, precise steps are carried out without agency: everything is explained and explainable in terms of local, autonomous interactions. Genes are switched on in response to activation by proteins not conscious action, domains of expression are refined without an interfering hand nudging them along towards a defined goal. It’s teleonomy, not teleology. We see gorgeously regular structures like the insect compound eye to the right arise out of a smear of cells, and there is no magic involved—it’s wonderfully empowering. We don’t throw up our hands and declare a miracle, but instead science gives us the tools to look deeper and work out (with much effort, admittedly) how seeming miracles occur.
One more compelling aspect of development: it’s reliable, but not rigid. Rather than being simply deterministic, development is built up on stochastic processes—ultimately, it’s all chemistry, and cells changing their states are simply ping-ponging through a field of potential interactions to arrive at an equilibrium state probabilistically. When I’d peel open a grasshopper embryo and look at its ganglia, I’d have an excellent idea of what cells I’d find there, and what they’d be doing…but the fine details would vary every time. I can watch a string of neural crest cells in a zebrafish crawl out of the dorsal midline and stream over generally predictable paths to their destinations, but the actions of an individual melanocyte, for instance, are variable and beautiful to see. We developmental biologists get the best of all situations, a generally predictable pattern coupled to and generated by diversity and variation.
One of the best known examples of chance and regularity in development is the compound eye of insects, shown above, which is as lovely and crystalline as a snowflake, yet is visibly assembled from an apparently homogenous field of cells in the embryo. And looking closer, we discover a combination of very tight precision sprinkled with random variation.
Both Twisty and Amanda seem a bit weirded out by this news that the fetus can be viewed as a kind of parasite. This story has been around long enough that a lot of us just take it for granted—I wrote about the example of preeclampsia a while back.
There are worse feminist-troubling theories out there, though. In particular, there is the idea of intersexual evolutionary conflict and male-induced harm. In species where there is some level of promiscuity, it can be to the male’s evolutionary advantage to compel his mate to a) invest more effort in his immediate progeny, b) increase her short-term reproduction rate, and c) suppress her ability to mate with other males. After all, his optimal strategy is to flit from female to female, copulate, and put her to work producing his offspring. The female’s preferred strategy, on the other hand, is to take her time, maximize her lifetime reproduction rate, and select the best genetic endowment for her children.
This sets up a cycle of counter-adaptations in the population. If a male acquires a mutation that increases his fitness at the expense of his mate’s—for instance, if some component of his semen works on her brain to suppress her interest in remating—it will spread through the population due to its positive effect on male fitness, even though it reduces female fitness. Subsequently, a female who acquired a counter-adaptive resistance to the male’s hormonal sabotage would have an advantage, and that gene would spread through the population, reducing male fitness by making them less capable of controlling female reproduction. Then, of course, males could evolve some other sneaky way of maximizing their reproduction rate—vaginal plugs, secretions that make the mated female unattractive to other males, proteins that put her ovaries into overdrive to produce more eggs now at the expense of the female’s long term survival.
It all sounds improbable and dystopian, but all of these mechanisms and more have been observed in that exceptionally promiscuous species, Drosophila. Drosophila seminal fluid has the property of reducing the female’s interest in remating, increasing her rate of egg-laying, and is also mildly toxic. Artificial selection in the lab can produce females that are resistant to the effects, and males that produce more and more potent semen to overcome their resistance, to the point where the line of “super potent” males, when crossed to unselected females, kill their partners with their ejaculations. There is literally a battle of the sexes in these species.
To speak up in my defense, though, not all males are evil exploitive pigs. The logic of this pattern of sexual competitiveness vanishes as species exhibit greater and greater monogamy—if you have only one mate, it is to your advantage to take good care of him or her, because a loss diminishes your reproductive fitness.
Rice WR (2000) Dangerous Liaisons. Proc. Nat. Acad. Sci. USA 97(24):12953-12955.
Rice WR (1996) Sexually antagonistic male adaptation triggered by experimental arrest of female evolution. Nature 381(6579):189-90.
Nah, I thought this has got to be a joke:
The Pentagon’s defence scientists want to create an army of cyber-insects that can be remotely controlled to check out explosives and send transmissions.
But no…there is actually a DARPA call for proposals.
DARPA seeks innovative proposals to develop technology to create insect-cyborgs, possibly enabled by intimately integrating microsystems within insects, during their early stages of metamorphoses. The healing processes from one metamorphic stage to the next stage are expected to yield more reliable bio-electromechanical interface to insects, as compared to adhesively bonded systems to adult insects. Once these platforms are integrated, various microsystem payloads can be mounted on the platforms with the goal of controlling insect locomotion, sense local environment, and scavenge power. Multidisciplinary teams of engineers, physicists, and biologists are expected to work together to develop new technologies utilizing insect biology, while developing foundations for the new field of insect cyborg engineering. The HI-MEMS may also serve as vehicles to conduct research to answer basic questions in biology.
The final demonstration goal of the HI-MEMS program is the delivery of an insect within five meters of a specific target located at hundred meters away, using electronic remote control, and/or global positioning system (GPS). Although flying insects are of great interest (e.g. moths and dragonflies), hopping and swimming insects could also meet final demonstration goals. In conjunction with delivery, the insect must remain stationary either indefinitely or until otherwise instructed. The insect-cyborg must also be able to transmit data from DOD relevant sensors, yielding information about the local environment. These sensors can include gas sensors, microphones, video, etc.
Although the idea of having a remote controlled dragonfly is very cool, I am very pessimistic, and have to dash a little cold water on the plan.
Evolution 101 has a brief definition of evo-devo.
I must purge the mailbox of a few worthy links…so here they are.
There are a couple of calls for submissions:
A few carnivals I failed to mention this week:
Freethought Filter is back up and running again!
Darksyde addresses the Fermi “paradox”. I don’t think it’s a paradox at all, and that the answer from his list is the rarity solution.
Enjoy a bracing, invigorating rant. And it’s so true.
There were all kinds of rumors today (from Drudge, of all places) that NASA was going to announce some major discovery related to life elsewhere in the solar system. While that would be incredibly cool, I was dubious—anyone remember the Martian “bacteria”? NASA has a rather poor reputation for this sort of thing.
Anyway, Bad Astronomy has the actual news: it’s interesting, but the media blew it way out of proportion. Plumes of water (they think) have been observed on Enceladus, a moon of Saturn.
I’d be more enthused if the earlier hype hadn’t switched on my skeptical gland and flooded my system with cyniclin, the hormone of disillusionment.
