I had to miss the Thursday night plenary session. (Side note: "plenary" is academic-talk for "fully attended". So, some irony there.) I did drag myself out of bed Saturday morning and take two Metra trains and a cab down to UC, and made it in time to get my nametag (I got my own nametag!) and sit down in the main lecture hall for the first talk of the morning. (The main lecture hall was for the biology-based talks, the upstairs hall was for history/philosophy. I stuck mainly to biology, but did wander upstairs for a few talks there as well.) My condensed notes are below the jump, so please continue on if you have no fear of science-talk.
All in all it was a good time. I got to meet PZ and Marc Hauser, and even ran into a few friends.
I'll also note that PZ Myers and Jerry Coyne also have posts up covering the conference.
Douglas Futuyma (Stony Brook):
"Evolutionary Ecology and the Question of Constraints"
Futuyma talked on the role that ecological and genetic constraints play in our understanding of evolution. He noted that many species display "phylogenetic niche conservatism", which means that they specialize to a certain lifestyle and don't venture far from it. For example, some species of insects have been feeding from the same species of plant for millions of years. We also observe a lack of genetic variation in places where we would expect it, and often see ecological niches go unexploited.So, what accounts for this stasis? We must consider that evolution can be contrained by many factors. There may be, for example, no genetic pathway for humans to grow scapular wings. So no wonder we haven't evolved the ability to fly. Adaptation can also be constrained by dependence on multiple unrelated genetic factors, i.e. certain characters may depend on multiple genes which are unlikely to mutate simultaneously. In addition, recombination in a population with high gene flow opposes character spread.
One interesting conclusion of all this is that environmental inconstancy can lead to morphological stasis, which is counter-intuitive to what we'd except. The prevailing wisdom is that when environment changes, organisms which are more fit for the new conditions are better able to survive, and thus natural selection acts to preserve them. Futuyma suggests instead that divergent local adaptations can lost as a result of collapse of population structure due to habitat tracking. (Organisms travel with their preferred environment as climate changes.) He then concludes that in such circumstances extinction is likely due to failure to adapt, and rapid evolutionary change is rare.
Peter and Rosemary Grant (Princeton):
"Natural Selection, Speciation, and Darwin's Finches"
The Grants have been studying speciation among Darwin's finches for 37 years. (!) Their work is a beautiful example of evolution in action among the finch species G. fortis and G. scandens. Their presentation starts off illustrating the ways in which natural selection selects for beak size among finches. In years of high rainfall, vegetation on the island flourishes, making life easy for small-beaked finches. In years of drought, however, the plants that survive have large, hard-shelled seeds which only the larger-beaked birds can crack. In both cases selection acts as expected, and the Grants are able to predict the beak size of the next generation of finches. Beak size is clearly based in (at least) two genes: bmp4 and calmodulin. These genes can be placed in other species to produce finch beaks.Rosemary Grant then goes on to describe the barriers to interbreeding between fortis and scandens. In this particular instance the barriers are pre-mating, i.e. based in morphology and behavior. The finches can distinguish between the songs and morphologies of the two species, and will not approach females that are not of their kind. Hybridization can sometimes occur when the nest is disrupted or the father dies, and young finches are imprinted with the song of the other species. In many cases, however, the hybrids then backcross - leading towards convergence of populations and away from speciation.
Douglas Schemske (Michigan State):
"Ecological Factors in the Origin of Species"
Schemske was a joy to listen to. His talk was clear and to the point while making room for amusing asides and anecdotes. He focused on a case study he performed among monkeyflowers, or Mimulus. The study's purpose was to answer the question: What are the reproductive barriers between these two species of Mimulus? The options are:- ecogeographic differences
- premating isloation
- post-masting pre-fertilization factors
- hybrid inviability
In addition to identifying which barriers are present, Schemske was interested in which were the most important. That is, which barriers contributed the most to reproductive isolation. Using the work of Jerry Coyne and H. Allen Orr, Schemske was able to calculate the relative contribution of each reproductive barrier. He concluded that the pre-zygotic barriers were the major contributors. (Both species are highly adapted to their altitudes, and both are pollinated by separate species of insects.) Post-zygotic barriers such as hybrid inviability are present as well, as was discovered when the species were artifically crossed, but the ecogeographic factors remained the most substantial agents of speciation.
Paul Sereno (University of Chicago):
"Evolution of Phylogenetic Reconstruction"
Sereno's talk was right after lunch and a bit over my head, so I must do him a disservice by not reporting on it in great detail. Here are his main points as I understood them:- Phylogeny is difficult because humans are more suited to ladder-thinking than tree-thinking. We prefer to see things as progress in a single direction, not a complicated branching tree of interrelatedness.
- In a similar vein, "static" is easier than "transformative". It's much simpler to say "this is a dog" than "this is a type of dog among a long line of previous dogs and a future line of dog descendents".
- In the philosophy of history there is a separation between chronicle and narrative. The chronicle being a simple recording of facts, and the narrative being the facts along with the causal relations between them.
- We need a similar philosophy of phylogeny. We must quantify and atomize character so that phylogenetic analysis can become more standardized and more useful in the study of evolutionary biology.
John Hedley Brooke (Oxford):
"'God knows what the public will think': Darwin and the Religious Response to the Origin of Species"
Brooke spoke on the conflict between evolution and religious belief, and presented a reasoned and nuanced approach. He pointed out that evolution by natural selection has been difficult to square with a beneficent deity, but that the modern young-earth creationism which makes our lives so difficult did not appear until the 1960s. (This was part of a larger historical overview of the creationist response to the Origin.)Brooke also argued that religious belief is a complicated beast. It is a reference system for interpreting the world and how it works, but it is also a community, a social group, a sense of purpose, etcetera. We should be careful not to distill religious traditions down to one or two characteristics that can be easily written off. Conservative religions may in fact be reinforced by such simple attacks.
It is true that evolution has been largely accepted by the governing bodies of most major religions. Archbishops and Popes, the 'enlightened, intellectual thinkers' have no issue reconciling their faith with the fact of evolution. It is popular religion, the churches of the people, which often show the staunchest resistance. To paraphrase Huxley, a deconstructed God need have no conflict with evolution.
Brooke closed with Dobzhansky's quote, "There is a tragic discord in the soul of man." He was referring to the fact that amongst all the animals, man is the only one that must contend with self-awareness. This has implications for how we deal with conflicting and contradictory ideas.
Jerry Coyne (University of Chicago):
"Speciation: Problems and Prospects"
Jerry Coyne talked on speciation, which is his specialty. He started by defining the three commonly accepted types:- allopatric (no gene exchange)
- parapatric (some gene excchange)
- sympatric (free gene exchange)
It's easy to theorize and find evidence for allopatric speciation. This is when a population is divided by geographic barriers, making it impossible for them to continue sharing genes. Given enough time, this will inevitably lead to reproductive isloation, which is Coyne'e preferred definition for a species.
It's more difficult to find evidence for parapatric speciation. The conditions are fairly easy to come by, but in order to have true parapatric speciation, you have to show that there was never an allopatric speciation event in the popluation's history, which can be understandably difficult.
There is theory and lab evidence that supports sympatric speciation, but it's diffcult to observe in nature. As Coyne says, "You really have to be there." He does give examples of sympatric speciation which he doesn't count as 'truly' sympatric due to 'trickery' which created a reproductive barrier:
- polyploidy
- non-genetic speciation via parasitic birds
- allochronic speciation
- phenological speciation (e.g. Lord Howe palms)
Coyne goes on to cite a few examples of true sympatric speciation:
- crater lake cichlids
- Littorina saxatilis
- Rhagoletis
Bottom line, sympatric speciation is very difficult due to the free exchange of genes. Future biologists should looks to figs and flukes for the best chance of securing natural evidence.
Philip Kitcher (Columbia University):
"The Importance of Darwin for Philosophy"
Kitcher starts with some problematic examples of Darwinism being applied to different fields, e.g. sociobiology and evolutionary psychology. He does think that Darwin's ideas can be useful to philosophy, specifically in the field of ethics. Ethics have a history and have evolved over time.He defines "The Ethical Project" which has been going on for ~50,000 years. It builds on our altruistic dispositions and responds to the limitations of those dispositions. In societies, problems arise due to failures of altruism. We can correct for those failures: the earliest way was to use normative guidance. By way of fear, respect, social approval, and dedication to community, we can guide community members towards correct behavior.
'Experiments in living' (different cultures in different places at different times) lead naturally to the evolution of ethical codes. These codes work to different degrees of effectiveness. It's important to note that natural selection does not promote any sort of 'truth' or 'progress' in the universal sense. So how do we make progress ethically? Kitcher suggests that ethics are a kind of social technology, and like all other technology, we should define progress as fulfilling and refining functions.
With that in mind, how do we reconcile the relative equality of early humanity with the high differentiation we find in modern society? Kitcher suggests that we need to move away from governing authorities and towards a community conversation. Community members are those whose lives are causally interwoven - in some cases, this includes our entire species. He advocates a move towards secularism and egalitarianism.
Daniel Dennett (Tufts University):
"Darwin's 'Strange Inversion of Reasoning': Confronting the Counterintuitive"
Dennett's talk was focused on the counterintuitive nature of the Darwin's theory. (Well, he talked about a lot, but this is the throughline I picked out.) He starts out referring to the 'tricke-down' theory of creation, that is, great things make smaller things. Darwin proposed the opposite, that small things can and have made great things over a long period of time.He compares this to Alan Turing's brilliant work with computers, wherein Turing realized that computers do not need to understand arithmetic. They have competence without comprehension. In fact, nature works the same way. Nature is exteremly competent without any comprehension of what it's doing. Only recently has a culmination of competence given rise to a mind which can comprehend it.
Evolution is a reason-finder. It goes about creating and modifying things until they work within their environment with what seems like reasoned purpose. The organism gets on just fine without knowing the reason, which is just thrift. It doesn't need to know.
Major transitions in evolutionary history (cranes) have gotten us to the point where we can understand the world around us and truly appreciate the 'strange inversion of reasoning' which Darwin proposed 150 years ago.
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