Descriptors of change, part 1

Stories, as the center piece of this blog, as conceptual markers that we use to make sense of our days and share them with others, are in many ways descriptions of a change in a state of affairs. A scenario is portrayed and certain conditions are laid out which in some way contribute to a process of change. I guess one of the beautiful things about stories is their metaphoric and allegorical qualities, such that the change elicited or described can be situated in the reader, the writer, or both.

The following is an account in which geometric relationships are centered as descriptors of change.

From March 6 to the 9th Kate and I accompanied the Living Routes program from the Monteverde Institute to the Santa Rosa National Park, in Guanacaste, Costa Rica.

http://www.acguanacaste.ac.cr/1999/ecoturismo/santa_rosa_tur.html

Since January I have been an instructor for a philosophy of science/social theory/service learning course. Kate recently joined our team helping out with budgets and logistical support. When we arrived at the park, we rearranged stuff in our car and made the slow trip down 13km of very bad roads to the beautiful beach of Naranjo. There we camped, hiked, swam (and I surfed). The next day we drove back up to the main camp site where we met another group of students from the Institute (these were from Mount Holyoke University and Goucher College).

As part of our activities, we had hikes during the day in which we examined the ecological relationships between soil quality and rhythms of change and diversification in the tropical dry forest. We also examined how the landscape had been immensely impacted by 500 years of cattle farming, which had resulted in terrible losses of what once was beautiful tropical dry forest. The great thing about these types of activities is that the evidence of past processes and the mechanisms of change can still be seen with just a quick walk through the forest.
One such evidence of change we noticed related to ways in which some seeds of present day trees were shaped by natural selection concerning their primary mode of dispersion. Among the seeds examined were those from the Guapinol and Jicarro trees. Both trees produce large seeds which are not appetizing to any living animal, but that once were consumed by now extinct mega-fauna. Technically and animal is considered as mega fauna if it exceeds 60 kilograms (around 125lbs). But for our present discussion, I am referring to animals—some of which were direct ancestors and some which weren’t—to present day mammals found in Central America. Such animals included giant sloths and armadillo-like creatures; others resembled modern day horses, etc. These large mammals ate the fruit of the trees we were examining, excreted them, providing rich organic material for the seeds to flourish in, and then new trees were born.

At around 10,000 years ago we had the end of the last ice-age—the Plio-Pleistocene , which resulted in the contraction of temperate regions and the concomitant expansion of the tropics. Now as a simple geometrical relationship, the volume of any given object increases at a rate much faster than the surface area of the same object. And since mammals produce heat by virtue of their metabolic activity, it turns out that a mouse has a much easier time cooling off than say an elephant. Now, putting the expansion of the tropics—with associated rises in temperature—together with our geometric relationship concerning the dissipation of heat in mammals, and what resulted was a large extinction process of big animals that used to inhabit this land (for those of you who have visited Latin America, Guanabana (soursop fruit) was also dispersed by mega fauna).

Now, several cool things stand out to me here. First is the hands-on experience for learning provided to students in which they can see the methods of inference, the structure of argumentation, and the lines of evidence used in evolutionary analyses. Second is the fact that trees with seeds that used to be dispersed by mega fauna survived the extinction of a key relationship in their ecological cycle. Clearly, there had to be variation in the patterns of seed dispersal for these trees (one source of stated variation being humans); this points to the richness and complexity, often overlooked in evolutionary dynamics. Things are never—or rarely—one to one. The ecological interconnections are too varied to support such reductive depictions of the history of life. These interconnections, I argue, should serve to remind us that we are but a speck on the Earth, insignificant in the unfolding of biological and other processes that have been taking place for billions of years before any primate of average intelligence began to walk upright.


At the beach, on our first night of our trip, waves crashed and lit up the sea. Millions of microorganisms displayed flashes of bioluminescence as a tactic to avoid predation. One small human step in the shore caused sparks. One small human steps set off chains of events involving millions of other life forms. From any perspective I look—large geological time scales involving speciation and extinction events or a step on the shore of a beach with a spark of light—I can’t but help and think that we are insignificant. This world is not our own. It never was and it will never be.