The Science Behind The X-Files:

Darkness Falls

• In this episode, Mulder and Scully find themselves stranded in the woods with a forest ranger and an ecoterrorist. Just for your edification, I've done a little bit of research on both professions (though I wouldn't recommend the latter). The National Forest Service is a part of the U.S. Department of Agriculture, and although there are a lot of National Forests located around National Parks, National Parks fall under the Department of the Interior. Both services (NFS and NPS) have many science-related jobs and if you're a fan of botany or zoology, social science or paleoclimatology, check out the links below.
  
  To find out more information on the science behind the National Park System, check out their "NatureNet" web site at http://www.nature.nps.gov/.
  To learn more about the USDA's National Forest Service, visit its homepage at http://www.fs.fed.us/.

• Ecoterrorism, on the other hand, seeks a more immediate response to environmental issues. (There's a reason that the word "terrorism" is in that job description, folks.) While almost any environmental group will agree that action needs to be taken in educating the general populace about the problems besetting the earth, ecoterrorists voice this call for action through crime, fear tactics, and destruction of property. There isn't much science involved in spray-painting messages on the sides of barns, so I'll take this opportunity to discuss ecology instead. Ecology is the study of the environment and the organisms that inhabit it; it's the science of environmental studies.
  
  Link to US News & World Report article: http://www.usnews.com/usnews/issue/981102/2fire.htm
  Definition of ecology: http://www.m-w.com/cgi-bin/netdict?ecology
  To find out more about ecoterrorism, read an editorial on the subject at http://sharetrails.org/mag/mar98/story3.htm.
  If you'd rather read up on ecology instead, go to the Virtual Library's page on Ecology, Biodiversity and the Environment at http://conbio.rice.edu/vl/, or visit the Mining Company comprehensive site at http://ecology.miningco.com.

• It's swiftly clear to Mulder and Scully that they're up against something a little less mundane than ecoterrorism when they find a human body cocooned in a tree and drained of all bodily fluids. Does this sort of thing happen in nature? Well, not to humans--but on a much smaller scale, spiders trap and drink their prey in similar, but not identical, fashion. Female spiders do spin cocoons--but to hold egg sacs, not to immobilize prey. Spiders also drink their food, but they don't just drain all of the fluids out of it, they predigest it, like most other arachnids (see 2SHY).
  
  For a brief article on spiders, read the Encarta Encyclopedia's entry on the creatures at http://encarta.msn.com/find/default.asp?ti=03AA0000.

• Further rooting around in the wilderness leads the agents to a very old tree that has been felled by the loggers. Within the rings (that are visible now that the tree has been cut open), Mulder notes a strange green ring toward the center of the trunk. The forest ranger takes a core sample (much like an ice core in ICE), and they take a closer look at the rings to figure out just what's going on. There's actually a science to tree coring, and it's called dendrochronology--the study of rings in a tree trunk to determine what kinds of conditions existed at different periods during a tree's life.
  
  Dendrochronology definition: http://www.m-w.com/cgi-bin/netdict?dendrochronology
  For a straightforward introduction to dendrochronology, check out http://www.sonic.net/bristlecone/dendro.html.
  If you'd like a more detailed, graphic tutorial on basic principles of dendrochronology, straight from Dr. Harold Fritts at the Laboratory for Tree Ring Research (University of Arizona), go to http://www.ltrr.arizona.edu/people/hal/princ.html.

• Mulder guesses that the mysterious, cocoon-making, lumberjack killer is actually a swarm of prehistoric, fluourescent insects who survived extinction by hibernating inside the ancient tree. If you don't think it's likely that a species of organism can lie dormant for thousands of years and then reemerge in such a deadly fashion, think again. Mulder mentions a "Spirit Lake amoeba" that was awakened when Mount St. Helens blew its top in 1980. I couldn't find any information on such a creature, but I found something much stranger--a toxic microbe called Pfiesteria piscicida that's still at large on the Atlantic coast of the United States. This single-celled critter is a regular master-of-disguise, assuming the appearance of lots of other organisms, such as amoebas and algae, over the course of its 24-stage life cycle. Awakened, in a manner of speaking, by pollution in the coastal waters, pfiesteria has posed a danger to both fish and humans with its toxic secretions that can cause sores on the skin, respiratory problems, and memory loss.
  Scientists are still trying to explain it.
  
  Spirit Lake link: http://vulcan.wr.usgs.gov/Volcanoes/MSH/Hydrology/Stations/SPL.html
  Mount St. Helens link: http://volcano.und.nodak.edu/vwdocs/msh/llc/cs/r1.html
  Intrigued? Read the EPA fact sheet on pfiesteria at http://www.epa.gov/owow/estuaries/pfiesteria/fact.html.
  If you'd like to read the story of the scientists who discovered the "phantom killer," check out the Charleston Post & Courier article at http://www.charleston.net/fish/microbe1.html.

• How do the deadly bugs in this episode glow in the dark? Scully suggests that they're oxidizing enzymes, much like fireflies. Fireflies create their light through a chemical reaction that combines an enzyme called luciferase with a substrate called luciferin (a substance the enzyme acts on), ATP (a source of cellular energy), and a little bit of oxygen. This process is extraordinarily efficient, because almost 100% of the energy created is emanated as light (not as heat or any other kind of energy); a lightbulb, under the same comparison, emits only 10% of its resultant energy as light.
  
  Substrate definition: http://www.m-w.com/cgi-bin/netdict?substrate
  ATP link: http://encarta.msn.com/EncartaHome.asp?z=1&pg=2&ti=06BCF000
  Find out more about the fascinating firefly at Marc Branham's slickly-designed FIREFLY FILES at http://iris.biosci.ohio-state.edu/projects/FFiles/.