Sight Unseen

Sight Unseen. 1996. 27 minutes, color. film by Nicholas Kurzon. For more information contact Documentary Educational Resources, 101 Morse St., Watertown, MA 02172.     

Hiding in plain sight

Although the principles of disruptive colouration are widely believed to explain a variety of animal colour patterns, there has been no field evidence that it works to reduce the detection rates of natural prey. In a recent paper, Cuthill et al. successfully address this shortfall, separating the benefits of background matching from those of disruptive colouration. Their results provide the first definitive field support for this long-recognized phenomenon and suggest several new avenues of research.     

Hiding behavior in domestic goat kids

This study assessed hiding behavior of domestic goat newborns when presented with appropriate hiding sites. The results indicate that hiding behavior in domestic goats has not been lost due to domestication. Newborn kids moved away from their mother and birth site 15–26 h after parturition, and secluded themselves from conspecifics for 4–7 days following birth. Mothers participated in the process by not attempting to induce following, by rejoining the adult herd group, and by maintaining a considerable distance from their young. Mothers were primarily responsible for determining the daily activity pattern and suckling frequency of their young. Kids were primarily responsible for choosing hiding sites, and achieving physical proximity to their dams at mother-infant reunions. These results demonstrate the importance of the active role of the domestic goat kid to the development of the mother-infant relationship.     

Losing Sight of Regressive Evolution

When we teach evolution to our students, we tend to focus on “constructive” evolution, the processes which lead to the development of novel or modified structures. Most biology students are familiar with the subjects of finches’ beaks, giraffes’ necks, and hair in mammals. Of course, there is nothing inherently wrong with a constructivist approach to teaching evolution, but if it is our only focus, we may overlook the flip side of the coin. By the flip side of the coin, of course, we are referring to regressive evolution: the loss or degeneration of a trait. Regressive evolution does not often make its way into biology textbooks, but it is of great relevance nonetheless. In all likelihood, when a new trait evolves or an existing one is modified, something is sacrificed in return. In order to develop a flipper, a marine mammal must sacrifice individual digits. You may be familiar with one or more of the following familiar characters lost through regressive evolution: teeth in birds, scales in mammals, and tails in higher primates. For aficionados of cave biology like us, one of the most interesting examples of regressive evolution concerns cave fish: Why do cave fish lose their eyes?     

Gerima's Imperfect Journey: No End in Sight

Imperfect Journey. 1994. 88 minutes, color. Haile Gerima. director, with Ryszard Kapuscinski. Andrew Coggins. producer. First Run/Icarus Films, 153 Waverly Place, New York, NY 10014. 800/876-1710.