No Darwin Day at zoo, disappointed curator says

IF the curator of the Assiniboine Park Zoo had his way this Darwin Day, there'd be a Darwin tour, complete with the links between humans and animals -- including the late, great Debby the polar bear."We share a distant common ancestry, as we do with all mammals," Zoological Society of Manitoba curator Dr. Bob Wrigley said in an impassioned email to the Free Press.

"We are in the hominid family in the order primates, and so humans are much closer to the chimpanzee and other members of our order. But go back far enough in time, and all mammals have a common ancestor -- mammal-like reptiles. And these came from amphibians, then fish, then invertebrates, all the way back for hundreds of millions of years to our common and original ancestor of all life: the bacteria," Wrigley said.

"We have two eyes, nostrils, digestive tract, four limbs, a backbone and numerous other body features because we inherited these long ago from fish. Our genetic complement includes many genes originally evolved in fish and earlier creatures."

He said the zoo would have commemorated the 200th anniversary of Darwin's birth Feb. 12 if it had the time and staff to do it justice.

"Both the zoo society and the zoo are hard-pressed to insert another program into an established schedule." Wrigley said zoo staff are working on Biodiversity Day May 22 but would have liked to participate "in a significant way" to the Charles Darwin anniversary celebration.

"If we had been able to direct staff time to this important event, I would have attempted to develop a Darwin tour, featuring zoo animals that could help explain to visitors some of Darwin's ideas and observations, particularly related to the principle of natural selection."

Wrigley talked about how species have affected one another.

"The zoo is a wonderful storehouse of wildlife from all over the world, with remarkable adaptations, and we do our best to use it for education, conservation and research. For example, the pronghorn antelope (native to the North American Prairie) is North America's fastest-running creature (up to 100 kilometres per hour), and so Darwin's line of questioning would ask why? What in the pronghorn's lifestyle and environment led to adaptations for such amazing speed?"

"What was the survival value of such changes in the body related to speed, i.e. powerful running muscles, large lung capacity, enlarged heart to pump blood required to supply the muscles?

"The answer is: to outrun its major predator, the American cheetah. Without fast predators like the cheetah, there would have been no stimulus to evolve blinding speed in prey species.

"The public does not realize that selection of traits in species is going on all around us. All our agricultural crops and animals are no longer mainly under natural selection, but are constantly being modified from their wild ancestors by human selection. In the news recently was the story about how human hunters are causing rapid genetic changes in animal populations -- i.e. big-horned sheep -- by most often selectively removing the largest and healthiest individuals.

"And just think, just as in the case that you would not have been born if either parent or grandparent had died before reproducing, this logic can be traced in an unbroken chain of ancestors all the way back to bacteria. Natural selection has been at work through all the 3.6 billion years of life on this treasured planet," says Wrigley.

"Every living species is related. This is why it is so tragic when we cause the extinction of other species, about 100 species per day at the current rate.

"These are our kin, and it has taken just as long to evolve these relatives as it has to evolve us -- the latest of at least 16 species of humans that have lived in the last six million years, a wonderful story, which Darwin revealed to humanity in a grander style than anyone else."

carol.sanders@freepress.mb.ca

Republished from the Winnipeg Free Press print edition February 8, 2009 B3