A hike back in geological time

Kevin Saldanha (center) takes people on a 12.5-kilometer hike back to the beginning of multi-cellular life on Earth to help them understand our connection to other living beings. (Photo: Courtesy of the Ancetor's Trail Hike)

If a single human stride (0.75 meters/.82 yards) is equivalent to 60,000 years, then 6.25 centimeters (2.46 inches) represents the duration of human civilization, which is only 5,000 years old. That means a 12.5-kilometer (7.7-mile) hike would cover approximately one billion years of evolutionary time, back to the beginning of multi-cellular life on Earth. But who would make such a calculation and why? Kevin Saldanha did. He's a veterinarian in Ontario, Canada, and the founder of the Ancestor's Trail Hike in Mississauga, Ontario.

The hike is an opportunity to combine education about the natural world. A pre-set route is mapped against a specific timeline in Earth's history. During the hike there are stops, called milestones, where hikers learn about different developments in the lifecycles of creatures on the planet. The goal is to go back in time to learn about human ancestors that didn't look like people but are still part of our biological family.

This in turn creates an opportunity for humans to understand the importance of preserving biodiversity. For Saldanha, one of the many volunteers who will participate in the third annual hike June 23, the link between humans and all living beings is essential to reverse the devastation of the natural world by human exploitation.

Having studied evolution during his schooling, Saldanha thought he had a good sense of the connection between humans and other living beings. But the notion of a common ancestry, that humans came from other beings and not just apes, isn't something taught in most schools.

"You know it at the back of your mind but it doesn't hit you until you realize that a fish is your cousin, a coral is your cousin," he says. "You've got the same DNA in your cells that those organisms have in their cells. The genetics, the DNA sequencing, proves that we have common DNA and genes."

The Ancestor's Tale: A Pilgrimage to the Dawn of Evolution by Richard Dawkins takes readers from modern day back through time to identify common ancestors. The book gave Saldanha the idea to recreate that virtual march through time along the