Today, scientist Andrew Boyd and nature's engineer. The University of Houston
presents this series about the machines that make our civilization
run, and the people whose ingenuity created them.
It's the largest rodent found in North America, weighing
forty to sixty pounds. It's also irresistible. Found throughout the northern
United States and Canada, beavers were nearly hunted to extinction by the
end of the nineteenth century. Their sumptuous coats propelled the fur trade during
colonial times, and that contributed to western expansion. Fur traders moved
further inland as beaver populations dwindled, and settlers followed.
Yet pelts aren't what make these animals special. It's their ability to
change the environment. Elephants are bigger; chimpanzees smarter. But
beavers engineer the world around them. Beavers have broad, flat tails, large
front teeth to gnaw through trees, and they waddle when they walk. They eat
many types of vegetation, including tree bark. Beavers also use trees for
construction projects.
The most important project is building a home, or lodge. Beavers prefer
to build in slow moving water two to three feet deep. A typical lodge is a
dome-shaped structure of sticks and mud. It stands ten feet high and twenty
feet across. Entrances to the lodge are underwater. That helps protect the
occupants from predators. The entrances also give beavers access to the water
when ponds are frozen. Branches stored under the surface during warm months
are used as food.
Inside the dome is a large central chamber where beavers raise their families.
Beavers are monogamous and live in family groups of around ten. A mother and
father will have a litter of one to six kits per year. These kits stay with
the parents for two years, so both older and younger ones live in the house
together. By the third year, the older siblings either leave on their own or
are pushed out by their parents. The parents stay in the family home unless
there's good reason to move.
When beavers can't find water that's just right for building a lodge, they'll
first build a dam. Dams are a mixed blessing, not for the beavers, but for
their surroundings. Dams can create ponds covering many acres. Environmentalists
are quick to point out that these ponds are the foundation of important natural
ecosystems. But a civil engineer finding a road covered in water is not very
happy. Neither is the homeowner whose property is slowly being submerged and
whose trees are disappearing.
Still, in spite of the trouble they can cause, beavers hold a special place in
North American culture. Many of the engineering schools in the country --
Oregon State,
Cal Tech,
MIT --
have the beaver as their school mascot. Both
New York
and Oregon have
adopted the beaver as their official state animal. But the highest recognition comes
from Canada, where, instead of a bald eagle, the industrious beaver is honored as
the national animal. It's even inscribed on the
Canadian five cent piece.
With their affable disposition, work ethic, family values, and environmental record,
it's hard not to feel a fondness for the beaver. You know, they sound like ideal
candidates for political office.
I'm Andy Boyd, at the University of Houston,
where we're interested in the way inventive minds
work.
(Theme music)
Dr. Andrew Boyd is an adjunct faculty member in the Department of Industrial
Engineering at the University of Houston. Dr. Boyd received his A.B. with
Honors at Oberlin College with majors in Mathematics and Economics in 1981,
and his Ph.D. in Operations Research from MIT in 1987. His new book is,
The Future of Pricing: How Airline Ticket Pricing Has Inspired a Revolution,
(New York: Palgrave-MacMillan, 2007).
See articles on beavers in the Encyclopaedia Britannica or in
Wikipedia.
Beaver. (1994).
Publication of the Alaska Department of Fish and Game.
(Retrieved December 15, 2007.)
Beaver picture from W. Hooker,
Natural History, 1864
Beaver dam picture from R. W. Hegner,
Practical Zoology, 1917
The Engines of Our Ingenuity is
Copyright © 1988-2006 by John H.
Lienhard.
