I used to think humans were pretty innovative — we’ve engineered ships to traverse vast oceans, engineered bacteria to produce lifesaving insulin and engineered sticks to take Instagram-worthy selfies.
All of our inventions seem adorably simple when compared with the natural engineering on display in “Nature’s Ultimate Machines,” a special exhibit at the Natural History Museum of Utah that runs through Sept. 3, 2018. From slug slime to whale flippers to electrical shocks, organisms have “engineered” impressive tactics to make a living on planet Earth. The interactive exhibit explains how some species glide through the air, endure extreme temperatures or crush 8,000 pounds in a single bite. After wandering around the displays in slack-jawed fascination, I talked to University of Utah biologists to better understand how every living thing has evolved to be an ultimate, survival machine.
Birds of a feather flock…differently
The museum gives visitors the chance to take flight… in a swivel chair. After fighting off elementary school children (they cut in line!), I sat in a chair armed with two types of “wings” — the long and skinny wing of an albatross, and the short, stubby wing of a sparrow. I flapped the long, skinny one. After a slow, shaky start, I began to fly in circles. Victorious, I swapped in the short, stubby wing. This time, I started spinning right away, but struggled to keep the chair turning.
Wings are one of the amazing adaptations that evolution “designed” to deal with forces at work against survival. The swivel chair experiment demonstrates how bird species have “tinkered” with wing design to achieve different movements. Millions of years ago, all birds had a common, ancient ancestor with an early version of a wing. Over time, genetic variation and natural selection drove the diversity of birds we see today. Offspring resemble their parents, but each individual has a distinct genetic makeup. Some genetic combinations may help that individual survive, reproduce and pass down their favorable genes. The environment can act as natural selection that “chooses” the gene combinations that survive, and those that don’t. Eventually, populations branch into a separate species equipped with their own tools for survival.
“Physics isn’t optional — things that live in water, things that live in air, are all subjected to the same pressures. All wings are a way of dealing with the problem of moving through a fluid that wasn’t dense like water. The birds’ answer to that was to reduce the arm bones, and have feathers,” said Lindsey Reader, a doctoral candidate in the Department of Biology. “We can learn a lot by paying attention to the context in which organisms are evolving.”
Reader researches bird biomechanics by approaching the problem as both an engineer and an ecologist. She dons her engineering cap to analyze how muscles, tendons and tissues let the birds do what they do, and wears her ecology hat to understand the environment in which the physiological systems evolved.
“The different features of the wings give clues about the birds lifestyle. There’s a spectrum of wing design, from the long skinny wings of an albatross to the short stubby wings of a sparrow,” Reader said.
The chair display gives you a small taste of those lifestyle differences. Albatross glide over hundreds of miles of ocean without needing to flap. The slender shape is perfect for long distances, but terrible for taking off quickly; albatross need a running start to get airborne. In contrast, small forest-dwelling birds such as sparrows have stubby wings that can maneuver through canopies and lift off with one flap, but they have to work to maintain flight.
A cheetah can’t win a marathon
I approached the display featuring nature’s ultimate speed machine, the cheetah. Its physique is equipped with specialized features to go from zero to 60 miles per hour in three seconds. Their flexible spines stretch out, their permanently extended claws get maximum traction and their massive lungs pull in the oxygen needed to power their muscles. Even their running style, called the rotary gallop, is unique; their paws hit the ground one-at-a-time, launching the cheetah airborne twice per stride.
“We can probably say that cheetahs have all these adaptations because there was a niche to catch fast prey with a super-fast acceleration,” said Amanda Cooper, a doctoral candidate in the Evolutionary Biomechanics Lab in the Department of Biology. “But there’s a trade-off. I’m interested in what makes nature’s sprinters, and what makes long distance runners. It’s intuitive that if you’re good at one of those things, you’ll suck at the other.”
Cooper’s research focuses on human runners; she has identified a few underlying physiological factors that distinguish sprinters and long distance runners. For example, the length of the muscle fibers.
Cooper and her team predict that sprinters, nature’s power athletes, share the long muscle fiber trait. Long muscle fibers contract more quickly than shorter fibers, giving sprinters quick bursts of powerful energy. Longer fibers are bad for long-distance runners, however; for a given force production all of that metabolically expensive tissue is activated. Sprinters gas out faster by losing oxygen and ATP that fuel the muscles.
“There’s the trade-off. Long distance running is an entirely different game. A marathon comes down to how good you are at conserving your energy and using it wisely,” said Cooper. “This is just conjecture, but along with the traits explained in the exhibit, cheetahs probably have long muscle fibers. Their chases are very fast, and over pretty quickly, so they need that extra power boost.”
“Nature’s Ultimate Machines” is spectacular; these two displays are just a fraction of Mother Nature’s awe-inspiring engineering. Don’t believe me? Watch the video to hear what the critics are saying.