One creature’s fast, long lifestyle may reveal how to slow aging

Let me describe a mysterious bird that vividly illustrates some of the biological challenges that birds have had to overcome in order to live as long as they do.

My mystery bird is tiny, weighing about the same as an American penny. When active, it requires so much energy that it must eat several times its own body weight daily to keep from starving. During the flight, its wings beat 80 times in a secondand each gram of its flight muscles produces up to 10 times more energy than the muscles of an elite human athlete when both are working at peak performance. In fact, it has the highest metabolic rate of any endothermic animal—and rightly so very endothermic. Its typical body temperature of 40 °C (104 °F) would be a dangerously high human fever. It needs so much fuel to maintain this level of energy output that when it’s not active, it lowers its body temperature to ambient temperature so it doesn’t starve to death while it sleeps. His heart beats like a machine gun at 20 beats per second. Even at rest, it breathes 250 times a minute, which is about the same rate as a dog panting to get enough oxygen. Finally, his normal blood sugar concentration would make him dangerously diabetic if he were human.

How long do you think it lives?

I just described a hummingbird – specifically the ruby ​​hummingbird (Archilochus colubris), a species commonly seen flying around parks and gardens in the eastern United States. Hummingbirds feed their frenetic lifestyles by sucking nectar—a rich mixture of sugars—from flowers. Along the way, they also suck up a few small insects for protein. Their flight is a wonder to see and hear. Their name, of course, comes from the deep hum of their wings, which beat so fast they are almost invisible.

Special abilities of hummingbirds

How do they do it?Janice Carter/500Px Plus/Getty Images

The roughly 330 species of hummingbirds—all native to the Americas—are the only birds that can fly forward, backward, and hover. They can fly straight up and down like a helicopter and even do somersaults and other aerial acrobatics. Men in particular court women with displays of aerial acrobatics that seem impossible even as you watch them. In addition, ruby-throated hummingbirds, despite their small size and high energy demands, fly 600 miles continuously across the Caribbean twice a year during migration to their tropical wintering grounds. If birds in general perform amazing physical feats, those of hummingbirds are among the most amazing.

If that was all you knew about this hummingbird, you would no doubt expect them to be short-lived. After all, they live life in the fastest of fast lanes, and with few exceptions, animals that live fast die young. But you would be wrong. Ruby-throated hummingbirds can live more than nine years in the wild, although they make their deadly flights across the Caribbean twice a year. They are not even the longest living hummingbird. A similarly large broad-tailed hummingbird (Selasphorus platycercus), with similar energy requirements, can live up to 12 years in the wild. The much larger mouse lives only a few months in the wild and only about three years as a well-cared-for pet. Therein lies a secret that, once fully understood, may help develop ways for people to stay healthy longer.

What is the secret of birds?

The Selasphorus platycercus the hummingbird is an extreme example of what birds have to teach us about aging.Alan Vernon/Moment/Getty Images

Hummingbirds are an extreme example, but virtually the entire biology of birds can be understood in terms of adaptation to the exceptional energy demands of powered flight. All these energy demands suggest that birds should have short lifespans, but the opposite is true. Their body temperature is higher than ours; their resting metabolism is up to twice that of mammals of the same size, and their metabolism revs up even more during flight. Even the gliding flight of gulls, vultures, and albatrosses may seem almost effortless to us, but it doubles or triples a bird’s resting metabolic rate. Fuel for their exceptional energy demands is supplied by blood sugar levels that would signal uncontrolled diabetes in humans. Uncontrolled diabetes resembles accelerated aging more than virtually any other disease.

High energy, high heat, and high blood sugar should accelerate a number of major processes that contribute to aging, one of which is the production of free radicals. Recall that free radicals are molecules that can damage all classes of biological molecules, including DNA. To maintain cellular health, free radicals must be quickly destroyed by our antioxidant defenses and the damage they inevitably cause must be quickly repaired. Birds must have exceptionally effective antioxidant defenses and exceptionally fast repair mechanisms. In fact, some of the few studies that have been done to understand the longevity of birds have found that their cells produce fewer free radicals at the same rate of energy production as mammals of similar size. However, we don’t understand how they do it. They can also withstand more free radical damage before their cells die. We don’t understand how they do it either.

Another aging process that, based on what we know about aging, should be accelerated in birds is protein browning. Proteins fuel the chemical reactions that define life. Proteins that play a role in driving chemical reactions must be folded in a complex and precise manner, like origami. Any slight deviation from perfect folding compromises their function. Imperfectly folded proteins not only lose function, but become sticky, causing them to clump together with other misfolded proteins. The plaques and tangles of Alzheimer’s disease are particularly well-known clumps of misfolded proteins, but there are many others.

In the chaotic, buffer environment of our cells, proteins spontaneously misfold and are broken down and their parts recycled regularly. However, one particular type of protein misfolding slowly recycles proteins and is most important to birds and diabetics. This is a browning reaction that is caused by heat and sugars. Sugars spontaneously attach to proteins and disrupt their precise folding. The higher the temperature, the more concentrated the sugar and the faster this browning reaction takes place. This happens very quickly at the temperatures we use in cooking. Meat and toast will brown when heated due to this reaction. The same thing happens in our body, only much more slowly. For example, our tendons and ligaments are composed of collagen, a protein that hardens with age due to browning. Aging athletes were tanned to thank for their increased risk of injury. Because of birds’ higher body temperature and increased blood sugar concentration, their tendons, ligaments and other tissues should brown much faster than mammals. But they don’t.

How birds prevent free radical damage and browning is something that could benefit human health. Do they have unique antioxidants that prevent free radical damage? Do they have unique ways of degrading damaged proteins? They must also have mechanisms that preserve cellular function in the face of life’s challenges. There hasn’t been much done on aging processes in birds, but there’s never been the kind of big, sustained effort that we might get if they were studied for cancer prevention. Medical research remains largely mired in the study of short-lived laboratory species such as fruit flies and mice, from which we can learn little to improve or extend human health. A Manhattan Project to understand the exceptionally slow aging of birds and their ability to maintain strength and endurance throughout life would be a good use of research money.

This article was originally published on Reader according to Steven N. Austad. Read the original article here.

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