How can Baby Yoda be 50 years old?
Animals that can protect themselves from being eaten tend to evolve long lifespans
Grogu, also known as “Baby Yoda,” is very much a toddler. He coos adorably. He rides around in a floating stroller. He even sticks random objects in his mouth. But this wide-eyed child in Star Wars’ The Mandalorian is a whopping 50 years old. This makes sense, given that one of the only other known members of his mysterious species — Yoda — lived to the ripe old age of 900.
Such slow-aging, long-living creatures are not unique to the galaxy far, far away where Star Wars is set. Earth has its own champions of longevity. Giant tortoises live more than a century. Greenland sharks survive hundreds of years. The oldest known quahog clam lived about 500 years. Meanwhile, mice live a couple of years and some worms survive mere weeks. Why does one animal — be it Grogu or a Greenland shark — outlive others?
In general, animals that can’t protect themselves age faster, says Richard Miller. He studies animal aging at the University of Michigan in Ann Arbor.
“Let’s say you’re a mouse. Most mice die within six months of age. They freeze to death. Or they starve to death. Or they get eaten,” Miller says. “There’s almost no pressure for building a creature that will be long-lasting … when you’re going to get eaten in six months.” As a result, mice are best suited for short lifespans where they grow up and have a bunch of babies within a couple of months. Their bodies have evolved to last just a few years at most.
“Now, let’s say you teach the mouse to fly, and you’ve got a bat,” Miller says. “Because they can fly, almost nothing can catch them and eat them.” Bats aren’t pressured to rush reproduction the way that mice are. They can stretch out their aging process, growing up more slowly and having babies over a longer stretch of time.
Animals that wait to have babies until they are more mature may make better parents, says Steven Austad. This biologist from the University of Alabama at Birmingham is an expert on aging. Having fewer babies at once over a longer period of time, he adds, could boost the odds that some young will be born in good environmental conditions that help them survive.
So, for bats — which stand a much better chance of avoiding death for longer than mice — it’s useful to have a body that can last decades. The result: Some bats have evolved to live more than 30 years. The ability to fly away from danger may also be why birds have evolved to live a few times longer than mammals of the same size, Miller says.
Another strategy for slow-aging species is size. Think of elephants, Miller says. “Once you’re a grown-up elephant, you’re more or less immune to predation.” This has allowed elephants in the wild to live about 40 to 60 years. Other big animals also tend to live longer than smaller ones.
The protective nature of the ocean also can lead to long lifespans. “The longest-lived animals are all in the ocean. And I don’t think that’s an accident,” Austad says. “The ocean is very, very constant. Particularly the deep ocean.”
None of these protections, though, seems to apply to Grogu. He can’t fly. He’s not a sea creature. He’s not even very big. But he probably has a big brain. His elderly kin, Yoda, was a wise Jedi Master. Even as a toddler, Grogu displays some impressive smarts — including an ability to communicate through the mystical Force. On Earth, big-brained animals, such as primates, seem to have an edge for longevity.
“Primates live two to three times as long as you would expect for a mammal of that size,” Austad says. Humans have especially big brains for primates and live about 4.5 times as long as expected. “Bigger brains make better decisions, see more possibilities, are more finely tuned to changes in the environment,” Austad says. Those insights help quick-witted animals evade death. That, in turn, could have opened up the opportunity for us to develop long lifespans, just like bats or elephants or ocean creatures. The same may be true for Grogu’s species.
For slow-aging animals like Grogu to last so long, their bodies must be highly durable. “You have to have incredibly good [cellular] repair mechanisms,” Austad says. An animal’s cells must be excellent at fixing natural wear-and-tear on their DNA. They must also maintain the health of their proteins, which have many jobs inside cells.
On Earth, one key repair tool for cells may be the enzyme Txnrd2. That abbreviation is short for thioredoxin reductase (Thy-oh-reh-DOX-un Reh-DUK-tays) 2. This enzyme’s job is to help protect proteins in cells’ mitochondria (My-toh-KAHN-dree-uh) from being oxidized. “Oxidation damage is bad for proteins,” Miller notes. “It turns them off and they no longer work.” But Txnrd2 can snip oxidation damage off proteins and repair them.
Miller’s team has found that long-lived birds, primates and rodents all have more of this enzyme in their mitochondria than do their shorter-lived relatives. In experiments, boosting the enzyme in the mitochondria of fruit flies helped the flies live longer. This hints that Txnrd2 may help slow-aging animals live a long time. Miller’s group also has identified other cell parts that seem to be connected with long lifespans.
Researchers hope to create new drugs that give humans more of the cellular machinery needed to slow aging. If they’re successful, we may someday boast the long lifespans of Grogu and Yoda.