Baby Yoda’s physical development is odd, but not entirely unprecedented

Ever since The Mandalorian premiered on Disney+, my mind has been stuck on one thing — Baby Yoda. As in, “How can I get one?” “Will it let me squeeze their cheeks?” “Does Baby Yoda need its diaper changed?”

You get the idea.

But there was one thing about Baby Yoda that perplexed me. Their age. When Star Wars fans met OG Yoda in The Empire Strikes Back in 1980, they were given relatively little of Yoda’s backstory, outside of the fact that he trained Obi-Wan Kenobi. However, there was one little tidbit.

When Luke remarks that he’s ready for training, Yoda replies, “Ready are you? What know you ‘ready?’ For 800 years have I trained Jedi. My own counsel will I keep on who is to be trained.”

Suddenly, eyes were wide. Not only did Yoda train Obi-Wan, he trained generations of Jedi! Just how old was Yoda? We’d get an answer in 1983’s Return of the Jedi when, after contemplating his pending death, Yoda humorously turns to Luke and remarks, “When 900-years-old you reach, look so good, you will not, hmmm?”

So we know that Yoda was approximately 900-years-old when he died, and he trained Jedi for around 800 of those years. Obviously, Yoda’s species is especially long-lived compared to humans. But beyond that, we don’t have much information on how Yoda’s species ages.

Part of that is the mystery behind Yoda’s species. I mean, I’m calling it “Yoda’s species,” because George Lucas never named it publicly and has kept it wrapped in mystery. We’ve only seen two more examples of Yoda’s species in the new canon material — Yaddle, a female representative that sits among the Jedi Council in The Phantom Menace, and the lovable Baby Yoda of The Mandalorian.

The data we have

Yaddle is a background character at best. She has no lines, and you might not even notice her if you weren’t looking for her. According to the fan wiki Wookieepedia, Yaddle is listed as 477-years-old in the canon reference book, Star Wars Character Encyclopedia: Updated and Expanded, by Pablo Hidalgo. Yaddle does appear to be younger, developmentally, than Yoda, with darker hair (and more of it).

Baby Yoda we know relatively little about, except that they are adorable. We don’t even know Baby Yoda’s biological sex. We do know, thanks to Werner Herzog’s character “The Client,” that Baby Yoda is 50-years-old, assuming “The Client” isn’t lying or working from false information.

So we have Baby Yoda, at 50-years-old, who developmentally resembles a human toddler; Yaddle, who developmentally resembles a human adult at 477-years-old; and Yoda, who resembles an elderly human at 900-years-old. But we also know that Yoda was capable of training Jedi when he was around 100 years of age.

While at first it might be tempting to say that Yoda is the equivalent of a 90-year-old human, and that Yoda’s species ages at a rate of about one year of human development per 10 years of age, Baby Yoda’s behavior throws a curveball into that analogy. After all, Baby Yoda seems more like a toddler than a kindergartner. And what to make of Yoda saying that he trained Jedi for over 800 years? Was he training others at the human age of 10?

Fortunately, science can help provide some insight on this peculiar matter.

A prehistoric analogue?

Importantly, as it turns out, animals do not age and develop at the same rates. While you might have heard that a year of a dog’s life is equivalent to seven years of a human’s, that’s not entirely true. Depending partially on the breed, dogs go through a relatively rapid acceleration in growth, passing through adolescence and becoming a full-fledged adult at about 18 months. Not a teenager, an adult. Their development cycle then slows down and they spend the rest of their lives as adults.

Given that dogs typically live about 10 years or so, a dog spends about 85% of its total lifespan as a mature animal. Compare that to humans, who don’t exit adolescence until 18 years or so in an 80-year life cycle (77.5% of lifespan as an adult).

This applies to other animals as well. A 2004 paper by Gregory Erickson et al examines the way the predatory dinosaur Tyrannosaurus rex developed relatively slowly for the first 10 years or so of its life, before having a rapid change in development and growth from a < 1,000 kg creature to a 5,000+ kg animal in under a decade.

These results were expanded upon in a paper published on January 1, 2020 (way to make me feel behind already), in which Holly Woodward et al examined the bone microstructure from two young T. rex specimens, and concluded that the annual growth between the two individuals was actually different, and that this variation would alter the accuracy of the more generalized body mass curve in the paper by Erickson et al.

The most publicized conclusion from the 2020 paper, however, was that the evidence found by Woodward et al supported the synonymizing of the dinosaur genus Nanotyrannus into Tyrannosaurus. This isn’t a new idea; the debate over Nanotyrannus has been contested for decades. However, the evidence presented suggests that the specimens of Nanotyrannus are, in fact, juvenile Tyrannosaurus rex, which– had they lived — would have developed quite rapidly from lithe, speedy hunters into true titans.

So while Yoda’s species doesn’t quite match our idea of aging and development, that shouldn’t be a shock. Animals develop at different rates right here on our own world, so it makes sense that they might develop even more dramatically on Unnamed Planet A.

Seriously, the most unrealistic thing about these guys is that those arrogant humans haven’t taxonomically classified them yet.

AIPT Science is co-presented by AIPT and the New York City Skeptics.