The legend of the first Titan, Ymir Fritz, details how the Titans' founder lived for a mere 13 years, and thereafter, no Titan could surpass that limit. Grisha himself was said to be proof of these limitations, feeding himself to Eren after having been in possession of the
Because it is impossible for anyone to surpass the Founder, each person who gained the power of the Titans was fated with the "Curse of Ymir" (ユミルの呪い Yumiru no Noroi?), which limited their remaining lifespan to only 13 years after first acquiring it.
In effect, Pure Titans are immortal. Combined with their physical strength and imperviousness, Pure Titans can withstand the ravages of time as well.
Before the operation to retake Wall Maria Keith Shadis tells Eren that he first met Grisha about 20 years ago. At this point the attack on Wall Maria which coincided with Grisha's death happened 5 years ago. So Grisha had in fact been inside the Walls for 20-5 = 15 years!
Bertolt attempted to convince Reiner to give up his aspirations, as he would only live for thirteen more years. But Reiner believed that after those thirteen years, he would be a hero to the people of Marley and be the best son in the world.
Ymir and her people were injected with the Titan serum by the Marleyan soldiers, and transformed into mindless Titans to be banished to roam on Paradis. 60 years later, still as a Pure Titan, Ymir encountered the young Warriors Marcel Galliard, Reiner Braun, Bertolt Hoover, and Annie Leonhart.
Can Eren live more than 13 years? No, unfortunately not. Even if a person gains a second Titan shifter power like Eren, they still only have 13 years to live. This is because the lifespan of all Titan shifters is predetermined and cannot be changed or extended by gaining additional powers.
The legend of the first Titan, Ymir Fritz, details how the Titans' founder lived for a mere 13 years, and thereafter, no Titan could surpass that limit. Grisha himself was said to be proof of these limitations, feeding himself to Eren after having been in possession of the Attack Titan for 13 years.
Ymir is officially documented by multiple sources (character bios on anime's website, character bio in the official guidebook) as being physically 17. She has now revealed that she has an extra 60 years tacked onto this, in which she did not age.
This Titan was the first Pure Titan shown to speak words with meaning. The second was Ms. Springer. This Titan was the only common Titan seen that displayed a range of emotions.
They do seem to become less active at night or if deprived of sunlight, and so it may be possible they draw their primary source of energy from the sun.
All Titans were originally humans of a race of people called the Subjects of Ymir. Ymir Fritz was the first Titan, who became one after merging with a strange spine-like creature in a tree.
The surface of Titan is one of the most Earthlike places in the solar system, albeit at vastly colder temperatures and with different chemistry. Here it is so cold (-290 degrees Fahrenheit or -179 degrees Celsius) that water ice plays the role of rock.
As a Titan Shifter, he suffers from the Curse of Ymir, which means that he has 13 years to live after gaining his powers.
Titan appears to have lakes of liquid ethane or liquid methane on its surface, as well as rivers and seas, which some scientific models suggest could support hypothetical non-water-based life.
Not only do they get better and more powerful as they practice, it "feeds" them. For that reason, Grisha, especially talented Grisha, age slower than other humans, sometimes living for centuries, assuming they continue to use their abilities regularly.
No, the Eldians need to consume a Titan Shifter in order to become one. If Eren dies without being eaten, then the Titan Shifters die with him.
Very quickly, Eren and viewers learn that he's not the only Titan Shifter around — and very few of them are on the side of humanity.
Since Erwin was attending school that time, I am going to assume that he was around 11-13, making him at least 2-4 years older than Levi (I'm pretty sure that Isayama has stated somewhere that Erwin is older than Levi).
2 They Are Distant Relatives
In the case of Mikasa and Levi, they share the surname Ackerman. While there's no way they are siblings— they have different parents, after all— there's evidence that the two of them are distant cousins, especially when considering the power they share with Kenny.
The reason why Levi Ackerman is so short is that when he was a child, Levi was extremely malnourished. Apart from that, since he spent most of his childhood in the Underground, Levi lacked access to direct sunlight, limiting his vitamin D intake, which is crucial for his physical development.
For 2,000 years, the Founder Ymir has been waiting--a slave to those with royal blood. However, Eren's yearning for freedom gives her a choice that could shake things up.
So, it's not like she couldn't regenerate, it's because she wanted to die. Unfortunately, even after her death, she continued to be a slave to the royal bloodline in Paths for more than 2,000 years. In conclusion, the best answer is that she wanted to die. Why didn't Eren regenerate after his head was cut off?
Due to the Curse of Ymir, we know Ymir Fritz died exactly 13 years after becoming the Titan progenitor, and that makes her roughly 23-years-old when she dies protecting the King. Dying as a 23-year-old fits Ymir's chronology following her capture by the Eldians.