Have you ever wondered why animals don’t live as long as us humans, well stop wondering because this is the answer!

     Lifespan is usually related to the animal’s size but this was work on a long time ago it is no longer accurate. Because you see some parrots can live until the age of 80 years old because the metabolic rate is related to the heart rate.

     But dogs do not follow this rule since a Chihuahua can live 10 years and a Great Dane is lucky to live 7 years old. We thought that one year of a dog is equal to 7 years but it is much more complex than that. Actually, the first year equals 15 years in our time then year two is about 9 years and for the rest, a year equals approximately 5 years. 

     A human could live until the age of 100 years old with no problem if they were in good condition. Before it was not the same, we did not have the same technology or none so, in the 1840s, people could die at the young age of 45 years. In prehistoric times, people lived until the age of 20 or a maximum of 30 years old. 

     Animals that can go back to a non-mature age do not exist except for the Turritopsis. It is located in tropic water. The little jellyfish’s full name is Turritopsis dohrnii or known also as the immortal jellyfish. This animal can not come back to life but when it is stressed or is physically aggressed, is sick or old, it can come back to a non-mature phase. So its size and heart rate don’t matter.