Why do Maine Coons stop growing later than other domestic cats?

The Internet tells us that Maine Coon cats grow up more slowly than your regular domestic cat. You will see many articles on this. They appear to be repeating each other in saying that Maine Coons do not reach their full size until they are 3-5 years old. Other domestic cats reach their full size and adulthood around 12-18 months of age. So why is this? They don't tell us 😢😒. Or is the information slightly misleading?

Another very large Maine Coon with a great coat. Image in the public domain in my view.

So, I have to work out the answer myself and it is probably this: there's a slight exaggeration about the development of the Maine Coon to adulthood. It has become a kind of badge of honour for the largest purely domestic cat breed to grow more slowly than normal. And secondly it might take longer to fully grow all of their anatomy because they are bigger. 

Perhaps their coat, such as their ruff (mane), continues to develop at year 3 but the rest of the cat has stopped growing at 2+ years. It might be as simple as that. 

I suppose logically it might make sense. There is more growing to do. For example, the African elephant doesn't become an adult until about 12 years of age, but their lifespan is much longer. The elephant becomes adult add about 1/6 of their total lifespan.

The Maine Coon appears to have a lifespan which is slightly shorter than the average domestic cat (on average). Let's say it is about 15 years of age and if it takes up to 5 years to become an adult that represents one third of their lifespan which is twice that of elephants and longer than for humans relative to lifespan. 

Humans stop growing at around one quarter of their total life i.e., at 20 years old based on a lifespan of 80 years.

RELATED: When will my Maine Coon kitten develop her full coat and neck ruff?

What I am getting at is that the overly long time to grow to adulthood of Maine Coons is a slight exaggeration. At the end of the growth period, it is tricky to say definitively that growth has stopped at a specific age. It is the blurring of the end of growth which might lead to slightly incorrect information.

Also, some non-Maine Coons will grow more slowly and might take up to 2 years to be fully grown. This is close to the time Maine Coons become adults. And Maine Coons may reach their full size at around 2+ years of age and not 3-5 years of age as is often stated. That seems more logical to me.

My tentative suggestion, therefore, is that Maine Coon cats don't take quite as long to reach adulthood as people say and domestic cats other than Maine Coon cats continue, perhaps almost imperceptibly, to develop and grow after the first 12 months. Not all domestic cat stop growing at 12 months of age. Beyond 12 months the growth rate will be much slower. 

One Maine Coon breeder describes "Maine Coons as juniors" between the ages of six months and two years. She says that after the first year her cats start growing fur extensions to give a fuller appearance. The coat length extends from about 1 inch to about 4 inches in length over that period of time.

She also says that at the end of the second year of their life most Maine Coon cats have stopped growing most of their adult hair and start to enter the next stage of their maturity. The lion mane develops at this time. Cats of this age are still a bit kitten-like remaining playful and inquisitive over the first couple of years of their life. They are full of energy and are too busy messing around to bother to snuggle up to their owner.

And at the age of about two years, they become more mature in their personality, and they have the time to snuggle up with their human caregiver on the sofa. She says that most growth occurs in the first 12 months of life and then from the end of that first year until about five years of age there is a gradual increase in weight and size and in terms of personality, maturity.

But she doesn't tell us why there's this apparent great disparity between Maine Coon cats and other cats. I don't think this big difference exists. Although, there will be a slight difference in growth rate because of the difference in size.