Do my ears keep growing forever?

Sofia Miettinen

Have you ever heard that babies are born with such large eyes because your eyes never grow any bigger? Or that your ears keep growing forever? So which parts of your body keep growing and do any parts stay the same size since birth? To answer these questions, we first need to think about the cells that make up our body parts.

 

A cell is the basic building block of life. Your body is made of up to 100,000,000,000,000 tiny cells that can only be seen under a microscope! Cells that have similar structures and functions are grouped together to make up tissues, such as muscle tissue. Different tissues which work together to do a particular job can come together to form organs such as the heart, lungs, and brain. There are over 200 different types of cells in your body and they are all specialised, meaning they all have their own special roles in the human body.

 

The human body grows by increasing the number of cells that make up its tissues and organs. This is called cell division, and one cell doubles by diving into two and so on. The human body begins as a single-celled structure called a zygote containing just an egg and a sperm cell joined together, and continues to grow from birth to puberty, at which point your body reaches its maximum size. Puberty tends to begin around 11 years of age for girls and 12 years of age for boys and lasts for around four years, but sometimes boys may not reach their full height till they are over 18 years old.

 

When you are an adult, your cells do not make as many copies of themselves so often anymore and will only make new cells to replace cells that have become damaged or died. When you break or stress a bone, bone cells called osteocytes detect damage to the bone and tell osteoclast bone cells to break down the old damaged boned and tell osteoblast bone cells to fill in and make new bone. Similar repair mechanisms happen if we damage our skin and other organs such as the liver. Cells send chemical messages to each other so that they stop growing and dividing when growth or healing is complete.

 

Some cells such as neuron cells, which send communications, cannot grow if they are damaged once you are an adult. Some muscle cells such as cardiac (heart) muscle cells also cannot grow once they are damaged. For women, they cannot grow new egg cells, and are born with all the eggs for their lifetime.

 

So, what about your eyes, do they never grow any bigger? Eyes do in fact grow bigger as you get older; babies’ eyes are about 70% the final size of eyes as an adult. As your eyes grow bigger, it can change shape slightly and this can cause people to need to wear glasses as they get older! Your ears and nose do keep growing too, and scientists have found that your ears grow about 1cm over 50 years.

 

When you die, no parts of your body keep growing, despite myths saying that hair and fingernails continue to grow when you die. Cells need energy to grow and once you die your body cannot provide energy forever.

 

Sometimes the growing process can go wrong, and some people who have a condition called acromegaly keep growing bigger even after puberty! The tallest man recorded was Robert Wadlow from the United States of America, who was measured as 2.72 metres tall; that is over a metre taller than the average American man!