Born in 1918, Robert Wadlow grew to enormous size and scraped the skies at 8' 11" thanks to hormonal issue that tragically also led to a cacade of health problems. He died in 1940 of consequences from an infection.

Other people have crested the 8' tall mark, but they are few and far between, and no one's come close to Wadlow's record, at least according to the officials at Guinness.

Can people ever grow to 9 feet tall or even beyond? This article from The Guardian points out that:

Normally, the growth of our bones is limited by our sex hormones. A good burst of sex hormones at the right time tells the ends of our bones to stop growing. In acromegalic gigantism, as the tumour grows, it destroys cells in the pituitary gland that stimulate the release of sex hormones. The bones, therefore, never get the signal to stop growing.

But surely there must be a limit to a person's height? John Wass, a specialist in acromegalic gigantism at the University of Oxford, reckons it would be impressive to survive for long if you grew taller than 9ft.

Here's why Wass thinks 9 feet tall is a ceiling, so to speak:

• blood pressure in the legs would be extreme and dangerous
• keeping blood circulating in such a person would strain the heart to the breaking point

Gizmodo points out that:

the primary [obstacle to mega growth] is our environment. Gravity, and the limited buoyancy of the air around us, means that our bones would have to grow exponentially larger to support a human that towered ten to twelve feet tall.

And this New York Times piece quotes Dr. Rob DeSalle, of the Sackler Institute for Comparative Genomics, who says:

Many joint disorders and bone problems exist for these individuals that impact average-height people much less. Engineering problems with respect to organisms and their evolution do not get solved easily.

All that said, Wadlow came within just 1 inch of 9 feet tall. Surely, some person, somewhere, will break the mark. But when?