The Y chromosome in human men is shrinking so quickly, it could disappear altogether – though that will likely take some 4.5 million years. But the good news is that human genetics could find a solution around the problem.

The Y chromosome is the sex-determining chromosome in humans and many other animal species. It carries the “master switch” gene, SRY, that determines whether an embryo will develop as female, with two X chromosomes, or male, with one X and one Y chromosome.

Darren Griffin, a professor of genetics at the University of Kent, explains there was once was a time when a man’s X chromosome was the same length as his Y, but that’s been changing over the last 200 million years or so.

Women’s X chromosomes haven’t changed much in the last 200 million years or so, men’s Y chromosome has been shrinking, and losing dozens of the genes it once shared with women.

So do all these changes mean that men are endangered?

“That’s a question I get asked an awful lot, and the answer is absolutely not,” Griffin told CTV’s Your Morning Wednesday. “… Males are not going away.”

Griffin said it’s possible that the SRY gene could simply move its sex-determining mechanism to a different chromosome. That’s what has happened with Japanese spiny rats and mole voles, who lost their Y chromosomes entirely, says Griffin.

But, even if that happens to humans, it likely won’t be for several million more years.

“We’re not awfully worried. I think we’ve got an awful lot of things to be worried about in the meantime,” he said.