ELI5: Why are so many country roads in Great Britain lined with hedgerows?

Many country roads in Great Britain are lined with hedgerows because farmers planted them long ago as living fences to keep their animals safe and mark their land.

Instead of building fences out of wood or metal, people planted thick bushes like hawthorn and hazel very close together. As these bushes grew, people bent and tangled the branches—a bit like braiding hair—to make a living wall that sheep and cows could not push through.

Here is why they became part of everyday life:

• Animal fences: If you are a farmer, you do not want your cows wandering into the road or into your neighbor's field of vegetables. The thorny bushes acted like a green shield to keep animals where they belonged.
• Property markers: Hundreds of years ago, kings and governments made rules saying open fields had to be divided up. Planting hedges was the easiest way for people to show, "This is my field, and that is yours."
• Nature's umbrella: The thick shrubs protected delicate crops and animals from strong, chilly winds and heavy British rain.

Today, farmers do not need to plant them as much, but people keep them because they are fantastic for the environment. They act like leafy highways for everyday British wildlife. Birds, hedgehogs, and dormice sleep in them, eat their berries, and travel through them safely without ever having to step onto the scary road where cars drive.