Why Animals Need Elbow Room

The story

Squeeze too many people into a small room and you can feel the change. Voices rise. Elbows bump. Everyone gets a bit scratchy. And here is something remarkable: scientists find changes like that all across the living world. Crowding does not just annoy animals. It can transform them.

The most astonishing example is the desert locust. Most of the time, a desert locust is a shy, quiet grasshopper. It lives alone, dresses in quiet greens and browns, and actually avoids other locusts. But sometimes rain makes the desert bloom, lots of locusts hatch, and then, as the green patches dry up and shrink, the locusts get pushed together, closer and closer. Jostled and bumped, touched again and again, the shy loners transform. Their colours turn bold, their bodies change, and instead of avoiding each other, they now seek each other out, gathering into marching crowds and flying swarms of millions. Scientists even found they could start the change themselves, just by gently tickling a locust's back legs the way a crowd would bump them. The touching releases a chemical inside the locust's body, and within hours the shy loner begins seeking out company. The bold colours and the new crowd-ready body take longer, arriving as the locust grows and moults, and the change can deepen over generations. Same kind of creature. Two utterly different lives. And the switch between them is elbow room.

Trees seem to know about elbow room too. Walk under certain tall forests, look straight up, and you may see something lovely: the treetops do not quite touch. Winding rivers of sky run between the crowns, as if each tree politely stops growing before it crowds its neighbour. Scientists call this crown shyness, and they are still working out exactly how it happens. Perhaps the wind knocks the twig-tips together until they stop spreading. Perhaps each tree can sense the light bouncing off its neighbour's leaves and grows the other way. Either way, in these forests many a crown keeps its own share of open sky, and sunlight streams down through the gaps to the forest floor below.

People who care for animals use this knowledge every day. Animal scientists have learned that hens, pigs and fish can behave differently when they are packed too tightly for their kind. They can get stressed, squabble more, and lose the chance to do their natural things, the scratching and rooting and exploring that make them themselves. Give the same animals the right amount of well-arranged room, and each kind needs its own amount, and they usually settle. That is why animal doctors and good farmers measure space so carefully. Room to move is not a treat for an animal. It is part of being well.

And you are an animal too, a clever, friendly one. You love company, and you also sometimes need a quiet corner where nobody's elbow can find you. Both needs are real, and both are very old. So when a crowded day leaves you feeling scratchy, remember the forest: even the trees keep a little sky to themselves.