Another one of those random questions that seem to come out of nowhere as it flits across our minds – Why Exactly are Eggs egg Shaped ?

There’s a widespread belief that the shape is the result of the egg-laying process but this fails to explain why some birds, such as ostriches, produce perfectly round eggs. A similar criticism can be made of the idea that the shape is dictated by the need for eggs to be as strong as possible: if this were the case, all eggs would be spherical but pigeons and diving birds lay eggs that are pointy at both ends.

mathematics has shown that the explanation appears to lie in the numbers of eggs laid

The shape of living things is often a reflection of a sophisticated evolutionary effect and recent research suggests the same is true of eggs. Dr Tamas Szekely, a mathematician at Bristol University, has shown that the explanation appears to lie in the numbers of eggs laid by different bird species.

Specifically, he found that eggs take on the shape they do in order that as many as possible can be packed together for warmth during incubation. For example, shorebirds like plovers typically lay approximately four rather pointy-shaped eggs which, allows the eggs to be around 8% larger for a given nest size. In contrast, birds like ostriches, which lay one egg, do best by having spherical eggs.

eggs take on the shape they do in order that as many as possible can be packed together for warmth during incubation

Inevitably, there are exceptions to the “optimal packing” rule. They include guillemots, whose single eggs are pear-shaped. This may be a reflection of the fact that guillemots make their nests on sheer cliff faces: pear-shaped eggs don’t roll in a straight line, thus helping to stop them rolling over the edge.