What does the square cube law say and how does it explain the absence of giant ants on Earth?

Answer 1

If you increase the length of every part of an ant by a multiple x, the cross sectional area of its legs increases by a multiple of x^2 whereas its mass increases by a multiple of x^3. Thus the cross sectional area of the weight-bearing parts increases significantly less than the weight that it has to bear.

Answer 2

The basic idea is that for objects that are geometrically similar (for example, two spheres; two cubes; or two ants constructed to scale):* The surface area is proportional to the SQUARE of the length (or of any linear measurement).

* The volume is proportional to the CUBE of the length.

For example, a cube of 1 cm length has a surface area of 6 square cm, and a volume of 1 cubic cm; a cube 10 cm in length has an area of 600 square cm (100 times as much), and a volume of 1000 cubic cm (1000 times as much).

For living beings, such as ants, several problems arise if they get too big (while maintaining their proportions), for example:

* The legs will no longer be able to support their weight.

* They will not get enough air. That's why larger beings, such as humans, require lungs or other special organs for breathing.

* They won't be able to find food fast enough.