What dose buoyancy have to do with jumping?

Buoyancy is a condition in which a physical body's average density is equal to the density of the fluid in which it is immersed.

The buoyancy offsets the force of gravity that would otherwise cause the object to sink (if the body's density is greater than the density of the fluid in which it is immersed) or rise (if it's less). An object that has neutral buoyancy will neither sink nor rise. 

Hope this helps! xx

The  grandmother cell  is a hypothetical  neuronthat represents a complex but specific concept or object.[1]  it activates when a person "sees, hears, or otherwise sensibly discriminates"[2]  a specific entity, such as his or her grandmother. the term was in use at least as early as 1966 amongst staff and students in the department of experimental psychology, university of cambridge, england. a similar concept, that of the  gnostic neuron, was proposed two years later