Due to advances in molecular biology, the process of reproduction, or self-replication, has become better understood. At the core of this process is the DNA molecule. Though not itself alive, DNA is usually regarded as the sine qua non of life. DNA is considered the identifying mark of a living system. We judge something as living if it contains DNA. Biologically, the human mind necessarily inherits a powerful drive to sustain self and kind. However, intelligence and volition can in principle allow a mind to overcome any such biological imperative. Psychologically, human minds are subject to many psychological limits in the areas of memory, perception, attention, concentration, volition, and cognition. There is a functional hierarchy of knowledge where there is a glass ceiling and glass floor, and are glass walls above which, below which, and beyond which the conscious cannot venture. Man will never know it all. The knowledge that we do have leads to very interesting possibilities.
A grasshopper nor preying mantis does not need to know the electrical or chemical or mechanical engineering, these things are just instincts by Nature. We need the knowledge of all people well-used for good-intentioned, well-used knowledge imparts service, comfort, and goodness. We need those with the knowledge to clean streets well as well as doctors, comedians, and disciplinarians. Man will challenge any boundary of knowledge. There are limits on the healthy amount of knowledge that a person or society can bear. Social and familial happiness and stability are being exchanged for the endless pursuit of knowledge. It would seem that there are many forms of knowledge kept from us as in the case of the amygdala having information about us that the conscious mind is kept away from. And, the details of the operation of the body are kept from us.