It is a super tough gland, able to rebuild its missing cells whilst regenerating damaged ones. It will function with only one fifth or less of its whole. In cancer cases, where varying percentages have had to be removed, months later the gland has grown back to its original size. Thus, it may be considered potentially immortal.
Nevertheless, constant abuse with malnutrition, harmful drugs, poisons and infection does eventually wear it out.
Man’s original food and environment were natural to the core. With civilization came gradual changes in man’s food and his eating habits. Food was cooked, salted and, later, processed and chemically treated. But man’s liver didn’t change. It remained the old pre-civilization model.