Figure 1.

Interrelationships among the death, birth and evolution of organisms. Left panel: The death and birth of organisms are balanced by the ecosystem, so that the earth will not be over-crowded by organisms and that there will not be any particular species dominating the earth. Deaths often occur when the environment is changed, whereas individual species, organisms, organs, etc., are not willing to die and will find ways to survive, resulting in evolution to new species and, sometimes, also to neoplasms that can be considered as “new species” at the tissue/organ level. Right panel: Phytoestrogens are, hypothetically, developed during evolution as a mechanism for plants to protect themselves from animals: The more an animal (such as a rabbit) eats a phytoestrogen-containing plant (such as a sort of grass), the more severely its reproductive function will be interfered with by the phytoestrogens. The plant is thus preserved by the decrease in the fertility of the animals.