Offspring Development Conditioning (ODC): A Universal Trend in Evolution of Higher Organisms’ Reproduction

Abstract Background All organisms evolve, according to Darwin. The question is how? Is there any generalpattern or trend in the organisms’ evolution? These are rarely asked and almost never answered questions. This situation makes the evolution frustrating an d mysterious to many.Results After surveying the reproductive modes in most animals and plants, we propose that all (at least most) of higher organisms demonstrate the similar trend underlying their reproductive evolution, namely, Offspring Development C onditioning (ODC). ODC benefit the organisms in two ways: one is enhanced physical protection, the other is secured nutrition supply.Conclusions This pattern makes the origin and evolution of reproductive organs in both animals and plants rational and co mprehensive . To the best of our knowledge, this pattern appears universal in higher organisms (including both plants and animals), although we encourage future colleagues to identify exceptions. We hope this will help frame the evolution of higher animals and plants, and make their evolution comprehensive to everyone.