Sexual reproduction creates new individuals that are all slightly different from each other allowing for the adaptation and resilience of the species to changing circumstances. Imperative to sexual reproduction is collaboration, however brief, between a male and female organism. The complexity of collaboration and the interdependency imperative to sexual reproduction is offset by adaptability, hence survivability, of the species. Collaboration in the most core process of life, being reproduction, has proved a highly beneficial and successful evolutionary strategy. Collaboration between individuals of a specie therefor is instrumental to life itself and a cornerstone of the evolution of species dependent on sexual reproduction.
A bewildering diversity of collaborative models can be seen across all species to bring offspring to the proverbial finish line. For many species to successfully reproduce offspring the collaboration between a male and a female organism in the process of the conception alone is not enough; the new born needs to be protected, fed and initiated to life’s challenges until it can survive by itself and reproduce on its own. Depending on the level of independency of the newborn at birth the parent organisms are involved to protect, feed and educate the offspring.
For some species, the collaboration needed amounts to no more than bringing the seaman to the ovum, for some one or both of the parents will take care of the offspring, for others also the group will take care of the offspring. The amount of collaboration needed is there for dependent on the requirements of the reproduction process for a given species and the way the tasks are divided over the parents and (possibly) the group they belong to.
For humans the amount of collaboration needed to raise offspring is arguably the most intensive and enduring of all species: complex collaboration comes natural to humans.