Why are there men and women, men and women?
The general process of life evolution is: from simple to complex, from low to high, from single cell to multi-cell, from invertebrate to spine, from asexual to sexual. It can be said that gender differentiation is a leap in the evolutionary history of nature.
Creatures are asexual at first, and their reproduction mode naturally belongs to asexual reproduction. The so-called asexual reproduction refers to the reproductive mode that directly produces offspring individuals without the combination of gametes (sperm and eggs, sexual reproductive spores and other cells). Asexual reproduction is economical and reliable, with low risk, but the disadvantage is that the variation of offspring is small, which is not conducive to the emergence of adaptive variation and more robust and lively offspring, and the gene exchange between populations is quite limited, which is not conducive to the evolution of the whole biological population in the long run. The dichotomy of bacteria, the creeping propagation of strawberries and the survival of some plants by cutting are typical asexual propagation.
Later, plants and higher animals appeared gender, and the differentiation of hermaphroditism completely changed the way of biological reproduction. First of all, the differentiation of male and female produces male and female germ cells, which each carry a part of genetic material and fuse to release their respective genetic DNA under certain conditions.
In this way, female gametes can choose from a considerable number of male gametes, and choose the most dominant, dynamic and robust male gametes to combine, thus producing excellent offspring. Male gametes, because of their quantitative advantages, can constantly try to get the maximum gene benefit, that is, to make their genes accepted by more female gametes as much as possible.
At the same time, offspring individuals have paternal traits because they have obtained paternal genes, rather than pure maternal inheritance. This reproductive process not only increases the possibility of beneficial gene variation, but also improves the survival rate of offspring.
In addition, gender differences make the division of tasks between the two sexes more clear. For example, our male ancestors were responsible for hunting, paying attention to manual labor and protecting the family, while women were responsible for looking after children and doing housework. The division of tasks obviously improves the work efficiency, improves the survival probability of groups in harsh environments, further enables us to survive in the wild era, and provides a solid foundation for long-term evolution.
Finally, gender differentiation makes it possible to choose a child (spouse).
Sexual selection is a cruel process. Generally, only individuals with strong body and obvious sexual characteristics will be favored by the opposite sex, because such individuals often leave a good sexy impression on their spouses, such as security, fullness, tenacity and strong parenting ability, and in fact, this is generally the case, which greatly improves the survival rate and health status of future generations and is still conducive to the survival of various creatures in nature.