The Descent of Man, and Selection in Relation to Sex(Darwin, Charles)

 1. All life on Earth comes from one stem.

We know well that humans and all other vertebrates were created according to the same universal model, that they all have the same early stages of embryonic development, and that they also have certain traces in common.

We must honestly admit that they all branched off from the same lineage.

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All vertebrates, including humans, started from similar-looking embryos, and their appearance, purpose, and function differ depending on each gene.

Based on this, all living things on Earth are differentiated into species like countless branches extending from one stem.

I think that the misconception that humans are the only different beings on Earth is an error that must be avoided.

The reason why many creatures can live on Earth is because the sun, water, oxygen, and various organic substances are optimized for living things.

The Earth does not exist for us; we are just parasites on the Earth.

Each has evolved to fit the environment, and certain traits have survived to this day because they have been passed down to the heritable.

Of course, just as many organs have degenerated due to lack of use, humans have also 'adapted' to the Earth and lived well according to the situation.

2. Let's live together.

Most of the individuals who lived alone and hardly cared for their fellows have gone extinct, but animals that benefited by maintaining close relationships were able to wisely avoid various dangers.

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I think that no living being can live alone.

This is especially true for humans.

Just as a newborn cannot survive without the care of its parents, even as adults, we live by helping each other.

Almost none of the items we use were made by ourselves.

For example, even a single grain of rice is grown by numerous farmers somewhere in the country or abroad, distributed by distributors, and displayed in supermarkets, and we conveniently cook rice in rice cookers made by companies.

Everything we enjoy, such as rice bowls, side dishes, water, electricity, houses, etc., cannot be achieved alone, but is possible because we all live together.

All systems and developments, such as architecture, economy, science, and culture, have been made so that people can avoid threats and live happily.

Therefore, I think we should continue to help and live together in order to live 'well' together.

3. Skin color is also ultimately a result of adaptation to the environment.

Hepatic fever is a disease that spreads along the 4,200 km coast of Africa, killing one-fifth of the white people who colonized Africa every year and sending one-fifth back to their homeland. It is thought that the immunity that black people have to this disease is partly inherited through a unique constitution that is unknown to the world, and partly as a result of adaptation to the environment.

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I was really curious about why people's skin color varies from region to region.

I was able to find a clue by reading 'The Descent of Man and Sexual Selection' that I read recently, where Darwin mentions differences in resistance to the environment and disease.

The fact that natives in Africa have stronger resistance to certain diseases (e.g. hepatic fever/malaria) than Europeans is clearly an example of natural selection adapting to the environment.

However, modern science has established that the main difference in skin color is the result of adaptation to the amount of ultraviolet (UV) rays.

In the strong UV rays near the equator, dark skin with a lot of melanin pigment would have been advantageous for survival and reproduction for skin protection (preventing folic acid destruction and skin cancer), and in high-latitude regions with weak UV rays, light skin with less melanin would have been advantageous for vitamin D synthesis.

The fact that dark skin and malaria resistance coexist in certain regions is likely because both characteristics were advantageous for survival in that environment.

Ultimately, humans have adapted to various factors in the environment they live in (UV rays, climate, diseases, etc.), and this can be understood as the cause of the various appearances we see today.

4. Be an attractive person.

Men and women with these abilities can mate and raise more offspring than those who are not. When selection occurs on both sides of the gender, that is, when more attractive and capable men prefer more attractive women, and when attractive women prefer attractive and capable men, the same result will be more certain.

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These days, both men and women tend to care about their appearance (makeup, plastic surgery, etc.) and value economic ability.

As Darwin mentioned in the book, individuals who are more attractive to the opposite sex have more opportunities to mate, and this may be the process of sexual selection in which certain traits are passed on to future generations.

The fact that men and women express their value through their appearance or (in modern society) economic power, and through this, meet an attractive partner and leave their genes behind can be understood from the perspective of sexual selection.

The desire to secure resources and raise offspring in a stable environment may also be an important part.

This can be seen as a strategy to pass on one's genes to future generations more safely and effectively.

The standard of human attractiveness is a combination of various factors such as personality, intelligence, humor, values, reliability, and sociality, and also varies depending on cultural background.

It is thought that developing one's own attractiveness according to each individual's situation will be advantageous for one's survival.