In this blog post, we will look at mitochondrial DNA, the key to unlocking the genetic origins of life, and its biological significance.

How does life begin: fertilization, heredity, and the contribution of women

All sexually reproducing organisms, including humans, are born through a process called “fertilization,” in which an egg and sperm combine to create new life.
Females and males each provide half of their genetic information, and when they meet and form a single fertilized egg, a new life begins. What we commonly refer to as “genes” generally refers to DNA (deoxyribonucleic acid) found in the nucleus of cells. However, in addition to the nucleus, there are numerous organelles within cells. Among them, mitochondria are particularly noteworthy.
Mitochondria play a key role in producing energy for cells and can be described as a kind of “power plant.”
Surprisingly, mitochondria contain their own unique DNA, which is completely different from the DNA found in the nucleus. This is strong evidence that mitochondria were once independent ancient bacteria that evolved into their current form through symbiosis with cells. This theory is called “endosymbiosis” and occupies an important place in evolutionary biology. It explains that different organisms formed today’s complex eukaryotic cells through symbiosis.

Mitochondrial DNA is inherited only from the mother

When sperm and egg cells combine, the DNA in the nucleus is provided equally by the male and female, half each. However, the cytoplasm, or the rest of the cell components excluding the nucleus, is mostly provided by the egg, or the female. For this reason, the DNA in mitochondria is inherited entirely from the mother, or the maternal lineage.
Because of this characteristic, mitochondrial DNA is analyzed to trace the maternal lineage when studying the evolution and phylogeny of organisms. This means that biological genealogy is based solely on the female lineage, which is in stark contrast to the culture of traditional genealogy, where only men’s names are recorded. Life science literally transcends the perceptions and prejudices of human society and tells the truth based on objective evidence.

The “male-centered” ideology that distorted biology

The prejudice and obsession that men must play a leading role in the process of fertilization and development have distorted the development of human society and science for a long time. Even European biologists in the 17th and 18th centuries were not free from such stereotypes. At a time when the existence of DNA was not yet known, some scholars claimed that sperm contained small humans in their completed form.
This claim, known as the “homunculus theory,” was based on the absurd idea that men possessed the essence of life and that women were merely the fields that nurtured the seeds. Women were considered to have no genetic contribution and only played a role in providing nutrients.
However, this theory immediately falls into logical contradiction.
If a complete human being already exists in sperm, then there must be another tiny human being inside that sperm, and inside that one there must be an even smaller human being, and so on, leading to an endless regressus ad infinitum. It is as if humans must exist inside other humans, like Russian nesting dolls.
Such unscientific ideas are bound to collapse in the face of scientific objectivity. The birth of life cannot be explained by the contribution of men alone.

Women’s contribution to the beginning of life is absolute

After fertilization, the sperm has fulfilled its role by transmitting the genetic information of the male, while the egg must provide not only genetic information but also the nutrients and cell organs necessary for early development. In other words, almost everything necessary for the beginning of life is provided by the female body.
Based on nuclear DNA alone, it is true that men and women contribute 50% of genetic information each, but the DNA of cell organelles, including mitochondria, is inherited only from females. Therefore, in terms of the total amount of genetic information and actual contribution, women can be said to play a greater role.
Nevertheless, it is biologically invalid for males, who have no understanding of the nature of life, to claim “legitimacy” simply because they provide sperm. This is not science, but an irrational claim based on social norms.

Science tells the truth about life

The process of life is the result of a marvelous collaboration between men and women. However, their roles are by no means symmetrical, and women’s contributions are much deeper and more essential. As mitochondrial DNA tells us, true continuity of life comes from the mother.
We must now look at life through the eyes of science. The birth of life is not the work of one side, but of mutually complementary beings, and the role played by the female body in particular deserves deeper respect, both biologically and in terms of bioethics.
Science does not distort the essence of life. Rather, it clearly shows us how sophisticated and magnificent the process of life is, and what role women’s bodies have played at its center. In the language of science, the genealogy of life begins with women’s bodies and continues through them.