The number of sperm from one generation to another is not as good as that of one generation. In the future, it may be inherited by artificial sperm.

In the popular Japanese anime "Attack on Titan", the actor's brother hopes to use the special abilities of the ancestor giant to make the Eldia with the "giant gene" incapacitated, and make the giants completely from the world in a hundred years. disappear.

Back to reality, such "sterilization programs" are happening to us, and most men may lose their fertility in decades.

▲The future world in "The Handmaid's Tale" has been severely polluted, and the birth rate has plummeted.

A study in the United States found that the sperm count of men in Western countries has dropped by nearly 60% in the past 40 years. By 2045, the median sperm count of men may drop to zero, which means that most couples cannot give birth naturally.

For a country like China that is about to enter an aging population, the fertility anxiety that has been trapped by high housing prices, 996, and involution has cast a new shadow. Even if the country encourages fertility, the sperm of one generation is not as good as one generation. The quantity may not help.

▲ Picture from: nippon

Some scientists have pinned the future of human reproduction on assisted reproductive technology that is more radical than test-tube babies-artificial sperm/eggs, skin is extracted to make germ cells, and humans can even reproduce parthenosexually. It is conceivable that this will face much ethical controversy. .

However, when the plummeting fertility and the problems of an aging society are intertwined, it may force people to look at these new technologies that challenge traditional ethics and morals.

The number of sperm in one generation is worse than one

"Your sperm count is only half that of your grandpa."

After analyzing nearly 40,000 male sperm samples from 1973 to 2011, Shanna Swan, professor of environmental medicine and public health at the Icahn School of Medicine at Mount Sinai in the United States, came to this conclusion.

This study found that in the past 40 years, the sperm count of men in Western countries including North America, Europe, Australia and other regions has decreased by 59.3%, and the sperm concentration has decreased by 52.4%.


And Shanna Swan, in his recently published book Count Down , also gave a shocking prediction: By 2045, the median number of male sperm will drop to zero .

"In 2045, we will enter a sterile world where most couples may have to use assisted reproductive technology to reproduce offspring."

Shanna Swan pointed out that the number of men with reproductive problems is increasing at a rate of about 1% per year, which is even faster than the rate of global warming, and calls on society to pay attention to this problem.

In fact, similar conclusions will not be new in the medical field. In the past few decades, many studies have been conducted on this topic, and most of them have reached similar conclusions.

In 1992, the Danish reproductive biologist Elisabeth Carlsen found after a meta-analysis of 61 studies worldwide that in the 50 years ending in 1991, the global sperm count fell by more than 40%.

In 2003, a seminar held by the World Health Organization also released the results of a survey, claiming that the quality of human sperm worldwide has been declining, and the semen density has dropped from 113 million/ml to 50 million.

The Chinese were not "exempt." CITIC Xiangya Reproductive and Genetic Hospital analyzed the samples of more than 30,000 applicants from the Human Sperm Bank of Hunan Province and found that from 2001 to 2015, the proportion of qualified sperm donors From 55.78% to 17.8%.

A similar situation also appeared in sperm banks in other cities. At the time, Professor Cao Xingwu, the chief physician of the andrology department of the China-Japan Friendship Hospital of the Ministry of Health, who had been engaged in sperm quality research for many years, expressed the same concerns as Shanna Swan in an interview with the media in 2008 :

If this continues, mankind will be extinct in 50 years!

However, some experts have questioned similar research. Allan Pacey, professor of andrology at the University of Sheffield in the United Kingdom, once wrote that the concentration drop by half seems to be a lot, but it is actually within the normal range.

Indeed, the average sperm concentration of men in the Shanna Swan study in 2011 was 47.1 million/ml, which is still much higher than the normal WHO standard of 15 million/ml.

However, it is worth noting that this standard is actually constantly decreasing. In the 1940s, the medical profession generally believed that it was normal for men to have at least 60 million sperm per milliliter.

▲ Picture from: Twitter

However, in 1999, the World Health Organization reduced this standard to 20 million. In the past few years, after the World Health Organization examined human semen, it lowered the standard again and lowered the baseline of normal sperm concentration to 15 million/ml.

What is the reason that the number of sperm in one generation is not as good as one generation? There is no accurate conclusion yet. Smoking, drinking, and lack of exercise are all considered to be one of the driving forces, and Shanna Swan believes that chemicals such as bisphenol A and phthalates are the culprits.

These chemicals are all over daily necessities such as food packaging, skin care products, and household products, and they can hardly be eliminated from life. It is obviously not an overnight issue to completely solve the problem of production materials.

It is precisely because of the various and unclear reasons that cause the decline in human fertility, many scientists believe that they must prepare for the worst-even if people are completely incapacitated, they can still breed offspring through technological means. This also gave birth to a market with unlimited money.

In the future, we will rely on artificial sperm/eggs to pass on the lineage?

On July 25, 1978, Louise Brown, the world's first test-tube baby, was born. Today, test-tube baby has become one of the most commonly used assisted reproductive techniques for infertile couples.

▲Picture from: Louise Brown

However, if the sperm count of men in the future does not reach the minimum standard, the current IVF technology will not be able to do anything. So a scientist came up with a bold idea: Since male sperm is not good, can we directly produce qualified sperm?

This is a technology called in vitro gametes (IVG). It no longer needs to extract sperm and eggs from both parents, and only through skin cells can produce sperm and egg cells.

Such a fantastic technology was unimaginable decades ago, but a 2007 study by Japanese scientist Shinya Yamanaka gave artificial sperm a theoretical basis.

▲ Shinya Yamanaka

Shinya Yamanaka discovered that by adding transcription factors to somatic cells, it can be transformed into pluripotent stem cells after reprogramming, and pluripotent cells can develop into almost all cell types. Shinya Yamanaka won the Nobel Prize in Physiology and Medicine for this.

A few years after Yamanaka's research was published, Jacob Hann, an Israeli stem cell biologist, successfully transformed human skin cells into primordial germ cells in 2014.

In 2016, the biologist Saito Tsuki of Kyoto University in Japan also published a research result in the journal Nature. He converted the cells from the tail of mice into eggs and implanted them in female mice. He successfully gave birth to eight healthy and viable mice. The offspring of fertile mice.

▲ Picture from: Hong Kong 01

By 2018, Saito Tsuki had successfully transformed the skin cells of a human female into oocytes. However, the oocytes are only a product of a stage in the egg development process and cannot be fertilized, but this is already a big part of IVG technology. Breakthrough.

In addition to artificial sperm/eggs, there are also some scientists who are developing artificial uterus technology and successfully experimenting on lambs. If these technologies mature, they may completely change the way of human reproduction and reproduction, but they may also open a Pandora's box.

In "The End of Sex and the Future of Human Reproduction" (The End of Sex and the Future of Human Reproduction), Henry Greely, director of the Center for Law and Biological Sciences at Stanford University, explores the possible impact of this technology.

This technology not only solves the problem of infertility. When fertility is no longer restricted by age and gender, it is no longer uncommon for old clams to produce pearls. Same-sex couples can also have their own "children", even those who have died. May reproduce offspring.

These few points alone may greatly impact existing ethical concepts, not to mention that a person’s parents may be the same person. Crazy fans may find a way to obtain the idol’s cells and have children with him. This also raises legal and regulatory requirements. huge challenge.

It can be seen that this technology will bring more potential problems than the previously controversial gene-edited babies. Therefore Henry Greely also believes that it will take at least 20 years for this technology to actually appear on the market.

Although it may still be difficult for many people to accept, there is indeed a huge demand and market behind it.

According to data from the China Population Association and the Health Commission, the number of infertility in China in 2018 was close to 48 million. The infertility rate has risen from 3% 20 years ago to 15% in recent years. One out of six couples is troubled by fertility problems, and this number is still on the rise.

In recent years, more and more Chinese couples have turned to assisted reproductive technology. Due to policy reasons, many overseas medical institutions will seek services such as IVF, frozen eggs/frozen embryos and even surrogacy, and the prices are often hundreds of thousands to millions. The renminbi varies.

An investigation report by Dongxing Securities showed that the potential market space for assisted reproduction in China alone reached 321.1 billion US dollars.

The target customers of assisted reproductive technology are not only infertile persons. LGBT groups, families who have lost only one child and some couples who wish to choose the sex of their babies are also potential customers. Ray, founder of "Tian Si Wu You" , an organization that provides assisted reproductive services It has been revealed that 70% of their clients are LGBT surrogates.

After the emergence of the "crisis" of sperm, more start-up companies have begun to provide sperm testing, freezing and training services for men. During the epidemic, many men chose to freeze sperm because of concerns that the new crown virus would damage their fertility. Some companies that provide frozen sperm services have their orders increased by 10 times during the epidemic.

Henry Greely believes that in the next 20-40 years, most people will no longer use sexual behavior to achieve childbirth, but use assisted reproductive technology to produce healthier children, and the scenes in science fiction movies will become reality.

The ethics, physical freedom and gender equality issues behind reproductive anxiety

The decline in sperm count has aggravated people's fertility anxiety, and people are increasingly relying on more advanced assisted reproductive technologies. While these technologies can alleviate fertility anxiety, they may also achieve true "reproductive freedom" technologically.

The biggest source of controversy about these technologies is "freedom of reproduction." In modern society, childbirth is not just a matter for two people. Regarding "reproductive freedom," it is a minefield where ethics, physical freedom, and gender equality are intertwined.

For example, in the first two years of concern for a single female in China to fight for egg freezing , a 30-year-old Xu came to a hospital in Beijing and wanted to freeze eggs. After checking his physical condition met the requirements for egg freezing, he was caught by her unmarried. Rejecting, Xu took the hospital to court for infringing on general personality rights.

Xu believes that this is unfair to women, because according to my country’s relevant policies and regulations, single men can store their sperm in a sperm bank for medical needs and for future childbirth, but at the same time they are not allowed to include single women. Assisted reproductive technology surgery including egg freezing.

It can be said that this lawsuit is actually women's fight for the right to "reproductive freedom." This is just the beginning. If reproductive freedom should be gender equal, should LGBT people also have such rights?

At present, my country’s laws do not clearly define reproductive rights, but the National Health Commission also stated that it is discussing egg freezing technology as a key topic and organizing research by experts in related fields such as medicine, law, ethics, and sociology. This problem can also be seen The importance and complexity of

The development of technology has given us more and more freedom, but unconstrained freedom often brings more chaos. However, how these freedoms should be restricted cannot be solved by technology.

Whether the empowerment of technology brings people freedom, happiness or the opposite, often does not depend on the technology itself. What assisted reproductive technology will bring to society and individuals may be experienced by us in the near future.

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