"Menstruation: The Intriguing Key to Human Evolution"
"Unveiling the Secret Biological Strategy Behind the Monthly Cycle"
A unique and enigmatic phenomenon found in several species on Earth is the menstrual cycle, a trait that humans share with only a handful of other mammals. This group includes monkeys, apes, bats, and possibly elephant shrews, making us the exclusive members of the menstruating mammal club. What's even more intriguing is that we humans engage in this cycle more frequently than any other animal, despite its apparent inefficiency and inconvenience. So, why does this uncommon biological process exist? The answer is embedded in the intricacies of pregnancy.
Pregnancy is a remarkable biological process where a mother's body allocates its resources ingeniously to create a nurturing environment for a developing fetus, establishing an internal sanctuary for the growing child. However, this is only one side of the story. The less-known aspect of pregnancy reveals a fascinating conflict of interests between a mother and her unborn child. In the evolutionary pursuit of propagating their genes, the mother is naturally inclined to provide equally for all her offspring. However, a fetus doesn't inherit genes solely from its mother but also from its father. These paternal genes are motivated to secure their survival by extracting more than their fair share of resources from the mother. This evolutionary conflict sets the stage for a biological tug-of-war that unfolds within the womb.
A key player in this internal struggle is the placenta, a fetal organ that connects to the mother's bloodstream, nourishing the fetus as it grows. In most mammals, the placenta is concealed behind a maternal cell barrier, allowing the mother to regulate the supply of nutrients to the fetus. However, in humans and a select few other species, the placenta takes an extra step, infiltrating the mother's circulatory system to directly access her bloodstream. Through this specialized placenta, the fetus sends a cascade of hormones into the mother's arteries, ensuring a continuous flow of nutrient-rich blood. A fetus with such unrestricted access can manipulate hormone production to raise the mother's blood sugar, expand her arteries, and elevate her blood pressure.
Unlike most mammal mothers who can expel or reabsorb embryos if necessary, in humans, once the fetus establishes this blood connection, severing it can lead to potentially life-threatening hemorrhaging. If the fetus develops poorly or perishes, the mother's health is placed in jeopardy. As the fetus continues to grow, its persistent demand for resources can result in severe fatigue, high blood pressure, and conditions like diabetes and preeclampsia. Given these risks, pregnancy is an enormous, and sometimes perilous, investment. Hence, it becomes essential for the body to thoroughly vet embryos to determine which ones are worth this formidable challenge.
This is where menstruation enters the picture. The journey of pregnancy begins with a process called implantation, where the embryo embeds itself in the uterine endometrium. The endometrium has evolved to create an environment where only healthy embryos can successfully implant. However, this stringent selection process also favors the most aggressively invasive embryos, establishing an evolutionary feedback loop. The embryo initiates a precisely timed hormonal dialogue that transforms the endometrium to permit implantation.
But what happens when an embryo fails to meet the mark? It might still manage to attach or even partially penetrate the endometrium. As it slowly withers away, it can leave the mother susceptible to infections while emitting hormonal signals that disrupt her tissues. To circumvent this predicament, the body simply eliminates every potential risk. Each time ovulation doesn't culminate in a healthy pregnancy, the uterus sheds its endometrial lining, along with any unfertilized eggs and any sick, dying, or deceased embryos. This protective process is what we know as menstruation, leading to the monthly period. This seemingly unusual biological trait, as perplexing as it may appear, is a crucial element that ensures the continuation of the human race.
About the Creator
Reader insights
Nice work
Very well written. Keep up the good work!
Top insight
Expert insights and opinions
Arguments were carefully researched and presented
Keep reading
More stories from Alisa İnnokate and writers in Humans and other communities.
"Witch Hunts: Unmasking the Dark Legacy of Hysteria"
In the German town of Nördlingen in 1593, an innkeeper named Maria Höll found herself accused of witchcraft. She was arrested for questioning, and denied the charges. She continued to insist she wasn’t a witch through 62 rounds of torture before her accusers finally released her. Rebekka Lemp, accused a few years earlier in the same town, faced a worse fate. She wrote to her husband from jail worrying that she would confess under torture, even though she was innocent. After giving a false confession, she was burned at the stake in front of her family. Höll and Lemp were both victims of the witch hunts that occurred in Europe and the American colonies from the late 15th century until the early 18th century. These witch hunts were not a unified initiative by a single authority, but rather a phenomenon that occurred sporadically and followed a similar pattern each time. The term “witch” has taken on many meanings, but in these hunts, a witch was someone who allegedly gained magical powers by obeying Satan rather than God. This definition of witchcraft spread through churches in Western Europe starting at the end of the 15th century. It really gained traction after the pope gave a friar and professor of theology named Heinrich Kraemer permission to conduct inquisitions in search of witches in 1485. His first, in the town of Innsbruck, didn’t gain much traction with the local authorities, who disapproved of his harsh questioning of respectable citizens and shut down his trials. Undeterred, he wrote a book called the "Malleus Maleficarum," or "Hammer of Witches." The text argued for the existence of witches and suggested ruthless tactics for hunting and prosecuting them. He singled out women as easier targets for the devil’s influence, though men could also be witches. Kraemer’s book spurred others to write their own books and give sermons on the dangers of witchcraft. According to these texts, witches practiced rituals including kissing the Devil’s anus and poisoning or bewitching targets the devil singled out for harm. Though there was no evidence to support any of these claims, belief in witches became widespread. A witch hunt often began with a misfortune: a failed harvest, a sick cow, or a stillborn child. Community members blamed witchcraft, and accused each other of being witches. Many of the accused were people on the fringes of society: the elderly, the poor, or social outcasts, but any member of the community could be targeted, even occasionally children. While religious authorities encouraged witch hunts, local secular governments usually carried out the detainment and punishment of accused witches. Those suspected of witchcraft were questioned and often tortured— and under torture, thousands of innocent people confessed to witchcraft and implicated others in turn. Because these witch hunts occurred sporadically over centuries and continents the specifics varied considerably. Punishments for convicted witches ranged from small fines to burning at the stake. The hunt in which Höll and Lemp were accused dragged on for nine years, while others lasted just months. They could have anywhere from a few to a few hundred victims. The motivations of the witch hunters probably varied as well, but it seems likely that many weren’t consciously looking for scapegoats— instead, they sincerely believed in witchcraft, and thought they were doing good by rooting it out in their communities. Institutions of power enabled real harm to be done on the basis of these beliefs. But there were dissenters all along– jurists, scholars, and physicians countered books like Kraemer’s "Hammer of Witches" with texts objecting to the cruelty of the hunts, the use of forced confessions, and the lack of evidence of witchcraft. From the late 17th through the mid-18th century, their arguments gained force with the rise of stronger central governments and legal norms like due process. Witch hunting slowly declined until it disappeared altogether. Both the onset and demise of these atrocities came gradually, out of seemingly ordinary circumstances. The potential for similar situations, in which authorities use their powers to mobilize society against a false threat, still exists today— but so does the capacity of reasoned dissent to combat those false beliefs.
By Alisa İnnokate8 months ago in Humans
The Intricate Process of Sleep
Sleep is a fundamental aspect of human life, occupying roughly one-third of our existence. Despite being a ubiquitous and essential part of our daily routine, sleep remains a complex and somewhat mysterious phenomenon. Understanding what happens when we sleep involves exploring the various stages of sleep, the physiological changes that occur, and the critical functions that sleep serves for our physical and mental well-being.
By mahsa latifiabout 5 hours ago in Humans
Tea set by a suffragette
Pankhurst is a name well known to the history of women’s suffrage. Who hasn't heard the name Emmaline Pankhurst, founder of the Women's Social and Political Union (WSPU), an all-women organisation campaigning for the right to vote? The group that helped to achieve the right to vote for women in Great Britain and Ireland in 1918. Some know of her daughter Christabel, both being honoured by the Pankhurst memorial in Victoria Palace Gardens, London, right next to the UK Parliament buildings. Sylvia Pankhurst is notably not included in the monument. Why? Because she split with the WSPU to campaign against Britain's entry into First World War.
By Raymond G. Taylor2 days ago in Art
Comments (1)
Excellent article which I think many will find useful and informative