One of the most remarkable changes in human evolution is the loss of our tails, a transformation that occurred around 25 million years ago. This pivotal shift not only altered the trajectory of our species but also marked a significant moment in the evolutionary history of primates. While scientists have long speculated on why humans lost their tails, the genetic cause has remained elusive—until now. A recent study published in Nature has finally uncovered the genetic factors responsible for this evolutionary change.
The Quest to Understand Tail Loss
The journey to unravel the mystery of human tail loss began in an unexpected way. Bo Xia, a graduate student at New York University, was inspired to investigate the origins of the human tailbone after injuring his own coccyx. This personal curiosity led Xia and his team to embark on a groundbreaking scientific investigation.
Through careful research, the team focused on the TBXT gene, which plays a crucial role in regulating tail length in various species. Their research revealed a unique genetic mutation within this gene, providing a major breakthrough in understanding human evolution.
The Role of Jumping Genes
A key aspect of this discovery lies in the role of Alu elements, often called “jumping genes.” These genetic elements, specific to primates, can move within the genome and cause significant changes. The researchers found that Alu elements inserted themselves into the TBXT gene, triggering a chain reaction that led to the loss of our tails.
This insertion activated a process known as alternative splicing, where RNA molecules are cut and restructured, which ultimately led to the deletion of a crucial exon. This change altered the structure and function of the resulting protein, leading to the tail loss seen in humans.
Validation Through Mice Studies
To confirm their findings, the researchers engineered laboratory mice with the same genetic mutations found in humans and apes. These genetically altered mice lost their tails, providing compelling evidence that the identified mutation plays a crucial role in the absence of tails in humans and other primates.
However, the study also uncovered a downside to tail loss: an increased risk of neural tube defects, such as spina bifida. This finding highlights the complex balance between evolutionary benefits and potential genetic trade-offs.
The Broader Implications
This discovery has profound implications not just for understanding human evolution, but also for human anatomy and health. The loss of our tails was not a random event but a genetic adaptation with lasting consequences. It illustrates the complex relationship between genetic changes and the way they shape our physiology over time.
As we continue to study our evolutionary past, these findings remind us of the intricate process of natural selection and genetic innovation that has shaped humanity. This breakthrough also underscores the power of scientific inquiry in uncovering the mysteries of our origins, offering insight into the past that can help us understand our future.
The identification of the genetic reasons behind tail loss is a testament to the persistence of scientific exploration and the ongoing quest for knowledge about our evolutionary journey.
An Elderly Woman Is Turned Away from Business Class until a Little Boy’s Photo Slips Out of Her Purse
A poor old woman decided to fly business class to get closer to her son. However, she faced rejection from passengers on board until they discovered her true identity.
Rhea felt self-conscious. The old woman had gotten on the first plane to leave the airport that morning, and she sat in a seat in business class where the well-to-do folks stayed.
As she entered the cabin, nobody spared her a glance, but when she located her seat and sat, eyes turned towards her. The reason was simple; she stood out like a sore thumb.
Where the other men and women present all wore fancy and expensive-looking clothes, Rhea wore her old, broken-in clothes — it was her best, but it looked drab compared to what the others were wearing.
The man next to her had his face completely buried in a newspaper when she sat down, so he did not quickly notice her. When he put down the issue, he looked to his side and winced at her appearance, then he signaled a flight attendant.
“What is this?” he asked, pointing to Rhea.
The flight attendant looked a bit mortified at the man’s tone, but after verifying the woman’s seat number, she faced the man and replied, “This passenger took a seat according to the ticket she paid for.”
The man looked like he would vomit at any minute because of Rhea’s presence, and before he even proceeded to talk, he unfolded a pristine handkerchief and used it to cover his nose. Then he said, “I don’t know what’s on her ticket, but I bought a seat in business class to get away from people like her, now it just feels like I’m in a cheap alley with homeless people.”
The altercation had gotten the attention of many in the cabin, and some seemed to be in support of the man. One plump woman bedecked from her head to her feet in jewelry piped up.
“If I wanted to fly with such riff-raff, I would buy an economy class ticket,” she said, and a murmur of agreement moved through the passengers.
The murmur quickly took on a life of its own and soon led to a squabble the attendant tried to quell, but the rich folks would not hear of it — the woman had to go.
“Can’t you see she doesn’t belong here?” one man said.
“Is this how low this airline has fallen? How can such a person afford the bill?” another asked.
“We want her gone and we want a formal apology for allowing us to come into contact with such filth,” the man beside Rhea said.
He and a few other passengers were on their feet and refused to sit until they got what they wanted. Rhea sat there, listening to them arguing and trampling all over her dignity.
“I’m okay, this too shall pass,” she kept repeating under her breath like a mantra.
Still, she heard how they spoke of her, and it hurt her very deeply that people could be so cruel. Before she knew it, sad tears cascaded down her slightly wrinkled cheeks.
“Perhaps I’ll just leave,” Rhea thought, then started to gather her things with shaky hands.
As she stood up to go, she stumbled, and rather than catch her as instinct should have made him, the man beside her flinched away as if to avoid getting splattered with mud.
Rhea fell to her knees and inadvertently spilled the contents of her purse. She started to collect her things with trembling hands, knowing she was the focus of everyone in the cabin.
An expensively dressed old lady who had been sleeping peacefully until the ruckus woke her got up from her seat and also went down on her knees to help Rhea.
At that, the cabin went silent, and the passengers stared dumbfounded as one of them treated Rhea like a human. The first thing the woman picked up was a passport photograph of a little boy.
“Thank you very much,” Rhea whispered as she collected it from her.
“This is my son,” she said with a teary smile, still on her knees. “He is the pilot of this plane.”
“He must have grown up to become a handsome young man,” the rich old woman said.
“How could I know? I had to give him up for adoption when he was just five because I had no means to take care of him.” As she spoke, tears fell from her eyes, and the cabin remained silent.
“I’ve been looking for him for years but I’ve not been able to find him. Recently, I found out he became a pilot so I started to go from airport to airport looking for him. Today I found him but the only way I could get close to him was by boarding this flight.”
Rhea looked up at the people around, most of whom averted their eyes shamefully, then she continued.
“I’m sorry for making you all feel uncomfortable but I just wanted to be as close to my son as possible which is why I saved up my money to get this chance. The business class is closer to him and I’ve never flown before so I thought it would make a great birthday gift for myself.”
The passengers listened to her story, and by the time she stopped talking, many were crying. Rhea got up eventually and went with the flight attendants, who were hell-bent on introducing her to her son.
“What if he doesn’t want to see me?” she asked, resisting their urging. “What if he hates me for abandoning him?” Before the flight attendant could speak, the man who had been against her sitting beside him beat her to it.
“You had no choice, I believe he will understand that,” he said before quickly diving behind his newspaper again. He was also ashamed. Rhea left with the flight attendant to finally meet her son.
After some time, a man’s voice was heard on the plane. “This is the captain speaking… there is a special person flying on this plane — my mom, and it’s her birthday today.”
Everyone applauded the old lady, and those who had ridiculed her before apologized for their mistake. When the plane landed, the pilot, whose name was Joseph, met up with his mother, and finally, after many years of estrangement, Rhea held her son again.
What did we learn from this story?
Choose to be kind. When the man beside Rhea started to clamor for her to leave the cabin, others joined in, and even though the woman had done nothing, they may have succeeded in making her leave. The only person who did not do what they did was another old woman. She stood up for Rhea even though she could easily have just joined the haughty passengers, and her decision changed everything.
Never give up. Rhea looked for her son for years but could not locate him; however, that did not stop her. She kept looking, and she was ready to do anything to meet him, including saving up her hard-earned money for an expensive business class flight. Her perseverance and sacrifices were rewarded in the end, and she was able to meet him.
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