Here’s a strange question: How do our toes and fingers grow? Most would think they grow outward, but cells “sculpt” them within a larger foundational bud. An international team led by cell biologist Bao Zhang at Sun Yat-sen University revealed this process comprehensively. They also made a video visualizing this process.
It’s easy to assume that we already know everything about the human body. After all, don’t scientists have enough time to study its entirety? Contrary to popular belief, we are still unsure about many details of our bodies, specifically their development. Fortunately, Zhang and his colleagues uncovered one of these mysteries for the world!
This article will discuss how human infants develop fingers and toes. Later, I will share a few recent discoveries about the human body.
How do human fingers and toes grow?
A joint international research project spearheaded by cell biologist Bao Zhang discovered that our digits grow from a larger foundational bud. That means the tips of our early arms and legs have these growths that eventually turn into toes and fingers.
The video above shows the expression of IRX1 (represented in blue-green or aqua) and SOX9 (represented in magenta). IRX1 is critical for digit formation, and SOX9 is important for skeletal development.
They overlap in five distinct lengths within the developing limb. After seven weeks, programmed cell death instructions activate in the undifferentiated cells converging between these lengths.
These aggregates indicate the expression of MSX1 represented in yellow in the clip. Eventually, the process reveals well-defined fingers and toes are revealed.
“We identified 67 distinct cell clusters from 125,955 captured single cells and spatially mapped them across four first trimester time points to shed new light on limb development. In doing so, we uncovered several new cell states,” the team wrote in their paper.
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“What we reveal is a highly complex and precisely regulated process,” says Hongbo Zhang, the study’s senior author. “It is like watching a sculptor at work, chiseling away at a block of marble to reveal a masterpiece. In this case, nature is the sculptor, and the result is the incredible complexity of our fingers and toes.”
Sarah Teichmann, another senior author, stated, “For the first time, we have been able to capture the remarkable process of limb development down to single-cell resolution in space and time.”
As a result, the research is “deepening our understanding of how anatomically complex structures form, helping us uncover the genetic and cellular processes behind healthy human development, with many implications for research and healthcare.”
Other recent human body discoveries
Another group of scientists found that our brains developed thanks to fermented foods. Katherine Bryant and her team discovered they provided extra energy needed for our ancestors’ brains to advance.
They were also easy to digest, encouraging their colons to become more efficient. Soon, they shrank and became more efficient in absorbing nutrients.
Bryant’s research delved deeper into the fact that human brains tripled in size over the last two million years of evolution. Moreover, an estimated 74% of colons shrunk, suggesting ancient humans broke down plant-derived food.
It led to her and her team coming up with their “external fermentation hypothesis.” It proposes that our ancestors’ brains may have evolved into our modern ones via food fermentation.
Our guts ferment food to gain energy, but outside our bodies, our organs can observe more. External fermentation produces adenosine triphosphate or ATP, which is an important chemical energy source for our metabolism.
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Fermentation only requires a simple storage space like a cave or hole in the ground. Consequently, people didn’t need tools to ferment food.
“Hunting, scavenging from large carnivores, and fire use carry their own risks. Perhaps the risks of fermentation were more predictable and thus more reliably mitigable through individual and cultural learning.”
Food fermentation also turned poisonous plants and animals edible. For example, this process removes cyanide from the cassava plant. “The offloading of gut fermentation into an external cultural practice… that laid out the metabolic conditions necessary for selection for brain expansion to take hold,” the researchers added.
Conclusion
Scientists discovered how human infants develop fingers and toes. Our limbs have specialized buds where genes reduce them into articulated digits.
Their discovery could help us uncover more ways to provide better healthcare. Also, it may give us new insights into how mice form limbs because they follow a similar process.
Learn more about this human development research on the Nature webpage. Moreover, check out more digital tips and trends at Inquirer Tech.