The Elemental Composition of a Human Body
The human body is a miraculous, well-oiled, and exceptionally complex machine. It requires a multitude of functioning parts to come together for a person to live a healthy life—and every biological detail in our bodies, from the mundane to the most magical, is driven by just 21 chemical elements.
Of the 118 elements on Earth, just 21 of them are found in the human body. Together, they make up the medley of divergent molecules that combine to form our DNA, cells, tissues, and organs.
Based on data presented by the International Commission on Radiological Protection (ICRP), in the above infographic, we have broken down a human body to its elemental composition and the percentages in which they exist.
These 21 elements can be categorized into three major blocks depending on the amount found in a human body, the main building block (4 elements), essential minerals (8 elements), and trace elements (9 elements).
The Elemental Four: Ingredients for Life
Four elements, namely, oxygen, carbon, hydrogen, and nitrogen, are considered the most essential elements found in our body.
Oxygen is the most abundant element in the human body, accounting for approximately 61% of a person’s mass. Given that around 60-70% of the body is water, it is no surprise that oxygen and hydrogen are two of the body’s most abundantly found chemical elements. Along with carbon and nitrogen, these elements combine for 96% of the body’s mass.
Here is a look at the composition of the four elements of life:
|Element||Weight of Body Mass (kg)||Percentage of Body Mass (%)|
Values are for an average human body weighing 70 kg.
Let’s take a look at how each of these four chemical elements contributes to the thriving functionality of our body:
Oxygen plays a critical role in the body’s metabolism, respiration, and cellular oxygenation. Oxygen is also found in every significant organic molecule in the body, including proteins, carbohydrates, fats, and nucleic acids. It is a substantial component of everything from our cells and blood to our cerebral and spinal fluid.
Carbon is the most crucial structural element and the reason we are known as carbon-based life forms. It is the basic building block required to form proteins, carbohydrates, and fats. Breaking carbon bonds in carbohydrates and proteins is our primary energy source.
Hydrogen, the most abundantly found chemical element in the universe, is present in all bodily fluids, allowing the toxins and waste to be transported and eliminated. With the help of hydrogen, joints in our body remain lubricated and able to perform their functions. Hydrogen is also said to have anti-inflammatory and antioxidant properties, helping improve muscle function.
An essential component of amino acids used to build peptides and proteins is nitrogen. It is also an integral component of the nucleic acids DNA and RNA, the chemical backbone of our genetic information and genealogy.
Essential and Supplemental Minerals
Essential minerals are important for your body to stay healthy. Your body uses minerals for several processes, including keeping your bones, muscles, heart, and brain working properly. Minerals also control beneficial enzyme and hormone production.
Minerals like calcium are a significant component of our bones and are required for bone growth and development, along with muscle contractions. Phosphorus contributes to bone and tooth strength and is vital to metabolizing energy.
Here is a look at the elemental composition of essential minerals:
|Element||Weight of Body Mass (g)||Percentage of Body Mass (%)|
Values are for an average human body weighing 70 kg.
Other macro-minerals like magnesium, potassium, iron, and sodium are essential for cell-to-cell communications, like electric transmissions that generate nerve impulses or heart rhythms, and are necessary for maintaining thyroid and bone health.
Excessive deficiency of any of these minerals can cause various disorders in your body. Most humans receive these minerals as a part of their daily diet, including vegetables, meat, legumes, and fruits. In case of deficiencies, though, these minerals are also prescribed as supplements.
Biological Composition of Trace Elements
Trace elements or trace metals are small amounts of minerals found in living tissues. Some of them are known to be nutritionally essential, while others may be considered to be nonessential. They are usually in minimal quantities in our body and make up only 1% of our mass.
Paramount among these are trace elements such as zinc, copper, manganese, and fluorine. Zinc works as a first responder against infections and thereby improves infection resistance, while balancing the immune response.
Here is the distribution of trace elements in our body:
|Element||Weight of Body Mass (mg)||Percentage of Body Mass (%)|
Values are for an average human body weighing 70 kg.
Even though only it’s found in trace quantities, copper is instrumental in forming red blood cells and keeping nerve cells healthy. It also helps form collagen, a crucial part of bones and connective tissue.
Even with constant research and studies performed to thoroughly understand these trace elements’ uses and benefits, scientists and researchers are constantly making new discoveries.
For example, recent research shows that some of these trace elements could be used to cure and fight chronic and debilitating diseases ranging from ischemia to cancer, cardiovascular disease, and hypertension.
Visualized: The Many Shapes of Bacteria
We introduce the visual diversity of bacteria and illustrate how they are categorized by appearance—from a single cell to an entire colony.
Invisible Diversity: The Many Shapes of Bacteria
Bacteria are amazing.
They were the first form of life to appear on Earth almost 3.8 billion years ago.
They make up the second most abundant lifeform, only outweighed by plants.
And most interesting of all: they exist in practically every environment on our planet, including areas where no other lifeforms can survive. As a result, bacteria exhibit a wide variety of appearances, behaviors, and applications similar to the lifeforms we see in our everyday lives.
The incredible diversity of bacteria goes underappreciated simply because they are invisible to the naked eye. Here, we illustrate how researchers classify these creatures on the basis of appearance, giving you a glimpse into this microscopic world.
A Life of Culture
Though bacteria may look similar to other microorganisms like fungi or plankton, they are entirely unique on a microscopic and genetic level.
Bacteria make up one of the three main domains of life. All life shares its earliest ancestor with this group of microbes, alongside two other domains: the Archaea and the Eukarya.
Archaea are very similar to bacteria, but have different contents making up their cell walls.
Eukarya largely consists of complex, multicellular life, like fungi, plants, and animals. Bacteria are similar to its single-celled members because all bacteria are also unicellular. However, while all Eukarya have nuclear membranes that store genetic material, bacteria do not.
Bacteria have their genetic material free-floating within their cellular bodies. This impacts how their genes are encoded, how proteins are synthesized, and how they reproduce. For example, bacteria do not reproduce sexually. Instead, they reproduce on their own.
Bacteria undergo a process called binary fission, where any one cell divides into two identical cells, and so on. Fission occurs quickly. In minutes, populations can double rapidly, eventually forming a community of genetically identical microbes called a colony.
Colonies can be visible to the human eye and can take on a variety of different shapes, textures, sizes, colors, and behaviors. You might be familiar with some of these:
Superstars of a Tiny World
The following are some interesting bacterial species, some of which you may be familiar with:
This species is unusually large, ranging from 200-700 micrometers in length. They are also incredible picky, living only within the guts of sturgeon, a type of large fish.
D. radiodurans is a coccus-shaped species that can withstand 1,500 times the dose of radiation that a human can.
Despite being known famously for poisoning food and agriculture spaces from time to time, not all E.coli species are dangerous.
Down in the depths of a South African gold mine, this species thrives without oxygen, sunlight, or friends—it is the only living species in its ecosystem. It survives eating minerals in the surrounding rock.
Known for causing stomach ulcers, this spiral-shaped species has also been associated with many cancers that impact the lymphoid tissue.
Most living things cease to survive in cold temperatures, but P. halocryophillus thrives in permafrost in the High Arctic where temperatures can drop below -25°C/-12°F.
‘Bact’ to the Future
Despite their microscopic size, the contributions bacteria make to our daily lives are enormous. Researchers everyday are using them to study new environments, create new drug therapies, and even build new materials.
Scientists can profile the diversity of species living in a habitat by extracting DNA from an environmental sample. Known as metagenomics, this field of genetics commonly studies bacterial populations.
In oxygen-free habitats, bacteria continuously find alternative sources of energy. Some have even evolved to eat plastic or metal that have been discarded in the ocean.
The healthcare industry uses bacteria to help create antibiotics, vaccines, and other metabolic products. They also play a major role in a new line of self-building materials, which include “self-healing” concrete and “living bricks”.
Those are just a few of the many examples in which bacteria impact our daily lives. Although they are invisible, without them, our world would undoubtedly look like a much different place.
Visualizing the Evolution of Vision and the Eye
The eye is one of the most complex organs in biology. We illustrate its evolution from a simple photoreceptor cell to a complex structure.
Roadmapping the Evolution of the Eye
Throughout history, numerous creatures have evolved increasingly complex eyes in response to different selective pressures.
Not all organisms, however, experience the same pressures. It’s why some creatures today still have eyes that are quite simple, or why some have no eyes at all. These organisms exemplify eyes that are “frozen” in time. They provide snapshots of the past, or “checkpoints” of how the eye has transformed throughout its evolutionary journey.
Scientists study the genes, anatomy, and vision of these creatures to figure out a roadmap of how the eye came to be. And so, we put together an evolutionary graphic timeline of the eye’s different stages using several candidate species.
Let’s take a look at how the eye has formed throughout time.
Where Vision Comes From
The retina is a layer of nerve tissue, often at the back of the eye, that is sensitive to light.
When light hits it, specialized cells called photoreceptors transform light energy into electrical signals and send them to the brain. Then the brain processes these electrical signals into images, creating vision.
The earliest form of vision arose in unicellular organisms. Containing simple nerve cells that can only distinguish light from dark, they are the most common eye in existence today.
The ability to detect shapes, direction, and color comes from all of the add-ons evolution introduces to these cells.
Two Major Types of Eyes
Two major eye types are dominant across species. Despite having different shapes or specialized parts, improved vision in both eye types is a product of small, gradual changes that optimize the physics of light.
Simple eyes are actually quite complex, but get their name because they consist of one individual unit.
Some mollusks and all of the higher vertebrates, like birds, reptiles, or humans, have simple eyes.
Simple eyes evolved from a pigment cup, slowly folding inwards with time into the shape we recognize today. Specialized structures like the lens, cornea, and pupil arose to help improve the focus of light on the retina. This helps create sharper, clearer images for the brain to process.
Compound eyes are formed by repeating the same basic units of photoreceptors called ommatidia. Each ommatidium is similar to a simple eye, composed of lenses and photoreceptors.
Grouped together, ommatidia form a geodesic pattern that is commonly seen in insects and crustaceans.
Our understanding of the evolution of the compound eye is a bit murky, but we know that rudimentary ommatidia evolved into larger, grouped structures that maximize light capture.
In environments like caves, the deep subsurface, or the ocean floor where little to no light exists, compound eyes are useful for producing vision that gives even the slightest advantage over other species.
How Will Vision Evolve?
Our increasing dependency on technology and digital devices may be ushering in the advent of a new eye shape.
The muscles around the eye stretch to shift the lens when staring at something close by. The eye’s round shape elongates in response to this muscle strain.
Screen time with cellphones, tablets, and computers has risen dramatically over the years, especially during the COVID-19 pandemic. Recent studies are already reporting rises in childhood myopia, the inability to see far away. Since the pandemic, cases have increased by 17%, affecting almost 37% of schoolchildren.
Other evolutionary opportunities for our eyes are currently less obvious. It remains to be seen whether advanced corrective therapies, like corneal transplants or visual prosthetics, will have any long-term evolutionary impact on the eye.
For now, colored contacts and wearable tech may be our peek into the future of vision.
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