Are Humans Bioluminescent? Learn How We Actually 'Glow' Radiantly

Visible light is a type of electromagnetic radiation that you perceive with your eyes.

It is a small portion of the electromagnetic spectrum, which includes x-rays, gamma rays, ultraviolet light, and infrared radiation. Humans are not bioluminescent, but some animals are.

Fireflies, for example, produce light through a chemical reaction in their bodies. This visible light is used to attract mates and ward off predators.

Some researchers believe that humans may have once been bioluminescent. A study published in 2009 by Kyoto University found that certain deep-sea fish emit visible light from their bodies.

The study's authors suggest that this ability may have been passed down from ancient fish to modern humans. While we may not be able to light up the night sky like fireflies, our bodies do emit visible light. This light is produced by our cells, and it is called biophotons.

Biophotons are emitted when our cells convert energy from sunlight into visible light. So, while you are not bioluminescent in the traditional sense, you do glow radiantly.

And, who knows? Maybe one day we'll find a way to harness our biophotons and use them to light up the world around us.

Are humans capable of bioluminescence?

Science had proved that all living creatures can yield even a little amount of faint light because of their cellular chemical reactions, which arises a question, do humans glow?

Various surveys were conducted with ultra-sensitive cameras on the upper part of human volunteers by professional researchers. They did it various times over the week and on-camera light produced by test subjects was noticed.

The survey reports have shown the light emission process maintains a 24 hours cycle. In the afternoon, it stays high, and at night it remains low. Contrary to the big parts, the cheeks, forehead, and neck of test subjects are parts to throw the brightest light according to thermal images.

The human eye is not sharp enough to see this. However, fireflies, glowworms, and deep-sea fish use this biological technique for illumination and to attract mates.

What kind of light do humans emit?

The human body releases electromagnetic radiation which has a lower frequency than visible light.

Anything that has non-zero temperature seems to produce thermal radiation. But realistically it is not possible to be at absolute zero, which makes everything produce thermal radiation. But thermal radiation and infrared radiation are not alike.

Thermal radiation leads the temperature source and transmits heat. The emitted light can be captured with high-end cameras.

The amount is variable for different individuals. Using infrared cameras, thermal images can be captured by heat emissions, which indicates skin temperature, despite skin color. Please note, It is not helpful to diagnose any medical conditions.

Is the inside of our body dark?

The human body cavity is supposed to be completely dark, but when a human body comes to near-infrared light, it becomes partially transparent. It includes every biological tissue, even bones.

Only a very bright light penetrates 1 in (2.54 cm) of tissues. Muscles are non-transparent. Whatever is beneath these muscle tissues, they can not be invisible light including the gut.

However, there are various kinds of electromagnetic radiation with the ability to penetrate the human body. Basically, it varies on the spectrum. Fat and connective tissues are a little more transparent.

Bioluminescence And Humans

Metabolic reactions cause bioluminescence. In the process during cell respiration, highly reactive free radicals came across free-floating lipids and proteins.

Molecules in their exciting stage make reactions with fluorophores for releasing photons. Human bioluminescence was studied for a prolonged period but recently technology made that possible to overcome doubts.

A single image with dim light sources was captured by high-end cameras, but it is not clarified yet how that constantly fluctuating light from the human body by heat emissions can be captured.

The practical applications are yet to be made in the future and there is also so much more undiscovered about the human body. N. Harvey started studying how bioluminescence works and its evolution over the time in 1932.

His hypothesis was it should be proto-bioluminescence that is involved in the process and they belong to respiratory chain proteins.

Although these manifestations did not stay for longer, they inspired other people to consider this. Later Howard Seliger mentioned luciferase enzymes which acted as catalysts during the evolution of bioluminescent.

Measurements Of Human Bioluminescence

Various research groups made surveys and they noticed on the spectrum that the light stays strongest at the red end. However, when the light is in the ultraviolet, it stumbles under detectable levels.

After the chemical reaction when light energy is discharged, bioluminescence happens. The process includes luciferin pigment and luciferase enzyme. The concept of bioluminescence has evolved more than 40 times and luciferins stay important.

Coelenterazine is a commonly involved pigment from the luciferin family. Not every species can synthesize coelenterazine, but some of them get it with diet. Different enzymes from the luciferin family work for different individual species.

The research team noticed variations between photon rate and spectral profile. The rate is variable with time for different individuals. Considering the anatomical location, the estimated photon rate of light from human skin is 170-600 photons/s/sq. cm.

Which other organisms glow in the dark?

Besides humans, there are more living organisms to have the same ability to glow in the dark with different purposes. During evolution, various animals from different families started to migrate deeper into the water and that lack of sunlight improved their eye sensitivity and enhanced visual signals.

In Japan, people are quite familiar with the species firefly squid. They use this ability to hide. They form a horizontal position and illuminate the downside of their body by emitting light energy.

Their body's surface gets mixed up with the surface light, which let them avoid predators. Angler fish have an intense hanging light over their head, which helps them prey upon other animals. Railroad worms, actually belong to a beetle family.

They are intensely toxic and illuminate themselves with light-emitting cells to warn predators. Lantern sharks have light-emitting cells in their abdomen and fins. The most common on this list would be a firefly.