Inner Nature: Bloody Colors |

By Vidya Rajan, Columnist, The Times

I’ve had good feedback from people who enjoyed my previous article on the similarities between eggs and seeds – two seemingly disparate things that serve the same function. This month, to celebrate the season of leaf color changes and the Halloween (or Halloween) season, I’m going to compare the colors of the fall leaves and the colors of blood. Yes, the colors of blood; the plural is used wisely.

Halloween is reminiscent of the ancient Celtic religion of Samhain, which commemorated the end of the harvest season, the time when animals stored food for the winter, and the apparent death of plants as temperatures turned colder. The night of October 31 was seen as the veil between this world and the next, with the dead entering through to walk among us. It linked the annual cycle of human behavior to the seasonal cycle; and why give up telling scary stories and dancing a Celtic jig around the fire, I ask you.

This funny event spread throughout the pre-Christian world because the Romans knew a good thing when they saw one and they carried it across Europe. Later, as Christianity was born and spread, the Church also knew a good thing when it saw one, and incorporated Samhain into the calendar under the larger celebration of All relics with Toussaint November 1 and All Saints’ Day November 2. Being too much of a bite for people (presumably drunk), it was shortened to Halloween, the eve of All Saints’ Day. Halloween also looks scarier – scary. The costumes originated from the belief that ghostly beings from the otherworld walked among us and, not wanting to get their attention, the living began to wear masks in order to blend in with the living dead. The practice of deceiving or treating evolved from the practice of leaving food on the doorstep to distract spirits and prevent them from entering the house.

Mexican El Dia de Muertos or the Day of the Dead was also born from a hybridization of the Aztec celebration of the harvest with the traditions brought by the Spaniards and Christianity. Less macabre, the celebration was for the dead to visit their loving living families. The tradition includes visiting the cemetery, making treats for the visit of the dear deceased, and setting up their belongings and decorated skulls and skull-shaped candies to welcome them again.

By the time Halloween arrives, the seasonal colors of fall are everywhere. Trees and gourds glow red, yellow and green, decorating the trees and doorsteps. Slasher movies with bloody scenes spray, drip, and sprinkle copious amounts of blood. But there is a deeper connection between the reds and yellows of blood and trees that is only apparent when we look below the surface and delve into their inner nature.

As the days grow longer and temperatures begin to drop, a profound biological change occurs in deciduous plants. Their leaves turn from green to glorious shades of orange, yellow and brown, then float downward, leaving the twigs bare and the branches bare. Among cone plants, only larch (larch larch) drops its needles which first turn a fiery yellow. The leaves of the ginkgo also turn yellow, but it is a gymnosperm like larch, although it does not have needles or cones. Why do the leaves change color? Would it surprise you to know that they don’t actually change color?

The color of the leaves does not change; rather, it is revealed. The onset of cold reveals colors that were previously hidden by the presence of a variety of green chlorophyll molecules that so effectively overwhelm other pigments and reflect the color green that our eyes do not pick up the hints of red, gold. and copper below. All summer long, chlorophylls make us believe that only green, green, green exists in the leaves. Then the truth of autumn begins, and the green fades to expose what was there from the start, especially in the Emerald Isles where Samhain brought the great revelation to an imaginative and storytelling people. Plants are photosynthetic because millions of years ago – about 440 million years ago, or so – they had the foresight to kidnap a cyanobacterium and keep it hostage in their cells. This cyanobacterium had a super power – it could absorb light to use energy to create bonds between carbon dioxide and water to make glucose. The molecules that absorbed the light were chlorophyll which gives algae and plants a green color, but also the orange carotenes found in the back of animals’ eyes – which is why carrots are good for night vision – and xanthophylls that glow yellow are abundant and are found in banana, ginkgo, black maple, aspen and larch peels. There are also anthocyanins which are sugar derivatives that dazzle with scarlet and brown colors, and are found in leaves, fruit skins and maple leaves.

And now for the biggest connection: the green chlorophyll in plants is the first cousin of the red hemoglobin in the blood. Both descend from the pigment found in bacteria – bacteriochlorophyll, which comes in many varieties befitting its ancient origins: a, b, c, cs, d, e, f and g, with different peaks of absorption . The problem with bacteriochlorophylls is that they photosynthesize without releasing oxygen. Chlorophyll also comes in several flavors: a, b, c1, c2, d, e and f. Evolution is like that – it creates variety. The more time he has to tinker, the more varieties he can produce.

Figure 1: Comparison of the structures of hemoglobin, chlorophyll and bacteriochlorophyll. Note that the pyrrole rings of chlorophyll and bacteriochlorophyll both have magnesium (Mg) as a coordinating metal ion, while hemoglobin has iron (Fe). All of these molecules work in redox reactions: gain and lose electrons to allow vision and photosynthesis. Compiled from Wikipedia sources ( and

The color red has many origins. Red paint is a colored glue that adheres better to walls than with a brush or other pieces of paint, and the red tint comes from lead oxide, iron oxide (rust), and sulfur sulfide. mercury. These are all inorganic molecules that reflect the red wavelength, but have the added benefit of not absorbing light or oxygen and breaking down. Lycopene, which gives tomatoes red, is a type of carotenoid that resists oxidation and remains a bright red hue even when used in spaghetti westerns to represent blood satisfactorily. Hitchcock used Bosco chocolate syrup in Psycho but, being a black and white film, color didn’t matter as much as consistency.

Organic red pigments are either bioflavonoids or carotenes. Anthocyanin is a water soluble bioflavonoid and is popular for its attractive shades of blue, black, purple, and red in flower petals and fruit bases. The variation in color is related to the concentration and to the pH. In low pH (acidic) solutions it is reduced and red, purple at neutral pH and colorless in very high pH solutions. Nutraceutical antioxidants are either bioflavonoids or carotenes, as the sensitivity to pH also makes them good redox molecules. (Remember that the high school LEO says mnemonic GER: losing electrons (or H or adding O) is a reduction, and gaining electrons (or H or losing O) is a reduction) This is also the reason why the wine varies in color between batches because fermentation produces variations in the amount of acid.

Compare that to hemoglobin, which oxidizes and breaks down when exposed to light and takes on a rusty color, as adding oxygen to the iron in hemoglobin produces rust. Blood even tastes metallic due to the presence of iron. Hemoglobin, like chlorophyll, is a redox molecule. When oxidized it is bright red and when reduced it is purple. The term “blue blood” comes from the appearance of blue veins under the translucent skin of aristocratic European ladies. Their use of lead powder as a face powder damaged their skin and allowed the capillaries to become more visible. To hide this unsightly strap, they used more lead powder and likely developed lead poisoning as well. True blue bloods are invertebrate molluscs and arthropods. Their blood contains hemocyanin, a pigment made from copper. The blood of the ancient horseshoe crab is not only blue, it is used in the pharmaceutical industry to monitor contamination, as even a small amount of bacterial endotoxin will cause it to clot. Millions of horseshoe crabs are bloodied for this purpose every year, although a new chemical called recombinant factor C (rFC) was recently approved by the FDA and the European Pharmacopoeia. There are also other colors: green is due to chlorocruorin, and the hemerythrin of some marine animals contains iron in another type of molecule. Melanin, the pigment found in the skin and hair of many animals, has red (phaeomelanin) or brown (eumelanin) tones and is used as a sunscreen to protect against radiation damage. Figure 2 shows the formulas of some of the pigments in blood.

Figure 2: The many pigments in animal blood. Animal blood evolved as an antioxidant and then was recruited to carry oxygen around the body. Credits: Reproduced under a Creative Commons Attribution license from

Back to Halloween! The recipe for “Western Spaghetti” fake blood is 4 parts tomato paste to 1 part water. Come to think of it, spaghetti intestines in seasoned tomato paste blood could make a Halloween-themed dinner entirely satisfying.

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