Why did Eve offer Adam a very red, ripe and appetizing apple? Precisely for that. Because it was appetizing in the eyes of Adam. He visually recognized her color, texture, symmetry, and consistency and perhaps even smelled her scent, which sent him the message “I’m ready for immediate consumption.”
It is as if the fruits came with their commercial included. Fruits send animals and humans subliminal visual messages in order for us to consume them. Why?
Plants, through the consumption of their fruits, achieve the geographical dissemination of their seeds to more fertile land, since animals and humans disperse their seeds contained in our fecal matter. Of course, as far as modern man is concerned, the mission entrusted to us by plants is made more difficult by the sanitized use of toilets and latrines.
What is the benefit for us?
Fruits and foods contain multiple nutrients that are generally INDISPENSABLE for our survival. And plants communicate this to us in many ways. We learn early – if not born learned thanks to epigenetic information – about the visual appearance of fruits that are ready for consumption, that will provide us with essential nutrients, while at the same time guaranteeing that they are totally healthy.
MIMETISM IS COMMON IN THE VEGETABLE KINGDOM.
The visual message of the plants has a further purpose than that of inviting the consumption of their fruits. The flowers take on an unexpected appearance with the purpose of “stealing” or “lending” insects that normally pollinate plants belonging to foreign or distant families.
There are plants, like the case of the native orchid of the Colombian Andes Dracula chestertonii, whose flowers take on the appearance of the fruits of fungi, with the cunning purpose of recruiting the flies that normally pollinate the fungi by laying their eggs on them. The insects lay their eggs on the orchid flowers, under the false impression that the Dracula flower is indeed a fungus.
On the other hand, the fungus Uromyces pisi infects the Euphorbia cyparissias plant, inducing pseudo-flowers. These adulterated flowers are made up of yellow leaves that grow in the form of a dense colorful rosette. The rosette is supplied with nectar like the natural flower, but actually contains the gametes of the infecting fungus.
Gametes that exude an aroma specific to the fungal taxonomy (different fungi exude different aromas according to their ecological need), are unknowingly transferred by insects that normally feed on the actual Euphorbia flowers. Perfume manufacturers take advantage of this aromatic mimicry for their commercial purposes.
IS THE PLANT MESSAGE ONLY OF A VISUAL NATURE?
Of course not. Plants communicate with each other by means of volatile substances. In effect, plants “spy” on their neighbors for airborne organic compounds released by plants under attack by herbivorous insects. This with the purpose of preparing its defenses before the arrival of harmful insects.
The insects cause more damage to the plants due to the pathogenic infectious agents that they carry with them, than due to the indiscriminate ingestion of the leaves of the victims. Plants can also anticipate imminent ecological competition by registering changes in the photonic flux of blue light that modulates the foliage of their neighbors, thanks to the help of photoreceptors such as photochrome B.
These light messages are translated in plants by ethylene, which serves as a “neurotransmitter”. It is interesting to see that tobacco plants that contain mutations in the ethylene receptor do not adequately perceive changes in photon intensity of blue light, and as such are at a disadvantage in “the pitched battle for light.”
Plants and fruits synthesize hundreds or even thousands of volatile agents that allow us to unconsciously “read” their biochemical content. This content may well be of a nutritional nature and that we should consume, or it may be of a toxic nature, and that we should avoid eating at all costs. Volatile agents are smelled and tasted as we visually perceive their physical origin (a ripe apple as in Adam’s case).
The nutritional value and the absence of food toxicity:
This initial multisensory integration is corroborated a posteriori by signals generated by sensors located in our gastrointestinal tract, which are sent by visceral autonomic nerves to the brainstem, where the vomiting (protective) center is located.
In other words, the art of good eating, more than art, is a neuro-gastrointestinal science that we learn from a very early age. It is important to highlight that the color of the fruit also offers us visual information that is perceived at an unconscious level and that translates into detecting whether or not the fruit or vegetable is appetizing, and as such contains nutritional value.
Ripe tomatoes, for example, contain carotenoids, pigments used to capture photons and have an anti-oxidant effect. Beta carotene is an essential precursor of retinol, retinal and retinoic acid, all of which are essential for good vision. In turn, carotenoids have an appetizing taste, thus facilitating the multisensory learning that we referred to above and that guarantees our survival.
WHY DO WE HUMANS SEE BETTER THAN WE SMELL?
Odors are chemical substances that activate specific receptors located in the cilia of the olfactory epithelium. The receptors couple to G-type proteins that stimulate adenylyl cyclase that results in the synthesis of cyclic AMP.
The latter facilitates depolarization of the olfactory cell membrane with calcium influx. This in turn results in the opening of chloride channels with the consequent egress of the anion and the added depolarization of the cell membrane.
Finally, the cycle is dampened and suspended with the suppression of cAMP synthesis when the intracellular calcium concentration reaches a critical point that reverses the process. The signal is amplified depending on the number of G-type protein molecules that activate each receptor individually.
The amplification of the olfactory signal is minimal since the action time of the odoriferous substance is very short. In contrast, the VISUAL signal is substantially amplified as one photon simultaneously activates many G proteins (“transducins”) in the retinal rods, due to the long-lived rhodopsin molecules, which are photoisomerized.
Although the same happens in animals:
Well – contrary to what happens in humans – they smell better than what they see in many cases, thanks to the convergence of odoriferous impulses of the same type that are implemented in their olfactory glomerulus, achieving that many short-term stimuli are added and outperform few long-lasting stimuli, as in the case of visual perception.
In conclusion, the perception of food using the sense of vision takes on more meaning in humans than its perception through smell. (This is the reason why pheromones are more important in animals than in humans, who -among other things because they are upright- use their vision better).
