Multicellular and multizoa organisms – Similarities and differences

Vision – An example of similarity

Some of the similarities between multizoa and multicellular organisms are truly striking. For example, it is a well-established fact that the images we consciously perceive as vision are not in fact the raw visual footage falling on the retina. ¹ If we were to perceive the images that come through the eye directly as they fall on the retina, we would have a blurry, upside down image that constantly shifts due to the eye’s micromovements, with a blind spot in the upper visual field of each eye where the optic nerve crosses the retina, with more color in the middle of the visual field than in the periphery, etc. (Figure 6a). In other words, it would not be the clear, full color image of our surroundings that we consciously perceive. However, what happens is that the neurons which specialize in processing visual images constantly “process” the images coming from the retina – they invert the image to have it right-side up, they mask the blind spot, they remove the microsaccades of the eye, they fill the visual periphery with color, and so on, to provide the full-blown images that you are now perceiving as you are reading this text.

In a similar way, the stunning images that we normally see of deep space, taken by telescopes such as Hubble are not the raw images taken by the telescopes themselves. ² For example, Hubble images are post-processed in a number of ways by the astronomers, including combining a number of Hubble images, coloring them – the original images are greyscale – removing artefacts, and performing a series of other tasks on them before they are released to the public (Figure 6b, Figure 6c). As NASA put it, “Creating color images out of the original black-and-white exposures is equal parts art and science”.

So, we can say that in both cases, the visual images captured by the organism’s visual organ (i.e. eye in the case of humans, telescopes in the case of human society) are first processed by their fundamental units (i.e. cells in the case of humans, humans in the case of human society) before being distributed throughout the organism (i.e. becoming conscious in the case of humans, becoming popular in the case of human society). Of course, the temporal and spatial order of magnitude differs between the two organisms – it takes a much shorter time for cells to process the images captured by the retina then it does for humans to process the images captured by the Hubble telescope. Also, the distances involved when it comes to cells and the retina are much shorter than the distances involved for telescopes and humans.

Nevertheless, the fact that we can express the same general process in a language that applies to both organisms is a testament to their striking similarity.

Basic unit individuality – an example of difference

Still, it is worth pointing out that there are notable differences between multicellular and multizoa organisms. Perhaps one of the most poignant for multizoa theory is the fact that the individual humans that make up multizoa organisms have a strong sense of individuality, one that is not found in the individual cells which make up multicellular organisms. That does not mean that cells do not display ingenious behavior individually. ^{4 5} But this sense of individuality inherent in humans is unlike anything seen in the cellular kingdom. For example, there is no such thing as “popular cells” within the body that all other cells know about, like there are popular people within human society, from politicians to actors to singers. This diverging feature has two potential implications:

1. The intergenerational process of multizoa evolution through natural selection might favor the survival and reproduction of societies that are more collective rather than individualistic, thus eliminating individualism over time. An example such a collectivist multizoa organism could be a society where the popular works of art created by people would be completely anonymized, so as to strip them of any individualist connotations.

2. Human individuality might play a role in the selection of particular “multizoa traits” during the process of multizoa evolution through natural selection in the Universe that have no parallel to multicellular “traits” and their evolutionary trajectory. For example, a multizoa organism that empowers that individuality in its humans might be evolutionarily successful in certain multizoa environments, something that has no parallel in the context of multicellular organisms.

This example aimed to show how a clear difference between multicellular and multizoa “traits” could be dealt with in the context of an evolutionary theory that encompasses both types of organisms.