EDIT Completely rewritten to be hopefully less condescending.
There are lessons from group selection and the extended phenotype which vaguely reduce to “beware thinking about species as organisms”. It is not clear from this essay whether you’ve encountered those ideas. It would be helpful for me reading this essay to know if you have.
Quick summary of a reason why constituent parts like of super-organisms, like the ant of ant colonies, the cells of multicellular organisms, and endosymbiotic organelles within cells[1] are evolutionarily incentivized to work together as a unit:
Question: why do ants seem to care more about the colony than themselves? Answer: reproduction in an ant colony is funneled through the queen. If the worker ant wants to reproduce its genes, it can’t do that by being selfish. It has to help the queen reproduce. Genes in ant workers have nothing to gain by making their ant more selfish and have much to gain by making their worker protect the queen.
This is similar to why cells in your pancreas cooperate with cells in your ear. Reproduction of genes in the body is funned through gametes. Somatic evolution does pressure the cells in your pancreas to reproduce selfishly at the expense of cells in your ear (this is pancreatic cancer). But that doesn’t help the pancreas genes long term. Pancreas-genes and the ear-genes are forced to cooperate with each other because they can only reproduce when bound together in a gamete.
This sort of bounding together of genes making disperate things cooperate and act like a “super organism” is absent in members of a species. My genes do not reproduce in concert with your genes. If my genes figure out a way to reproduce at your expense, so much the better for them.
Like mitochondria and chloroplasts, which were separate organisms but evolved to work so close with their hosts that they are now considered part of the same organism.