Just a daydreamy, science-fictiony sort of thought, inspired by the Fermi Paradox (why we have not conclusively met any aliens who have traveled here).
Humans conquered this planet without direct coordination among them, using tools and intelligence and ambition and sometimes cooperation. This is the way humans evolved to function, and it works (perhaps too well).
I was trying to think of other ways that a single species might become dominant on a planet, especially ways that would probably not lead to space travel (but not limited to that). For example, some kind of mold could develop to be bullet proof in some way so that it just kept growing until it was all that was left (not sure what it would then eat, not sure what molds do eat, maybe it would be so successful it would itself then die out, leaving the planet barren). The usual examples of ants or bees for enforced cooperation could dominate other species, I guess, if none of the other species had any higher intelligence.
Science fiction has generally focused in a few areas, I’d love to see speculations here that I haven’t already seen on the small or big screen.
I would say the strongest candidates are insects, particularly ants and termites. They already dominate the Earth by biomass and numbers; they are highly adaptable, and they have a social order. They can significantly alter soil, forests, and nutrient cycles. Ant colonies would expand into cities, and termites would reclaim wooden structures, assuming humans weren’t around to stop them.
Do you mean, spread all over the planet? Multiple species could do that at the same time. Do you mean “wipe out most or all other species”? That as you point out may be self limiting. Do you mean “affect drastically the ecology of the planet”? Then I give you cyanobacteria and oxygenation.
Yeah I will also question the premise. By biomass plants dominate mightily. Then bacteria. Then fungi, archea, protists …. Within the animal group arthropods are number one. We humans are way down there.
I mean, the argument could be made that there’s always been a dominant species, even before humans evolved. Or for that matter, depending on the definition, humans may not be the dominant species even now.
I would think that adaptability would be the primary thing that would make a species dominant. Generally speaking, evolution tends toward tailoring species very specifically for their particular ecological niche, meaning that they’re sometimes extremely specialized. Think animals that thrive only on their particular lee side of a mountain on some island in the South Pacific in those specific conditions. Meanwhile humans can live in the Arctic, the Sahara, the jungle, and everywhere in between.
For about 60 million years after trees and plants evolved lignin, nothing could break it down. This not only meant that dead trees piled up but presumably would have made parts of them extremely resistant to being digested or pathogens while alive.
So we can imagine a scenario where a protein evolves that is so effective and advantageous from an energy point of view that it just screws up a whole planet’s biome.
At least in the case of humans we have become widespread and successful by being able to exploit an ever-expanding array of econiches. Our evolutionary ancestors started out as omnivorous scavengers, neither widespread nor numerous. Weapons allowed us to become hunters, while fire expanded the range of plants we could digest (potatoes for example are almost indigestible without cooking). Clothing allowed us to expand out of the tropics. Ranged weapons made hunting less risky and more successful. The domestication of hunting dogs is thought to have further expanded what prey hunters could catch or take on. Canoes allowed us to colonize land masses we couldn’t have reached before. Nets meant that we could now feed on schools of small fish we couldn’t before.
When most proboscideans went extinct outside of Africa and southern Asia, they left open a particular econiche: that of apex herbivore, one capable of altering its environment by bulldozing vegetation. Humans took over the role of apex herbivore via farming. The domestication of horses, sheep, goats and camels made survival in marginal desert or steppe lands possible.
So using technology humans have become extremely adaptable.
We see a number of clades - whales, birds, bats, pterosaurs, and mosasaurs in particular, although there may well be others - who “unlock” a whole new set of niches by adapting to a new environment (flying or swimming, in all of these cases) and then rapidly radiate into dozens of species that exploit every possible niche in the new environments they unlocked.
Humans were able to adapt to a whole host of niches just by adopting different cultures and tools, with no need for speciation.
Well yeah. That allows for adaptation to novel and changing environments in a rapid manner. That’s the aspect that would probably lead a species to space travel, a very novel environment (albeit one that bacteria and viruses could and likely have accomplished). The OP was asking about other paths to planetary “dominance” though.
I think the point I was trying to make is, to dominate the world, a clade needs to adapt to a bunch of different environments and niches; if you don’t have technology or some other adaptation that makes you ultra adaptable as an individual, you probably accomplish this by evolutionary radiation into a bunch of different species.
Maybe we could imagine a species whose larval stage spreads it far and wide and whose adult form depends on the conditions the larval stage exists in.
There is an alien in Ian m Banks Culture series that developed direct generic manipulation of other species very early on in their development and so completely changed all the other species on the planet to suit their needs.
iIRC the main characteristic this lead to was an extremely sense of supremacy for their species and all other species were viewed as raw materials.
But are they truly adapted to a whole host of environments? Or are they well adapted to the specific environment “the margins of human settlement” and benefit from us spreading that environment?
Sorry I wasn’t more clear. Perhaps I didn’t think this through enough, but I’ll try to flesh it out.
I was simply thinking of dominance based on the way humans dominate this planet. Not measured by numbers, or necessarily by being the most widespread, but by effect. As long as there are (enough) humans, there is no room for another species to develop that could dominate us*.
Now think of some other kind of planetary ecology, completely alien and different, that has one single species that holds that place in the order of things on that planet. Imagine such a species, and give them qualities that allowed them to become dominant on their planet, but that are different from the qualities that humans used, like those I listed in the OP.
Perhaps, for example, on a planet with weather extremes where many species suffer die-back during winter, only one species has mutated to have the ability to preserve themselves from dying from the cold. This species dominates the resources, guaranteeing their own survival, and eventually figure out how to keep their food sources from dying from the cold as well, allowing them to expand their population. But maybe their life cycle is too short for them to have more ambition than that. So they gradually cover the planet as much as they can, preserving the species they want and letting the others continue to die back in the winter, until the population plateaus, and they go on like that indefinitely.
*Let’s assume that is true for the sake of the exercise. Debating the premise might be fuel for a different thread.
To meet the OP’s qualifications, I’d say a species like ants, but much larger. That way it evolves slower and takes up more space, and so has a good chance of spreading over the whole planet before evolving into multiple species.
I’m thinking the species thing is very earth life centric and needlessly restrictive. Part of ants adaptability is the problem solving capacity of the colony as a whole. Having colonies work together at a next level of communication, even as they are distributed broadly, might meet the “dominance” criteria, even if they speciate.
Also
The phenomenon is referred to as phenotypic plasticity or polyphenism and occurs to some degree in spadefoot toads. Two distinct forms based on the current environment, a carnivore or an omnivore.
