A World Increasingly Complex
Life on Serina has now evolved for over 250 million years.
From its beginnings over 3.75 billion years ago, life has demonstrated a general tendency toward increasing complexity, and among the animal kingdom intelligence, that is perhaps most readily observed looking back upon the history of the vertebrates, beginning some 620 million years ago. When the first amphibians - the distant ancestors to all the mammals, reptiles, and yes, the birds of Serina - first appeared and took those fateful steps onto land, the world had never before seen such an advanced, large-brained animal as these sluggish salamander-like creatures that now fiercely hunted the invertebrates that had until then dominated the land uncontested. Their descendants continued this trend, with the first synapsids (the group of animals which would give rise to the mammals) and the sauropsids (the ancestors of reptiles, including birds) showing larger brain cases and presumably more complex behaviors still. By the end of the reign of dinosaurs some 316 million years ago, even the most small-brained of these great reptiles likely were substantially more clever than their amphibian predecessors, and some forms, particularly those close to the line leading to birds were even more advanced. The small raptor-like feathered dinosaurs leading up to the bird lineage were clever predators of smaller animals and almost certainly some of the smartest animals ever to have lived by that time, and yet only sixty-six million years later by the time mankind came to dominate the planet, surviving birds with similar brain proportions such as chickens were now nothing special. Newer groups, smarter still - in particular the passerines and parrots - had by now appeared and diversified and these had evolved even larger and more complex brains. Mammals, though irrelevant to life on Serina they are too demonstrated the trend well, evolving from opossum-like tree-dwellers into human beings in the same time span, with wholly unrelated lineages as distant as the whales and elephants also developing along similar brainy lines independently. Not even invertebrates, generally considered lowly and beneath the vertebrate creatures, are totally excluded; the cephalopods and in particular the octopus also demonstrated the evolution of very impressive cognitive abilities by 250 million years ago from much less complex ancestors. Were this not a trend, it is highly improbable so many animal groups would have reached such a high level of mental ability simultaneously.
Of course, a trend is not a universal law, and evolutionary success does not necessarily depend upon a larger and more complex brain. Animals that find themselves isolated from predators and without competitors, as happens upon island environments - and in the early days upon a newly terraformed planet - often demonstrate a decline in the extent of their mental faculties, as a large brain is energetically expensive to produce and if the animal can get by with less it is likely to do so. It was so that the canaries first introduced to Serina initially broke the general trend very clearly and, as a whole, became dimmer-witted. Large, ungainly grazers without fear of predators hardly needed to be smart to survive. But little by little, as the ecosystem developed, the trend returned as other groups of birds learned to exploit the weaknesses of others to feed themselves. Predators adapted to exploit the herbivores, and the grazers in turn had to become smarter to avoid the predators in a feedback loop that would over the ensuing epochs bring many Serinan species toward higher complexity, just as evolution on Earth had done to their ancestors since the beginning of time.
By the Pangeacene at least one bird crossed the threshold of sapience altogether and by Ultimocene this trend towards ever-smarter animals continues in earnest. The evolutionary "brain's race" as it could be called, of competition and predation, has led not just one or two but numerous lineages toward cognitive advancement on a wider scale than ever before seen. The average bird in the Ultimocene is now broadly equivalent to some of the smartest bird groups of 250 million years ago such as jays and parakeets - and extremely intelligent animals like the elephants, apes, parrots and crows of the Holocene are no longer outliers but quite abundant and represented by dozens of independently-evolved lineages including the sparrowgulls, bumblets, softbills and metamorph birds.
This trend upon Serina is not limited to the birds, and neither is it exclusive to vertebrates. Though the birds seem to have had a head-start versus the fishes and invertebrates also introduced to Serina, the dynamics of the "brain's race" have not acted upon them in isolation. Coexisting with birds in a relative evolutionary vacuum has resulted in strong selective pressures among these "lowly" creatures to evolve toward greater cognitive complexity too, in some cases driving them toward similar levels of cognition to the birds in a much shorter span of time. Tribbets in particular, due to their terrestrial nature and frequent interactions with birds, are most influenced and several groups have reached levels of intellect that we would very clearly recognize as advanced, approaching that of the carnivoran mammals and the primates. Even underwater, however, ray finned fish have continued down their own unique evolutionary paths and 250+ million years has been ample time for them to reach their own higher tiers in the ladder of life's complexity, with different forms having adapted their own increasingly complex behaviors and social interactions largely independent of life on land.
Among invertebrates the effects of the trend are generally less obvious, but not absent. Eusociality among ants has continued to refine to even greater levels - some ants in the Ultimocene take the hive-mind theme to new extremes with mobile colonies that operate as a single conducive large organism more perfectly than any before them. Individual high intelligence, though more difficult at very small sizes due to the needed room in the brain to store information, has occurred among aquatic invertebrates which are able to reach larger sizes due to the support of the water; among them, the bountiful nutrient-rich seas of Serina have allowed snails to reach new heights, not only with the new physical diversity but also in the snarks an incredible increase in general intelligence that in some now rivals that of the cleverest birds.
As Serina approaches a still-distant end, the early Ultimocene serves as the climax of the world's natural history: a culmination of all that has occurred in the prior 250 million years. Biodiversity is at a pinnacle, not yet subjected to the climactic upheavals that will rock the world in coming millennia. Now, not only is the interaction of life and ecosystems upon Serina dependent upon the increasingly strange and derived physical forms of its players, but their intellects. In a world where the prey begin to match their predators play-for-play intellectually, where sapience strikes quickly across the world from multiple lines of life, the dynamics of the ecosystem and evolution will never be the same. As the "brain's race" comes to a head, intelligence becomes common, the spark of self-awareness strikes many times and among many creatures culture slowly begins to dictate evolution as much as physical attributes. Sapience, we will come to realize in the Ultimocene, is not just some level of evolution suddenly attained but rather is a spectrum - and it is not ultimately tied to civilization as we would know it. We are familiar with the dynamics of a world with one highly-intelligent, civilization-building culture, and the repercussions their actions can have upon the rest of a global biosphere. But sapience does not always lead to the same end. To build a civilization requires a specific sequence of conditions that may never repeat again, as well as the physical means to build one. When sapient creatures are still subject to the food chain, and especially when multiple animals begin to think about the world around them at the same time, things can play out very differently. But whenever ecosystems form with multiple highly intelligent creatures in conflict, the natural order of things is still bound to be disturbed.
Intelligence becomes a central theme in the Ultimocene.