In train with the concept of selection as competition is the notion that the outcome of natural selection represents evolutionary progress. After all, if selection is competitive, the winner must be better.
Nothing can be more hopeless than to attempt to explain this similarity of pattern in members of the same class, by utility or by the doctrine of final causes. ~ Charles Darwin in 1859
Inconsistently, despite his espoused belief in the randomness of evolution, Darwin and other naturalists in his wake believed that life advanced in evolutionary time, evolving from more “primitive” species to “higher” ones. They were likely influenced by the philosophers Georg Hegel and Herbert Spencer, who envisaged history as advancing toward perfection. Ascendance through descent is still widely accepted.
The evolution of life has ascended increased grades of complexity. ~ American molecular biologist Sean Carroll
The supposed overarching trend has been complexity, sold as a story. Life started simple and single-celled. From this arose more complex multicellular organisms, with evolution eventuating to backbones, bigger brains, and so on, culminating in the grandest creature of all: humans.
This fable forgets that prokaryotes possess effective communication skills, are gregarious, have adaptation abilities beyond all others, and remain essential to all eukaryotic life. Proposing the history of life as progressive was due solely to ignorance about microbial life.
Organic life, we are told, has developed gradually from the protozoon to the philosopher, and this development, we are assured, is indubitably an advance. Unfortunately, it is the philosopher, not the protozoon, who gives us this assurance. ~ Bertrand Russell
Statistically, by numbers of species or populations, microbes are the monarchs of life. By this reckoning, the vector victor may be found on the doorstep of evolution, not in the grander mansions constructed much later.
The lifestyles of viruses are practically miraculous when it comes to wiles with next to nothing for physicality. If anything, the ostensible simplification of dropping bodily baggage and living zealously Zen is as remarkable as the specialization that characterizes multicellular organisms.
In evolution, complexity is easy. (And simplicity is hard.) ~ American evolutionary biologist Daniel McShea