“Medieval naturalists placed living things along a linear scale called the great chain of beings, or scala naturae. This hierarchical sequence ranked creatures such as worms and slugs as lowly and humans as the highest of earthly beings. In the late 1800s the enormous mass of evidence contained in Charles Darwin’s masterwork, On the Origin of Species, convinced most of his scientific contemporaries that evolution was a reality. Darwin explained that modern species were related by physical descent and saw the relations among species as resembling the diverging branches of a family genealogical tree.”

This quote is from Scientific American Mind Article . The idea of the chain of beings lingered on. The immediate interpretation of evolution was ‘humans are descended from monkeys’ when it should have been ‘humans and monkeys have a common ancestor’.

“Over the past 30 years, however, research in comparative neuroanatomy clearly has shown that complex brains—and sophisticated cognition—have evolved from simpler brains multiple times independently in separate lineages.”

We do not just need to look at what other mammals can do with their brains but also birds, fishes, mollusks and even insects. In our outlook on other animals we should teach ourselves not to think in terms of the ‘chain of beings’. In a sense all living things with us today are approximately the same in terms of newness or oldness, and approximately the same in terms of being well adapted to their environment. There is no clear criteria for ranking species into higher and lower along a chain of beings. Some are bigger, some are faster, some of smarter, some can stay under water longer, some are more fearsome, some are better fliers, some live longer, some have more offspring, some have larger ranges, maybe some are happier, but all of them are approximately equally successful.