Ancient but not primitive

Why we shouldn’t judge fish by their age

HUMANS AND fish evolved from a common ancestor. Early humans appeared on the planet just 6 million years ago and modern humans not until about 195,000 years ago. By contrast, the genealogy of fish goes back more than 500 million years. They’ve been evolving for far longer than their land-based descendants, making them the most highly evolved of Earth’s vertebrates.

This means ancient does not equate with primitive. Scientists no longer see vertebrate evolution as a linear progression rising from primitive to sophisticated, with humans at the top and the human brain as the gold standard. Rather they see it as a radiation from a common ancestor, with different animal groups evolving in parallel.

As Culum Brown has written: “Following this reasoning, biological and cognitive complexity is not defined by how closely animals are related to humans but rather by the niche they occupy and the problems they commonly face during everyday existence... There has been ample time for fish to evolve complex and diverse behaviour patterns as well as the cognitive hardware that goes with it to match the diversity of ecological niches they occupy.”

What this means, he says, is that most fish species are no more ‘primitive’ than we are.