It's reassuring to think humans are evolution's ultimate destination – but research shows we may be an accident

• It’s reassuring to imagine that complex bodies and brains like ours are the inevitable consequence of evolution, as if evolution had a goal.
• However, by the mid-19th century, Charles Darwin showed that natural selection has no direction, and will sometimes make organisms simpler.
• If true, this could be a blow to our human sense of significance as the most complex organisms.
• While driven trends need not imply divine purpose, they at least suggest that complexity was mostly an improvement, which is reassuring for us humans.
• Rather than marching towards greater complexity, mammals evolved in lots of different directions, with only some lineages pushing the upper bounds of complexity.

Surely nature selects for complexity just a bit?

• These are most visible in our vertebral column (or spine) and ribs, and in the six-pack of a lean athlete.
• Counting the number of bones in different regions can quantify one aspect of complexity across all mammals.
• This suggests higher complexity can be a winning formula, and that selection is driving this in multiple branches of the mammal tree.
• Research into the evolution of complexity has only recently started gathering pace, so there is much we still don’t know.