What is man?

Dictionary definitions of man are inadequate.
Many of the obstacles that are met in the quest for the origin and nature of our species arise from a fundamental and persistent mistake, that of drawing a line between ourselves and every other creature on the planet. If this puzzling error were to be discarded, a world of ideas would open, but assumptions about who we are remain tainted by supernatural bias.

The Merriam-Webster Dictionary manages to straddle the fence between natural and supernatural ideas with this less than satisfying definition:
MAN: Living being representing the most evolved species on Earth, characterized especially by upright stance, spoken language, and a large brain.

This type of definition provokes easy objections. “Most evolved” cannot be proven. One would have to demonstrate that evolution is directed toward an ultimate "winner" among species and that Homo sapiens is the fulfillment of that goal. There is no such goal: evolution is a process by which species evolve to fit specific environments, and we obviously aren’t the most well-adapted animal on tropical reefs, or in the leaf litter on a jungle floor.