This is an interesting question. Neoteny is the preservation of juvenile features into adulthood and is a hallmark of domestication. Humans have been undergoing self-domestication so features like rounder faces and softer jaw lines are persisting past sexual maturity.

We _know_ the human brain is finishing its development in our early to mid twenties, maybe 10 years post puberty. This extra brain development likely needed for our advanced social and tool needs, and is a unique niche for humans. Our hidden brain development does make a difference. Other primates don't display this.