Humans walk right on time

A couple of neurophysiologists from Lund University in Sweden had the interesting insight (actually I don't know if they are the first, but it's the first it's been brought to my attention) to use conception rather than birth as a starting point for comparing motor development and brain development among mammals. If you do that, humans walk right when they should.

The Lund group has now compared 24 species, which together represent the majority of existing walking mammals. Some, like the great apes, are closely related to us evolutionarily while others, such as rodents, hoofed animals, and elephants, diverged from our evolutionary path about 90-100 million years ago.

Despite this, and regardless of differences in various species' brain and body size, gestation time, and brain maturity at birth, the comparison shows that the young from all species start walking at the same relative time point in brain development. 

This brings to mind the fact that mammals all live about a billion heartbeats. Except people.