Walking upright may have provided greater vision regarding predators, reduced direct heat and greater circulation, and allowed for greater ground coverage.
The oldest tools discovered - rock fragments to cut and scrape - are nearly 3 million years old.
It was 1 million years later when the whole rock, not the fragments, was fashioned and used as an axe.
This tool-making then evolved over the next million years. Language is important because that implies 'culture' - the spread of knowledge; copying and informing.
The science of genomics - the genetic study of the genomes and DNA sequence of organisms - helps explain this.
The genomes of humans and apes differ by little more than 1%, but this in fact means there are over 30 million point mutations.
This would make it the oldest known sculpture, or manuport [a natural object which has been moved from its original context by human agency but otherwise remains unmodified] known.
The Tan-Tan sculpture, discovered in ancient river deposits of the river Draa, Morocco, is between 500,000-300,000 years old.
The overall shape of this little quartzite pebble, almost 6 cms in height, resembles a human figure but is entirely natural and unmodified by human action.
Found near stone tools, it is possible that the pebble was simply collected and kept by someone who noticed its human shape.