Hardly ever has a scientific prediction so bold, so ‘out there’ for its time, been upheld as the one made in 1871 – that human evolution began in Africa.
The 1.2% chimp-human distinction, for example, involves a measurement of only substitutions in the base building blocks of those genes that chimpanzees and humans share.
A comparison of the entire genome, however, indicates that segments of DNA have also been deleted, duplicated over and over, or inserted from one part of the genome into another.
From the perspective of this powerful test of biological kinship, humans are not only related to the great apes – we are one.
The DNA evidence leaves us with one of the greatest surprises in biology: the wall between human, on the one hand, and ape or animal, on the other, has been breached.
While the genetic difference between individual humans today is minuscule – about 0.1%, on average – study of the same aspects of the chimpanzee genome indicates a difference of about 1.2%.
The bonobo ( humans all show this same amount of difference from gorillas.
A difference of 3.1% distinguishes us and the African apes from the Asian great ape, the orangutan. All of the great apes and humans differ from rhesus monkeys, for example, by about 7% in their DNA.
Geneticists have come up with a variety of ways of calculating the percentages, which give different impressions about how similar chimpanzees and humans are.
DNA, or deoxyribonucleic acid, is the molecule that makes up an organism’s codes for proteins – the building blocks of our tissues and their functions.
It also consists of the molecular codes that regulate the output of genes – that is, the timing and degree of protein-making.
Even though Europe and Asia were scoured for early human fossils long before Africa was even thought of, ongoing fossil discoveries confirm that the first 4 million years or so of human evolutionary history took place exclusively on the African continent.