There usually is some degree of variability in a sample (golfers do not use only titleist balls; students do not always eat at taco bell). the is a measure of the variability in a sampling distribution.

There are several measure to describe the distribution of some observations. The mean for example give an idea about the average observation. The measure that gives us an idea about variability is the standard deviation; Intuitively it measures how much observations differ from the average.

Many archeologists and anthropologists disagree with dr. thorne's view.  thorne strongly believes that what many calls "homo erectus"  was in fact  homo sapiens,  and that they migrated out of africa almost 2 million years ago and dispersed throughout europe and asia. that's way different  from what scientists have always believed about the evolution of the species.