“Junk DNA” may help explain human-chimp differences

For years, sci­en­tists thought an ex­plana­t­ion would soon turn up for the vast dif­fer­ences be­tween hu­mans and their clos­est rel­a­tives among the an­i­mals, such as chim­panzees. The dif­fer­ence must be in the genes, bi­ol­o­gists rea­soned.  But this hy­poth­e­sis ran in­to trou­ble when it lat­er emerged that hu­man and chimp genes are nearly iden­ti­cal.