It carries out this suggestion, that Palæolithic man ranged widely and was distributed, thinly indeed but uniformly, throughout the world, that the Palæolithic remains we find are everywhere astonishingly uniform. To quote Sir John Evans,[71] “The implements in distant lands are so identical in form and character with the British specimens that they might have been manufactured by the same hands.... On the banks of the Nile, many hundreds of feet above its present level, implements of the European types have been discovered; while in Somaliland, in an ancient river-valley at a great elevation above the sea, Sir H. W. Seton-Karr has collected a large number of implements formed of flint and quartzite, which, judging from their form and character, might have been dug out of the drift-deposits of the Somme and the Seine, the Thames or the ancient Solent.” Phases of spreading and intermixture have probably alternated with phases of settlement and specialization in the history of mankind. But up to a few hundred years ago it is probable that since the days of the Palæolithic Age at least mankind has on the whole been differentiating. The species has differentiated in that period into a very great number of varieties, many of which have reblended with others, which have spread and undergone further differentiation or become extinct. Wherever there has been a strongly marked local difference of conditions and a check upon intermixture, there one is almost obliged to assume a variety of mankind must have appeared. Of such local varieties there must have been a great multitude. In one remote corner of the world, Tasmania, a little cut-off population of people remained in the early Palæolithic stage until the discovery of that island by the Dutch in 1642. They are now, unhappily, extinct. The last Tasmanian died in 1877. They may have been cut off from the rest of mankind for 15,000 or 20,000 or 25,000 years.