Forty years ago, for example, palaeontologists thought that hominids, the group of primates that includes modern humans, had been distinct from other apes for some 25m years.

• 比如四十年前，古生物学家就认为原始人（包括现代人在内的灵长类群体）与大约2500万年前的其它类人猿明显不同。