I started keeping a log of such announcements while I was working on my recent book As We Know It: coming to terms with an evolved mind. Some of the claims, it is true, crumbled almost as quickly as they had arisen, but that's all part of the fun. The tests and arguments applied to claims about the ages of bones or ancient drawings have recently attained a level of sophistication that makes even the disproof of a claim a rewarding process to observe. And most of the announcements have endured.
In the past few years, we have learned that the type of hominid known as Homo erectus, traditionally believed to have died out deep in prehistory, may have still been living in Australasia at a time when modern humans were established in Europe. Researchers have announced the discovery of the oldest stone tools yet found, dating back two and a half million years, and of the first DNA sequences extracted from Neanderthal bones.
We have also gained striking evidence that hominids who were around the best part of half a million years ago had a very sophisticated capacity for functional design. The stone artefacts of that era, which are pretty much all we've had to go on until now, are actually distinguished by their lack of variety. This uniformity was sustained for a million years, inducing the anthropologist Mary Leakey to dismiss Homo erectus as "that dim-witted fellow".
Together with Steven Mithen, an evolutionarily minded archaeologist, I have put the argument that these hand axes were held constant in form because they served as criteria for mate choice. They worked in the same way as men's formal suits, which offer accurate guides to their wearers' wealth and status precisely because the range of styles and colours is so limited, making it possible to compare like with like. The thousands of hand axes now in museums may not therefore be much of a guide to their makers' mental capacities.
On the other hand, the three spears unearthed from a brown-coal mine at Schoningen, in Germany, are clearly not the work of dim-wits. Thickest closer to their points and tapered towards their far ends, they are the work of beings clever enough to understand the principles behind the javelin.
We can say with confidence that the next few years will see equally remarkable discoveries, which will doubtless alter our understanding of how we came to be what we are. But, if that understanding changes so fast, is it really worth very much? Are we not just telling stories; imposing our contemporary prejudices upon the past?
Exploring human evolution is certainly a way of reflecting upon the modern human condition, and stories about our prehistory reflect the mood of the times. But nowadays the people engaged in researching our origins are aware of this. They use careful field techniques and elaborate mathematical models to make their work less of an art and more of a science. They are synthesising knowledge from an array of themes, from primates and fossils to hunter-gatherers and game theory.
They are going somewhere, unlike the obscurantists who make out that evolution is just another story.
Marek Kohn's `As We Know It: coming to terms with an evolved mind' is published by Granta, pounds 17.99