Ian Tattersall (° 1945) has more than earned his spurs as a paleo-anthropologist, he is considered one of the great specialists in that field. Since his retirement he has published several overviews, each of which provides a very transparent introduction to the earliest human evolution. In my opinion, this short book, only 120 pages, is nothing short of a gem. This is mainly because Tattersall doesn’t offer spectacular titles nor screaming exclamations, as unfortunately happens far too much in that sector. He rightly writes, for example, that our old image of the human lineage, modeled on a simple tree trunk, is very misleading: “It is becoming increasingly apparent that the evolutionary history of the hominid family has not been a straightforward story of the fine-tuning of a major central lineage over the eons. Instead, it has been a dynamic saga in which multiple hominid species have originated, done battle in the ecological arena, and, more often than not, gone extinct. It has been a story of evolutionary experimentation, of exploration of the many ways in which it is evidently possible to be a hominid.” In the same vein, he also presents a very thoughtful theory of the appearance of the hominids and the homo sapiens species: not with sudden jumps, but very gradual and through a lot of hybrid transitions.
Tattersall is rightly cautious about the great leap in homo sapiens-evolution towards symbolic behavior (art, religion, etc.), both in dating and in explaining that leap. According to him, also that is a matter of very slow evolution: “The underlying anatomical substrate for symbolic thought was born with the major structural adjustment that gave rise to our species— but was not expressed immediately in new behaviors. It must have lain fallow for many millennia, until its unprecedented uses were discovered by human ancestors who had until then possessed this new capacity unknowingly. The story seems to be that, with the necessary biological structures in place, this new potential awaited its “release,” not by any biological innovation but by a cultural stimulus of some kind.”
And rightly he makes a link with language: “Like thought language involves forming and manipulating symbols in the mind, and our capacity for symbolic reasoning is almost inconceivable in its absence. Imagination and creativity are part of the same process, for only once we have created mental symbols can we combine them in new ways and ask “what if?” Language is particularly attractive in this role because it is an external, communal property, in contrast to other potential releasers such as “theory of mind”— the ability to read the minds of others. Unless, that is, the primary function of language is to promote thought, rather than communication.”
And so, unlike many of his colleagues, Tattersall opts for a fairly late leap in cognitive evolution: “However it came about, the origin of the human capacity for thought was a rather recent happening and an emergent one. It did not result from a gradual process of perfecting earlier trends. Much as paleoanthropologists like to think of our evolution as a linear process, a gradual progression from primitiveness to perfection, this holdover from earlier days of the science is clearly in error. We are not the result of constant fine-tuning over the eons, any more than we are the summit of creation.”
Perhaps this book is becoming a bit outdated by now, because it was published before the gulf of ancient-DNA analyses that have changed our view on prehistoric history quite radically. But if only there were more scientists in this field who think as prudent and balanced as Ian Tattersall!