THE ORIGIN OF THE HUMAN CAPACITY 
Just what is it, that strange quality of our consciousness that sets 
us off from all other living organisms—and which, as importantly, 
makes us feel so entirely different from them all, even those to 
whom we know ourselves to be quite closely related? And, whatever 
it is, how and when did we acquire it? While these questions come 
close to being unanswerable except in the broadest of terms, they 
beg to be asked; for they encapsulate the most basic and profound 
of all the many mysteries posed by our strange and (occasionally) 
wonderful selves. It is thus natural that they should have been 
raised—in a variety of different ways and from an equally large 
number of perspectives—by several earlier James Arthur lecturers 
on The Evolution of the Human Brain. 
My talk today is no exception, and I have even borrowed part of 
my title from one of my distinguished predecessors as a James Ar- 
thur lecturer, Alexander Marshack, who coined the term “the human 
capacity” to denote this elusive quality that makes humans so dis- 
tinctive. In his lecture, Marshack (1985) explored the origins of the 
human capacity in the context of the Ice Age art and symbolism 
that are its most dramatic early expression. Today I would like to 
cast my net a little wider, looking at the evidence for the emergence 
of what we might call cognitive novelties throughout the hominid 
fossil and archaeological records, and asking whether it is possible 
to discern any consistent pattern among them. More precisely, I shall 
ask whether the final step to becoming fully human—the acquisition 
of the human capacity—was an abrupt or a gradual event, and 
whether it simply represented the culmination of earlier trends in 
human evolution, or was an unprecedented, emergent event that 
could not have been predicted from what went before. And I shall 
also inquire into possible causes or at least correlates of this fateful 
step. Before I begin to do this, however, it’s necessary to digress for 
a moment to look briefly at the evolutionary process itself, because 
the way in which we view this process profoundly affects the man- 
ner in which we interpret its manifold results. 
