Is there only one way to become s apiens? : How Homo became sapiens: on the evolution of thinking by Peter Gärdenfors. Oxford University Press 2003. £25.00 (250 pp.) ISBN 0 198 52850 7

Abstract

A basic theme of this book is that there are progressive increments in cognitive capacities that culminate in the appearance of free will and language in humans. Although the idea of a progressive increment of cognitive abilities makes perfect sense from a scala naturae point of view, it is more problematic when viewed from an evolutionary viewpoint. Although it can be said that, in general, organisms have increased in complexity from unicellular to multicellular organisms and from simple to complex nervous systems, taking this increase-in-complexity argument at face value can be misleading. There have been decreases in complexity throughout evolutionary time. For instance, parasites have often lost many of their body regulatory functions because they are performed for them by their hosts. Similarly, animals such as moles living exclusively underground have considerably reduced capabilities of their visual system. Examples in cognition are also available. Dogs present a 20% reduction in brain size compared with wolves with an equal head size [6xEvolution of working dogs. Coppinger, R and Schneider, R. : 21–47See all References][6]. There is even some evidence suggesting that dogs may have ‘lost’ some problem-solving abilities in comparison with wolves, although they may have gained some communicative abilities with humans [7xA simple reason for a big difference: wolves do not look back at humans, but dogs do. Miklosi, A et al. Curr. Biol. 2003; 13: 763–766Abstract | Full Text | Full Text PDF | PubMed | Scopus (254)See all References][7]. Note that dogs and wolves shared an ancestor relatively recently – approximately 100 000 years ago [8xMultiple and ancient origins of the domestic dog. Vila, C et al. Science. 1997; 276: 1687–1689CrossRef | PubMed | Scopus (515)See all References][8].So when it comes to a progressive increment of capacities one has to be cautious and take into consideration selective pressures that have operated on each species over evolutionary time. For instance, neocortex in mammals has been associated with social intelligence and frontal cortex is thought to be ‘the seat of higher cognitive functions’ (p. 25). However, birds also show social complexity and complex cognition without a cortex. This illustrates that there is more than one path to complex cognition – and humans do not have the patent on all of them.In conclusion, this is a highly stimulating book that, in my opinion, could have been even better if the author had taken a broader comparative and evolutionary perspective. In the end, we are left with the impression that self-consciousness, seeking hidden causes, planning for the future, time-awareness and free will are uniquely human skills. However, we should acknowledge that in reality we do not know whether this is the case because these topics have not received much comparative research attention yet. It is acceptable to presume human uniqueness in these cognitive functions as a working hypothesis from which to test other species, but we should be ready to change our theories if and when new evidence proves them inaccurate. More importantly, we should also not fall into the trap of expecting that those functions, once they are properly investigated in other species, will be identical to those found in humans in every detail.Humans are by definition unique, just like any other species on the planet. Thus, whether other animals think like us is not, in my view, a very interesting question. A better question is how other animals think. It is only when we abandon the idea of a scale with humans at the top and begin to learn more about the diversity of cognitive systems in nature that we will begin to better understand how humans (and some other animals) became sapiens.