In my chapter CLEVER CORVIDS I review a great deal of work that suggests (but does not satisfactorily prove - any more than the chimp research) that corvids - crow family birds - can operate abstract causal rules in tool manufacture, selection and use - and not just rely on lower-level cognition such as that provided by reinforcement. In this paper the New Zealand scientists who work with New Caledonian crows significantly up the ante in trying to convince us that something high-level is going on. Here, as the abstract below spells out - they asked the crows to perform a complex 3-stage metatool problem (the use of a tool upon a tool...). Truly amazing. See GENE EXPRESSION's link from my blog side-bar section for an article with a piece of video of the task. The experiment has proved so eye-catching that it merits a section on the editorial page of today's Guardian newspaper!! Fame assured!
"Apes, corvids and parrots all show high rates of behavioural innovation in the wild. However, it is unclear whether this innovative behaviour is underpinned by cognition more complex than simple learning mechanisms. To investigate this question we presented New Caledonian crows with a novel three-stage metatool problem. The task involved three distinct stages: (i) obtaining a short stick by pulling up a string, (ii) using the short stick as a metatool to extract a long stick from a toolbox, and finally (iii) using the long stick to extract food from a hole. Crows with previous experience of the behaviours in stages 1–3 linked them into a novel sequence to solve the problem on the first trial. Crows with experience of only using string and tools to access food also successfully solved the problem. This innovative use of established behaviours in novel contexts was not based on resurgence, chaining and conditional reinforcement. Instead, the performance was consistent with the transfer of an abstract, causal rule: ‘out-of-reach objects can be accessed using a tool’. This suggests that high innovation rates in the wild may reflect complex cognitive abilities that supplement basic learning mechanisms."
Are we humans simply remodelled apes? Chimps with a tweak? Is the difference between our genomes so minuscule it justifies the argument that our cognition and behaviour must also differ from chimps by barely a whisker? If “chimps are us” should we grant them human rights? Or is this one of the biggest fallacies in the study of evolution? NOT A CHIMP argues that these similarities have been grossly over-exaggerated - we should keep chimps at arm’s length. Are humans cognitively unique after all?
Wednesday, 21 April 2010
How Important Are Gene Expression Changes To Morphological And Physiological Evolution?
In my chapter THE RIDDLE OF THE 1.6% I try to resolve the age-old question of how two closely-related species at the DNA sequence level - humans and chimpanzees - could be so different at the level of morphology, physiology and, of course, cognition. Part of the answer lies in the importance of the evolution of a large number of ways in which gene activity is regulated - how hard genes work to produce protein, and when they do it. But, in a general sense, how important is this phenomenon of gene expression to the evolution of any organism? In this paper, Jianzhi Zhang and colleagues analyze over 5,000 mouse genes, some of which influence morphological features, others physiological ones. They found that "morphogenes" evolve faster in terms of expression than in DNA gene sequence compared to "physiogenes". They "are grossly enriched with transcriptional regulators". This, they say, is because morphogenes are more likely to be essential and pliotropic (affecting more than one morphological aspect of the phenotype) and are less likely to be tissue specific. There is thus an increased likelihood, via sequence evolution, of throwing a genetic spanner into a complex works, which is why gene expression routes to phenotypic change have been favoured.