Mormyrid Fish Brain
figure 7.11 Longitudinal section through the brain of a mormyrid fish. Note, in particular, the immense size of the cerebellum, which comprises all parts of the brain above the dotted line. The various parts of this hypertrophied structure include the remarkable valvula cerebelli Va , the central cerebellar lobes C1 to C4 , the crista cerebellaris Cr , the electrosensory lateral line lobe ELL , the transitional cerebellar lobe TL , and the caudal cerebellar lobe CL . Total length of the brain...
Info Qdg
See J. D. Currey et al. in Proceedings of the Royal Society of London B, vol. 268, pp. 107-111, 2001, and also V. de Buffr nil and A. Casinos in Annales des Sciences naturelles, Zoologie, Paris, vol. 16, pp. 21-32, 1995. J. D. Currey 1999, citation is in note 28 , p. 3289. In his paper Currey also draws attention to the convergence between the teeth of the sea urchins on which see R. Z. Wang et al. in Philosophical Transactions of the Royal Society of London B, vol. 352, pp. 469-480, 1997 ,...
Key
gt 1 Jupiter mass gt 1-4 Jupiter masses gt 4-11 Jupiter masses gt 11 Jupiter masses figure 5.3 A sample of extra-solar planets, scaled to our Solar System and the size relative to Jupiter. An astronomical unit is the distance from the Earth to the Sun, and is equivalent to 1.49 x 1011 m. Data taken from websites given in note 33. unimaginable. As we shall see later Chapter 6 , this has not prevented speculation about possible forms of life, although such hypotheses are unlikely to be...
returning the gaze
Yet, concerning the eyes there is an obvious difference.20 Vertebrates, including humans, use a camera-like arrangement, whereas the crabs employ the compound eye that is typical of most arthropods. Has the principal of convergence broken down Not at all, because it is among eyes that we find some of the most compelling examples. The existence of camera- and compound eyes reminds us, of course, that solutions to biological evolution need not be unique, but are simply very strongly...
The nonprevalence of humanoids
What we know of the social insects, and especially the extraordinary organization of agriculture and warfare among the ants, is striking both in terms of their convergence and in the almost alien nature of these complex societies. Certainly the jointed skeletons, the compound eyes, the miniaturized clones, and apparently robotic social organization are a familiar staple of science fiction. Suppose that there are advanced extraterrestrials will they be like us, at least vaguely hu-manoid, or so...
giant brains
The many convergences documented in the last chapter, from the agriculture of ants to the vocalization of birds, are strong evidence that the evolutionary emergence of many complex systems is highly probable, if not inevitable. Yet the sceptic will still pause in thought. figure 9.1 Jack standing against the trolley with Mr Wide note the lever frame in the background. Photograph courtesy of Euan Nisbet, Royal Holloway, University of London. figure 9.1 Jack standing against the trolley with Mr...
ii Towards a theology of evolution
Let us suppose that I am an immensely successful biochemist, and happen to be engaged in experiments involving gene manipulation. A couple of years ago I was attending a conference - keynote speaker, naturally - when I fell into conversation with a curious individual, who for some reason seemed much older than he actually looked. As we talked, it seemed we were walking across a plain of infinite dreariness, but his voice, his demeanour, how can I describe it He knew all about our work, and as...
converging on the ultimate
Giant brains, tool use, bipedality, and even a precision grip are not, therefore, specific to humans. To be sure, in our species they are each developed to a high order, but their independent emergence suggests that in principle there is no reason why they could not be similarly honed. Still, that does not rule out the possibility that the human lineage possesses unique features, which if lost by some chance would never be able to evolve again in the contingent turmoil of continuing evolution....
universal rhodopsin
As it happens, a number of other proteins can act as light receptors, and they too provide some illuminating cases of convergence. Yet the rhodopsin molecule seems to offer various advantages as Russell Fernald156 has remarked, in the context of vision although an opsin 'is not the only way to detect light it has proven irresistible for use in eyes'.157 Rhodopsin is remarkably widespread, and apart from its near-universal adoption in the various visual systems this molecule has long been known...