How the Leopard Changed Its Spots : The Evolution of Complexity
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Do genes explain life? Can advances in evolutionary and molecular biology account for what we look like, how we behave, and why we die? In this powerful intervention into current biological thinking, Brian Goodwin argues that such genetic reductionism has important limits.
Drawing on the sciences of complexity, the author shows how an understanding of the self-organizing patterns of networks is necessary for making sense of nature. Genes are important, but only as part of a process constrained by environment, physical laws, and the universal tendencies of complex adaptive systems. In a new preface for this edition, Goodwin reflects on the advances in both genetics and the sciences of complexity since the book's original publication.
fields of particular kinds, as we shall see in more detail in the next chapter. The hereditary material plays a very important role in stabilizing certain aspects of this spatial and temporal order. But it does not generate the order, and it is no more immortal than is the rest of the organization of the cell on which it depends for its replication. However, there is one very important respect in which the DNA is special and exceptional. It is the only macromolecular constituent of a cell that is
resulting in a mixed batch of females and males. Below 26°C and above 36°C the eggs fail to develop, so there are often undeveloped eggs in a nest. This species uses an environmental variable to regulate its sex ratio. 40 How the Leopard Got Its Spots Most species do this via genes, as in humans with X and Y chromosomes-XX for a female, XY for a male. The result is a near fiftyfifty sex ratio, and this genetic method of determining sex seems to be a much more sensible way of regulating what
of this data, which reveal any prominent rhythms as frequencies, show well-defined frequency peaks. The activity is still quite "noisy," for some individual ants continue to be active when the majority are at rest, and some are at rest during activity bouts of the colony as a whole. In contrast, among individuals or small colonies, the absence (e) (a) ':~~ f 6000 .!1 4000 2000 0 l'--r gf'100000 ::E 100 200 300 400 3 4000 2000 150000 1100000t gp 50000 ::E 500 630 760 890 1020
Genericity The patterns of phyllotaxy in higher plants are clearly candidates for generic biological forms-naturally stable states of a generative process in the developing organism, in this case in the meristem. What role do genes play in producing these? As suggested in the preceding chapter, genes define the region of parameter space where a particular species starts its development. This is determined by such quantities as the turgor pressure within the cells of the meristem, the mechanical
specific protein. These are the two extraordinary jobs that the DNA can do. Of course, the DNA does not achieve these feats on its own. There is an elaborate machinery of other molecules and structures inside cells that are essential for DNA copying (replication) and for the production of mRNA 4 Whatever Happened to Organisms? 5' 3' \ Ho, 5._,.. H H ,...c..._ 4'/. H/ 0 '-.....,y/OH C H H C '-.1 I / 'H J•C-Cz• I OH I H ¥ OH here m ribose maJor groove . / mmor groove 5' Figure 1