Matter as such produces nothing, changes nothing, does nothing; and however convenient it may afterwards be to abbreviate our nomenclature and our descriptions, we must most carefully realize in the outset that the spermatozoon, the nucleus, the chromosomes or the germ-plasma can never act as matter alone, but only as seats of energy and as centres of force.Science is a human endeavor that is rarely if ever just about science: it is also a social, political, and economic enterprise. As such (...) it is structured around an ethos: a belief system, or theory, that accounts for the nature of relevant aspects of existence. Much like other belief systems in the broader culture in which they occur, we build stories in defense... (shrink)

For at least a century it has been known that multiple factors play a role in the development of complex traits, and yet the notion that there are genes “for” such traits, which traces back to Mendel, is still widespread. In this paper, we illustrate how the Mendelian model has tacitly encouraged the idea that we can explain complexity by reducing it to enumerable genes. By this approach many genes associated with simple as well as complex traits have been identified. (...) But the genetic architecture of biological traits, or how they are made, remains largely unknown. In essence, this reflects the tension between reductionism as the current “modus operandi” of science, and the emerging knowledge of the nature of complex traits. Recent interest in systems biology as a unifying approach indicates a reawakened acceptance of the complexity of complex traits, though the temptation is to replace “gene for” thinking by comparably reductionistic “network for” concepts. Both approaches implicitly mix concepts of variants and invariants in genetics. Even the basic question is unclear: what does one need to know to “understand” the genetic basis of complex traits? New operational ideas about how to deal with biological complexity are needed. (shrink)

The mammalian dentition is a segmented organ system with shape differences among its serially homologous elements (individual teeth). It is believed to have evolved from simpler precursors with greater similarities in shape among teeth, and a wealth of descriptive data exist on changes to the dentition that have occurred within mammals. Recent progress has been made in determining the genetic basis of the processes that form an individual tooth, but patterning of the dentition as a whole (i.e. the number, location (...) and shape of the teeth) is less well understood. In contrast to similarly organized systems, such as the vertebral column and limb, Hox genes are not involved in specifying differences among elements. Nevertheless, recent work on a variety of systems is providing clues to the transcription factors and extracellular signalling molecules involved. (shrink)

Two recent papers1,2 report extensive nuclear DNA sequence from a 38,000‐year‐old Neandertal fossil, comparing it to modern humans and estimating when it diverged from, and whether it contributed to, our gene pool. Based on 65,250 and over a million base‐pairs of sequence across the genome, respectively, the groups arrived at slightly different interpretations. The data are an exciting and interesting new contribution, but are not surprising, and a sense of history and question helps put them in perspective. BioEssays 29: 105–110, (...) 2007. © 2007 Wiley Periodicals, Inc. (shrink)