Gene expression and the concept of the phenotype

Ohad Nachtomy, Ayelet Shavit, Zohar Yakhini

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


While the definition of the 'genotype' has undergone dramatic changes in the transition from classical to molecular genetics, the definition of the 'phenotype' has remained for a long time within the classical framework. In addition, while the notion of the genotype has received significant attention from philosophers of biology, the notion of the phenotype has not. Recent developments in the technology of measuring gene-expression levels have made it possible to conceive of phenotypic traits in terms of levels of gene expression. We demonstrate that not only has this become possible but it has also become an actual practice. This suggests a significant change in our conception of the phenotype: as in the case of the 'genotype', phenotypes can now be conceived in quantitative and measurable terms on a comprehensive molecular level. We discuss in what sense gene expression profiles can be regarded as phenotypic traits and whether these traits are better described as a novel concept of phenotype or as an extension of the classical concept. We argue for an extension of the classical concept and call for an examination of the type of extension involved.

Original languageEnglish
Pages (from-to)238-254
Number of pages17
JournalStudies in History and Philosophy of Science Part C :Studies in History and Philosophy of Biological and Biomedical Sciences
Issue number1
StatePublished - Mar 2007

Bibliographical note

Funding Information:
We would like to thank Rafael Falk, Emily Grosholz, Oren Harman, Yaron Ramati, and two referees of this journal for very helpful comments and critical reading of early versions of this article. Finally, we would like to thank the Israeli Science Foundation, grant number 354/06 and The Mobility 6 program, Marie Curie (OIF), no. 040436, for supporting this research.


  • Concept extension
  • Gene expression
  • Genotype
  • Phenotype


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