Publications on the 16 yeast chromosome sequences group together over 400 different authors from Europe, Japan, Australia and the USA. When research is not organised in networks, it is carried out in large sequencing centres such as the Sanger Centre in Britain, the Helix Institute in Japan or Saint Louis University in the USA. Both cases illustrate the collective nature of knowledge creation. Other examples of co-operation between numerous researchers in various countries, more closely related to innovation, might also be mentioned, such as the development of software for comparing proteins or DNA sequences. Collective publications reveal the collective nature of research, whether it is carried out by major consortia (the case of yeast) or around large research facilities (such as the synchrotron or major genome sequencing centres). This collective nature stems from two factors: (1) the advantages of co-ordinating efforts on major projects (e.g. economies of scale and of collection) and (2) very strong interdependency in the creation and utilisation of knowledge (related to cumulativeness).