Several authors suggested that there are dimensionless ratios of key biological parameters which are invariants across different species. In a recent paper published in Science.2005;309:1236-9 Nee et al. show that these studies would create in fact an illusion. They write "essentially, this is because life-history variables have been regressed against themselves". That suggest to me two questions for this forum: What is your opinion on the statistical Nee's reasoning? If Nee at el are true, how would we search for invariants? Are you in agreement with the approachs suggested by Nee et al in their paper?