Center for the Philosophy of Biology

The maximum size of organisms has increased enormously since the initial appearance of life >3.5 billion years ago (Gya), but the pattern and timing of this size increase is poorly known. Consequently, controls underlying the size spectrum of the global biota have been difficult to evaluate. Our period-level compilation of the largest known fossil organisms demonstrates that maximum size increased by 16 orders of magnitude since life first appeared in the fossil record. The great majority of the increase is accounted for by 2 discrete steps of approximately equal magnitude: the first in the middle of the Paleoproterozoic Era (approximately 1.9 Gya) and the second during the late Neoproterozoic and early Paleozoic eras (0.6-0.45 Gya). Each size step required a major innovation in organismal complexity--first the eukaryotic cell and later eukaryotic multicellularity. These size steps coincide with, or slightly postdate, increases in the concentration of atmospheric oxygen, suggesting latent evolutionary potential was realized soon after environmental limitations were removed.

Page 1. The Tendency for Diversity & Complexity to Increase in Evolutionary Systems BIOLOGY'S FIRST LAW DANIEL W. MeSHEA & ROBERT N. BRANDON Page 2. Biology's First Law Page 3. Page 4. Biology's First Law The ...

Our special Issue on Evolutionary Patterns for the Journal Evolutionary Biology is out now. Many thanks to the editor-in-chief, Benedikt Hallgrimsson (http://www.ucalgary.ca/morpho/personnel), for providing us with an excellent venue, to the authors for contributing, and to Eveline Kolijn for the artistic cover (http://evelinekolijn.com/?project=evolutionary-patterns).

Springer is granting free access to the full issue through December 31st, 2016 at http://link.springer.com/journal/11692/43/4/page/1

Feel free to leave comments on the issue in this session!