Earth history is punctuated by a huge variety of transitions and perturbations in climate and global biogeochemical cycling. These may be linked to major extinctions or evolutionary innovations, and may exhibit evidence for greenhouse warming and CO2 release and hence potentially hold direct future-relevant information. However, in interpreting proxy measurements in terms of the nature of past environmental change, very different modes of biological productivity in the ocean and carbon cycling have been invoked. This should not be a surprise, as evolutionary innovations have the potential to give rise to profoundly different behaviours of the biological `pump´ in the ocean further back in time. But given the still rather incomplete understanding regarding how the modern marine carbon cycle works, evaluating these ideas is not entirely straightforward. In this seminar I will illustrate, in numerical model-world, some of the currently topical ideas regarding what controls the biological pump today (`ballasting´, temperature and metabolic rate, and dissolved organic matter) and what the implications of enhancing or suppressing them are for our understanding of the geological record.