Sadly, we don’t have time machines that would permit us to go back and see ancient evolution in action. So we have to make do with such devices and stratagems as inference, surmise, speculation, good honest-to-goodness old-fashioned guesswork, and investigating modern-day equivalents that might mimic the original phenomenon. Take for instance colonisation of the land by ‘plants’. Arguably, this was one of the most important events in creation of the modern-day planet we call home, but how could ‘terraphyte’s’ ancestors survive a much drier land-living existence and thus pave the way for a terrestrial take-over? Trying to get a handle on early plant adaptation to land, Linda Graham et al. have studied how well assumedly obligately aquatic algae could survive an ‘aeroterrestrial’ existence (i.e. living on and in soil, or covering surfaces such as rocks and tree barks; http://www.algaterra.org/AT5.htm). The group used ‘two species of the experimentally tractable, complex streptophyte algal genus Coleochaete’, chosen because it is one of the extant green algal genera most closely related to the embryophytes – the so-called ‘land plants’ ( see Burkhard Becker and Birger Marin’s Botanical Briefing in Annals of Botany) – and therefore a plausible putative palaeological plant progenitor. What they discovered suggests that ancient complex streptophyte algae could grow and reproduce in moist subaerial habitats, and persist through periods of desiccation – as you’d need to in order to occupy a drier habitat. Consequently, land colonisation could be envisaged by ancient Coleochaete-like organisms (which are freshwater aquatics). Which is good to know, and also accords with the very latest ideas in terms of identifying the nebulous ‘crucible of creation’, which may not have been the oceans – as long thought – but freshwater ponds, according to work by Armen Mulkidjanian et al. (PNAS). Whilst this may upset the apple-cart of received wisdom in that field in challenging firmly held, long-cherished beliefs, at least it’s still arguing for an important aquatic dimension (even though it can be argued that it actually proposes that life on Earth originated on land – but let’s leave further deliberation thereon to the semanticists…). But! – and as pointed out by others – this 21st Century idea is reminiscent of the notion that evolution may have begun in a ‘warm little pond’, posited by a certain Mr C. Darwin in 1871. Which only goes to show that there’s practically nothing in biology that has not already been created by CD (and that ideas about evolution just keep evolving!).
[Mr Cuttings thought he’d invented the word terraphyte in penning this item. Well, he had, but not originally it would seem. In a ‘covering his backside’ moment, an internet search has revealed that the term has been used previously by ‘aquetus’ – interestingly in an article that has a strong warning about plagiarism – Ed.]