What’s a black smoker?
A black smoker is a hot undersea volcanic vent belching sulphur, typically found today in the peaks of the midoceanic ridges, where the continental plates are spreading apart.
Hydrothermal vents in the primeval sea1 have been posited as one potential site for the origin of life, for a host of reasons—not the least of which is that the hot waters, rich in sulphur, are ideal environments for the chemolithoautotrophic hyperthermophilic archaea2. These organisms frequently thrive in warm and hot waters, and require sulphur as a fundamental part of their metabolisms—and thus find the environment of such vents quite amenable.
One group of such organisms from within the Archaea3—the Korarchaeota—are believed to be the most similar of extant organisms to the most recent common ancestor of all life4, following studies of the relative similarities between species of the highly conserved ribsomal RNA molecules common to all life—in other words, all life we know may be descended from something very small, that liked hot, sulphurous waters. This, along with other potentially advantageous qualities of the environments for the formation of life from nonliving precursors, has lead to the interest in such vents5 as the potential cradle of all life in our biota.
Why the name?
The applet is named as it is because it models a relatively simple, relatively self-contained environment, in which relatively simple6, asexual life forms that synthesize their own food are the root of the metabolic chain. As is the case in black smokers.
Note however that while this applet does model a lot of things, it doesn’t presume to take a stab at the origin of life itself—the illustration here is meant primarily to be the shaping effect of natural selection on random variation in originally functioning units. Though yes, you may see previously ‘junk’ genes actually start doing something useful if you watch long enough, this is still a long way from modelling the start of self-replication itself. Apologies to anyone who got unduly excited about the choice of name.
Further reading
On black smokers—Cindy Lee Van Dover’s The Ecology of Deep-Sea Hydrothermal Vents (Princeton, 2000) is accessible enough for the serious amateur, and gives a nice overview of the state of the science at the time of its printing.
Richard Fortey’s Life—a natural history of the first four billion years of life on earth (Random House, 1997) is readable, nontechnical, even engrossing, and provides a very accessible, though brief, description of the hydrothermal vent origin hypothesis, in the course of a travelogue that moves throughout the geologic ages, describing natural history over the long haul, after the current theoretical perspective.
On the origin of life—A web version of Mike Russell et al’s “The emergence of life from iron sulphide compartments at a submarine hydrothermal redox and pH front” paper on alkaline hydrothermal vents as the site of the emergence of life is at http://www.gla.ac.uk/projects/originoflife7.
On cold seeps—Van Dover’s book (above) discusses these in some detail as well. See also http://bonita.mbnms.nos.noaa.gov/sitechar/cold.html, for a biological overview of the seeps in Monterey Bay, California, USA.
Also worth a read, short, and aimed at a general audience, is A.G. Cairns-Smith’s Seven Clues to the Origin of Life (Cambridge 1985), in which the microcrystalline precursor hypothesis (the idea that organic life arose on a scaffolding consisting of self-replicating clays) is described, in the context of a lengthy description of the formidable difficulties facing any theory of the genesis of life from nonliving precursors.
— Last update 03/05/2011
Notes
1 An earlier version of this page also mentioned (cold) pyritiferous seeps as being of interest. My understanding is the current hypothesis focuses rather on the warmer vents—principally because the steep temperature gradients allow more diverse reactions. A (hydrothermal) vent is a hot chimney, usually associated with spreading centres. A (cold) seep is a colder formation, though also generally quite mineral-rich, not necessarily so associated—seeps occur in more varied areas than do vents. Note also, however, that technically, the vents of currently greatest interest in this regard are not the hottest, acidic black smokers, but rather cooler (though still warm) alkaline vents—see also note 5.
2 The uncomfortably long “chemolithoautotrophic hyperthermophilic” designation is just a description—it means they make their own food from inorganic precursors (as do photosynthesizing plants) but that the source of the metabolic energy is a chemical one (in this case, the transformation of FeS to FeS2) as opposed to a photosynthetic one, and that their preferred environment is really, really hot. The “archaea” term identifies the kingdom— see note 3 for more on these.
3The Archaea—formally and briefly referred to as the “Archaebacteria”—are one of the three kingdoms of life—distinct both both from Eukaryota and Eubacteria in several important ways. See the UCMP’s An introduction to the Archaea for more on the group.
4This interpretation, is, for the record, disputed, by some, and very little is known of the group as yet. There’s a sequencing project in progress, however, which will presumably resolve this. Note also that, as a matter of clarification: the known Korarchaeota are chemolithoautotrophs and thermophiles, but were found in a terrestrial hot spring, not in a deep-sea vent.
5While this applet system has long been named AJ’s Black Smoker, and previous versions of this page did talk about the hydrothermal vent/origin of life theory as ‘the black smoker hypothesis’, this is something of a misnomer, and potentially misleading, as black smokers, specifically, are acidic and hot, and Mike Russell (see Further Reading), a principal champion of the hypothesis that hydrothermal vents might have been the seat of the origin of life, identifies rather cooler (though still warm) alkaline vents as the likely location. See also the correction in the notes below. Microbial life at black smokers, does, however, go back quite some time on the basis of fossil evidence—though not to the purported origin of life—see the discussion here, re such evidence, and re the distinction, and this page, re the broader ‘sulfur world’ theory (Note added 2011 May).
6 All things being relative. Before anyone gets disparaging about these organisms being “primitive” in some vaguely pejorative sense, you try living at 90 degrees Celsius, in water thick with sulphur. While the archaea may be “primitive” in the sense of their place on the relative ribosomal sequence map, and relatively simple (against metazoans, at least) in terms of morphology, those who know and love them may legitimately praise them as intricately, brilliantly adapted creatures in their own right.
7 Earlier versions of this page stated here that Russell talks about black smokers as the origin of life. Russell, however, specifically identifies rather cooler alkaline hydrothermal vents as the likely site; see also note 5.