Lignin is a primary structural (strengthening) component of wood.1 It enables land plants to support themselves as they grow upward through the air, and is crucial to transporting water from roots up to the leaves. It has long been thought, and taught, that this feature is unique to land plants because aquatic plants, nicely bathed and supported by the surrounding water medium, do not have any lignin.
That textbook teaching is overturned now, however, by the discovery of lignin in marine algae.
Not a big deal, you might think, except that this discovery “has major evolutionary implications”.2 As the lead researcher, University of British Columbia Assistant Professor Patrick Martone, explained:
All land plants evolved from aquatic green algae and scientists have long believed that lignin evolved after plants took to land as a mechanical adaptation for stabilizing upright growth and transporting water from the root.3
Hitherto, according to evolutionary theory, lignin evolved on land about 475 million years ago, so this discovery pushes its mooted evolutionary origin earlier than that. In fact, much earlier, because the aquatic lignin wasn’t discovered in green marine algae, but red—specifically, the intertidal red alga seaweed Calliarthron cheilosporioides—i.e. on a completely different branch of the ‘evolutionary tree’:
Because red and green algae likely diverged more than a billion years ago, the discovery of lignin in red algae suggests that the basic machinery for producing lignin may have existed long before algae moved to land.3
So, this discovery is forcing a dramatic “billion-year revision”3 of the plant evolution timeline in textbooks. But the story isn’t set in concrete yet, because some evolutionary researchers, no doubt aware of the flow-on ramifications of pushing the origin of lignin back to more than a billion years ago, are leaving open the possibility that lignin arose in marine red algae and land plants independently (what they refer to as ‘convergent evolution’). They note that windy weather stimulates lignin production in land plants, and that a similar phenomenon seems to be at work in red algae (“As articulated fronds bend back and forth under breaking waves … lignin biosynthesis … may be mechanically stimulated by bending stresses”).2 And so they suggest the selection pressure from surging surf favoured the evolution of the machinery for lignin production in seaweed:
Selective pressures in the marine environment differ from those on land, but the wind-induced drag forces that presumably contributed to the evolution of wood in terrestrial plants are mirrored by flow-induced drag forces on aquatic algae.2
However, proposing independent evolutionary origins of lignin production raises another problem. That’s because “the basic machinery for producing lignin” is no small matter, as study co-author Mark Denny, Professor of Biology at Stanford’s Hopkins Marine Station, bluntly pointed out in a news release:
The pathways, enzymes and genes that go into making this stuff are pretty complicated, so to come up with all those separately would be really, really amazing. Anything is possible, but that would be one hell of a coincidence.3
In fact, in their scientific paper, Martone, Denny and colleagues didn’t just use the phrase “pretty complicated” but rather “exceptionally complex”!2 Therefore they stated in their paper’s conclusion that it “seems unlikely” that marine red algae and land plants evolved the lignin-producing machinery completely independently (i.e. the researchers instead leaning toward a single evolutionary origin over a billion years ago). One might reasonably paraphrase them thus: It’s hard enough that lignin production evolved once, let alone twice.4
Actually, one of the words used by the researchers themselves in their paper holds the key to unlocking what’s really at issue here—the word innovation:
Lignified cell walls are widely considered to be key innovations in the evolution of terrestrial plants from aquatic ancestors …2
An innovation is something new, that didn’t previously exist. Winds, waves and currents might well act as agents of natural selection5 to favour plants that already have the machinery to produce lignin, but they will never produce such “exceptionally complex” machinery. You can’t get machinery, no matter how basic, out of ‘thin air’, no matter how strongly the wind blows, and no matter how long you might wait (even billions of years!).6 Nor from surf, either—as shipwreck survivors would testify; breaking waves smash things, and the longer the buffeting, the worse the damage.7
In short, innovation requires an innovator—and the Bible tells us who that was: the Master Innovator, our Creator, who made the heavens, the earth, the seas, and all that is in them in just six days (Exodus 20:11),8 only about 6,000 years ago.9