Two hundred years after Darwin’s birth, the theory of evolution is still evolving — and finding relevance in realms far outside the biological.
Evolution is being scaled up to the level of populations, even whole ecosystems. Moreover, scientists say evolution is intertwined with other dynamics in ways science is just starting to understand.
"The process of evolution is fundamental to the universe,” said Carl Woese, a University of Illinois at Urbana-Champaign microbiologist and one of the first proponents of this newly revised evolutionary framework. “Biology is the most obvious manifestation of it.”
Darwin described how changes in an organism are passed from generation to generation depending on their contribution to survival. Biologists later combined this with genetics, which hadn’t been discovered in Darwin’s time.
The fusion — called neo-Darwinian evolution — describes evolution as we know it today: Genetic mutations produce changes that can become part of a species’ heritage and, when enough changes accumulate, produce new species.
It’s one of the most powerful descriptions of the world dreamed up by humans, central to understanding the natural world and applicable to engineering, economics and even software design.
But to Woese and other scientists, neo-Darwinism isn’t so simple. Change and selection need to be studied at other levels — and there are lots of big, unanswered questions.
Bacteria, for example, engage in what’s known as horizontal gene transfer: Genes drift from one microbe to another without any need for reproduction. What this means for microbiology isn’t yet clear, let alone biological history — how did multicellular organisms evolve, anyway? But it’s hugely important to figure out.
Another mystery is the tendency of some genes to mutate at unusually high rates. The driver appears to be a process called biased gene conversion, which goes against the notion that evolution is driven by random mutations. Natural selection still operates on its outcome, but is not driving the process itself.
Scientists are also studying evolution at levels beyond the single organism. Some insect colonies — ants and honeybees being the best-known examples — can be collectively regarded as individuals, known as superorganisms.
Superorganism dynamics are still a mystery — how, for example, does a colony evolve different traffic rules? — but they may apply to other ecological collectives, including human societies.
When taking this macro-scale approach, some of the trickiest non-Darwinian evolutionary phenomena become apparent. Properties emerge at critical points — known as saltations — in complexity, but again can’t be explained by mutation and selection in a sub-unit of the whole.
Superorganisms, for example, are sometimes the only way to make sense of phenomena like eusociality, in which individual insects care for offspring unrelated to them.
Another example of this may be the jump from unicellular to multicellular life; another may be the fantastic forms taken by human societies in a networked age, with millions of once-isolated people linked by data networks whose visual representations are uncannily similar to the neural connections of a brain.
Evolution has moved not only beyond the individual, but beyond the biological. It is being used to understand the transition of a few primitive compounds to the chemical building blocks of life. Somewhat more pertinently, language seems to evolve towards efficient, easily propagated linguistic constructs.
Applying an evolutionary framework to language may seem strange, but at least it’s relatively simple. Cultural evolution, on the other hand, may be just as complicated as biological evolution.
Selection and mutation — and whatever other biological analogues apply — may act simultaneously at the levels of the meme, of traits like boat design or tool use, and of entire bodies of thought.
What, exactly, is a cultural organism — and how does its evolution affect the development of, say, individual humans and their community, which itself might be an organism?
Maybe by the time Darwin turns 300, we’ll have some answers.
Images: WikiMedia Commons / Polaroid.sx70, from our Darwin Photoshop Tennis contest.
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