Or Why Metaphors are Dangerous
Language is imprecise. Language is especially imprecise and imperfect when it comes to describing scientific concepts. And the irony of using the tools of language to write about its own shortcomings is not lost on me.
Think about the oft repeated phrase – “survival of the fittest” and how it is used in school science textbooks to describe the theory of evolution and especially the concept of natural selection.
Darwin came up with the concept of natural selection in the first edition of On the Origin of Species (1859). It explains how certain traits become more or less common in a population over generations, based on their impact on an organism’s ability to survive and reproduce.
The term “survival of the fittest” was coined by Herbert Spencer in his book Principles of Biology. He coined this phrase after reading Darwin’s work as he wanted to describe natural selection in simpler, more general terms. Spencer was a philosopher and sociologist and wanted to align his theories on social and economic competition with Darwin’s ideas. Darwin clearly liked the simplicity of “survival of the fittest” as he adopted it in later versions of his book, but clarified that it was only a metaphor.
Over the past one and half centuries though – the extreme adoption of this metaphor has essentially meant that most people have misunderstood evolution and natural selection. Evolution happens at a population level. It is not about the individual and it doesn’t happen over one generation. Sometimes it is gradual and sometimes it is precipitated by the onset of extreme sudden external factors. And “fittest” does not mean strongest or best or toughest or most aggressive. Sometimes the average survive.
We grew up with this image of three giraffes: the first one had a really short neck and couldn’t reach the leaves on a tree, the second one had a longer neck but still not long enough to reach the leaves and the third one had the longest neck and was happily munching on the leaves. Giraffes with the longest necks survived – so giraffes now have long necks.
But this type of natural selection (as opposed to artificial – as in the case of crops and dog varieties) is only one of three types of natural selection. It is called directional selection. It occurs when one extreme phenotype (an observable trait or characteristic of an organism) is favored over others, causing the population’s traits to shift in a particular direction.
Example: The Peppered Moth (Industrial Melanism)
- In pre-industrial England, light-colored peppered moths were more common because they blended well with light-colored tree bark.
- During the Industrial Revolution, soot darkened the trees, making dark-colored moths better camouflaged.
- Over time, the population shifted toward more dark-colored moths because predators could easily spot the lighter ones.
The second type is stabilizing selection (or equilibrium selection). This occurs when intermediate phenotypes are favored, and both extremes are selected against. This maintains the status quo and reduces variation in a population.
Example: Human Birth Weight
- Babies with very low birth weight are more likely to suffer from health complications, while very large babies may cause complications during delivery.
- The intermediate birth weight (around 6.5-8.5 pounds) has the highest survival rate, so this trait is favored.
The last type is called disruptive selection. This occurs when both extreme phenotypes are favored over the intermediate phenotype. This can lead to a population splitting into two distinct groups.
Example: Beak Size in African Seed-Cracking Finches
- In environments where only large, tough seeds and small, soft seeds are available, birds with either very large beaks (to crack tough seeds) or very small beaks (to efficiently eat soft seeds) are favored.
- Birds with medium-sized beaks are less efficient at handling either seed type and are selected against.
- Over time, the population diverges into two distinct groups.
The more I think about these different types of natural selection, the more I am inclined (perhaps foolishly) to apply this theory to start ups and products. The genetic instructions (culture, people, founders) and the environment (market, economic conditions) combine to give rise to observable traits and characteristics (product, marquee VCs, funds raised). But as we have seen, extremes are not the only “victors”. The “best” product doesn’t always win. The most funded startups sometimes go belly-up.
But I am re-reading the first paragraph again and realizing that I am falling for a trap sprung by the imprecision of language. Metaphors are dangerous.