Does Evolution Have a Direction?


Makes me go ballistic every time (says my wife) – here’s another example of anthropomorphic description of how evolution seems to have a purpose, in the sense of proactive adaptation (“driving”) versus what I claim MUST be viewed as passive filtering by an always-changing environment.  

Through random mutation, evolution is relentlessly tinkering with the animal body plan, driving species toward diversification and various modes of living.

And this from the Skeptic! No, evolution is a result and not a cause. The cause is always the simplest conceivable cause that could exist: change. Time is change, change is time, that is all we know and all we need to know to understand evolution. The sentence should read something like this: 

Through never-ending change in the external environment – some of which life feeds back into, for example a growing reef newly shading the bottom beside it – species thrive or fail according to how well they happen to fit today’s conditions and how well their offspring, randomly mutated, happen to fit tomorrow’s evolving conditions. Environmental changes filter changes in species.

 Do I make sense? Does it matter? Clearly I think it does…


First, I’d say that as most mutations are either harmful or neutral, it makes more sense to say that species tend toward extinction, not toward “diversification and various modes of living.” Indeed, what has happened nearly every species that has ever appeared?

Next I’d say that as life begins with simple forms, and there is a minimum in the direction of simplicity (that is, not being alive, and the first organisms, we’d guess, were just barely complex enough), it appears as if evolution tends to greater complexity. Viewing all life together as it changes over time, the mean or median species tends to become more complex because the ecological niches with more complex forms start off vacant. I recall reading in Stephen Jay Gould that when the paleontologists pick some starting species of some moderate complexity, so there is space to increase or decrease complexity, tend to have some descendants who are more complex and some who are less complex. Put another way, the paleontologists can find apparent trends in various species that go in both directions. There are mechanisms that produce trends, such as arms races between predators and their prey, or sexual selection, through which random matters of female taste drive males to extremes that may be harmful to their survival, such as the peacock’s tail or the swordtails’ tail.

Finally, I’d add that the ancient Greek philosophers thought about causes, and (if I remember from a long time ago) Aristotle identified four causes: design, material, efficient, and the intent or goal. These have fancy names in philosophy, as teleological, which is the last one. A person wants a house to help her keep warm and out of the rain. That’s the teleological cause. There will be no house without that. She hires and architect who creates a blueprint. There will be no house without a plan. I guess this is called the formal cause. Then the wood, dry wall, nails, glass, shingles, and electrical wires must exist. There will be no house without the material cause. Finally, she needs to hire a carpenter, an excavator, a brick layer, an electrician, and a roofer. The house will not exist without them either. These are the efficient causes.

To say that evolution has a goal to which it drives species is to identify a teleological cause to the origin and diversification of species. Indeed, so-called Lamarkian evolution is the idea that giraffe’s necks get longer from one generation to another because they are always stretching them. Now that we know, as the 19th century researchers did not, the origin of the variations within a population in the random, undirected mutations in germ cells, researchers believe that there is no goal or direction to evolutionary change. These days, for the most part, science deals in efficient and possibly material causes.

While scientists do not deny the possibility of teleological causes, they don’t see evidence for them, and, so far, they’ve been able to advance our knowledge and understanding of nature without them. This point is a key issue between those who hold the scientific, empirical world view and many religious people. Many religious people believe that the world and everything that happens is the result of the plans of a powerful supernatural being. These thinkers tend to believe that their existence and their lives are the result of some purposes of that god. As when, for example, we read a survivor of some disaster saying “The Lord must not be finished with me yet.” These people, we see, are thinking of a teleological cause as the answer to the question “What’s it all about?” or “What is the meaning of life?” They, and others, are also thinking of a teleological cause when they say reify or personify evolution and assert that it has a goal.

Often, however, scientists and others who speak this way about evolution do this out of linguistic convenience. They speak metaphorically, as if evolution had a consciousness awareness and was capable of planning, when they don’t believe that it does. It’s just seems easier to speak this way instead of carefully explaining the details of modern evolutionary theory and how it produces the appearance of design and planning.

And another thing: a note added in proof, and wandering off topic.

Here we have a good current example of religious teleological thinking in the first paragraph, and I’d say, an unintentional argument for the progressive income tax right out of the Gospels. (quoted from a Guardian article about the Rubio campaign)

‘… the Rubio campaign also released a remarkably pious television ad in an effort to woo Iowa’s more religious voters. “The purpose of our life is to cooperate with God’s plan,” says Rubio, wearing flats.’

‘”To those who much has been given, much is expected. And we will be asked to account for that. Were your treasures stored upon earth or in heaven?”‘

In his argument for the progressive income tax, which I’m sure he didn’t notice, he’s paraphrasing from Luke chapter 12, verse 48, known to all educated Christians, I’d say:

“Every one to whom much is given, of him will much be required; and of him to whom men commit much they will demand the more.”

This is from one of Jesus’ famous parables. He’s been telling his disciples various stories and lessons, and they ask him if these stories are just for them or for everyone. He says that he’s telling them these valuable things (about the future and about how the Lord will judge everyone), which makes them responsible to being loving and kind and helpful, indeed caring and responsible, for everyone to whom they owe help (because they have been given these gifts, the knowledge Jesus gives to them). So, not just for the progressive income tax, but a continuation of Jesus’ frequent admonitions to help the widow, the orphan, the sick, the poor, and the stranger, which I’d take it as a repudiation of the Republican party’s platform and the proposals of all of their presidential candidates and leaders (with the slight exception of John Kasich, who worked to expand Medicaid in Ohio on precisely these grounds, but otherwise is a standard conservative Republican).

You might enjoy looking at the other parables and sayings in Luke Chapter 12, where Jesus takes to task people for being rich, for worrying more about material things than about their future lives with God, and so on.

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Filed under Biology, Evolution, Natural Science

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