two kinds of evolutionary thinking

Two kinds of evolutionary thinking

Darwinism and Lamarckism

John Wilkins Apr 9, 2023

Some quotes

“Evolution is so simple, almost anyone can misunderstand it” – David Hull

“Natural Selection is not Evolution ” – Ronald A Fisher

“Nothing in biology makes sense except in the light of evolution” – Theodosius Dobzhansky


Star Trek Evolution Why is it so

popular? Where does

this idea come from?

What should we think about evolution?


The popular version Grades Direction Perfection Steady Humans are the goal


The scientific version Branches Randomness + selection Irregular No direction but locally Humans are one animal among

many


Names The popular version is called many things:

Great chain of being Ladder of progress Lamarckism

The scientific version is also called many things: Darwinism Neo-Darwinism The Modern Synthesis


Progress Depends on the “target” Jacob’s Ladder - God at the top,

something ugly at the bottom Evolution has always been

thought to be progressive Until Darwin (and even then)


There are two kinds of evolution The one Lamarck developed and

made known. The one Charles Darwin developed

and made known Only Darwin’s is truly novel, and

yet it is the least well known, and so it takes the longest to really “get”.


Before evolution Western thinking was historical

because of Christian theology, but change tended to a goal

Everything was ranked from lowest to highest

Higher things were “more perfect” than lower things


The medieval view

Stones … mere being

Fire … + motion

Plants … + growth

Animals … + sense

Man … + reason

Heaven … + incorruptibility

Angels … + knowledge of good

God … with the lot + perfection

Raymond Lull, 1512


The chain was also moral

Bovillus 1510


Great chain of being A view that goes back to the Greeks Everything is lined up along a scale Made into a time series in the 17th

and 18th centuries Lamarck one of the first

evolutionists, and followed this view


Three “Lamarckisms” That changes to individual

organisms are likely to be inherited or will affect the hereditability of traits.

That things evolve on a preprogrammed pathway to perfection

That change is predictive of the needs (or wants) of organisms


Lamarck’s scale from lower to higher At first a single scale Later, two, one for invertebrates,

one for vertebrates Each “species” underwent change

up the scale


Lamarck’s view of evolution


Spontaneous generation Lamarck accepted the constant

generation of living things in their simplest form, from the non-living

Each new spontaneous generation started a lineage

Each lineage would evolve through the same stages as the earlier ones had

Later, he allowed for some branching


Lamarck’s view of evolution 2


Bees and brains “It is absurd to talk of one animal being

higher than another – We consider those where the cerebral structures intellectual faculties most developed, as highest. – A bee doubtless would where the instincts were.” Charles Darwin, Notebook B

“Never say ‘higher’ or ‘lower’” Darwin What about the flowers? What would

they say?


Darwin’s view Things get better locally, not globally

Being “fitter” is a matter of being able to do well then and there only

Populations, not whole species, evolve Evolution branches all the time Everything has evolved as much as

everything else!


Branching evolution

No real progress here


The origin of species


The tree of life is a coral tree


Darwin used the tree metaphor This, too could be misused Although Darwin’s tree was not

directional at first, others came to be


Haeckel’s mighty oaks

Central trunk leads directly to humans, and everything on the trunk is somehow “important”


Indirect progressionism

Patten (1925) makes a direct line through arthropods (bugs) to vertebrates (non-bugs)


Indirect racismNotice how the earlier (and “less evolved”) forms are shown at the left of the diagram. Now notice the “races” of Homo - in order, African (i.e., the “Negro”), Australian (aboriginal), Mongolian (the “Asiatic”), and of course the European.

Diagram c1920. There was no geological evidence at the time (or now) of any of this.


Direct racism (1799)


Intelligence still at the top of the chain…

Despite the divergence of evolution until now, Teilhard (1955) still thinks that it will all come together with humans as the final players. At least he isn’t racist about it – all “socialised” humans will evolve to the Omega Point.


Missing links and ancestors


Any ancestors at all? We cannot be sure that a fossil or

living species is actually an ancestor

Might be a sibling of the ancestor Might be the ancestor, but how to

tell? At best, we have likelihoods


Populations All evolution happens to

populations Not individuals (that’s

“development”) Not entire species (that’s

“speciation”) Not larger groups (that’s artificial)


Natural selection Does not equal “evolution” Is the process of adaptation (of

populations) Is not all that happens in evolution

(that’s called “panadaptationism”)


Selection

Follows the fitness peaks (available ways to make a living).

They have to be reachable, and they have to be better than what is already in place.

Changes the frequency of genes in populations.


Lessons to be learned Progress is not necessary

There is no “next step” Selection is not all there is to

evolution Everything is as evolved as

everything else


Further reading Bowler, Peter J. Evolution: The History of an Idea.

Berkeley: University of California Press, 1984. Dennett, Daniel C. Darwin’s Dangerous Idea: Evolution

and the Meanings of Life. New York: Simon and Schuster, 1995.

Jordanova, L. J. Lamarck, Past Masters. Oxford; New York: Oxford University Press, 1984.

Lovejoy, Arthur O. The Great Chain Chain of Being: A Study of the History of an Idea. Cambridge, Mass.: Harvard University Press, 1964 (1936).

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