Does history matter to understand the theory of evolution?
spoiler alert: F#&k yeah!
Science is, at it’s core, all about discussion. Thus, controversy has always accompanied the evolution of biological knowledge.
Understanding the roots of controversy and the historical context of ideas is important because it brings clarity to definitions of contemporary concepts and reinforces the important notion that science is eternally preliminary.
That said, let’s dive into some biology drama (if you just want the gossip, jump to the end).
On Lamarck’s rumored dumbness, Darwin’s confusion, stinky giraffes & IKEA furniture:
In high school, I was taught Darwinism as an opposed theory to Lamarckism, practically devoid of historical context. School manuals and exam questions made it seem that both theories were contemporary and antithetical. That idea was stuck in my mind:
Evolutionary theory began with a fight. Darwin smart. Lamarck dumb?!
Later, in college, a professor for “history of the biological thought” (ironic.) told us that “Darwin was nothing but a Lamarckist!” (I sporadically heard/read further versions of this claim)
Wait, so now they are not opposed… They are the same?!
Three years ago, a highly regarded evolution and behavior professor said, during a public debate, that “Darwin and Lamarck are the same!”.
Oh F#@! no.
Turns out that these are very stinky things to say… So, in my plea to clear the air, I put together what I would’ve liked to have learned on the evolution of… well, Evolution… in less than 10 minutes:
First of all, let’s get some dates right:
Lamarck (as he is known), was born in 1744. His big evolutionary ideas (previously seeded in his lectures) come to methodical light in 1809, with the publication of Philosophie Zoologique.
Quite poetically, 1809 is also the year of Darwin’s birth!
Philosophie Zoologique stated 2 laws, which supported the idea of transmutation in Nature:
I. Use and disuse
Here, Jean-Baptiste claims that upon environmental challenges brought by L’influence des circonstances *a-hem* pardon my french… the frequent and continuous need of the use of an organ will result in its further development, strengthening and enlargement. This organ will develop proportionally to the intensity of its need (besoins) and consequent effort to use it. De la même façon, an organ that it’s not needed anymore will tend to disappear.
II. Inheritance of Acquired Characteristics
And then, Jean-Baptiste stated that all the modifications resulting from law I (development or loss) were passed on to the next generation, upon reproduction, provided that the acquired characteristics were present in both the male and female.
So, “the habits (…) and all other influential circumstances have, with time, constituted the form of the body and the parts of animals” (Lamarck 1801, p. 15).
As organisms developed new organs in response to their environmental circumstances, they would proceed linearly towards higher complexity, driven by Le pouvoir de la vie (the complexifying force).
How does Darwin get in the feud?
He… doesn’t?! (but if you like gossip check the footnotes at the end)
Lamarck dies in 1829.
30 years later, Darwin fairly acknowledges Jean-Baptiste’s genius (nop, never called him dumb…) in his publication of an enlightening (and beautiful) essay:
“On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life”
There, for the first time ever, a coherent body of empirical observations & thorough description solidified the concept of biological evolution into a completely materialistic scientific theory.
Darwin developed 4 main ideas that can (to this day) explain the evolution of biodiversity:
I. Common ancestry
II. Descent with modification
III. Gradualism
IV. Natural Selection (which Wallace also hypothesized)
So, with a little bit of history on a simple time line, it’s easy to see that…
…these theories were not contemporary and the nature of their relationship is what science is made of: additional evidence, new ideas and further understanding of natural patterns and processes.
While they both agree that organisms change in response to their environment, the fundamental differences rest on the “How”
Wanna know more? Let’s look at stinky giraffes!
“From so simple a beginning”: ramps or trees?
Lamarck stated that species would evolve from other “least perfect” species, following a progressive path towards higher levels of complexity and perfection. At the top of this linear path, way ahead of all others, rests Homo sapiens.
There was no extinction in this process, just constant transmutation. New initial life forms would constantly appear through spontaneous generation, allowing the ramp to be climbed over and over.
Invertebrates, for example, were the organisms “perhaps by which nature began, when, with the aid of much time and favorable circumstances, she formed all others” (Lamarck 1801, pp. 11–12).
So, according to Lamarck: simple, imperfect & spontaneously generated beings were at the base of the ramp and, due to demanding environments, needed organs would be acquired, moving the organism upwards in the scale of complexity & perfection.
Darwin later hypothesized that the link between species, past and present, was similar to a genealogical tree. It was irregular, devoid of tendency or privileged direction.
There was common ancestry where from an initial life form, through natural selection and adaptation, different species would branch, each of them a better competitor in specific environment.
The ancestors? Extinct, as they could not adapt to the demands of the environment and were thus supplanted by the variations that could better survive and reproduce.
This means that a giraffe shared ancestors with beetles, with you and with every other creature on earth, at some point in time. Thus, beetles are not inherently less complex or perfect than giraffes, they are just different branches of the diverging tree-of-life, adapted to different environments!
The way in which species originate & diverge, and the existence of a single evolutionary peak of complexity are main points of divergence between Lamarckism and Darwinism.
Les girafes: neck stretch or neck variation?
According to Lamarck, if Acacia trees would change and start to sprout leaves only at the canopy, giraffes would stretch like hell to reach those delish leafs…
This would result in neck elongation, during their life-time, and consequent longer-neck babies through the inheritance of acquired characters, meaning that post-natal physical changes would pass to the next generation. But notice that for Lamarck all giraffes would stretch their neck equally and all giraffes would have the same neck length in the end.
Darwin hypothesized that in a population of giraffes the neck length varies: some have longer necks than others. The ones with longer necks can reach leaves easier, eat more frequently and are thus better competitors!
So, in a population of giraffes, the ones with longer necks are well nourished and have higher fitness: a lot of stamina to make more surviving babies... Because the baby giraffe’s characteristics are a mix of their parents, they will also be born with a longer neck, becoming the better competitors in the next generation.
This is what he called natural selection.
Less drama, please! It’s all about reproductive success…
Dramatic illustrators like to depict all short-neck giraffes dead in the Savannah… Giraffes with shorter necks don’t have to immediately starve to death!
They may be selected against simply by having fewer surviving babies each generation (lower fitness). Their characteristics will not pass on with the same frequency, and they are eventually gone from the population, losing the struggle for survival.
Over time, more and more longer-neck baby giraffes are born and survive to have their own babies. The frequency of long-necks will increase gradually due to it’s associated higher fitness!
Wanna know more? Let’s go to IKEA!
Where does the population neck variation come from?
It’s stored in the most beautiful “book” of all: the genome!
The Giraffe’s closest relative is the Okapi. “Closest” meaning that they had a common ancestor approximately 11.5 million years ago.
Okapis have longer necks than most ruminants, but nothing compared to the 2-meter neck of giraffes & the genomes of these two are quite different.
The species’ IKEA manual is where variation is stored!
Genomes are basically the IKEA manual of instructions for building a living organism.
We inherit the manual from our parents, and it encodes the instructions in DNA, which is made of specific pairs of four nucleotides: adenine, thymine, cytosine and guanine — A-T, C-G.
These four letters make up sequences (the instructions) and the variation in those sequences between individuals is how genetic diversity is stored within populations of a same species and, in a larger scale (more differences), between species.
So, basically, with the same tools and little variation in the instruction manual, you can have a SÖRVALLEN or a NOCKEBY: Both are sofas, with the same number of seats, but the shape & length of the pillows varies.
Same with necks! The raw material is the same: bone; The instruction for the number of vertebrae is the same: “assemble 7 of these”; but the instruction controlling cervical vertebrae length has a different ATCG sequence for an okapi and a giraffe.
We, the Giraffe and the Okapi all have 7 typical cervical vertebrae. What varies is the length of each vertebrae, because the mammalian IKEA instructions differ.
On an exploratory analysis, scientists looked comparatively at 13,581 ATCG sequences of okapi, cow and giraffe and discovered 70 genes in which giraffes seem to have specific differences!
Some of these are known to influence skeletal changes, thus becoming very strong candidates of the IKEA instructions that diverged and might be responsible for the giraffe’s unique morphology.
So, natural selection can operate on morphological variation encoded on the genome, maximizing the adaptation of Giraffes to sub-Saharan Africa, Okapis to the Ituri Rainforest and Humans to… everywhere.
Then, what did natural selection… select?
Some researchers (including Darwin) hypothesize that the longer neck allows giraffes to reach food higher than any other herbivores, thus avoiding competition (as in our example)….
However, others hypothesize that predator detection, in the tall Savannah grass, and their avoidance, is the key…
Others hypothesize that it’s all about sexual selection: males use necks to fight and defend territories, thus bigger stronger necks would mean access to more females (more babies!)
We still don’t have a definitive answer to why giraffes have such long necks! There’s ongoing passionate debate on this topic.
It might be a combination of all, since all of these strategies would contribute to maximize the fitness of a giraffe.
Ok, enough of giraffes. Let’s wrap this up with some gossip!
So, Darwin was right & Lamarck was dumb?
… Have you learned nothing?!
We know now for sure that evolution does not follow a linear route towards humanization, that there is no such thing as spontaneous generation, and that biodiversity can indeed be visualized in a beautiful tree.
We know for sure that natural selection is one of the driving forces of evolution and that it acts upon variation within populations.
These facts result from more than 150 years of research & fierce debate built on Darwin’s observations, but he was also confused about a lot of things!
- Heredity — Mendel was a dear and solved this one for us ❤
- Marriage — unsure about marrying his cousin…
- Peacock tails — too gorgeous, made him sick…
- The ability of women to understand science & other things — I can’t even…
And it turns out, that there might be some merit to Lamarck’s idea of inheritance of acquired characters:
- Epigenetics — some changes to our IKEA genomic manual might occur after birth and be passed on to the next generation!
Other than that, Lamarck was an exceptional zoologist that contributed immensely to human knowledge!
There’s so much we still don’t know, and that’s ok!
Imagine a world of finite knowledge… F#&k$n@ boring!
What we need to do is try to understand where the knowledge and concepts that we currently have stem from and think critically about it. That’s progress. That’s science.
Like Lamarck and Darwin, every researcher out there intends only to gather knowledge and further understand Nature’s patterns and processes, and that’s not dumb!
Go into nature. Observe other species and ask yourself how could those have evolved?
Speculate & debate! Read into it! But most of all, enjoy the tree-of-life ❤
The gossip section
Omg you guys… It turns out that someone mistranslated the French word “besoins” from Lamarck’s work into “want” instead of “need” making it sound like he was saying that the animals desired to develop their organs, instead of it being an environmental demand…
So, in a letter to his bff Hooker (January 11th, 1844), Darwin says this is “non-sense” (real quote) and then his other bff Lyell was like “wtf Darwin, that’s not what the man is sayin’!” (not an actual quote)… but it turns out Lyell had also thrown some shade at Lamarck before! Anyway… then Darwin writes like 2 pages with sweet praise to Lamarck on the Origin, so I guess everything was good.
But no! At Lamarck’s funeral, Cuvier was a. total. asshole. and ridiculed the man’s genius… Saying that speculation was not science and whatever in the eulogy! And guess what! It was also because he read the translation of “besoins” to “want” and he was like “This dumbass is attributing will to animals… like wtf!” (not an actual quote) Imagine if there was twitter at the time…
Then it seems that Darwin, at some point, was like “You know what?! Lamarck might have a point here, because like, if the Blacksmith gets super ripped then his arm’s muscles will release an excess of gemmules into his reproductive cells and then his kids will be born with super strong arms which are made from these inherited cells! Am I right?!” (not an actual quote) and then people are like “ OMG he’s a Lamarckist!” and I’m like… ahm… no.
Like, Darwin’s belief of the theory of inheritance was Pangenesis and he’s the first to admit that he’s like super confused of how the hell things are inherited. How does this bring down all the other fundamental differences between their theories?! Like… take a chill pill…
If you have more historical gossip, please leave it in the comments!
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- Illustrations by Marisa Xavier
- If you want to read more on this try “The Growth of Biological Thought: Diversity, Evolution and Inheritance" or “ Lamarck revisited” by Ernst Mayr
