Documentary - What Darwin Didn't Know 1 The Struggle for Existence

Summary

This script explores the evolution of Darwin's theory of natural selection, highlighting its initial appeal and the subsequent challenges it faced. It delves into the complexities of species diversity, the Galapagos finches, and pigeon breeding as evidence of evolution. The script also discusses the opposition Darwin faced, including from his peers, and the rise of mutationism as an alternative to natural selection. It concludes by reflecting on the state of evolutionary theory by the early 20th century, noting the controversy and near extinction of the idea of evolution by natural selection.

Takeaways

• 🌏 The world is filled with a vast diversity of species, particularly highlighted by the unique fish species found in Lake Malawi.
• 📚 Charles Darwin's 'On the Origin of Species' proposed the concept of evolution and the idea that species give rise to other species over time.
• 🧬 Darwin's theory of evolution was simple yet seductive, but it had logical weaknesses and lacked strong evidence during his time.
• 🕊️ Darwin observed differences among species, such as the Galapagos mockingbirds, and hypothesized a common ancestor for these variants.
• 🐦 Darwin's work with pigeons illustrated how creatures could evolve from a common ancestor through selective breeding.
• 🎯 Natural selection was central to Darwin's theory, suggesting that favorable traits would accumulate over generations, leading to new species.
• 💀 The fossil record initially seemed to contradict Darwin's theory, showing sudden appearances and disappearances of species rather than gradual change.
• 🤔 Critics, including Richard Owen and Thomas Henry Huxley, challenged the validity of natural selection and the evidence supporting Darwin's theory.
• 🔄 The concept of blending inheritance was a theoretical trap for Darwin, potentially undermining the mechanism of natural selection.
• 📉 By the early 20th century, scientific consensus had shifted against Darwin's theory of evolution by natural selection, considering it almost extinct.
• 🔬 Hugo de Vries' mutation theory emerged as an alternative to natural selection, suggesting that dramatic changes, or mutations, could lead to the creation of new species.

Q & A

What is the significance of Lake Malawi in the context of the script?

Lake Malawi is significant as it exemplifies biodiversity, with hundreds of fish species found nowhere else, illustrating the concept of species diversity and evolution.

Who is Charles Darwin and what did he publish 150 years ago?

Charles Darwin was a naturalist and biologist who published 'On the Origin of Species' 150 years ago, a seminal work that introduced the theory of evolution by natural selection.

What did Darwin argue about the origin of species diversity?

Darwin argued that the diversity of species is the product of evolution, where species give rise to other species and undergo changes over time, resulting in the variety we see today.

What is the Galapagos Islands' significance in Darwin's theory?

The Galapagos Islands were significant for Darwin as they provided evidence for his theory of evolution. The differences among the mockingbirds from different islands sparked his curiosity about species transformation over time.

What role did pigeons play in Darwin's understanding of evolution?

Pigeons served as a microcosm of evolution for Darwin, demonstrating how creatures could be transformed into different forms from their ancestors through selective breeding, a process he likened to natural selection.

What is natural selection according to Darwin?

Natural selection, according to Darwin, is the process by which nature favors certain traits over others, allowing some to survive and reproduce while others fade away, leading to slow, incremental changes over generations.

Who was Richard Owen and what was his stance on Darwin's theory?

Richard Owen was a prominent paleontologist who coined the term 'dinosaur.' He was critical of Darwin's theory, believing in intermittent species change under divine influence rather than the Godless evolutionism proposed by Darwin.

What were the criticisms against Darwin's theory of natural selection?

Critics argued that natural selection was not clearly demonstrated in the fossil record, which showed species appearing abruptly without gradual change. Additionally, the concept of blending inheritance seemed to contradict the stability of variation required for natural selection.

Who was Thomas Henry Huxley and what was his view on natural selection?

Thomas Henry Huxley, known as 'Darwin's Bulldog,' was a strong supporter of evolution but had doubts about natural selection. He questioned whether Darwin had provided sufficient evidence for natural selection actually occurring.

What was the inheritance theory proposed by a Scottish engineer named Fleming Jenkin?

Fleming Jenkin proposed that if variation blended in offspring, as Darwin suggested, then any advantageous variation would be diluted over generations, undermining the effectiveness of natural selection.

What is the significance of Hugo de Vries' work with the evening primrose?

Hugo de Vries' work with the evening primrose was significant because he discovered mutations that produced stable, new variants, challenging the gradualism of Darwin's theory and suggesting that mutation could be a driving force in evolution.

What was the general scientific consensus on natural selection by 1909?

By 1909, the scientific consensus had shifted against Darwin's theory of evolution by natural selection, with many scientists finding it controversial and lacking sufficient evidence.

Outlines

00:00

🐟 Evolution and Biodiversity in Lake Malawi

This paragraph introduces the concept of evolution and the remarkable biodiversity found in Lake Malawi, which serves as a backdrop to discuss Charles Darwin's theory of evolution. Darwin's seminal work, 'On the Origin of Species,' is highlighted for its influence and the questions it raised about the origins of life's diversity. The paragraph also touches on the weaknesses in Darwin's original theory, such as the lack of evidence for gradual change and the shaky logical foundations of natural selection. It sets the stage for the film's exploration of the evolution of Darwin's ideas and the modern understanding of evolution.

05:03

🕊️ Darwin's Finches and the Galapagos Islands

This section delves into Charles Darwin's observations of the Galapagos finches, which played a pivotal role in shaping his thoughts on evolution. It explains how the subtle differences among the finches from different islands led Darwin to hypothesize about species transformation over time. The paragraph also discusses Darwin's work with pigeons, illustrating how selective breeding can lead to significant changes in a species. The challenges Darwin faced in proving natural selection, including skepticism from fellow scientists like Richard Owen, are also highlighted.

10:05

🔬 The Debates and Difficulties of Darwin's Theory

This paragraph examines the criticisms and internal inconsistencies within Darwin's theory of natural selection. It discusses the concept of blending inheritance, which posed a significant challenge to the idea of natural selection, as it suggested that variations would blend out over generations. The paragraph also mentions the work of Thomas Henry Huxley, who, despite supporting evolution, questioned the validity of natural selection. The discussion includes the theoretical trap that Darwin found himself in and the difficulties he faced in defending his theory against critics.

15:06

🦒 Lamarckian Evolution and the Giraffe's Neck

This section contrasts Darwinian evolution with Lamarckian evolution, using the giraffe's neck as a classic example. It explains how Lamarck's theory of the inheritance of acquired characteristics was an alternative to Darwin's natural selection. The paragraph discusses how Darwin, in his later years, seemed to incorporate elements of Lamarck's ideas into his own work, suggesting a shift in his stance on the mechanisms of evolution. The limitations of using a single species, such as the giraffe, to explain a broader evolutionary principle are also touched upon.

20:09

🌸 Mutationism and the Rise of an Alternative to Natural Selection

This paragraph explores the rise of mutationism as an alternative to Darwin's theory of natural selection. It discusses the work of Hugo de Vries, who discovered mutations in the evening primrose plant, suggesting that sudden, dramatic changes could lead to the emergence of new species. The paragraph also reflects on the broader implications of mutationism for the understanding of evolution and how it challenged the gradualism inherent in Darwin's theory. The controversial status of natural selection by the early 20th century is highlighted, indicating a shift in scientific consensus away from Darwin's original proposal.

Keywords

💡Evolution

Evolution is the process by which species of organisms change over time through the gradual accumulation of small genetic variations. In the video, it is the central theme, illustrating how Charles Darwin's theory of evolution by natural selection has shaped our understanding of life's diversity. The script discusses Darwin's theory and how it has been tested and refined over the years.

💡Natural Selection

Natural selection is the mechanism by which species adapt to their environment through the differential survival and reproduction of individuals with advantageous traits. It is a cornerstone of Darwin's theory, as mentioned in the script when discussing the 'engine of evolution' and how it was initially met with skepticism but has since become a fundamental concept in biology.

💡Darwin

Charles Darwin is the key figure in the script, known for his work 'On the Origin of Species,' which introduced the theory of evolution by natural selection. His ideas are discussed throughout the video, highlighting both their influence and the challenges they faced in gaining acceptance among the scientific community.

💡Galapagos Islands

The Galapagos Islands are a significant location in the script as they are where Darwin observed the mockingbirds, which varied from island to island. This observation was pivotal in his development of the theory of evolution, as it provided evidence for the idea that species can change and adapt over time.

💡Pigeon Breeding

Pigeon breeding is used in the script as an example of how traits can be selected for over generations, leading to the development of new breeds. This process illustrates the concept of artificial selection, which is a subset of the broader principle of natural selection.

💡Fossil Record

The fossil record is the primary source of evidence for studying the history of life on Earth. In the script, it is mentioned as a point of contention for Darwin's theory, as the fossil record did not initially provide clear evidence of gradual change, which was expected according to the theory of evolution by natural selection.

💡Inheritance

Inheritance refers to the passing of traits from parents to offspring. The script discusses Darwin's ideas on inheritance, which were later challenged by the discovery of genetic principles. Understanding inheritance is crucial for grasping how traits can be selected for or against through natural selection.

💡Lamarckism

Lamarckism is an early theory of evolution proposed by Jean-Baptiste Lamarck, which suggests that traits acquired during an organism's lifetime can be passed on to its offspring. The script contrasts Lamarck's ideas with Darwin's, highlighting the historical debate over the mechanisms of evolution.

💡Mutation

Mutation is a change in an organism's genetic material that can result in new traits. In the script, mutation is discussed as an alternative to natural selection for driving evolutionary change, particularly in the context of Hugo de Vries' work with the evening primrose.

💡Synthetic Theory

The synthetic theory, not explicitly mentioned in the script, is a modern evolutionary theory that combines Darwin's concept of natural selection with Mendelian genetics and other scientific findings. It provides a more comprehensive understanding of evolution, integrating various mechanisms such as mutation, genetic drift, and gene flow.

💡Extinction

Extinction is the permanent loss of a species. The script touches on the idea of species being 'swept away' in great catastrophes, which is a process that can drive evolution by altering the selective pressures on the remaining species.

Highlights

Darwin's theory of evolution by natural selection is introduced, explaining the diversity of species.

Darwin's ideas on evolution were initially seductive and simple, yet had logical and evidential weaknesses.

Charles Darwin's visit to the Galapagos Islands and his observations on the mockingbirds' variations sparked his interest in species transformation.

Darwin's pigeon breeding experiments illustrated how creatures could evolve from a common ancestor.

Natural selection as the engine of evolution was central to Darwin's theory but faced criticism for lack of clear evidence.

Richard Owen's negative review of 'On the Origin of Species' highlighted the absence of fossil evidence supporting gradual change.

Thomas Henry Huxley, known as 'Darwin's Bulldog,' acknowledged the logic of natural selection but questioned its empirical proof.

Darwin's theory of inheritance, blending of traits, was challenged by the argument that variation would disappear, thus undermining natural selection.

Darwin's self-critique in 'Difficulties of the Theory' where he openly discussed the weaknesses of his theory.

Jean-Baptiste Lamarck's theory of evolution based on the inheritance of acquired characteristics was contrasted with Darwin's.

Darwin's consideration of Lamarckian ideas in the later editions of 'On the Origin of Species', suggesting a blend of natural selection and use-inheritance.

Hugo de Vries' mutation theory, which proposed that large, heritable changes could lead to new species, challenged Darwin's gradualism.

De Vries' experiments with the evening primrose, which showed stable, non-blending variations, supporting the mutation theory.

The rise of mutationism and its impact on the perception of natural selection as an unnecessary force in evolution.

The 1909 exhibition at the British Museum of Natural History commemorating Darwin's work but avoiding the controversy of natural selection.

By 1909, the scientific consensus had shifted against Darwin's theory of evolution by natural selection, indicating its near extinction in scientific thought.

Transcripts

we live in a world of Exquisite

vacity with more species than we can

possibly

count here in Lake Malawi for instance

there are hundreds of different fish

that are found nowhere

else why so many why so different

150 years ago Charles Darwin published

On the Origin of

Species and in that one great book he

asked the right question and gave the

right

answer where asked Darwin does all this

diversity come from and answered that it

must be the product of

evolution species he argued give rise to

other

species and as they do so they change

the changes are minute and subtle but

given enough time the results could be

spectacular and so they

are Darwin's explanation for life on

Earth was so seductive and so simple

that it seems obvious today and yet

Darwin's explanation of how Evolution

Works was riddled with hols its logical

foundations were shaky

his evidence was weak there was so much

he did not could not

know Darwin trusted that future

generations of scientists would complete

his work and prove the essential truth

of his vision and for 150 years that is

what we have been

doing in this film I'll chart the

decline fall and ultimate Triumph of

Darwin's ideas and I'll show how

evolution theory has itself evolved so

that it is now far more vast and subtle

than ever he

imagined in September 1835 Charles

Darwin arrived in the gpus

archipelago and did what he always did

when arriving at a new

place he got out his gun and began to

collect among the many inhabitants of

the galapagus:

they're mocking

birds each comes from a different Island

and each is subtly different from the

others they differ in the shape of their

bills and the size of their bodies and

the color of their

plummage it was these differences that

first caused Darwin to wonder whether

species might transform over

time Darwin surmised that the birds were

variants of the same species and must

therefore descend from a common ancestor

a mocking bird which had somehow found

its way to the galapagus:

Darwin bread pigeons they were for him a

microcosm of

evolution they showed how any creature

could given enough time be transformed

into something very different from its

ancestor

for implausible though it may seem these

gorgeous monstrous inbred Aristocrats of

the Aven world the scander the frillback

the jacoban not to forget the mooki are

all descended from this The plean Rock

Pigeon all pigeons are at Birth subtly

different from each

other breeders select those with

desirable features to survive and

reproduce and they called the

rest the desirable features accumulate

from generation to generation and become

exaggerated and so remarkably quickly

the birds

evolve nature Darwin said works like

that it favors some features and permits

others to weer

away he calls to this process natural

selection all this explains why the

first chapter of the Origin of Species

is not about the wonders of the natural

world but rather about

pigeons understand the pigeon he is

saying believe the pigeon and all the

rest

follows or does

it for Darwin had a

problem natural selection was the

Cornerstone of his theory it was for him

the engine of evolution

and yet it was by no means clear that

natural selection really

worked there is he said a war of

nature famine violence and death are

everywhere species and individuals are

locked in a struggle for

existence the strong survive and

reproduce while the weak go to the

wall given enough variation this

selective pressure is enough to bring

about slow incremental

change this was the theory of evolution

by natural selection that Darin unveiled

in the Origin of

Species while the idea of evolution was

not in itself new no one had argued it

more forcefully or documented the

evidence for it with greater

rigor but was it right

had Darwin really made his

case of course Many religious types

hated the very idea of

evolution but some of Darwin's fellow

scientists weren't to Keen

either notably Richard Owen who wrote

one of the first reviews of the

origin Richard Owen Premier

paleontologist coined the term dinosaur

helped design these

things rampaging through a South London

Park these marvelous reconstructions

were built in the

1850s they are a tableau of dinosaur

life based on Owen's

research Owen had vague evolutionary

leanings he thought that species change

intermittently under the influence of

some Divine Law and that periodically

they are Swept Away in some great

catastrophe he loathed Darwin's Godless

evolutionism Owen was a thoroughly nasty

piece of work his review of the origin

rich in Malice dripping with sarcasm

dams Darwin even as appr Praises himself

all anonymously of course Mr Darwin's

rash speculations degrade science he's

as bad as the French and continues Owen

he doesn't know anything about fossils

if he did he would know that eosa appear

in the lower Jurassic stay there pretty

much unchanged and then just disappear

no sign of evolution

there Owen's Venom was probably born

from Mere

spite still he did seem to have the

fossil record on his

side according to Darwin's theory

gradual change should be visible in the

Rocks but it

wasn't instead species seemed to arrive

toart leaving little in

between such gaps in the fossil record

would haunt Darwin's theory the evidence

for natural selection simply wasn't

there even his friends had their

doubts Thomas Henry Huxley worked here

at Imperial College London where I now

work a fire brand and a populist they

called him Darwin's

Bulldog Huxley also review the origin

it's a magnificent work it makes the

case for evolution but then he turns to

Natural

Selection yes it's logical yes it's

simple but has Mr Darwin actually seen

as species originate by natural

selection can he even Pro that it really

exists well no it's a hypothesis perhaps

the best one going but and I say this as

a friend you understand Mr Darwin really

hasn't proved his point

Huxley said natural selection can't be

seen others said it doesn't

work they claimed that it was logically

flawed that it was inconsistent with

Darwin's account of

inheritance of how species transmit

their features from one generation to

the next

this is how Darwin thought inheritance

Works suppose one parent has dark

feathers fur skin the color of black

coffee while the other is milky white

their progyny would be a mix of the

two they would be

blend it seems like an innocuous idea

quite a reasonable one too after all

isn't this how human skin color is

inherited

but Darwin had walked into a theoretical

trap and a Scottish engineer called

Fleming jenin sprang

it this is how jenin phrased the

argument imagine that a white man

arrives on an island of negroes he would

no doubt make himself King he would take

many negro wives and father many molat

children yet no matter how how

successful our hero is no matter how

Superior his coffee colored descendants

would become progressively darker within

a few Generations all trace of his

presence would

disappear Let's ignore if we can the

Casual racism this is Scotland in the

1860s and jenin had a point variation is

the stuff of evolution and if variation

Blends then it disappears and as it

disappears so so the power of natural

selection EVS

away jenkins's challenge was serious and

Darwin had no

response how could he his theory

required some system some law of

inheritance in which variation did not

blend but remained stable over the

generations and yet no one really knew

how such a system could

work the thing is Darwin knew all this

and we know that he knew because he told

us

so perhaps the most wonderful chapter of

the Origin of Species is chapter

6 it's called difficulties of the theory

Charles Darwin exposes with unbearable

cander devastating honesty all the

weaknesses of his theory he tells us all

the reasons he may be wrong the reasons

that as critics pointed out and more but

then appeals to Future generations of

scientists to draw inspiration from his

book solve the difficulties with which

his theory is

riddled it's easy to forget that Darwin

was not the first

evolutionist 50 years before the Origin

of Species a Frenchman had proposed a

theory of

evolution albeit less coherent and

comprehensive than

DARS his name Jean Baptist l

AR Lamar was professor of zoology at the

mum

Dell he published his ideas on evolution

in the year that Darin was born they

were however very

different when an animal any animal uses

an organ Lamar argued it becomes

strengthened and

enlarged that's fairly obvious we all

know that exercise modifies the shape of

our body it's the same for other

creatures as

well but Lamar went

further he argued that these changes

acquired in one's lifetime were passed

on and it is this the inheritance of

acquired characteristics as it came to

be known that's the engine of

evolution the icon of lamaris is the

giraffe according to Lamar some

ancestral giraffe had stretched its neck

reaching for leaves on the highest

branches that stretched neck had been

passed onto its Offspring who in turn

had stretched their necks even further

so that now all giraffes have long

necks there is a seductive intuitive

quality to LaMar's logic one that Darwin

confronting the inadequacies of his own

Theory found increasingly hard to resist

the giraffe's neck is a cliche it's in

every textbook that explains the

difference between darwinian and lamaran

evolution but if you actually read what

Darwin says about the giraffe in the

sixth and final edition of the origin

what you find is something rather

different first he talks about natural

selection that's what gives you the

giraffe's neck but then he adds another

line about the inherited effects of the

increased use of Parts together they

give you the giraffe's snack increase

use of Parts what's going on here that's

pure Lamar can it be that Darwin in his

dotage is becoming less

darwinian well yes perhaps natural

selection is not as powerful as once he

had

thought a

recantation no just the cander of an old

man who had spent his life trying to

understand the

world Darwin died in April

1882 he had wanted to be buried quietly

near his house in Kent but his

supporters arranged a funeral here at

Westminster

Abbey they turned the agnostic into a

saint of the new secular materialist age

it was the apotheosis of Charles Robert

Darwin he had become a Great

Britain but the eulogies rang

Hollow Darwin had shown that life on

Earth was the result of natural laws but

what were those

laws everyone everyone that is who

mattered agreed that Evolution was a

fact but natural

selection no thanks

even as Darwin lay in state some

darwinian were breaking

ranks Chief among them Dutch botanist

Hugo

def inspired by Darwin he was searching

for a suitable organism with which to

investigate the workings of

inheritance and found

one he chose a plant called inthera

Lamar

Iana but gardeners will know it as the

evening primrose for it blooms a

dusk it's found throughout the dunes

that protect Holland from the sea and

it's really just a weed though lovely

for all

that def discovered that in athera

lamarana occasionally produces progeny

that look very different from

itself that have different stems

leaves

flowers these new variants he found did

not blend but were stable as stable as

new

species coining a term def called these

dramatic

Transformations

mutations following his Discovery def

was made director of the botanical

gardens in

Amsterdam he bred and cross spread more

in atheras 53,000 of

them it seems like a lot but then again

he was

DCH this is the Palm House that

Amsterdam built for Def and these are

some of his flowers pressed for

posterity they're ancient and desiccated

but you can still see the differences in

growth and

form mutation it seemed could produce

radically new plants

it could even said t produce new

species this was all very UND

darwinian what of the vertiginous time

scales the Infinity of incremental

steps the Grandeur of Darwin's view of

Life irrelevant said de what

the the Origin of Species requires only

one thing thing

mutation he called it his mutation

Theory it made him famous for Lamar he

said the Origin of Species was a natural

phenomenon for Darwin the object of

scientific investigation for def he

liked to talk of himself in the third

person it was the object of experimental

inquiry Lamar Darwin def no doubts about

his place in the pantheon

then what T or no one else realized at

the time was that inthera lamarana was a

genetic

freak few other organisms mutate so

spectacularly he had based his entire

theory on one very peculiar

species that however didn't stop the

rise of mutation

ISM others began to investigate The

Oddities of

nature in Britain a Cambridge biologist

William baton published materials for

the study of

variation a collection of two-headed

turtles girls with four ears and eight

finger at hands it was a medieval

monsters and Marvel's book reworked for

The evolutionary

age mutation was the real creative force

behind

Evolution and natural selection said the

mutation just wasn't needed

London

1909 Darwin is long dead and his theory

is 50 years

old the British Museum of Natural

History celebrates with an exhibition of

doin specimens letters

manuscripts it's a magnificent

celebration a worthy commemoration of

the man who gave us

Evolution but something is missing

something upon which the organizers

refuse to be

drawn natural

selection you might have expected that

the South Kensington Museum now a temple

of evolutionism would have wanted to

tell the public about Darwin's theory

but no that's all too controversial for

the keepers and curators who'd much

rather not commit themselves in the

great Evolution

debate hardly courageous but

understandable by 1909 scientific

consensus had shifted against Darwin's

theory evolution by natural selection

was almost extinct