Surprising truths about Charles Darwin · 2020-04-20 · •Voyage of the Beagle 1831-36 •Retired to Down 1842 •The Origin of Species 1859 •Died 1882 Darwin’s home at Down,

Surprising truths about Charles Darwin

David Pannell

University of Western Australia

Lifeline• Born 1809• Study

(Edinburgh and Cambridge) 1825-1831

• Voyage of the Beagle 1831-36

• Retired to Down 1842

• The Origin of Species 1859

• Died 1882Darwin’s home at Down, near London

Started out on path to clergy

“The Darwins had produced lawyers and military men, but Charles lacked the self-discipline. There was, however, a safety net to stop second sons becoming wastrels: the Church of England.

An aimless son with a penchant for field sports would fit in nicely.” (Desmond & Moore)

Joining the Beagle Voyage

• Not paid for 5 years on Beagle.

• Actually, he had to pay!

• Was lucky to get on

– replaced someone who was shot in a duel

– his father opposed him going

• Mainly asked because of his class, to keep Captain Fitzroy company

The Beagle: Only 90 foot long, but carrying 74 people.

http://www.youtube.com/watch?v=OTo1X9EzFDQ

http://www.fanpop.com/spots/charles-

darwin/images/13131411/title/zoology-voyage-hms-beagle-

photo

Galapagos, 1835

• He was hugely homesick

• Did not recognize significance of trip until back in England, 1837.– Worked out theory much later.– First inkling of natural selection in 1838.

• Tortoise & finches were key evidence– On boat home, ate tortoises, dumped shells– Thought finches different species; didn’t even label

them properly

• Different Galapagos islands had different food sources.

• The birds with beaks that helped them get food better

survived better and reproduced more.

Common ancestor finch

Finches found on different Galapagos islands

Finches found in the Galapagos Islands

Natural selection

Darwin developed his theory:

– in complete isolation

– In face of violent opposition

– With no knowledge of genetics

– With no knowledge of DNA

– With no observations of natural selection actually occurring

Not first to propose evolution• French tradition

– Jean-Baptiste Lamarck– Etienne Geoffroy St

Hilaire

• Erasmus Darwin (Grandfather)

• Robert Grant (Mentor)

• Was expounded in a popular book (“Vestiges”) 15 years before “Origin”

Jean-Baptiste Lamarck

Slow to publish: Why so long?

• Anguish

• Illness

• Slow development of ideas

• Detailed analysis, collection of a wealth of evidence

– pigeons

– barnacles

Anguish• Social class

– Respectability

– Evolution subversive - against his class

• Religeous considerations

– especially worried about hurting wife Emma who grieved for his soul

• Scientific prejudice against “speculation”

• “Like confessing a murder.”

Illness

• Sea sickness

• Problems throughout life

– violent shivering, vomiting, exhaustion, palpitations, hands trembling, head swimming, sleeplessness, headaches, flatulance, stomach problems, ringing of ears, fainting, copious palid urine

• In 1841 could work “an hour or two a couple of days a week.”

• Chaga’s disease or just nervous?

Darwin was

married to his

first cousin and

had 10 children,

(not all of which

survived to

adulthood).

Children of close

relatives are more

likely to have two

copies of bad

recessive genes,

leading to poor

health.

Principles of Natural Selection

Organisms produce more offspring than can survive

Variations are found among individuals of a species

Some variations enable members of a population to survive and reproduce better than others

Over time, offspring of individuals with helpful variationsmake up more and more of the population.

For example, a bird with a certain kind of beak can eat certain foodsbetter than others.