Where Do We Come From, What Are We, Where Are We Going

Paul Gauguin, 1897

“Nothing in biology makes sense except in the light of evolution.”

Theodosius Dobzhansky

Theories of Evolution

• Origin Myths/Cosmologies– Greek – Prometheus– Genesis

Left: Prometheus and AthenaTop: God and Adam

Western examples

Bishop James Ussher

(as painted between1640-1656) Bishop John

Lightfoot

(b. 1601- d. 1675)

Creation as Calculated from The Bible

Ancient Greek philosopher Anaxiamander (611-547 B.C.) and the Roman philosopher Lucretius (99-55 B.C.) conceived of the idea that all living things were related and that they had changed over time.

Lucretius

Aristotle’s Great Chain of

Being(Scala Naturae)

Comte de Buffon

(Georges Louis Leclerc)

1707-1788

Early Ideas about Evolution

Baron Cuvier

1769-1832 Jean-Baptiste Lamarck

1744-1829

Erasmus Darwin

1731-1802

Other Theories

• Creationism accounts for biological diversity by referring to the

divine act of Creation as described in Genesis.

• Catastrophism is a modified version of Creationism, which

accounts for the fossil record by positing divinely authored

worldwide disasters that wiped out the creatures represented in

the fossil record, who were then supplanted by newer, created

species.

• Intelligent Design states that modern physics and cosmology

have uncovered evidence for intelligence in the structure of the

universe and this intelligence seems to act with us in mind and

that the universe as a whole shows evidence of design.

Jean Baptiste Lamarck, 1744-1829

• French geologist and naturalist

• published Philosophie Zoologique in 1809

• speculated about mechanisms of biological evolution, offered no evidence

• Lyell discussed Lamarck’s ideas in his Principles of Geology

Ideas of Lamarck that were rejected by Darwin• evolution is a process in which living things gradually

become more perfect (more human-like)• because species that evolve and improve leave a gap, new

species must be continually created by spontaneous creation

• the inheritance of acquired characteristics is the mechanism of evolution

(but inheritance of acquired characteristics was not entirely rejected by Darwin)

Charles Darwin: failed medical student, failed divinity student, ardent beetle collector, naturalist on HMS Beagle

Voyage of H.M.S. Beagle, 1831 - 1836

90 feet of ship, 74 people living together for 5 years...

Darwin’s voyage on HMS Beagle took five years and went east to west, staying largely within the SE trade winds in the southern hemisphere. This is a favorite route for cruisers today, but not racers, who prefer to go west to east and stay in the roaring forties around Antartica.

Understanding the Depth of Time

James Hutton

1726-1797

Charles Lyell

1797 - 1875

Populations

Thomas Malthus

1766-1834

Understanding Populations

Thomas Malthus

1766-1834

Darwin and Alfred Russel Wallace (1823-1913)

• Darwin developed ideas on natural selection in early 1840s (1844 essay), but did not publish

• He received a letter from Wallace in 1858 outlining natural selection

• His friends organized an 1858 presentation in London of Wallace’s and Darwin’s work

• 1859 publication of Origin of Species

Darwin and Wallace Volumes

Darwin’s Theories of Evolution

Natural Selection• Individuals within species vary• Some variations are passed to offspring• More offspring are produced than can survive

(Malthus’ influence)• Survival and reproduction is not random.

Individuals that have favorable variations more often survive to reproduce, or reproduce more.

The Darwinian view of life has two main features

• the diverse forms of life have arisen by descent with modification from ancestral species

• the primary mechanism of modification has been natural selection working over enormous tracts of time

The Beagle in Sydney Harbor

Darwin’s Theories of Evolution

Common descent every group of organisms descended from a

common ancestor

Carl Sagan’s Universe Calendar

• 24 days = 1 billion years• 1 second = 475 years

• “Big Bang” January 1• Milky Way May 1• Solar System September 9• Life on Earth September 25• Humanlike Primates December 31, 10:30pm

Milky Way