•natural selection occurs slowly,need very old Earth
•lived ~50 miles NW of Dover
•erosion of the Weald Dome (in: The Origin of Species)
•"Hence, under ordinary circumstances, I conclude that for a cliff 500 feet in
height, a denudation of one inch per century for the whole length would be an
ample allowance. At this rate, on the above data, the denudation of the Weald
must have required 306,662,400 years; or say three hundred million years."
•not accurate, but at the time no-one even knew how many digits (thousands,
millions, or billions)
•"order of magnitude" estimate: hundreds of million
Three examples of geologic estimates
Darwin 300 million years (minimum bound)
Phillips 96 million years (minimum bound)
Joly 95 (+/- 5) million years
note: similar "order of magnitude" all are lower bounds, not precise estimates
aside: much very fundamental science just establishes orders of magnitudes; precise
values come later.
•ex. How many light-years, atoms, neurons, genes?
•An error of an extra digit (+1000% ) or one less digit (-90% ) is trivial
at this initial level of science
5. cooling of Earth
•Isaac Newton (1643-1727)
omathematician and physicist
o"one of the foremost scientific intellects of all time"
o1687 Philosophiae naturalis principia mathematica
o"a red hot iron equal to our earth, that is, about 40,000,000 feet in
diameter, would scarcely cool in above 50,000 years"
Georges-Louis Leclerc, Comte de Buffon
•studied botany, math, medicine in Angers duel in 1730, left for Dijon; there he
met Duke of Kingston with whom he traveled, returned to estate near Dijon in
•1749 first volume of "Histoire Naturelle" (39 volumes in all)
•1774 member of Academie Royale
Buffon postulated evolution of Earth in 7 stages:
1. formation of molten Earth
2. cooling to hand-hot
3. enveloped in universal sea