Question

To get a sense of evolutionary time scales of cells, it is useful to draw an analogy with human time scales. If the age of life on Earth is analogous to one year, what would, proportionally,various other time scales be alalogeous to? Specififcaly, the times since the origin of animal life? Of primates? Of the genus Homo? Of civilization? Since the extinction of dinosaurs? A human life span?

Answer 1

The simple formula to answer these questions is

Known age of past event Analogeous value of the event (in year)
____________________ = ______________________________________ = Analogeous value of the event (in yrs)
Known age of the Earth Analogeous value of the age of earth(i.e 1 year)

Known age of earth is 4,600,000,000 years.

1. Origin of life, 3,800,000,000 years

Therefore, Analogy of origin of life = 3,800,000,000 / 4,600,000,000 yrs = 0.826 yrs

2. Origin of primates, 55,800,000

Analogy of Origin of primates = 55,800,000 / 4,600,000,000 yrs = 0.012 yrs

3. Origin of genus Homo, 2,500,000

Analogy of Origin of genus Homo = 2,500,000 / 4,600,000,000 = 5.4 X 10^-4 yrs

4. Origin of civilization, approx. 6,000 yrs (Mesopotamia)

Analogy of Origin of civilization = 6000 / 4,600,000,000 = 1.3 X 10^-6yrs

5. Since the extinction of dinosaurs, 65,000,000

Analogy of Since the extinction of dinosaurs = 65,000,000 / 4,600,000,000 = 0.014 yrs

6. A human life span (Average), 79

Analogy of a human life span = 79 / 4,600,000,000 = 1.71 X 10^-8 yrs

NOTE : Age of events might change from data to data but the method to solve such questions is as above.