You may also like

Ladder and Cube

A 1 metre cube has one face on the ground and one face against a wall. A 4 metre ladder leans against the wall and just touches the cube. How high is the top of the ladder above the ground?

Archimedes and Numerical Roots

The problem is how did Archimedes calculate the lengths of the sides of the polygons which needed him to be able to calculate square roots?

More or Less?

Are these estimates of physical quantities accurate?

Time to Evolve

Age 14 to 16
Challenge Level


An evolutionist suggests that at some distant point 400 million years in the past one of his ancestors was an early form of fish. Try to estimate the number of generations that link the scientist to the fish. To make your estimation, you will need to fill in sensible values for the species in the table below (you will possibly need to research these numbers, and feel free to use a spreadsheet for the calculations. A good place to start is

    First appearance (million years ago)
    Similar modern day example
    Similar modern day creature Time from birth to producing first offspring Lifespan (years)
    Bony fishes 400 Coelacanth
    Early mammals
    Small dogs
    Apes 15 Gorillas
    Charles Darwin 30 73

    Can you produce a sensible estimate for a number that you are confident exceeds the actual number of generations?

    Can you produce a sensible estimate for a number that you are confident is definitely less than the actual number of generations?

    There will be various estimates and assumptions that you need to make in this question. Can you clearly state the most important factors?





    Suggested timelines for evolution form fascinating reading.

    Interestingly, the bony coelacanth fish was considered extinct by scientists until fishermen caught one alive in 1938. Now they occasionally turn up, caught in deep-water nets.