Question

A molecule that can be used as a molecular clock has a neutral mutation rate of one mutation per 20 million years. How many years ago did two species share a common ancestor if the molecules found in these two species differ by a total of six mutations?

Answer 1

6*20 = 120

120/2 = 60 million years

Answer 2

Answer:

60 million years ago

Explanation:

The formula needed for this problem to calculate the correct number of years is:

Number of Base Pair Mutations × (Number of Years ÷ Mutation Rate) = Years of Evolution

Just like in math, simply substitute the corresponding numbers to get the desired answer:

6 Base Pair Mutations × (20,000,000 Years ÷ 1 Mutation) = 120,000,000 Years of Evolution

Then, divide the amount of time that separates these two species in half to determine how long ago their lineages shared a common ancestor. The formula needed for this part is:

Total Years of Evolution ÷ Number of Species (Lineages) = Years of Evolution From a Common Ancestor

Again, substitute the correct numbers in their place to get the answer:

120,000,000 Years of Evolution ÷ 2 Species/Lineages = 60,000,000 Years of Evolution From a Common Ancestor

Hope this helps :)