Try it on paper first. A hint, the key idea and the worked solution are here when you need them.
Use these NCERT dates: Homo erectus lived about 1500000 years ago. The Neanderthals appeared about 100000 years ago. Cave art developed about 18000 years ago, and agriculture began about 10000 years ago. The Earth is 4.5 billion years old, shown as one day of 24 hours.
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Given. The dates in years ago, and hours of seconds make seconds.
Plan. Subtract for the gaps. For the clock, scale years of billion to seconds.
Step 1. (a) years.
Step 2. (b) years.
Step 3. (c) seconds.
Answer: years; years; seconds.
Check. The whole of agriculture, the cities and the written word fit into less than a fifth of a second of the Earth's day.
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NCERT brain capacities: Homo habilis to cc, Homo erectus about cc, Neanderthal man about cc. A percentage increase is .