One of the earliest examples of primitive humans, Australopithecus, lived in Africa between about 4 and 1 million years ago. For what fraction of Earth history have hominids been around?
To determine the fraction of Earth's history that hominids have been around, we first need to calculate the total duration of Earth's history and then compare it to the time span in which hominids existed.
1. Calculate the total duration of Earth's history:
The age of the Earth is estimated to be about 4.6 billion years.
2. Calculate the time span in which hominids existed:
Australopithecus, one of the earliest examples of hominids, lived between about 4 and 1 million years ago.
Now let's calculate the fraction:
Total duration of Earth's history = 4.6 billion years.
Time span of hominids = 4 million years.
Fraction of Earth's history = Time span of hominids / Total duration of Earth's history
Fraction of Earth's history = 4 million years / 4.6 billion years
To simplify the calculation, we can convert the million to billion by dividing 4 million by 1,000:
4 million years / 1,000 = 4 thousand years
Now we can calculate the fraction again:
Fraction of Earth's history = 4 thousand years / 4.6 billion years
Simplifying further:
Fraction of Earth's history = 1/1,150,000
Therefore, hominids have been around for approximately 1/1,150,000th fraction of Earth's history.