What does the following sentence mean?
Our ancestors living on the great planes of Africa would have lived in small groups, because it was more practical.
Does that mean that it was ours ancestors's nature to live in groups? Tell me please if I am wrong, and If I am, then what does that mean?
It is one way of expressing a deduction about the past.
Nobody knows for sure how our ancient ancestors lived. But we can work out that they probably lived in small groups.
Other examples:
Shakespeare's father made gloves. Shakespeare would have learnt the trade as a boy.
(we don't know for sure, but most boys in shakespeares time would learn their fathers trade)
Compare
He went to market this morning (certain fact)
He would have gone to market this morning, (uncertain, worked out based on evidence)
The "would" here is modal. This is used if the event didn't occur (e.g. "I would have done x but,...") or in this case if a measure of speculation is involved. The speculation here is the reasoning of it being more practical, which should be the actual part of the sentence to make bold in asking this question.
As to why it was more practical the text here does not say. Maybe it goes on to elaborate or maybe this is just the authors presupposition.
