Observe this family tree:
- Imagine from the point of view of the boy labelled ‘Me’
- He is similar to his brother . They share common characteristics.
- This is because they have a recent common ancestor, their parents .
- But the similarities between the boy and his cousins are even less .
- This is because they do not have recent common ancestors .
- But they will still share some common characteristics as their grandparents are common ancestors .
- Similarly for all organisms, we can trace backwards and find similarities and differences.
- If we trace backward we can even reach a single species that gave rise to all species we know today.
- Different theories of the origin of life are discussed by scientists.