The answer is physically fit older people. this is because ageing causes changes to the brain size, vascalature and cognition. Brains shrinks with increasing age and there are changes at all levels of molecules morphology.
The answer is DNA. I am very sure of this .
Phylogenetic trees always show increased branching, representing increased diversity over time.
Explanation:
A new branch in phylogenetic trees appears when new species appear, meaning that diversity increases. The appearing of new branches can show speciation processes and it can also help to understand how a certain lineage evolved through time or the specific divergence in one point.