The causes of the gradual development of evolution are: mutation, genetic recombination, changes in the chromosome number and structure, natural selection, reproductive isolation- this is all called Neo-Darwinism.
The first species is Dryopithecus:
- They lived in Africa, China, India and Europe.
- They were supposedly predominantly herbivorous.
The second species is Ramapithecus:
- They lived in Punjab, Africa and Saudi Arabia.
- They're more advanced than dryopithecus because of their robust jaws, thickened tooth enamel, shorter canines, upright posture and use of the hands for food and self defense.