Meiosis is a process where a single cell divides twice to produce four cells containing half the original amount of genetic information. That means that they will never be a copy of their parents because of their different genetic material. Characteristics, such as eye color, hair type and color, the shapes of facial features, and height and build, and attribute the combinations of these to the portions of DNA inherited from each parent which makes them different but still carry the DNA of their parents.
From my speculation it is loss of habitat and global warming
There you go sir! Hope I helped
Because nowadays, many horses are domesticated, and food they would have eaten in the wild, they don't usually eat anymore. They have learnt to adapt to eating other foods, like hay, that require molars to ingest. This is why over time, their tooth structure has changed.