Youngest to oldest would be: 3, 4, 1, 5, 2. Since it's from the bottom, the ones furthest from the bottom would be the youngest at the top. The oldest fossils would be closest to the bottom.
Answer:
In humans, genetic variations are caused because humans reproduce by a sexual life cycle which is termed as meiosis. In such a life cycle, the offspring receives half the chromosomes from the mother and half from the father. Crossing over and random assortment of chromosomes are two phenomenons which occur during meiosis. Due to these two phenomenons, genetic variations are caused.
During crossing over, the exchange of DNA segments between the homologous chromosomes takes place which brings about the genetic variations.
I believe it's the temperature in the core
