Why, in rare cases, atavisms appear in individuals?

1) Signs of ancient ancestors (atavisms) are embedded in the human genome;
2) in the process of evolution, some ancient signs lose their meaning and the genes that control them go into a “sleeping” state and the signs do not appear in the phenotype;
3) in rare cases, these genes begin to function and there is a violation of the individual development of the body, signs of ancient ancestors are manifested.

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.