crystalpraise
...so does that mean that according to the theory all ethnic groups appeared at the same time?
"Ethnic groups" aren't the same thing as "races". You've been asking about race up until now, and I'm kind of curious why you used the other term... but since you did, I'm going explain what the differences are before getting to your question two times.
An
ethnic group/ethnicity is a socially-defined category of people who identify with each other based on common ancestral, social, cultural or national experience. Membership of an ethnic group tends to be defined by a shared cultural heritage, ancestry, origin myth, history, homeland, language and/or dialect, symbolic systems such as religion, mythology and ritual, cuisine, etc.
Race (as a social construct) is a pseudoscientific term used to classify group of people who share similar and distinct physical characteristics. Starting from the 19th century, the term was used in a taxonomic sense to denote genetically differentiated human populations defined by phenotype, suggesting that there were several subspecies of humans. However, there is no biological basis to back this up, because all humans are members of the species
Homo Sapiens. (Well,
technically we're
Homo Sapiens Sapiens, but I digress.)
Concerning ethnicity, the answer to your question is "no". Various ethnic groups have appeared (and continue to appear) over time, but they are all members of the same
species.
Concerning race, the answer to your question is both "no"
and "yes". Since humans all are of the same species, the idea of "appearing at the same time" isn't really applicable, but since humans share the same common ancestor, that means we all
did appear at once, then branched out from there over time.
Did that make sense?