AboutJohn Shea Expertise Questions about Old World prehistoric archaeology (especially Stone Age) of Europe, Africa, and Western Asia, prehistoric human and hominid behavior, primitive technology, origin of modern humans, extinction of the Neandertals.
Experience
Publications Journal of Field Archaeology, Journal of Archaeological Science, Lithic Technology, Evolutionary Anthropology, Current Anthropology, Mitekufat HaEven (Journal of the Israel Prehistoric Society), Paléorient, Annual of the Department of Antiquities of Jordan, American Anthropologist, Geoarchaeology.
Education/Credentials Ph.D (Anthropology) Harvard University, 1991.
BA (Archaeology) Boston University, 1982.
Question I am curious to know why we have only one species of humans given that we in habit every ecosystem on the planet. Other creatures evolved along different pathways to adapt to their environment but we seemed to have used one model for all contingencies. Is there an explanation for this phenomenom?
Thanks!
Dan
Answer Dear Dan
The most likely reasons are that we are a very numerous species (hard for mutations to become fixed [100%] in a subpopulation) and that we have a very broad ecological niche (difficult for behavioral differences to arise between subpopulations). These are the major factors. The only ways to get a new human species would be for there to be a huge population reduction such that groups of humans were reproductively isolated from one another for hundreds of thousands of years. Alternatively, space colonization would involve such long distances that species-level differences might arise among dispersed humans.
Sincerely
John Shea
