not cumulative changes will ever create new species, nor they have done in the past
1. You're making unfounded statements (refs please)
2. Speciation has been observed in nature as well as under laboratory conditions (Seach for "speciation" in PubMed or Google Scholar)
3. Comparative genomics of humans and chimps/bonobos demonstrate that we shared an ancient common ancestor, just as comparative genomics of you and your sibling would demonstrate that you shared a recent common ancestor. (Nielsen et al 2005, Polavarapu et al 2006)
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