Irrational animals, including subhuman primates, are capable of complex sentient behaviors often approaching or imitating the rational activities of true man.
But an animal either possesses a spiritual, intellectual soul or not.
Paleoanthropological claims of gradual appearance of specifically human traits fail to comport with a true philosophy of human nature. Thomas Aquinas demonstrates that true man is distinguished essentially from lower animals by possession of an intellectual and immortal soul, which possesses spiritual powers of understanding, judgment, and reasoning ( I, 75).
While these qualitatively superior abilities are manifested through special forms of tool making or culture or art, they need not always be evident in the paleontological record.
Effective population size estimates can vary from as high as 14,000 (Blum 2011) to as low as 2,000 (Tenesa 2007), depending on the methods used.
For such reasons, some experts have concluded that effective population size cannot be determined using DNA sequence differences alone (Sjödin 2005; Hawks 2008).
Indeed, the most famous genetic study proclaimed as a “scientific objection” to Adam and Eve turned out to be based on methodological errors. Ayala appearing in the journal, (1995), led many to believe that a founding population of only two individuals was impossible.
Such methodology produces, at best, solely conclusions, based on available evidence and the assumptions used to evaluate the data.
There is the inherent possibility that an unknown factor will alter the conclusion, similarly as was the unexpected discovery of black swans in Australia, when the whole world “knew” all swans were white.