The Catechism twice [28, 360] quotes Acts 17:26-28: “From one ancestor [God] made all nations to inhabit the whole earth…” That the Catechism refers to a single person is confirmed in footnote number 226  which cites Tobit 8:6, “Thou madest Adam and gave him Eve his wife as a helper and support. From them the race of mankind has sprung…” Thus, the “one ancestor” could only be Adam. This is confirmed in  which quotes St Peter Chrysologus, “St Paul tells us that the human race takes its origin from two men: Adam and Christ…The first man, Adam,…was made by the last Adam.” The Catechism clearly teaches that polygenism is irreconcilable with Catholic Tradition.
So what is the Catholic doctrine, compared with “out there”?
The first teaching comes from Leo XIII – Adam & Eve were our first parents, by direct divine intervention and Eve was created from a portion of Adam’s body (Arcanum Divinæ Sapientiæ of Pope Leo XIII, 1880). Polygenism is thus impossible – that mankind arose from many first parents – the fairy-tale which is perpetrated today by most evolutionists.
Then from the Pontifical Biblical Commission in its response of 30 June, 1909, On the Historical Character of the First Three Chapters of Genesis, the declaration:
a) that those pseudoscientific exegetical systems elaborated for the purpose of “excluding the literal historical sense of the first three chapters of Genesis” are not based upon solid arguments (EB 324; DS 3512).
So as Fr Harrison rightly points out in Did The Human Body Evolve Naturally? A Forgotten Papal Declaration:
“We are not dealing here with a mere Allocution, a Motu Proprio, a Brief, an Apostolic Exhortation, or a* Nuntius*, but a fully-fledged piece of pontificating endowed with no less inherent or formal authority than Humani Generis or Providentissimus Deus: the Encyclical Letter *Arcanum Divinæ Sapientiæ *of Pope Leo XIII on Christian Marriage, dated 10 February 1880.”
POLYGENISM. The theory that, since evolution is an established fact, all human beings now on earth do not descend from one human pair (Adam and Eve), but from different original human ancestors. This theory is contrary to the official teaching of the Church, e.g., Pope Pius XII, who declared: “It is unintelligible how such an opinion can be squared with what the sources of revealed truth and the documents of the Magisterium of the Church teach on original sin, which proceeds from sin actually committed by an individual Adam, and which, passed on to all by way of generation, is in everyone as his own” (Humani Generis, 1950, para. 38). (Etym. Latin poly, many + gen, race + ism.)
Modern Catholic Dictionary by Fr. John A. Hardon, S.J.
Infallible doctrine is: Adam & Eve were our first parents, by direct divine intervention and Eve was created from a portion of Adam’s body (Arcanum Divinæ Sapientiæ of Pope Leo XIII, 1880). Polygenism is impossible.