A group of scientists maintain that hominids with different characteristics may still belong to the same species.
A group of scientists has proposed that human beings emerged from one single evolving human species rather than branching from a tree of multiple, early ancestral species.
The new hypothesis, while still disputed, fits even better with the Catholic Church's position that humans came from one source, in that they were freely created by God, said two experts in science and faith.
"Certainly, confirmation of humanity's origin in one single lineage, just like modern humanity belonging to one species (as is proposed by the recent study), fits better with the understandings of the faith," said Msgr. Fiorenzo Facchini, an expert paleontologist and anthropologist.
Legionaries of Christ Father Rafael Pascual also said the new theory "is close to what one finds in the teaching of the Church: the origins of the human being from one single 'source.'"
A new study published in Science magazine Oct. 18 said there is "direct evidence" that the many physical differences displayed by the fossil remains of early humans do not represent different species, but rather represent simple "morphological variation within and among" early hominids of the same lineage.
The seven-author scientific study compared the skull remains - found in Dmanisi, Georgia - of five individuals who lived about 1.8 million years ago.
The study said the five skulls showed varying features, which, had they been discovered in different locations, would probably have been catalogued as belonging to different species.
Like today's humans, there could have been a range of physical variations that do not indicate a difference of species, supporting experts have said.
Facchini told Catholic News Service by email that the study does call into discussion "the tendency to readily identify a species on the basis of morphological differences."
"Besides (the problem of) the scarcity of remains, identifying species . . . in human fossils is very problematic," he wrote.
Significant physical differences can emerge over time because of "environmental factors," like diet or climate, or other factors, the priest told CNS.
While he said he could not give an opinion on whether there were many or just one human species in prehistoric times, he said when it comes to one single "human lineage with its roots in an African population, I have no doubt."
Facchini, and other experts, said the Dmanisi skulls represent the earliest evidence of primitive humans beyond Africa and "the expansion of mankind into Eurasia" and the Caucases, which connected three continents.
The Italian monsignor also said he believes the common thread of culture in the human species "is a factor that goes against" theories of multiple human species.
Pascual, director of the Institute of Science and Faith at Rome's Pontifical Regina Apostolorum University, told Vatican Radio that the Church is open to science and any findings that are not in conflict with the faith.
"To maintain that God has a plan and he wanted to create mankind and that God could also have used the process of evolution is not a contradiction," Pascual said.