Welsh language TV channel S4C has been accused of airing a "biased documentary" about Charles Darwin and Alfred Russel Wallace, the co-founder of the theory of natural selection.
In the programme it is claimed Darwin "lied and cheated" in order to gain full credit for the theory.
But a member of the British Society for the History of Science, Dr John van Wyhe, said the claims had no basis.
The programme suggested that Darwin had "lied and cheated" in order to gain full credit for the theory of evolution.
A key claim made is that Darwin received a letter from Wallace, from Usk in Monmouthshire, 15 days earlier than he claimed he did.
During the programme Roy Davies, the author of The Darwin Conspiracy, claims that he can prove this to be a fact.
But this is rejected by an expert and author of Darwin and Wallace, who tells the story of the discovery of evolution by both men.
Dr van Wyhe is founder of the Complete Works of Charles Darwin Online as well as being a member of the British Society for the History of Science.
He claimed the programme had made "incorrect and uninformed accusations" in favour of Wallace.
"Even worse, their picture of Wallace as the wronged or forgotten working-class genius who was in any way cheated or treated unfairly is simply fantasy.
"The accusation about the mail route has been utterly refuted and is now a non issue to any serious scholar."
Wallace died 100 years ago this year and celebrations of his life have included a new statue and two-part BBC documentary presented by comedian Bill Bailey, who called him a "maverick genius".
Julian Carter, the curator of an exhibition about the life of Wallace on show at the National Museum Wales, also said the S4C programme was one sided.
"I'm not convinced by the conspiracy theory. Other people have produced evidence to counter the argument and it was a massive failure for that programme not to reflect that.
S4C's factual programmes commissioner Llion Iwan said the programme contained some very controversial viewpoints but they were based on facts.
"It's not surprising that such views have attracted a response from those who reject the idea of a plot against Alfred Russel Wallace," he added.
"What the programme does is to explain the case of the people who strongly believe that the research shows that Wallace suffered an injustice and that it was him who should have been given the credit for the theory of evolution, or at least shared it.
"The programme does this in a lively and clear manner and the whole context makes it clear that the views of the people taking part are not conventional ones regarding how the theory was discovered and by whom."
"I've known Roy Davies for nearly 20 years and can say that he's an honest man and a principled journalist who, through his work, discovered that there was a story here that people should know about," she said.