Liberal Democrat senator David Leyonhjelm says there are doubts about whether Aboriginal people were the first occupants of Australia.

"There are some anthropologists who argue that," he said this morning, when asked his view on a referendum to recognise Aboriginal and Torres Strait Islanders in the constitution.

Senator Leyonhjelm cited the cave art known as the Bradshaws or Gwion Gwion in the Kimberley in Western Australia, although he mistakenly said they were in the Northern Territory.

"There are some anthropologists around who say they are so distinct from more recent Aboriginal cave paintings, that they suggest that there was a previous culture ... to the Aborigines," he said.

"Now I'm not saying that's true or not, I'm not an anthropologist and I don't necessarily accept that, but the fact that there is even a doubt raised about it would suggest to me that it is not necessarily a good thing to put in the constitution."

A joint select committee has today called for a referendum to be held to recognise indigenous people.

Senator Leyonhjelm said there was a serious debate in anthropological circles as to whether or not the Aborigines were the first culture in Australia.

"It's not something on which I'm taking sides, all I'm pointing out is that if there is any doubt at all then you have to say, well, why would you put history into the constitution under those circumstances?"

"It has not been done before — we don't put history about other things into our constitution. Why would you go there?

"Let historians and anthropologists fight it out. In 100 years' time, perhaps there will be more evidence to suggest one was right and one was wrong.

"But if there is any possibility, [if] there is any doubt about it, then it would be bizarre to go putting it into the constitution."

Labor senator and Indigenous woman Nova Peris was deputy chair of the committee that called for the referendum to recognise Aboriginal and Torres Strait Islander people.

"That opinion deserves no recognition," Senator Peris said. "In fact, he should put his head back in the sand.

"We've been here since more than 40,000 years. If he wants to go have a fight with scientists and anthropologists then that's where he needs to take that fight up."