The new study raises hope of saving one of the last animals of this kind.
Victim of poaching, the northern population of white rhinoceroses has been reduced to only two females that can not reproduce.
DNA evidence shows that the rhinoceros are more closely related than previously thought with its southern white cousin.
The creation of rhino hybrids using in vitro fertilization can have a positive result, say the researchers, although this option is considered a last resort.
The white rhino divided into two divided populations living in the north and south of Africa about a million years ago.
But extensive DNA analysis of living rhinoceroses and museum specimens shows that northern and southern populations are mixing and breeding sometimes after this date, maybe even 14,000 years ago.
"Despite the fact that they began to change a million years ago, we show that they are exchanging genes during this period, probably as recently as the last ice age, when the African savannah has expanded and reunited two populations," lead scientist Dr Michael Bruford of Cardiff University said BBC News.
"So, if they've recently exchanged genes, it might mean they can do it now."
A cross-breeding using assisted reproductive technology could potentially help rescue the northern white rhino from its current location, he said.
How many northern and southern white rhinos remained?
Northern white rhinos were once common in the north of the African continent, including Uganda, South Sudan, DRC and Chad.
Illegal hunts to meet the rhino demand caused a sharp drop in the wild level, and the rhino subspecies were declared extinct in the wild in 2008.
Earlier this year, Sudan, the last male northern white rhino, died at the age of 45.
Two women remain – his daughter and granddaughter, who lives in the Ol Pejeta Conservancy in Kenya, where they are guarded around the clock. However, they both have their own health problems and can not reproduce naturally.
Southern white rhinoceroses occur in southern Africa, including South Africa, Namibia and Zimbabwe.
The numbers fell to several hundred people about a hundred years ago, but efforts to protect have led to recovery. About 20,000 exist in protected areas and private game reserves.
What would you have to do to save the white rhinoceros?
The survival of the northern white rhino looks gloomy and relies on a heated debate on recent conservation measures that include in vitro fertilization and cloning.
An invaluable store of frozen sperm from male northern white rhinoceroses still exists, but nature conservation activists are divided as to how they are used.
In July, one team took eggs from female southern rhinoceroses – which number about 20,000 in the wild – and used frozen semen from the male northern white rhinoceros to create hybrid embryos.
A new study suggests that this approach may pay off, given that the two rhinoceroses are genetically closer to what they once thought.
"We think it improves the chances," said prof. Bruford. "It is difficult to predict what might happen if we cross two subgenres, but given the current options for the northern white rhino, it becomes a more viable option if other approaches fail."
Other options include the use of frozen tissue from a larger pool of northern white rhinoceroses to produce stem cells that can develop in eggs and sperm.
This will avoid dilution of the gene pool, but it is more difficult to achieve.
Research carried out by scientists in the United Kingdom, South Africa, the Czech Republic, Austria, Germany and the USA was published in the Proceedings of the Royal Society of London B.