Scientists have sequenced the genomes of 20 lions for the first time, including extinct cave lions, revealing their family tree. Researching the origin, scientists believe that they have come up with a solution, how to save big cats from extinction.

Three thousand years ago, different species of lions roamed the planet Earth, hunting prey on four continents. One of the most numerous, the cave lion, raced from Spain to Eurasia all the way to present-day Alaska and the Yukon, and was often depicted in prehistoric cave art.

Meanwhile, the American lion, which was larger than the African lions and saber-toothed tigers, lurked throughout North America and probably in parts of South America. Other lions of various sizes and appearances inhabited Africa, the Middle East and India. Most of these creatures have disappeared since then, but scientists have managed to collect genetic clues that shed new light on them and offer a better insight into the study of their modern cousins, who are now facing extinction.

Over the last 150 years, the global population of African lions has dropped more than 20 times, to less than 25,000, mainly due to poaching and habitat loss. Approximately 600 Asian lions remained in India. To save the remaining lions and to better understand how the different species are related, an international team of scientists has created complete genomes of 20 individual lions, 14 of which died a long time ago. Among those fourteen, there are two cave lions 30,000 years old, preserved in the eternal frost of Siberia and the Yukon. In a study published May 4 in the Proceedings of the National Academy of Sciences, researchers found that cave lions do not mix with other lion species, found that Asian lions separated from their ancestors about 70,000 years ago, and other secrets of the evolution of large cats.

The work looks to the past to inform about the future. If we only looked at today's lions, we would not see the complete story.

Out of Africa

The results of the study support the idea that lions came from Africa in migrations, somewhat similar to humans. Cave lions were the first to leave Africa, and separated from the African race about 500,000 years ago, documents say. These lions then evolved and developed slightly different characteristics. For example, we know "based on good cave art in Europe, that males did not have manes.

They spread throughout Eurasia and North America. However, it is surprising that cave lions and the ancestors of today's African lions were not intertwined, genetic analysis reveals. This is strange, because it is known that most big cats occasionally mate when given the opportunity - even very different animals, such as lions and tigers. There seems to have been something at the time that prevented them from interfering - and it's not just geographical distance, because their habitats once overlapped in southwest Asia.

The reason is perhaps that cave lions did not have manes, because females of African lions recognize the mane as an important signal of fertility.

Another migration and separation occurred when the ancestors of the Asian lions separated about 70,000 years ago. These lions used to move from Saudi Arabia to India. There is now a small, isolated population left in the Gir forest in western India.

Thanks to conservation efforts, the population has almost tripled since the 1990s, but this is practically a "native" population, with a low level of genetic diversity. As a result, male Asian lions have malformations in sperm and testosterone about 10 times lower than those in African lions.

Extinct cats

As part of the study, the researchers also collected genomes from individuals from three other extinct lineages: from Berber lions from North Africa, Asian lions and lions from South Africa. These three species differed slightly in appearance, but new genetic information indicates that they do not qualify as different species.

Their work largely supports the current dominant view that there are two major subspecies of lions: Asian lions and African lions (populations in Central and West Africa - currently collectively classified as Panthera leo leo; and in East and South Africa known as Panthera leo melanochaita).

After a detailed study, the scientists, as a solution for the conservation of the species, proposed the reintroduction of lions to West Africa, where they are critically endangered; there are only about 400 left. Since West African lions are genetically similar to extinct Berber lions, West Africa could provide a good population if efforts to reintroduce bear fruit - although this is still an unlikely scenario.